Central trochlear palsy

SURVEY OF OPHTHALMOLOGY VOLUME 30. NUMBER 5 l MARCH-APRIL 1986 zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCB REVIEW zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Central Trochlear Palsy AHMAD M. MANSOUR, M.D.,’ zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFED AND ROBERT D. REINECKE, M.D.’ zyxwvutsrqponmlkjihgfedcbaZYXWVUT ‘ Department of Ophthalmology, American University of Beirut, Lebanon, and Albert Einstein College qf Medicine, Bronx, hiew York, and ‘W ills &ye Hospital, Philadelphia. Pennglvania Abstract. Historically, the trochlear (IV) nerve has been “neglected” by neurologists and ophthalmologists. However, the reported incidence of trochlear palsy in two large series has more than doubled in the past two decades, indicating increasing awareness of this nerve. Trauma is the most common cause oftrochlear palsy, as the trochlear nerve is anatomically more vulnerable to trauma than the other ocular motor nerves. Trochlear palsy can also be caused by vascular and inflammatory diseases, congenital factors, toxic substances and tumors. Diplopia secondary to vertical and horizontal deviation is the most common presentation. The trochlear nerve has a relatively high recovery rate after the underlying cause of injury has been corrected. In this article, the anatomy and physiology of the trochlear nerve are described, and the various etiologies, methods of diagnosis and differential diagnosis of trochler palsy are reviewed. (Surv Ophthalmol 30:279-297, 1986) Key words. congenital disorder trochlear nerve trochlear palsy l l l lesions vascular l ocular disorder motor palsy l trauma l Of the cranial nerves, the trochlear nerve has reI. Anatomy of the Trochlear Nerve ceived the least attention in routine neurological and ophthalmogical examinations and in the literature. Trochlear palsy affects both sexes with mild The trochlear nuclei are located at the level of the male predominance, and all ages with an average superior part of the inferior colliculus ventrolateral age of 20 years at presentation. Recent increasing to the cerebral aqueduct (Fig. 1). They indent the awareness of this cranial nerve is reflected by the dorsal surface of the medial longitudinal fasciculus. increase in the reported incidence of isolated trochThey are the direct continuation of the oculomotor lear palsy from 7.2% in 19661T6 to 17.2% in 1981’28 nuclei and are in series with the abducens nuclei. based on two series of 1000 patients with ocular The nuclei are the smallest cranial nerve nuclei, both in area (0.6 mm square)“’ and in number of motor palsies. moBased on literature reports and a series of 82 panerve cells (3400). ‘6gThe fairly large multipolar tor neurons (40-50pm) stain heavily with basophiltients with isolated trochlear palsy followed by one ic dyes, and make up the spherical trochlear nuclei of us (RDR) at Albany Medical Center between (Fig. 2) .41The fibers run first dorsolaterally around 1972 and 1981, we will discuss the anatomy and the aqueduct of Sylvius, reach the lower border of physiolopy of the trochlear nerve from its nucleus to the inferior colliculus and pass medially to decusits exit from the brain, the various causes of trochlein the superior medullary velum ar palsy, and the presently available’ diagnostic mosate completely”5 and emerge from its dorsal surface in the form of dalities. zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA 280 Sun, Ophthalmol zyxwvut zyxwvutsrq 30(5) March-April 1986 MANSOUR, REINECKE F&. 1. Section of the midbrain at the level of the inferior colliculus. The trochlear nucleus is above the medial longitudinal fasciculus. Top: X 16, Modified Bielschowsky stain for axon. Bottom X 100, Modified Biel- schowsky stain for axon. rootlets. The number of the rootlets of origin varies from one to six on each side, with an average of two.‘03 These join to form the most slender cranial nerve with one millimeter thickness.‘*’ The course of the nerve can vary. In some cases, it courses laterally and upwards to emerge from a relatively rostra1 part of the inferior colliculus. Similarly, the level of decussation in the brainstem may be more rostraL5* It continues ventrally around the lateral aspect of the midbrain and passes between the posterior cerebral and superior cerebellar arteries between the midbrain and the temporal lobe. The nerve courses along the tentorium cerebelli for one or two centimeters and becomes embedded in this membrane to lie central to the third nerve and pierce the dura to face the lateral wall of the cavernous sinus15’j above and medial to the trigeminal ganglion and lateral to it enters the orbit the pituitary fossa. Finally, through the superior orbital fissure to innervate the superior oblique muscle. A horsetail branching of the trochlear nerve occurs before it penetrates the belly of the superior oblique muscle. Of the cranial nerves, the trochlear nerve has the longest intracranial course (75 mm). ‘6gThe fibers of the trochlear nerve are mostly medullated and large (12 to 19 micra in diameter) (Fig. 3).g The ratio between the large and small fibers has been reported to be 3 : 1 in man and dog’ by light microscopy, and 49: 1 in goats by electron microscopy.“j5 The ratio between the fibers of the trochlear nerve and the cells in the trochlear nucleus is 1: 1 .14’J65 The superior oblique muscle (the “reading” muscle) has the highest den- CENTRAL TROCHLEAR ‘81 PALSY F&J. 2. Top left: Trochlear nerve (TN) from nucleus to exit from brain. Cerebral aqueduct is represented by the middle notch. Cross section I of the superior part of the inferior colliculus shows the trochlear nucleus and the dorsoiateral course ofTN. Cross section II ofmiddle part of inferior colliculus shows the TN running medially and dorsally round the aqueduct. Cross section III ofsuperior medullary velum illustrates the decussation, rootlet formation and dorsal exit. Bottom left: Section I through the nucleus shows the large multipolar motor neurons zyxwvutsrqpo 640. ModiGed Bielschowsky stain for axon). Bottom right: Section I II shows the decussation of axons i X 100, Modified Bielschowsky stain for axon). (X with each other or with the \-cstihulo-ccret)ellum in sit)- of nerve fiber innervation per muscle spindle. “I the form ofvestibulo-ocular projections.” Ixsions in No communication between the trochlear nerve and the vestibular nuclei zyxwvutsrqponmlkjihgfedcbaZYXWVUT of the cat” and in the mt’sencethe sympathetic system has been reported.“’ phalic tract of nerve V in the macaque animal”’ A supernumary orbital structure may originate resulted in degeneration ofsome fibers in the trochfrom the medial border of the levator palpebrae sulear nerve. However, autoradiographic studies in perioris and insert on the trochlear fascia, and this the cat reported no cerebellar fibers terminating in must be dillercntiated from an anomalous superior oblique muscle.“’ This structure, the oculomotor n,uclei.“’ The evidence for an affernamed the levatorrnt system in the frochlear nerve remains controvertrochlear muscle, was present in 7 out of 98 cadavsial.’ ” ers.‘“” This muscle is to be differentiated from rare fbrms of complete reduplication of the superior III. Embryology of the Trochlear Nerve oblique muscle’” and retractor bulbi muscle.“” zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFED The ocular motor nuclei are derived from the meII. Physiology of the Trochlear Nerve sodermal condensation of the premandibular cavity.” The oculomotor nuclei first appear at the 8-9 Physiological studies have suggested the presence mm stage followed directly by the appearance of the of interneurons in the ocular motor nuclei in additrochlear nuclei at the 9 mm stage. The trochlear tion to the motor neurons.“’ These interneurons are nerve nucleus lies lateral to the narrow communicathought to connect the different ocular motor nerves 282 Surv Ophthalmol 30(5) March-April 1986 zyxwvut M ANSOUR, REINECKE TABLE Etiology of Isolated 1 I’ ersus M ixed Involved Etiology 90 78 14 45 3 26 Total 111+1v (35) (30) (6) (18) (1) (10) III+Iv+VI 5 (9) 15 (26) 11 (19) 14 (12) 21 (18) 49 (42) 1 (2) 1 (1) 13 (22) 13 (22) 7 (6) 24 (21) 256 (100) 58 (100) *Data compiled from two series totalling with ocular motor palsies.‘Lb,‘zR TABLE Etiology qf Isolated Palsies 122 81 a4 107 90 80 Total 564 (100) [No. (%)I IV (22) (14) (15) (19) (16) (14) 90 78 14 45 3 26 (35) (30) (6) (18) (1) (10) 256 (100) *Data compiled from two series with ocular motor palsies.““.‘28 3. Top: Light micrograph through the trochlear nerve. Note the predominance of the large myelinated fibers ( X 1020). (Reprinted from Weidman TA, Sohal GS’“” with permission of the authors and publishers of Bruin Research.) Bottom: Intracranial course of TN (Reprinted from Kline LB: Tolosa-Hunt syndrome. Surv 1982, with permission of the auOphthalmol 27:79-95, thor.) 2000 patients 2 III Undetermined Trauma Neoplasm Vascular Aneurysm Other 116 (100) of the Ocular Motor Nerves* Nerve Involved Etiology Palsy* Nerve [No. (%)] IV Undetermined Trauma Neoplasm Vascular Aneurysm Other Trochlear totalling VI 236 125 220 120 30 203 (25) (13) (24) (13) (3) (22) 934 (100) 2000 patients Fig. bryo.“’ Depriving the trochlear nucleus from its peripheral innervation, as by extirpation of the optic primordium, leads to variable degrees of hypoplasia that are mostly related to the timing of the extirpation.“‘,“” Thus, trochlear nuclear aplasia may be primary, or secondary to aplasia of a related peripheral structure during embryonic development. zy IV. Etiology of Isolated Trochlear Palsy tion between ion.“’ The the metencephalon abducens nuclei rapidly and mesencepha- follow at the 10 mm stage. By the sixth to seventh week, the trochlear nerve is prominent, and by the end of the eighth week, all the ocular nerves have reached their respective extraocular muscles. From studies in duck embryos, it seems that approximately half of the cells in the trochlear nucleus and 98% of the trochlear nerve fibers are lost between day 11 of incubation and hatching. The cell/ fiber ratio changes from 1: 20 on day 11 of embryonic life to 1 : 1 at hatching and stays constant thereafter.‘+” Similar results were found in the chick cm- The etiological patterns of isolated trochlear palsies vary considerably from those of mixed trochlear palsies (Table 1) and isolated palsies of the other ocular motor nerves (Table 2). In these groups, space-occupying lesions account for a relatively large proportion of the cases, while trauma is the most common cause of isolated trochlear palsies. This review is primarily concerned with isolated trochlear palsies. It is based on 22 series reporting 895 patients, whose etiological characteristics are summarized in Tables 3 and 4 and discussed below. A. TRAUM A Closed head trauma is the most common cause of trochlear palsy in most series, and trochlear palsy CENTRAL TROCHLEAR 283 PALSY TABLE 3 zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIH Etiolqgies zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDC of Isolated Trochlear Pa&v Reported Etiology Author Year (Ref) No. of Patients Bilateral Trauma [Number Tumor Vascular (Percent)] Undetermined xot Mentioned Other 28 (33) 13 (16) Rucker ( 126) 1966 84 23 (27) 7 (8) 18% Khawam (76) 40 2 (5) 1967 27 (68) 8 (20) 1 (2) 100% 14 11 (79) 1970 Crone (27) 0 (0) 0 (0) 0 (0) 2 (6) 6 (18) 7 (21) 1970 :33 13 (40) Burger i 19) 100% 6 6 (100) 1970 Chapman (22) (1 (0) 0 (0) 0 (0) 7 0 7 (1001 Miller (97) 1970 0 (0) 0 (0) 0 (0) 0 Raskind ( 118) 3 3 (100) 1973 0 (0) 0 (0) ‘) (0) 8 (20) 2 (5) Rougier ( 125) 1973 40 26 (65) 1 (3) 8% 78 (78) 100 22 (22) 1976 hlittelman (98) 0 (0) ‘1 CO) 16 (31) 8% 19 (36) 12 (23) 1977 52 Young’ i 173) 2 (4) 9% 0 10) Wright ( 172) 1977 23 8 135) 4 (18) 9 (39) 15 (35) Coppptto (25) 0 9 (21) 1978 43 ‘3 (7) 9 (21) 54% Neetens (106) 1979 43 26 (60) 18 Harley (57 I 12 (67) 1980 5 (28) 0 (0) Fells (37) 100% 1980 31 25 (80) 3 (10) 0 (0) 0 13 (48) 27 Nemet (107) zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA 1980 0 (0) 172 8% 55 (32) 62 (36) 34 (20) 1981 Rush (128) 38% 33 Sydnor I 148) 33 (100) 1982 0 (0) 0 (0) \Vise I 168) 100% 1983 3 2 (67) 1 (33) 0 (0) zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQ 20 (ion) ‘0 Reynolds ( 120) 1984 0 (0) 0 (0) 100% 1985 21 Pollard ( I 14) 17 (82) 82 9% 48 (59) 1986 Reinerke (present 28 (34) 2 (2) study] Total - 895 356 (40) 91 (10) 324 (36) 30 13) 35 (,1) 59 (7) = not mentioned TABLE Etiulqv of Isolated Trochlear Palsy Related to .? $veA ffected and Sex of82 I‘rauma Congenital :\neurysmt Diabetes Tumor: Clndetermined Other$ 28 43 1 1 1 5 3 Total 82 (100) represents one-third i2.‘“4Ii4 Head cases with oculomotor of all traumatic trauma accounts or abducens in ,416ary Medical (35) (52) (1) (1) (1) (6) (4) ocular Center Series* Sex Distribution OD OS ou Male 16 27 0 0 0 2 2 7 14 1 1 1 3 1 5 2 0 0 0 0 0 15 27 0 1 0 2 2 13 16 47 28 47 35 *Present series, Reinecke (A large number ofthese patients of rongrnital cases.). t I nfraclinoid. ZSuprrior cerebellar glioma. $Hydrocephalus; dysthyroid myopathy, scleral buckle. palsies. Patients Eye Affected No. (o/o) of Patients EtioloE, ,4 motor were children, cult childbirth accounting are some for the larq of the usual Female I 0 I 3 1 number forms of trauma for zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA 16% of the responsible for trochlear palsy. One case was depalsy and 32% of cases with trochlear palsy.“ ’ This is why the trochlear nerve is called the “ trauma nerve.“ 7” Motor vehicle accidents, falls from a height, and diff+ scribed After forehead, following electric shock.” a sudden speed deceleration or a blow to the the brain continues to move backward against a stationary skull. This leads to “ contrecoup 284 Surv Ophthalmol 30(5) March-April 1986 contusion” against the delicate attachment of the fourth nerve at the medullary velum with subsequent avulsion of the fourth nerve rootlets. Direct compression of the lower midbrain can also occur, injuring the nerve directly or the nucleus with focal bleeding.“’ The susceptibility of the trochlear nerve is explained by its relation to the tentorial edge which is a major determining factor in the distribution of contusions.g0 Because of the symmetry of the contusion forces in common trauma, bilateral trochlear palsy is common after closed head injury. 22~27~76~‘06~‘58 A sudden bilateral palsy is almost always due to trauma.** The exact intensity of head trauma needed to induce trochlear palsy is not clear. Most of the patients with traumatic trochlear palsy in our series suffered a moderate to severe degree of head trauma as evidenced by a prolonged episode of loss of consciousness, but many cases of trochlear palsy have been observed following minor or insignificant trauma.76 In the latter category, the trochlear palsy may be attributed erroneously to a congenital cause. We hypothesize that individual differences in nerve susceptibility to trauma could be related to the number of rootlets formed after decussation. Trochlear palsy from minor head trauma could be the first sign of a basal intracranial tumor.‘05 B. VASCULAR DISORDERS MANSOUR, 2. Atherosclerosis REINECKE and Hypertension Like diabetes, atherosclerosis and hypertension are implicated in around l-10% of trochlear palsy cases. Trochlear palsy was the first indication of hypertension in a man who later suffered myocardial infarction.‘72 In another case, it appeared following hypertensive episodes.3” 3. Aneurysms Aneurysms have predilection to the cavernous sinus and the infraclinoid region. They involve the trochlear nerve in 2 1% of cases, generally after affecting the other ocular motor nerves.‘jJ8 Aneurysms are one of the leading causes of isolated oculomotor nerve palsy in adults, while they account for only 1% of isolated trochlear nerve palsy.“8,‘30 Aneurysms in the posterior fossa cause isolated trochlear palsy by involving the posterior cerebral artery3’.lg5 or the posterior cerebellar artery. In three cases, trochlear palsy was the first sign of expanding intracranial aneurysms. 12* 4. Infratentorial Arteriovenous Malformations Infratentorial arteriovenous malformations including the oculocephalic vascular anomaly of Bonnet, Wyburn-Mason,‘“” are reported to cause isolated trochlear palsy2” and, more commonly, multiple nerve is incranial nerve palsies. I50 The trochlear volved in 19% of patients with carotid-cavernous fistula.5 Branches of the posterior cerebral artery and superior cerebellar artery, namely the paramedian arteries and the quadrigeminai arteries, supply the 5. Migraine trochlear nuclei and nerves. Because of the small Migrainous ophthalmoplegia is a rare finding size of the nucleus and its nerve, trochlear palsy is with an occurrence of 8 out of 5000 migraine admisrarely seen alone and, more frequently, it will be sions.4 The third nerve is most frequently affected, masked by the presence of oculomotor palsy. with the abducens nerve involved one-tenth as ofOphthalmoplegia as a sign of arterial insufficiency ten, and the trochlear nerve rarely involved.* or occlusion is more frequently present in carotid Strokes, subarachnoid hemorrhage,‘** vascular than in basilar artery disease. Vascular causes were coronary angiogembolization (e.g., following involved in about one-tenth of the cases of trochlear raphy’28) and hypoxia (secondary to neonatal hypalsy we reviewed, including diabetes, atheroscleropoxia) have been listed with the causes of trochlear sis, aneurysm, arteriovenous malformation, and palsy. vascular accidents. Rush’s series reported the incidence to be about 20%.“’ zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA C. INFLAMMATORY DISORDERS 1. Diabetes Mellitus 1. Acute Meningitis The blood supply to the cranial nerves and nuclei is affected in diabetic ophthalmoplegia. Axonal reaction in the ocular motor nuclei and atherosclerosis of the vasa nervora have been documented pathologically.3’ Screening for diabetes is mandatory with unexplained trochlear palsy in the old-age group. Diabetic ophthalmoplegia occasionally presents as transient repeated attacks. Four recurrent episodes of isolated unilateral trochlear palsy were observed in a diabetic patient.“” Ocular palsies are said to be among the most common signs of involvement of cranial nerves in meningeal disease, especially in the acute epidemic meningitides. ” Cases of trochlear palsy have occurred following acute meningitis.lz8 2. Tuberculous Meningitis Tuberculous meningitis affects predominantly the VI and III cranial nerves, respectively, in around 11% and 6% of patients.‘“O In India, tuber- CENTRAL TROCHLEAR 285 PALSY culitis. In “cephalic tetanus”, facial palsy and, less commonly, ptosis (10%) were noted.“O Only one patient with tetanus suffered trochlear palsy with evidence of bulbar palsy; recovery occurred after one week.“Z Tetanus toxin is thought to have a direct neurotoxic activity that may not be reversible in all patients, as evidenced by many recent reports of brain stem lesions in patients dying from tetanus.‘” Botulism is known to cause complete external ophthalmoplegia on the basis of interference by the 3. zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Neurologic Sarcoidosis botulinurn toxin at the neuromuscular junction. Yet, multiple ocular motor nuclei lesions have been Neurologic sarcoidosis in its subacute course has documented pathologically.i’ Three cases of diphinvolved every cranial nerve, including the trochletheric toxin-induced trochlear palsy were menar ner1.e. The facial nerve is most commonly affecttioned. VI nerve palsy occurred in 9 out of 64 cases ed, followed by the optic nerve.“‘.13” In its chronic of severe diphtheria while I I I nerve palsy is reportcourse, the optic nerve is the main site of inflammaedly rare.“” tion and ocular cranial nerves are usually spared. culous meningitis was the most common cause 01‘ ocular motor palsies.“g Out of an Indian series of 100 patients, 26 had tuberculous meningitis, onethird with isolated oculomotor paralysis, one-third with abducens affection, and one-third associated with other ocular motor nerve palsies. The thick caseous exudate filling the basal cisterns as a result of basal meningeal reaction, along with the presence of inflammation, leads to pressure atrophy of the ocular motor nerves and other cranial nerves. 4. Ocular Motor Syphilis D. COLLAGEN-VASCULAR Gumma formation in the superior orbital fissure peripherally or in the meninges centrally affects the various ocular motor nerves.“‘” In incipient tabes dorsalis, transient ocular motor nuclei inflammation may occur with subsequent spontaneous recovery.“’ Collagen vascular disorders accounted for three cases of isolated trochlear palsy in Rucker’s series,“” and three cases in Rush’s series.‘?‘.‘l” One of Rush’s patients had systemic lupus erythematous and two had progressive systemic sclerosis.“’ Progressive systemic sclerosis is known to cause myopathy”’ with secondary diplopia.” Polymyalgia rheumatica (and hence probably temporal arteritis) was involved in one case of mixed ocular motor nerve palsies.“’ Intermittent ophthalmoplegia is seen occasionally in temporal arteritis and is important as a premonitory sign.“” There is no specific mention of trochlear palsy in temporal arteritis. 5. Miscellaneous In acute poliomyelitis and epidemic encephalitis whooping cough), ocular (mumps, chickenpox, signs are among the most common manifestation of the disease.‘” Isolated trochlear palsy has been observed in these conditions.“’ In postinfectious polyneuritis (Cuillain-Barri syndrome), the cranial nerves are involved in half of the patients. Facial palsy- is most common, followed respectively by affection ofnerves III, IV, VI, V, IX, X, XI, XII.‘“,‘“’ Four cases of isolated trochlear palsy associated with postinlectious polyneuritis have been report,d,‘Wl?’ Ophthalmoplegia was thought to rarely complicate attacks of herpes zoster ophthalmicus,“g but a literature review”” and a prospective study revealed an incidence of ophthalmoplegia of 3 1% .‘I Trochlear palsy occurred in 21 cases in a series of 2250.“’ Some 35 cases of trochlear palsy have been reported in association with herpes zoster. ‘~3.73,86.91.132 The third nerve is most frequently involved, followed by the sixth and fourth nerves. Ophthalmoplegia may occur contralateral or bilateral to the side of the rash.“” Demyrlination and inflammation of the ocular motor nerves and perivascular infiltration of the supplying \fessels within the cavernous sinus have been observed.“” Herpes zoster virus is thought to affect the ocular motor nerves directly inside the cavernous sinus, or indirectly by a virus-induced vas- DISEASES E. TOXIC SUBSTANCES Direct lesions of the fourth cranial nerve were noted following exposure to various toxic substances. In kernicterus, the III and IV cranial nerves were among the most vulnerable, being affected in about 60% of pathologic specimens in which the trochlear nucleus had a spongy appearance.” The abducens nucleus was generally spared. In Pamaquinc naphthoate (Plasmochin) or other quinolinc poisoning, considerable nerve cell loss occurred in the III, IV and VI nerve nuclei with focal degeneration in the basis pontis.“’ Strabismus follows the ingestion of methylchloride or sodium fluoride. An abrupt onset of strabismus should make us suspect lead poisoning,‘!’ especially in the presence ofpapilledema in children, in whom the central nervous system involvement can be rapid in onset. The ocular motor nerve palsy in lead poisoning is said to be a result of increased intracranial pressure due to increased permeability of the blood brain barrier. Papilledema and ocular motor nerve palsies have bran reversed after multiple spinal taps.“‘.+’ 286 Surv Ophthalmol 30(5) March-April MANSOUR, 1986 TABLE Pathology and Location Year No. of Patients 1959 5 Suzuki (147) Rucker ( 126) 1962 1966 4 7 Khawam (76) Burger ( 19) 1967 1970 1 7 Rougier ( 125) Robert ( 122) King (77) Scully ( 136) Younge (173) Wray (171) Coppetto (25) Boggan ( 17) Kay (72) Rush (128) Ho (65) Samii ( 130) Murray ( 102) Reinecke series 1973 1973 1976 1976 1977 1977 1978 1979 1979 1981 1981 1981 1985 - 2 2 1 1 4 2 3 1 1 7 1 1 1 1 Author (reference) Zielinski (174) NERVOUS SYSTEM 5 zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIH of Neoplasms in Trochlear Pathology Palsy and Location 1 parietal/l occipital/l brainstem/l spinal cord/ 1 hemangioma 4 pinealomas 2 midbrain gliomas/l meningioma/3 primary (brain)/ 1 metastatic “brain tumor” 4 cerebellopontine angle tumor/l cerebellum/ 1 nasopharyngeal carcinoma/l metastatic-lung 2 brainstem tumors 2 pituitary tumors 1 schwannoma 1 medulloblastoma at medullary velum 2 gliomas/2 metastatic-breast, ovary 2 pituitary tumors 1 ependymoma/I medulloblastoma/l acoustic neuroma 1 schwannoma 1 metastatic-midline malignant reticulosis 2 meningioma/l brain primary/4 metastatic 1 schwannoma I schwannoma 1 metastatic-lung adenocarcinoma 1 superior cerebellar glioma Intravenous gold therapy has caused transient mixed ophthalmoplegia in less than 15% of patients. Gold has also induced a vascular spasm with secondary transient palsy.35,‘46 Alcohol caused isolated bilateral trochlear palsy with partial recovery in one case.‘72 Ophthalmoplegia, which can progress to its complete external form, is one of the triad of Wernicke-Korsakoff encephalopathy. The lesions are confined to zones around the aqueduct, III and IV ventricules, and mamillary bodies. The ocular motor nerve palsy could be secondary to multiple vitamin deficiency. For example, pellagra is known to affect the brain stem nuclei.2g F. CENTRAL REINECKE DISORDERS Various central nervous system diseases are expected to affect the trochlear palsy. Primary hydrocephalus34.‘28 and pseudotumor cerebri7s54 are infrequently involved in trochlear palsy. (Five cases of hydrocephalus and two cases of pseudotumor cerebri have been reported). 7,34,54,‘2* The “false localizing sign” of trochlear palsy is rare compared with the abducens palsy that manifests frequently in patients with increased intracranial pressure. Primary convulsive disorders were associated with isolated trochlear palsy in few reports,34,‘73 although the relation was unclear. In migraine, III nerve involvement is ten times more common than VI, and trochlear palsy is rarely seen.“j3 TABLE Incidence of Various Neoblasmr 6 in Ocular Motor Palsies* Nerve Involved Neoplasm Pituitary adenoma Craniopharyngioma Glioma-Pons Glioma-Midbrain Chordoma Meningioma Other primary Nasopharyngeal Other metastatic 22 1 0 4 Total 84 9 5 44 0 9 6 43 21* 83 1 12 11 1 32 14 *Data compiled from two series totalling with ocular motor palsies.‘26~‘2R 220 2000 patients A history of diplopia was found in 97 of 295 patients with multiple sclerosis, but no cases of trochlear palsy were documented.” Trochlear palsy was documented in only six cases of mutiple sclerosis zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONML 2 5 ,2 7 .l2 6 .1 2 8 ,1 7 3 G. NEOPLASMS SYSTEM Tumors trochlear OF THE account palsy. Of CENTRAL for approximately the ocular motor NERVOUS 3-4% nerves, of the CENTRAL TROCHLEAR PALSY ‘Hi /;i,q. 4. Ixli: Midline sagittal rrconstruction CT shows a midlinr cystic Irsiotl \\ith a thick rnhancing \r, a11. ‘1.11~Irsion. 2.5 cm in diameter, is wedged between the pineal region, quadri,qrminal platck and thr superior \x,rmis. Note the c.nlitrqrd I IId ventricle above the lesion, and the IVth ventricle below it. Ri,yht: CIros4 srction at the lc\~4 ol‘tht. tcntorial hiatus showinK thr enhancing lesion between the superior vermis and thr dorsum ol‘the midbrain (Rt~printrd Itom Krohrl (;H. Lfansour Ahl. et al: Isolated trochlear nerve palsy secondary to a juvenile pilocytic astroc‘) toma. ,/ zyxwvutsrqponmlkjihgfedcbaZ (;/in .\~~rc ,-o -O ~~hlhnl,nf,i _‘ :I 1%123. 1982. with permission of’ rhe publishers of,/ourntrl ?f‘ C ’ lirzic -nl.~~u~o -O )~hfhnl,,lo (o ,p ~.I after removal of the adenoma in these c;~ses.‘~’ Ii’ ner\re is least alrected by tumors, as it is hledutlohlastoma was present in two cases with well protected by being “hidden” in the thick tentorial bed. Table 5 summarizes the pathology zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA offifty trochlear patsy.“.’ ‘I’One of these tumors was in tht region of the medultary velum, and was missed on cases of tumor-associated isolated trochlear patsy rhe first computed skull tomography only to br apreported in the literature. Table 6 compares the parent after ocutomotor patsy had set in.““’ incidence of various neoplasms in nerves III, IV and VI. The most common primary brain tumors in\potved with trochtcar palsy are the gtiomas of the In most of the cases cited in Table 5, trochlear ccret~ettum and midbrain. \Vc recentI\. encountered patsy fiAtowed other cranial nerve afrection or was a case of upper crrrbettar pitoc‘vtic astroc\~torna in a due to tumor-induced increased intracranial presseven-year-old girt with isolated ctircct attkction ot‘ sure. :I third of the cases were metastatic spread from Iumors of the nasopharynx,“’ lung, ovary. the trochtear nerve (Figs. 4 and 3). Primary brain breast or elsewhere. Trochtear palsy was the first tumor, particularly gtioma. is a mot-c common cause of ocular motor ncr\*e patsy in children. ” t>ircct si,gn of metastasis in one case.“’ Diplopia from bitroctilcar nerve involvement b): tumors is rar( lateral crochtear palsy was the presenting symptom rnou~~h to make trochlear palsy a “brniq“ palsy, ill 01‘ metastatic pulmonary adenocarcinoma as demonstrated h!. computed tomography of the head and contradistinction to the ahducens nerve. In a srrics of303% cases oftumors of the brain. 90”/~ had ocular subsequent needle aspiration of the pulmonary tesion.“” Pineatomas commonly involve the trochtear symptoms. Papittedema was present in 61%. optic alrophy in IS%, visual tietd d&acts in 38%. and nerve at its point ot‘cmergencc. In one series of24 pineal tumors, trochtear patsy was seen in four cases ocular motor paralysis in 22% of patients.“’ white, the III nerve was involved in 18 patients Intracranial schwannomas originate usually from sensory nerves and seldom arise from motor nerves. (bitatcrat in 16 ) and the \:I nerve was involved in two patients.“’ There arc ei,ght reports of intracranial schw~annoLAcoustic neuroma and ccrebellomas involvin,q the ocular motor ncrvcs. follr in\Y~t\,pontine angle tumor account for around 15% of in,? the trochtear nerve ““‘~” “” and t&r involving tumors with trochtear pats);. Parasellar and tentorthe oc.utomotor nerve. Schwannoma ot‘ the abduial mcningioma account fi)r 10%. Enlarging pitutens nerve has not been encounrrred. The majority; itary adenomas involved the trochtear nerve and the of schwannomas arise from the \‘I 11 ni’rve and a oculomotor nerve in four patients. Ocular motor smaller group from the V nerve.’ I.’‘I’ nerve patsies are noted in 1% to 14% of pituitary Trorhtcar patsy ti-om minor hcad in-jury ma!’ ht tumors (average of 5% in a total of 436 patients the initial sign of an intracranial (urnor as demonfrom tijur scxries): the third nerve is the most comstrattbd in three cases ofbasal intracranial lumors.“” monly involved. The ocular patsy resolved rapidly trochlear 288 zy zyxwvutsrqpo Surv Ophthalmol Fig. 5. Pathological 30(5) March-April 1986 MANSOUR, REINECKE sections of the lesion seen in Fig. 4 demonstrate large unipolar and bipolar cells and a highly vascular tumor with strong affinity for neurologlial stains. Top: Hematoxylin and eosin, X 210. Bottom: Argentaffin stain, X 200. (Reprinted from Krohel GB, Mansour AM, et al: Isolated trochlear nerve palsy secondary to a juvenile pilocytic astrocytoma. J Clin Neuro-Ophthalmol 2: 119-l 23, 1982, with permission of the publisher of Journal of Clinical NeuroOphthalmology.) H. CONGENITAL-IDIOPATHIC 1. Congenital Causes Congenital aplasia or hypoplasia CAUSES zyxwvut of the trochlear have been described in isolated formP and in gross deformities such as hydrocephalus, and Goldenhar-Gorlin syndrome. Unilateral agenesis of trochlear nerve nucleus and other brain stem nuclei was demonstrated at autopsy in such a syndrome.” It is likely that an impaired growth of facial structures in utero results in hypoplasia of various extraocular muscles. In more severe cases of Goldenhar-Gorlin syndrome, both the extraocular muscle and its respective brain stem nucleus are underdeveloped.’ The association of Goldenhar-Gorlin syndrome with Duane’s syndrome and the findings of hypoplasia of the VI nerve nucleus in Duane’s syndrome add evidence to the autopsy findings of nunucleus clear aplasia in oculo-auricuIo-vertebral dysplasia. Rafuse et al”’ reported paralysis of the trochlear nerve in a case with the dysmelic syndrome (phacomelia). Moebius syndrome with paralysis of the oculomotor and abducens nerves is a common sequela of the teratogenic effects of early thalidomide intake by pregnant mothers.“7 Aberrant innervation of the trochlear nerve to the levator palpebrae and orbicularis oculi muscles have been described, as well as various communications of the trochlear nerve with the supratrochlear, infratrochlear, and nasal nerves, and with the frontal and lacrimal branches of the opthalmic division of the trigeminal nerve.“‘” Congenital absence of the superior oblique muscle is rare; the most often missing muscle is the inferior rectus.“’ Sixteen cases have been reported with absence of the superior oblique tendon CENTRAL TROCHLEAR PALSY diagnosed at surgery, confirmed by coronal tomographic views of the orbit, or found at autopTh ere is a high incidence of absy. X.59.b?.10~1.111.11h.131 sence of extraocular muscles and especially the superior oblique in craniofacial dysostosis.““,zg Absence of the superior oblique tendons was noted in one case of anencephaly.R One case of congenital trochlear palsy had a hard mass in the upper nasal orbit. At exploration, the palpable mass proved to be a hard and thickened superior oblique muscle. Biopsy of the muscle belly revealed connective tissue fibers, hyaline cartilage but no muscle fibers.” This is a unique form of choristomatous growth ofa fibrotic superior oblique muscle presenting as trochlear palsy and as an orbital mass. TABLE Percent Rate ofRecoveryof Cause A Jected III Vascular Cndetrrmined Trauma 73% 5 I% 36% ‘l’otal 48% *:\dapt’d 7 zyxwvutsrqponmlkjihgfedcbaZY Ocular Motor Nerves* IV VI from Kush.‘“” palsy following spinal anesthesia, and ocular motor palsies are seen occasionally after general anesthesia, especially ether.‘“,“” Other causes of superior oblique muscle paralysis include: cavernous sinus thrombosis; dural sinus 2. zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Idiopathic Causes thrombosis; paratrigeminal syndrome (Raeder’s syndrome); epidermoid cyst near the gasscrian ganThe idiopathic variety Ibrms the largest category glion: Tolosa-Hunt syndrome (trochlrar nerve in(50% zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA ) of‘ trochlear palsy in the pediatric populavolved in 47% ofcases);’ myasthenia gravis;‘” ” th),tion.‘?” Proposed causes include: trochlear nuclear roid ophthalmoplegia;“’ Paget’s disease: chondroma hypoplasia. birth trauma to the trochlear nerve or of the trochlea;” paranasal sinus infection (ethmoithe superior oblique muscle, hypoplasia or absence ditis, mastoiditis);7” orbital periostitis (including of the superior oblique muscle, anomalous insertion syphilitic) and cellulitis; superior oblique entrapof the muscle, muscle fibrosis, fibrous adhesions bement secondary to orbital zyxwvutsrqponmlkjihgfedcbaZYXWV roof fracture and trochletween various muscles, muscle sheaths, and orbital ar nerve trauma in orbital fractures;“’ rheumatoid walls.“” “<:ongcnitat-onset” trochlear palsy is innodule of the superior oblique tendon. ‘I’rochleitis cluded in the idiopathic category because it is still of with superior oblique myositis is a self-limited and undetermined etiology. Trochlear palsy may be delocalized type oforbital pseudotumor: 13 cases have tected at birth or it may go undetected until adolesbrcn described by Tychsrn et al.” cence”’ or even adulthood. as seen in our series. The theor), ot‘dccompensation of a congenitally existent trochlear palsy seems more related to a decompensation in the fusion mechanisms than to a further progression of the palsy. Most unexplained trochtear palsy starting in early childhood has been termed “congenital,” while most unexplained adult cases can hr attributed to senile degeneration, repeated cumulati\.e minor trauma or a “small stroke” of the trochlcar nerve.“” Trochlear palsy has followed simplc upper respiratory tract infection,‘2H fever in children,” ’and. possibly, emotional stress in adults.‘” Two reports have described familial occurrence of‘ trochlrar palsy. One family was reported by Franceschetti in 1926, “I “’ and three families by Astle and Rosenbaum in t98.‘,.’ No definite pattern of genetic transmission could be established. The rare rntity offamilial brnign recurrent cranial nerve palsies has included reports of palsy of the third and the ahducens nerves onlv.‘x I. MISCELLANEOUS Se\.eral postsurgical cases of trochlear palsy have fijIlowed c.raniotomy’7~““.“H.‘7’.‘7” or posterior fossa exploration. Trochlear palsies may also be induced by anesthesia. One woman developed left trochlear J. CYCLIC AND RECURRENT PHENOMENA Rarely, superior oblique myokymia may follow trochlear patsy,” and it seems that there may be an intermittent lack of supranuclear inhibition as a result of zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPON a nuclear lesion with subsequent partial recovery. “I’ Superior oblique myokymia is a benign condition characterized by periodic microtremor caused by spontaneous contraction of the oblique muscle.” Carbamazepine therapy”’ or surgical intervention”“’ give variable results. \4’e suggest the possibility of’ some similarity between superior oblique myokymia and cyclic paralysis ol‘thc oculomotor nerve (paralysis of ocutomotor nrr\.e with alternating phases of spasm and relaxation involving the sphincter muscle and other palsied mus(.les ),111 CJl Recurrent trochtear palsy is a rare phenomenon.““.“,‘l” The differential diagnosis of‘ recurrent trochlear palsy should include the following: ophthalmoplegic migraine, 1 herpes zoster ophthatmicus, i’i diabetes mellitus,“” sarcoidosis,“” GuillainBarr-f syndrome,“” Tolosa-Hunt syndrome or painful ophthalmoplegia, ‘S a newly described entity benign multiple cranial nerve palof “recurrent 290 Fig. 6. Surv Ophthalmol Congenital-onset the inferior oblique 30(5) March-April bilateral muscles, 1986 MANSOUR, trochlear palsy. The cardinal underaction of the superior fields reveal left esotropia on primary gaze, overaction oblique muscles, and “V”-pattern esotropia. sies,““? familial recurrent cranial nerve palsies,‘04 postfebrile recurrent cranial palsies,‘@ and dysglobulinemia with or without cryoglobulinemia.R2 Recurrent multiple benign cranial nerve palsies is a distinctive syndrome, yet the clinical findings and pathologic findings of granulomatous inflammation involving the perineurium of the cranial nerves tend to overlap Vertical Deviations Deviation in Primary Position (In Diopters) Average Congenital? Trauma: Undetermineds Total Patients (Percent) *Adapted tAverage SAverage SAverage 19 years of 18 11 16.5 with Tolosa-Hunt of syndrome.” zyxwvutsrqponmlkj V. Recovery of Affected Ocular Motor Nerves Ofall the ocular motor nerves, the trochlear nerve has the highest rate of recovery (Table 7). Recovery is estimated to occur in about 75% ofcases of troch- TABLE Etiology REINECKE zyxwvutsrqpo 8 in 100 Patients W ith Trochlear Palsy* Position of Gaze of Greatest Vertical Deviation Range UP Down Comitant 8-40 4-18 4-40 18 4 15 6 11 9 12 7 18 37 (37) 26 (26) 37 (37) Total Patients 36 22 42 100 (100) from Mitteln~an.qR deviation was 21 for patients < 5 years of age, 15 for patients > 5 years of age. age: 31 years. deviation was 18 (range, tS40) in patients < 19 years ofage and 13 (range, 4-25) in patients age. > CENTRAL TROCHLEAR PALSY lear palsy from vascular causes, 55% of cases from undertermined causes, and 44% of cases caused by trauma. Spontaneous resolution occurred in 65% of unilateral traumatic trochlear palsy and in 25% of bilateral traumatic trochlear palsy.‘“” Recovery occurred as early as one week’“” and as late as six months after onset, with an average of 10 weeks.“” zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDC VI. Diagnosis Diplopia is the most common presentation of trochlear palsy. It is secondary to the vertical and horizontal deviation and only occasionally are torsional difficulties a complaint. The patient’s main problem mav be abnormal head posture, torticollis and e\en scoliosis. History-taking should include the time of onset of trochlear palsy as well as looking at old photographs for a head tilt. General principles fbr diagnosis of trochlear palsy are presented below.‘; A. AMBLYOPIA Visual acuity measurement may be important in localizing the side of the muscle palsy. Amblyopia is uncommon in trochlear palsy, but it is seen in patients with congenital onset trochlear palsy with horizontal deviations. In our series, one girl had a visual acuity of 20/200 in one eye with large esotropia secondary to superior oblique palsy. Amblyopia greater than one line was found to be present in 12% of patients.” Fig. 7. The patterns ofspread of’ concomitance. Type I is the commonest pattern, II and II L arc occasionally noted, and IV, V, and VI are rarely noted (one case of each in our series). (***) refers to the palsied muscle; RH’f ;md LHT = right and left hypertropia; SR = superior rrctis; IR = inferior rrctus; SO = superior ohiique: ( + 1 refers tn the degree of hypertropia. B. HYPERTROPIA The classic form of trochlear palsy is an incomitant hypertropia greatest in the adducted depression position of the involved eye (Fig. 6). This pattrrn is well illustrated in the fresh traumatic cases and is found in 26% of all cases of trochlear palsy (Table 8). However, spread of comitance may occur with time. Commonly, secondary inhibitional palinvolves one of the following muscles: consy,t’.H”.‘r”~“‘i tralatcral superior rectus, contralateral inferior oblique, ipsilateral inferior rectus or a combination of these (Fig. 7). Hypertropia is decreased in cases of bilateral trochlear palsy (Fig. 6). Asymmetry of the vertical invohement is the rule in bilateral cases.7g,“” One case in our series had no hypertropia. Vertical deviation \raries inversely with age in any category of trochlcar palsy. It is greatest in the congenital-onset group and least in the traumatic group. In the former group, it is maximal on upward gaze and in the latter group, it is maximal on downward gaze (Table 8). C. HORIZONTAL A large proportion of esotropia reaching 65 diopters. Many patients in our series had had multiple operations for a “congenital esotropia.” Trochlear palsy should he suspected in infants with a history of crossed ryes in whom cardinal field measurements are difficult to obtain. Funduscopy becomes a valuable diaanostic test for torsion. “V” pattern is seen in halfof the cases with zyxwvutsrqponml U nildt era1 palsy and in the majority with bilateral palsy (Table 9). It is due to the loss of the abducting power of the superior oblique muscle. In our series, “V” rxocleviation was as common as “V“ rsodevia- TXBLE zyxwvutsrqponmlkjihgfedcbaZYX 9 Patterns of‘ Hori;ontal Iler~iation in 40 Patients Pal3 v* DEVIATION of our cases had a high degree *:\dapteci from Khawam.“’ 127th Trochlear 292 Surv Ophthalmol 30(5) March-April 1986 MANSOUR, REINECKE tion. Exodeviation is due to the overaction of the inferior obliques. Absence of “A” or “V” pattern is seen in the other half of unilateral cases and is a consequence of spread ofcomitance. The “A” pattern ofdeviation is rare. “A” esodeviation is expected to be secondary to the innervational palsy of the contralateral inferior oblique muscle while the “A” exodeviation is related to the ipsilateral inferior rectus inhibitional palsy. We observed a single case of “A” esotropia with bilateral trochlear palsy. D. HEAD POSTURE Head posture is described for its tilt, turn, and chin elevation or depression.‘97 Head tilt to the side of the nonparetic eye is found in half of the patients with unilateral palsy, and the tilt is present in twothirds of patients with bilateral palsy (Fig. 8).76 The absence ofspontaneous head tilt in trochlear palsy is attributed to amblyopia or to extremely large amplitudes of vertical fusion. Acute cases do not present with head tilt. Some patients have a tilt to the side of the paretic eye in order to get more suppression,‘7 and one patient in our series alternated the head tilt from the paretic to the nonparetic side. Bielschowsky head tilt is positive in 90% of patients with trochlear palsy,76.‘73 and positive in a higher percentage of cases with an abnormal head posture. 34In bilateral trochlear palsy with “V” pattern esotropia, chin depression is commonly adopted, thereby allowing fusion on upward gaze. Likewise, chin elevation is expected in “V” exotropia to allow fusion on downward gaze. A young boy was placed on 9 months of traction (Glisson’s sling) for a torticollis without success. After the diagnosis and correction of the trochlear palsy, the ocular torticollis disappeared.15’ E. CYCLODEVIATION Fig. 8. Bilateral trochlear palsy. Top: Left head tilt and face turn with chin down position. Bottom: Lees’ screen test reveals bilateral excycloversion of 20 degrees and a “V” pattern esotropia typical of bilateral trochlear palsy. rest.3+ The absence of cyclotorsion is a consequence of spread of comitance, especially to the ipsilateral inferior rectus, thereby compensating for the extorsion. Lancaster-Hess-Lees screen tests can measure qualitatively as well as quantitatively the amount of torsion. They also provide a rough cardinal field measurement without the use of prisms, and the laterality of the palsy (Fig 8). Funduscopy is the simplest and quickest method for testing cycloversions (Fig. 9). Hypertropia and extorsion of the optic disc are noted in superior oblique palsy. Quantitation of torsion can be done with a fundus camera. a’ Funduscopy is the only objective test and the only available means to measure cyclodeviations in young children. In cases of bilateral trochlear palsy with minimal hypertropia, and negative Bielschowsky’s test, cyclotropia determination may help to localize the side of trochlear palsy. Patients with trochlear palsy uncommonly complain of the torsional component until after correction of the tropia. Moreover patients can tolerate well large torsional amplitudes. The average and the range of the vertical as well as the horizontal torsional fusional amplitudes in degrees are, respectively: 28.6 (range, 23-44) and 15.2 (range, of excyclotorsion and in12-29). ‘52 Large amounts creased incidence of torsional diplopia characterize bilateral trochlear palsy. ‘4RCommonly used tests for cyclotropia include the Maddox double prism, the Maddox rod single or double,‘4.6”,g8.‘6’.‘62the Maddox F. SACCADIC VELOCITY wing, the red and green streaks, the major amblyoVertical saccadic velocity determinations showed scope, the Lancaster-Hess-Lees screen tests, and marked slowing of down saccade in the adducted funduscopy. position in trochlear palsy patients compared to Double Maddox rod testing was positive in 85% controls. This finding can be used to differentiate of patients for excyclotorsion and negative in the zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDC CENTRAL TROCHLEAR 293 PALSY 3. Primary Versus Secondary Inferior Oblique Overaction: Transmission Electron Microscopic Studies It was noted that the presence of mitochondrial aggregates favored the diagnosis of primary inferior oblique muscle overaction; these aggregates were less prominent in case of secondary overaction from trochlear palsy (by transmission electron microscopy of biopsy material from inferior oblique muscles) .‘)I’ C. CENTRAL PALSIES I;(?. 9. Funduscopy in the diagnosis of trochlear palsy. I and 11 represent left hypertropia. III and IV represent left hypotropin. I and II I represent extorsion of the disc. I I and IV represent intorsion ofthe disc. I corresponds to superior oblique, II to infer-ior rectus, III to superior rectus, and IV to inferior oblique palsies of the left eye. CAUSES OF VERTICAL GAZE Central causes of vertical gaze palsy include skeu deviation (supranuclear dysfunction f?om brain stem lesions)” and Parinaud’s syndrome (supranuclear paresis of bilateral vertical movements usually by tumors that affect the periaqueductal area),l’J”XX.l’X D. SIMULATED UNILATERAL OBLIQUE MUSCLE PALSY SUPERIOR 1. The Three-Step Test palsy.“’ zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Bielschowsky head tilt interpretation assumes VII. Differential Diagnosis that the patient has a single cyclovertical muscle A. HEAD POSTURE palsy. By following the three-step diagnostic technique (described by Parks,“’ modified by HarThe ocular causes of abnormal posture were studdesty.” and simplified by Vazquez”‘“), many entities ied in a prospective series of 188 patients.” Out of 70 can he seen to mimic unilateral trochlear palsy. cases with \.ertical incomitance, 66% had trochlear KushnerHt found 48 such cases including four cases palsy. 10% inferior oblique palsy, 9% Brown’s synof hilateral trochlcar palsy, four cases of contraladrome. 7% blow-out fractures of the orbit, 4% douteral inferior rectus restriction, and 32 cases of hyble elevator palsy. and 4% superior rectus palsy. pertropia with intermittent exotropia and no B. VERTICAL PALSIES zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA oblique muscle dysftmction (as evidenced by resolution ofhypertropia after horizontal muscle surgery). 1. Statistical Data oblique from recti muscle According to Bielschowsky,” 90% of acquired vertical palsies are secondary to trochlear palsy. The differential diagnosis of vertical muscle palsy was presented in the following sequence”4: superior ohliquc, double elevator, inferior oblique, Brown’s syndrome, orbital floor fracture with inferior rectus thyroid myopathy, myasentrapment or palsy, thrnia gravis, and progressive external ophthalmoplegia. Isolated paresis of the vertical muscles supplied by the third nerve is quite rare.“’ 2. Normal Variants Mild degrees of superior oblique muscle underaction with inferior oblique muscle overaction are normal variants resulting from differences in the orientation and insertion of the superior oblique tendon. The superior oblique tendon undergoes a large change in its orientation relative to the trochlea during fetal development. 2. Additional Diagnostic Steps To avoid overdiagnosing trochlear palsy, auxiliary steps can help to differentiate paralytic from restrictive strabismus, single from multiple, and unilateral from hilateral muscle palsies. These tests include: Bielschowsky “missing” test or the “fourth” step (checking hyprrtropia on upward and downward gaze in the primary position);” measurement of saccadic eye movements, forced ductions, and ,generated force testing;;“’ qualitati\:e mrasuremrnt of cyclodeviation (the “fifth” step). This step hecomes essential in cases of mixed palsies. A combined palsy ofthe superior oblique and the contralateral inferior rectus muscles’” would simulate an isolated inferior rectus of the contraiateral eye by the three-step technique. The finding of an extorted right eyr would establish the diagnosis of concomitant superior oblique palsy. 294 Surv Ophthalmol 30(5) March-April 3. “ Masked” Bilateral Trochlear Surgical Failures 1986 zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA MANSOUR, REINECKE Palsy and Bilateral trochlear palsy should be recognized before strabismus surgery is attempted. “Masked” bilateral superior oblique palsy has been recognized following operation for a seemingly unilateral trochlear palsy. Urist’“” reported the first two cases, and since then 25 cases have been added.63 It is safe to assume trochlear palsy is bilateral until proven otherwise. The following findings suggest bilateral trochlear palsy: a large “V” pattern in excess of 25 prism diopters; angle of cyclotorsion greater than 10 degrees; bilateral excyclotorsion; and minimal hypertropia in the field of the seemingly nonaffected eye. 61.148 Acknowledgments Acknowledgments to Dr S. Goldberger for help in prepar- ing the manuscript, Dr. T. Yamamoto for providing the pathological material, DrJ.L. Smith for reviewing the manuscript, G. Chrysanthou for supplying clinical material, N. Mansour and B. Mansour for preparing the illustrations. References I. Aleksic S. Budzilovich G, Choy A, et al: Congenital ophthalmoplegia in oculoauriculovertebral dysplasia-hemifacial microsomia (Goldenhar-Gorlin syndrome). A clinicopathologic study and review of literature. Neurolo~ 26:638-644, 1976 2. Arnett FC, Michels RG: Inflammatory ocular myopathy in systemic sclerosis. A case report and review of the literature. Arch Intern Med 132:74&743, 1973 3. Astle WF, Rosenbaum AL: Familial congenital fourth cranial nerve palsy. Arch Ophthalmol 103:532-535, 1985 4. Bailev TD. O’Connor PS. Tredici Tl. Shacklett DE: Ouhthalmoplkgic migraine. J Clin Neuro-oph&mol 4:225-228,‘1984 5. Bajandas FJ: The six syndromes of the sixth nerve, in Smith JL (ed): Neuro-Ophthalmology Lipdate. New York, Masson Publishers, 1977, pp 49-67 6. Bajandas FJ: The four causes of fourth nerve palsy, in NeuroOphthalmology Board Revieul Manual. Thorofare, NJ, Charles B Slack, 1980, pp 91-97 7. Baker RS, Buncic JR: Vertical ocular motility disturbance in pseudotumor cerebri. J Clin Nemo-ophthalmol 5:41-44, 1985 8. BarnesJ, Boniuk M: Anencephaly with absence ofthe superior oblique tendons. Sure Ophthalmol 16371-374, 1972 9. Barrat JOW: Observations on the structure of the third, fourth, and sixth cranial nerves. J Anat Phvsiol 35:214-223, 1901 10. Beaty HN: Tetanus, in Petersdorf RG. Adams RD, Braunwald E, et al (eds): Harrison > Principles oflnternal Medicine, V’ ol I, Part 4. New York, McGraw Hill, 1983, ed 10, p 1003-1006 dysplasia 11. Berkman MD, Feingold M: Oculoauriculovertebral (Goldenhar’s syndrome). Oral SW 24:408-417, 1968 A: Lectures on M otor Anomalies. Hanover, NH, 12. Bielschowsky Dartmouth College Publications, 1940, pp 73-80 13. Birndorf LA, Levy NS: Isolated sixth nerve palsy following prolonged general anesthesia. JPed Ophthalmol11:5% 6l, 1974 14. Bixenman WW: Diagnosis of superior oblique palsy. J Clin Nemo-ophthalmol I; 199208. 1981 Ophthalmo15. Bleeker GM: Parinaud’s vertical ophthalmoplegia. logica 263:44-45, 1971 16. Blumenthal H, Miller C: Motor nuclear involvement in progressivfe supranuclear degeneration. Arch Neurof 20:362, 1’969 ML. Wilson CB: Neurilemmoma of 17. Boegan IE. Rosenblum the fourth cranial nervre. J Neurosurg .50:51%521. 1979 18. Brodal A: Neurological .4natom_v in Relation to Clinical Medicine. New York, Oxford University Press, 1981, rd 3, pp 535-571 I9 Burger cranial 20 Cantillo fracture. 21 Castren oblique L, Kalvin N, Smith J: Acquired lesions of the fourth nerve. zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQP Brain 93:567-574, 1970 N: A case of superior oblique palsy in an orbital floor Am Orthoptic J 28: 124-126, 1978 JA, Tarkkanen A: Malformation of the superior muscle simulating orbital tumor. A cta Ophthalmologica 42:97>979, 1964 LI, Urist MJ, Folk ER, Miller MT: Acquired bi22. Chapman lateral superior oblique muscle palsy. Arch Ophthalmol 84: 137-142, 1970 23. Choyce DP: Diagnosis and management ofocular leprosy. Br J Ophthalmol53:217-223, 1969 24. Cooper ERA: The trochlear nerve in the human embryo and foetus. Br J Ophthalmol31:257-275, 1947 25. Coppetto JM, Lessell S: Cryptogenic unilateral paralysis ofthe superior oblique muscle. A rck Ophthalmol % : 27&277, 1978 26. Cowan M’M, Wenger E: Cell loss in the trochlear nucleus of the chick during normal development and after radical extirpation of the optic vesicle. .J Kxp Zoo1 164:267-280, 1967 27. Crone A, Lcuridan 0: Les paralysies bilaterales des grands obliques. Bull Mem Sot Fr Obhtalmol 83:490-500. 1970 28. Dailey EJ, Holloway JA, M&to RE, et al: Evaluation ofocular signs and symptoms in cerebral aneurysms. Arch Ophthalmol 71:463-474, 1964 29. zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONM Diamond GR, Katowitz JA, Whitaker LA, et al: Variations in extraocular muscle number and structure in craniofacial dysostosis. Am J 0phtha1mo190:416418, 1980 30. Donaldson GWK: The diameter of the nerve fibers to the extrinsic eye muscles of the goat. J.&p Phvsiol45:25-34, 1960 31. Drevfus PM. Hakim S. Adams RD: Diabetic ouhthalmooleeia. 1 <1 Arch Neural Psych 77:337-349, 1957 32. Duke-Elder NS: System of Opkthalmologv, St Louis. C V Mosby Co, 1963, vol II, part I, pp 223, and vol III, part 2, p 989 33. Edgerton AE: Herpes zoster ophthalmicus. Arch Ophtkalmol 344:114-153, 1945 34. Ellis FD, Hehreston EM: Superior oblique palsy: diagnosis and classilication. Int Ophthalmol Clin 16(3):127-135, 1976 35. Endtz LJ: Complications nerveuses du traitement auriqueapercu des symptomes neurologiques et psychiatriques, resultats du traitement par le BAL. Rev Neural 20.458. 1970 36. Farnarier F, Farnarier G: Paralysie diphterique de la IV paire. Rev Oto-Neuro-Opktalmol 18: 183-185, 1946 37. Fells P, Waddell E: Assessment and management of bilateral superior oblique pareses. Tram Opktkalmol Sot L/K 100:485-488, 1980 38. Fox .JL: Intracranial Aneurysms. New York, Springer-Vcrlag, 1983, pp 163-183 39. Franceschetti kongenitale (familiare) A: fiber doppelseitige, Trochlearislahmung und ihre Beziehung zur alternierenden Hyperphorie. Z Augenheilkd 59: 17-34, 1926 40. Francois .J: Congenital ophthalmoplegias, in Brunette J-R, Barbeau A (eds): Progress in Nemo-Ophthalmologv. Amsterdam, Excerpta Medica Foundation, 1968, pp 387-421 41. Gacek RR: Anatomical demonstration of the vestibulo-ocular projections in the cat. A cta Oto-larvngologica (Suppl) 293:1-63. 1971 42. Getman I, Goldstein JH: Diagnosis ofan isolated vertical muscle palsy. A cta Ophthalmologica 61:85-93, 1983 43. Gibson,JL: Plumbic ocular neuritis in Queensland children. Br Med J2:1488-1490. 1908 44. Gibson JL: Ocular plumbism in children. Br J Ophthalmol 15: 637-642, 1931 45. Gilroy J, Meyer JS: Medical Neurologv. New York, Macmillan, 1979, ed 3, p 279 46. Glaser JS: Neuroophthalmologic examination - General considerations and special techniques, in Duane TD (ed): Clinical Ophthalmologv, Vol2. Philadelphia, Harper and Row, 1980, pp 8-13 47. Gobin MH: The diagnosis and treatment of IVth cranial nerve paralysis. Ophthalmologica 173:292-295, 1976 E: Ophthalmological and Neurological Symp48. Godtfredsen toms of Malignant Nasopharyngeal Tumors. A Clinical Study Comprising 454 Cases. Copenhagen, Einar Munksgaard, 1944, pp 178-191 CENTRAL TROCHLEAR &!I.Gdthdscn E: Ophthalmo-neurological tion with malignant ‘“)i _. PALSY nasopharyng-ral in conncr- 79. Knapp Hr ,I O#h/h&tu~ oblique symptoms tumors. .~/:7K_lUO. 1947 Xl. Godth-cdsvn E: Pathogcncsis 01 cranial nrrve lesions, notably ophthalmoplc,~ias, complicating hrrpes zoster ophthalmicus. .4c/n P<_,rh ,Veurol ?.1:69-77. 1948 Gr.mt \\‘hl: Tosicohqy of the Eyr. Springfield, IL,, C:harlrs CT ‘I‘homas. 1974. cd 2. p I97 Gro\rs,JS: Octdar manifcstatium of head injuries. Tranr Oph/ha/mo/ Sot 1 ‘K RI:6 13-623. I!)62 Hall GR. Hurdc RM: Superior ohliqur myukymia. .4rn Ortho~/,f w.5wis. Halprrn localizing Hardcstv Oph/ha/t&l I978 Jl. Gordon \VH: ‘I’rochlcar nervr palsy as a false sign. :lnn Ophthalmol lY:53-56. 1981 HH: Diagnosis 01‘ parrtic vertical rotators. Jm J .i/i:tll IL8 16. I X7 -95 108.5 A. ct al: Patholog-y 01 58. Hdym‘t’ku 12‘. Xlarg-lrlcs C:. Prntschrw kwni( twus and postictcric wwphalopath). in Kerrrir/eruc and Ii0 r/j Importanre in C’u~bral Pal!). Springli&i. II,. C:harlrs C: ‘l‘homa,, I9Ol. ,‘I’ 21L28 H.I\ m;lkrl- N’. Kuhlcnbrck H: IXsordrrs ofthr brainstrm and it\ uxnial ncrvcb. in Baker AB, Baker 1,H (cds): CZ~ical~‘~~~uroloqr. lb/ .‘j. Phildrlphia. Harpw and Row. 1980. pp 5-52 Hcalc~ I..\. \Vilskc KR: 7’hr .Srs/tmic Jlani/~s/a/ions Temporal 1971 Koch St,: ‘I‘hc structure ofthr third. rleventh. and twelfth cranial nwvcs.,] options in supuior 137-149. 1976 ol’hrpvrtropia. Am Or/hop/,/?l:29-37, 81. ILurth, fifth, sixth. ninth, C,‘w@ h$urol?fi:.j 11-552. 1916 82. R3. Kreindlrr A. Macovri-Patrichi hl: Rrcurrcnt cranial tll‘r~t palsics oTdysglobulinarmir ori!$n.~].Veeuro/ Sri h‘: I I7- 123. I!)68 Ktlshncr B~J: Ocular causes ofahnormal head posturr. Ophthalltol~gr x1. Kushnrr %:2115-2125. 1979 B,J: Simulated suprrior 1981 I,a FontaineJ: lx chcnc ohliqut palsy. .4nn Ophthnlmul I.‘i..337PS43. 85 ct Ir rosc’au. in l,rj Fob/e\ de La I“un/a~nr rdition). 1961. Paris. Garnicr-Frrrr. p 1.5 Lavin I’jhl. Younkin SC;. Tori SH: ‘l‘hr pathology ~Llyhthamuptcgia in hcrpcs zostcr (lphtll;llnlicll\. .~~un,-r~ph/halmolor:i 4:7>80. I984 1,~ ,J 1’: Superior ohliquc mwkymia. .-In-h Ophthalmol I//?. t 178. t 170. I984 (IKW 86 1963 Harlr\ RI): I’aralvtic strabismus in children. Etiologic inridrnw ,md manaqmcnt of thv third. rourth. and sixth ncrvr palsir\. Ophthalmulog~ H7:2+ l.%, 1980 and management ol”abnormalitirs 57. Harlcv RI): ‘l‘hr diagnosis 01‘ the vrr-tic-ally act’inc oc.ulnr musclrs. Ophthalmic LSur,c 16. :!!I 80. P. Moorr S: Dia~nusis and surgtcal surgrry. In/ Oph/halmol C/in 1613): Knapp P:Diagnosis and surgical treatmrnt 87 88 I.crrrn Xl. Iiosary I. Cohen B. Parinaud’s sydrrmc m .iqu(‘duct stcnusis, its mechanism .tnd ~rntt-icul(~~ral)~~i~ li~aturc\. Hr ,/ Radial Q:31+312. 1969 Ixvirw M. Zahoruk R: t)isk-marula r&~tionship itI diagx)ais ul wrtlcal muscle parcsis. .4m ,J Ophthalmol 7.1:20:! %!I. 1972 I.indcnburgR: Significance (11 the tcntorium in hc,ld injurle liom blunt lorcrs. C/in .Veum.cur,q IP: I?~1 II’. 1901) zyxwvutsrqponmlkjihgfedcbaZY 89 9(1 9l I.otwrnMd c.lic sp.*sm. IE:. ‘l‘hompstm HS: Oculomutor A critical rrvirw ol’thc litcraturc pawsis \cith (‘1 ,tnd a new vahc. .Sun Oph/halmol N:81-124. 1975 of zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDC LlcCZar-t) DJ: drthritir and.illied C.‘ondl/mn\. Philatlrlphi.c. 1.~~ & Frhiqrr. 1979. cd 9. p 762-8111 93 hlarsh IXJ. Dullry H. Krll! \‘: External ocular muter palsies in ophthalmic zostw: a rc\ iw. Nr,] Ophthalmol h‘l:677LhH2. I!)77 trst Tar diagnosis ofparah tic. ami/ 9-l 11azo1~ XII.: ‘l‘hc Iixtr-step 01 wsttictivc strabismus. ~~~~/~~~~~#~~,~~ #/jycic I397- 1IOIl. 1!17!l 0, Rowr ,J. Kiommcrclt G: Prcnuctrxr pxtw~\ III‘ 9.5 Llrirnbcrg 92 lil 62 Vi 0 I 96 (ii 97 Ijt) 98. I,i h~~molatcral i&c&r rcctub and c~mtralattw1 supcriol IIbli(lllv PVC musclrs. .4rrh .Veurol .‘~.~:2”11-2:~3. I078 .Hqrr E. Ludatschcr R\l. %unis S: Prim,irv ,tnd arxw~da~-\ wuac-tinq inferior ohliquc m udC s: a t, tIItr;lstru(.tllr,~l stud\ . ljr ,/ Ophthalmol &‘:4 lt&420. 1984 .\Iillrr 11’1‘. I!rist h1.J. Folk F:R. ct aI: Suptri<,r ~,blicluc pal\\ ptwscnting in late childhood. .-lm,] Ophthalmol i/l:2 IL’%2I+. 19711 .\littclman I), Folk E: ‘l‘hr cv;tluation and twatmwt ol’supvriOI oblqw musclr pair\ Tran\ Am .4~nd Ophthalmol Otnla~~n~rd zyxwvutsrqponmlkjihgfedcbaZYXWVUT H/:89:3-89X. 68 1976 zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA !I9 Orthoptir C:~~ngrcss, Amstcrdnm. lY71. cd 2. Lxwrpta hlctli( ‘I Intrrnational C:crngrcss Series. No 2 15. pp 26t;WI IUO. blumma,J\‘: Surgical prwcduw fur conqwital abscnw ol.thc bupcrillr ohliqur. :irch Ophthalmol !C’:22 lL223. I!)i-l IUI. 77 Llun~.lt ‘II., Barnrs JlX: Rrlatirm (11’multiptc t r‘m~l ncr\ dvsfunction to the Gulllain-B,trrc svndronw ,/.2*umi .V~rtro.rur,~ I’\vhia/rv X:1 15-120. I965 c 296 Surv Ophthalmol 30(5) March-April 1986 zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFE M ANSOUR, REINECKE 110. Park DM: Cranial nerve palsies in tetanus: cephalic tetanus. J Neural Neurosurg Psvchiatv 33:2 12-2 15, 1970 111. Parks MM: Isolated cyclovertical muscle palsy. Arch Ophthalmol60:1027-1035, 1958 112. Pate1 RP, Sorokin M: Cranial nerve palsy in tetany. Br MedJ 1:681, 1973 113. Pinchoff BS, Sandal1 G: Congenital absence of the superior oblique tendon in craniofacial dysostosis. Ophthalmic Surg 16.375-377, 118. 119. 120. 121. 122. 123. 124. 125. 126. 127. 128. 129. 130. 131. 132. 133. 134. 135. 136. 137. 138. 139. 140. 1978 dos musculos oculares. Arquivos 1959 143. Steele JC, Vasuvat A: Recurrent multiple cranial nerve palsies: a distinctive syndrome of cranial polyneuropathy. J Neural 142. Sousa M: Invulgar Portagueses 1975 114. Pollard ZF: Classilication and treatment of bilateral superior oblique palsy. Ann Ophthalmol 17:127-131, 1985 115. Porter JD, Guthrie BL, Sparks DL: Innervation of monkey extraocular muscles: Localisation of sensory and motor neurons by retrograde transport of horseradish peroxidase. J Camp New01 218:208-2 19, 1983 116. Posey WC: Concerning some gross structural anomalies of the muscles of the eye and its adnexa. Trans Am A cad Ophthalmol 117. ing trochlear nucleus. Exp zyxwvutsrqponmlkjihgfedcbaZYXWV Neural 51:684-698, 1976 141. Sohal GS, Weidman TA: Development of the trochlear nerve: loss of axons during normal ontogeny. Brain Res 142~445465, anomalia de Oftalmologia 11.6 l-65, Neurosurg Psvchratrv 33.828832, 1970 Sternberg I, Ronen S, Arnon N: Recurrent, isolated, postfebrile abducens nerve palsy. J Pediatr Ophthalmol Strabismus 17:323-324, 198 1 145. Sugimoto T, Mizuno N, Uchida K: Distribution of cerebellar liber terminals in the midbrain visuomotor areas: an autoradiographic study in the cat. Brain Res 238;353-370, 1982 146. Sundelin F: Die gold Behandlung der chronischen Arthritis. A cta Med &and (Suppl) 117:6% 287, 1941 28.243-257, 1923 147. Suzuki ,J, Wada ‘I‘, Kowada M: Clinical observations on tuRafuse EV, Arstikaitis M, Brent HP: Ocular findings in thalimors of the pineal region. J Neurosurg IQ:441-445, 1962 domide children. &:anJ Ophthalmol2:222-225, 1967 148. Sydnor CF, Seaher JH, Buckley EG: Traumatic superior Raskind RH: Acquired bilateral superior oblique palsy. Dot oblique palsies. Ophfha~mofogv 89: 134-138. 1982 Ophthalmol34:335-344. 1973 149. Symonds C: Recurrent multiple cranial nerve pa1sies.fA'ekroi zyxwvutsrqpo Reddy PS, Reddy RC, Satapathy M: Actiological study of the Neurosurg Psvchiatry 21:95-l 00, 1958 third, fourth and sixth cranial nerve paralysis. Indian JOphfhal150. Tandon PN: Tuberculous meningitis, in Vinken PJ, Bruyn GW (eds): Handbook of Clinical Neurologv? 1’ 0133, Part I. Amstermol 20:15%163, 1972 dam, North-Holland Publishing Company, 1978, p 213 Reynolds ,JD, Biglan AM’, Hiles DA: Congenital superior of afferent fi’bers in the 151. I‘aren JA: An anatomic demonstration oblique palsy in infants. Arch Ophthalmol 102:1503-1505, 1984 IV, V, and VI cranial nerves of the macaca mulatta. Am J Rintelen F: Trochlearisparese. Med W elt (Stuttgart) 18: 165& Ophthalmol 58:408-412. 1964 1651, 1977 152. Trautmann JC, Barnett CR: Diseases of the third, fourth, and Robert CM, Feigenbaum JA, Stern WE: Ocular palsy occursixth cranial nerves, in Dyck PJ! Thomas PK, Lambert EH, et ring with pituitary tumors. J Neurosurg 38:17-19, 1973 al (eds): Peripheral Neuropathv, Vol2. Part B. Philadelphia, WB Rosenbaum AL, Carlson MR, Gaffney R: Vertical saccadic Saunders, 1984, ed 2. pp 1203-1223 velocity determination in superior oblique palsy. Arch Ophthal- zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCB artcriovenous communica153. Troost ‘I, Glaser ,JS: .i\neurysms, mol 95:821-823, 1977 tions, and related vascular malformations, in Duane TD (ed): Rosenberg ML, Glaser JS: Superior oblique myokymia. Ann Clinical Ophthalmologv. 1’01 2. Philadelphia, Harper and Row, ,Veurol /3:667-669, 1983 1980, pp 14-22 Rougier.J, Girod M, Bongrand M: Considerations sur l’etioloSV: Cyclotropia. Am Orthoptic J 22:36-43, 1972 154. Troutman qie et sur la rCcupera_tion des paralysies du pathetique, en 155. Tychsen 1,. Tse DT, Ossoing K, et al: Trochleitis with superior milieu neurologique. A propos de 40 observations. Bull .Soc ohlique myositis. Ophthalmologv 91: 1075-1079, 1984 Ophtalmol Fr 73:739-744, 1973 156. Umansky F, Nathan H: The lateral wall of the cavernous Rucker CW: The causes of paralysis of the third, fourth, and sinus. With special reference to the nerves related to it. JNeurosixth cranial nerves. Am J Ophthalmol 61:1293-1298, 1966 turg 56t228234, 1982 Rush ~JA: Isolated superior oblique paralysis in progressive 157. Urich H: Pathology of tumors of cranial nerves. spinal nerve systemic sclerosis. Ann Ophthalmol 23:217-220, 1981 roots, and peripheral nerves, in zyxwvutsrqponmlkjihgfedcbaZY Dyck PJ, Thomas PK. LamRush JA, Younge BR: Paralysis ofcranial nerves III, IV and bert EH, et al (eds): Peripheral Neuropathy. Lb1 2. Philadelphia, VI - cause and prognosis in 1000 cases. Arch Ophthalmol WB Saunders, 1984, ed 2, pp 2253-2599 99:76-79, 1981 158. Urist MJ: Bilateral superior oblique paralysis. Arch Ophthalmol SacksJG: The levator-trochlear muscle. A supernumerary or49:382-391, 1953 bital structure. Arch Ophthalmol 303:54% 541, 1985 paralysis. 159. Van Senus AHC: Missed diagnosis of trochlear Samii M, Jannetta PJ: The Cranial Nerves. Anatomy, Patholo~cv’ . Ophthalmologica t&:242-243, 197 1 Pathophysiologv, Diagnosis, Treatment. Berlin. Springer-Verlag, 160. Vazquez RI,: A graphic three step test. Arch Ophthalmol 102: 1981 98-99, 1984 Sanfilippo S: Acquired ocular palsy in children. Am Orthoptic J 161. von Noorden GK: Clinical and theoretical aspects of cyctotro27~134-137, 1977 pia. J Pediafr Ophihalmol Strabismus 27: 12t% 132, 1984 ScharfJ, Meyer E, Zonis S: Trochlear nerve palsy in a case of in cyclodeviations. 162. von Noorden GK: Clinical observations herpes roster ophthalmicus. Ann Ophthalmol t/:568-570, 1979 Ophthalmology 86: 145 I- 146 1, I979 Schellenbeck R: Agenesie des Musculus obliquus superior-Ein Baltimore, 163. Walsh FB, Hoyt WF: Clinical Nemo-ophthalmologv. Fallbericht. Klin Monatsbl Augenheilkd 160:70~710. 1972 Williams and Wilkins, 1969. ed 3, pp 235-236, p 1934 Scott WE, Naukin SJ: Isolated inferior oblique paresis. Arch 164. Ware CFW: Superior oblique myokymia of Hoyt and Keane. Ophthalmol 95.15861593, 1977 Dot Ophthalmologica 44; 173-l 78, 1977 Scott WE: Dilferential diagnosis of vertical muscle palsies, in of the 165. Weidman TA. Sohal GS: Cell and liber composition Helveston EM et al (ed): New Orleans Strabismus Symposium. St trochlear nerve. Brain Res 125:34&344, 1977 Louis, CV Mosby, 1978, pp I18134 166. Whitlield R, Wirostko E: Ocular syphilis, in Locatcher-KhorScully RE, Galdabini JJ, McNeely zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA BU: Case records of the azo D (rd): Microbiologv oJthe Eve. St Louis. CV Mosby, 1972, Massachusetts General hospital - Weekly clinicopathological pp 3’12-349 exercises, case 36-1976. N Engl J Med 295:553-561, 1976 167. Whitnall SE: An instance of the retractor bulbi muscle in man. Seaber JH: Clinical evaluation of superior oblique function. J Anat Phvsiol 46:36-40, 1911 Am Orthoptic J24:13-17, 1974 168. Wise J, Gomolin ,J, Goldberg LL: Blaterat superior oblique Shallat RF, Parol RP, Jerva MJ: Significance of upward gaze palsy: diagnosis and treatment. Can J Ophthalmol 18:2832, palsy (Parinaud’s syndrome) in hydrocephalus due to shunt 1983 malfunction. J Neurosurg 38:717-721, 1973 169. W olff E: Anatomy of the Eye and Orbit, revised by Roger Silverstein A, Feuer MM, Siltzbach LE: Neurologic sarcoidoWarwick, Philadelphia and Toronto. WB Saunders, 1976. ed sis - study of I8 cases. Arch Neural 12:1-1 1, 1965 7, pp 291-292 Sohal GS: An experimental study of cell death in the developneurologic complications. II’zsc 170. Woltman HW: Postoperathze 144. CENTRAL TROCHLEAR PALSY 297 F. Central nervous system disorders G. Neoplasms of the central nervous system 17 I. Wray SH: Neuro-ophthalmologic manifestations of pituitary H. Congenital-idiopathic causes and parasellar lesions. C/in Neurosurg 24:8&l 17, 1977 I. Miscellaneous 172. Wright HG. Honsotia I’: Isolated fourth cranial nerve palsies: J. Cyclic and recurrent phenomena etioloev and urognosis. Wise .Med 1 76~2628, 1977 V. Recoverv of afFected ocular motor nerves F: Analysis 0’: trochlear nerve palsies 173. Younge BR, &&a VI. Diagnosis Diagnosis, etiology and treatment. MU_YO Clinic Proc 52:l l-18, A. Amblyopia 1977 B. Hypertropia bei intra174. Zielinski HW: Paresen der auBrren Augen-muskeln C. Horizontal deviation kraniellen raumfordernden Prozessen - ein Uberblick die D. Head posturre Beobachtungen an uber 3000 fallen. zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Zbl Neurochir 29.235-251, E. Cyclodeviation 1959 F. Saccadic velocity VII. Differential diagnosis Outline A. Head posture I. ,\natomy of’ the rrochlear nerve B. Vertical palsies II. Physiology of the trochlear nerve I Statistical data III. Embryology of the ttochlear nerve 2. Normal variants IV. Etiology of isolated trochlear palsy :<. Primary versus secondary inltrior (2. Trauma oblique overaction B. Vascular disorders C. Central causes of vertical gaze palsies I Ijiabetcs mellitus D. Simulated unilateral superior oblique 2. Atherosclerosis and hypertension muscle palsy :3. Aneurysms 1. The three-step test 1. Infratentorial arteriovenous malformations 2. Additional diagnostic steps 5. Migraine 3. “Masked” bilateral trochlrar palsy (:, Inflammatory disorders I. .1cute meningitis 2. ‘Tuberculous meningitis Supported in part by the Lebanese Council for Srientilic RF.<. Ncutologic sarcoidosis search. 1. Ocular motor syphilis Reprint requests should be addressed to Robert D. Reinecke, 5. Miscellaneous M.D., Wills Eye Hospital, Ninth and Walnut St., Philadelphia, PA 1). (:ollagen-vascular diseases 19107. E. ‘I‘oxic substances Yl