Journal of Neuro-Ophthalmology, June 1989, Volume 9, Issue 2

Bilateral trochlear nerve paresis in hydrocephalus.

Three patients with nonneoplastic hydrocephalus had bilateral paresis of the trochlear nerves. Associated signs, including paresis of upgaze, light-near dissociation of the pupils, and convergence-retraction nystagmus, suggested rostral involvement of the mesencephalon. Trochlear nerve paresis and accompanying signs improved after revision of ventricular shunts in two patients. Bilateral trochlear nerve paresis may be a localizing sign of involvement of the superior medullary velum (the anatomic site of trochlear nerve decussation) by a dilated sylvian aqueduct and/or downward pressure from an enlarged III ventricle.

Journal of Clinical Neuro- ophthalmology 9( 2): 105-- 111. 1989. Bilateral Trochlear Nerve Paresis in Hydrocephalus John R. Guy, M. D., William F. Friedman, M. D., and J. Parker Mickle, M. D. ~ 1989 Raven Press, Ltd., New York TIuee patients with nonneoplastic hydrocephalus had bilateral paresis of the trochlear nerves. Associated signs, including paresis of upgaze, light- near dissocia­tion of the pupils, and convergence- retraction nystag­mus, suggested rostral involvement of the mesenceph­alon. Trochlear nerve paresis and accompanying signs improved after revision of ventricular shunts in two pa­tients. Bilateral trochlear nerve paresis may be a localiz­ing sign of involvement of the superior medullary velum ( the anatomic site of trochlear nerve decussation) by a dilated sylvian aqueduct andJor downward pressure from an enlarged III ventricle. Key Words: Trochlear nerve paresis- Hydrocephalus­Parinaud's syndrome. From the Departments of Ophthalmology O. R. G.), Neuro~' ogy O. R. G.), and Neurosurgery o..~. G., ~_ F. F.: J. P. M- l" Urn­versity of Florida, College of MediCIne, Gal1lesviJIe, Flonda. Address correspondence and reprint requests to Dr. Joh~ Guy, Neuro- Ophthalmology Serv~ ce, JHM. HC ~ ox J- 284, Unt­versity of Florida, College of MediCIne, Gamesville, FL, 32610, U. S. A. 105 Hydrocephalus may be associated with signs of rostral involvement of the midbrain. These include paresis of upgaze ( Parinaud's syndrome), light­near dissociation of the pupils, and convergence­retraction nystagmus ( 1- 3). Ventricular dilatation may also result in compression of the anterior vi­sual pathways ( 4). While paresis of the trochlear nerves may occur with involvement of the superior medullary velum by tumor ( 5) or traumatic contu­sion ( 6), the associated signs and likely mechanism of trochlear nerve paresis has not been fully de­scribed ( 2,7,8). We report three patients with bilat­eral trochlear nerve paresis and nonneoplastic hy­drocephalus. CASE REPORTS Case 1 A 33- year- old woman complained of vertical diplopia, somnolence, and difficulty with short­term memory for 6 months. Similar symptoms had resolved after placement of a ventriculoatrial shunt for hydrocephalus 1 year earlier. Nelio- ophthalmic examination revealed visual acuity to be 20/ 50 in the right eye and 20/ 40 in the left eye. The pupils measured 7 mm and were slowly reactive to light, with a right afferent defect. Goldmann visual fields showed enlarged blind spots and generalized constriction in both eyes. There was paralysis of upgaze, although Bell's phenomenon and oculocephalic maneuvers pro­duced upward eye movements. Convergence­retraction nystagmus was elicited with attempts at upward gaze. Motility measurements revealed a 10 PO right hypertropia in primary gaze, which increased to 16 PO in left gaze and changed to 5 PO of left hypertropia in right gaze. Consistent with bilateral trochlear nerve paresis, the right hyper­tropia increased to 14 PO with right head tilt and 106 f. R. GUY ET AL. the left hypertropia was 5 PO with left head tilt. Double- Maddox rod testing detected 100 of excy­c1otorsion of the right globe and 50 of excyclodevi­ation of the left globe. Abduction of the left eye was limited to 80' lr of normal, with a 4- PD esotro­pia in primary gaze that increased to 14 PO of es­otropia in left gaze and was absent in right gaze. Ophthalmoscopy disclosed chronic papillede­ma. Neurologic examination revealed bilateral trochlear and left abducens nerve paresis, truncal ataxia, bilateral hyperretlexia, and extensor plantar responses. Computerized tomography ( CT) showed en­largement of the lateral and IIIrd ventricles, with dilation of the suprapineal recess ( Fig. 1). A shunt tap had an opening pressure of 130 mm. Analysis of the cerebrospinal fluid ( CSF) revealed the fol­lowing: protein, 14 mg/ dl; glucose, 75 mg/ dl; 216 red blood cells/ mm3 ; and no white blood cells. A ventriculoperitoneal shunt was placed, and the pre- existing shunt was left undisturbed. In or­der to relieve vertical diplopia, an 8 PO Fresnel prism was placed basedown over the right eye. Two years later, visual acuity had improved to 20/ 25 in each eye. Papilledema, upgaze paresis, FIG. 1. CT scan of case 1 showing hydrocephalus with dilation of the ~ uprapmeal recess of the IIlrd ventricle ataxia, abducens nerve paresis, and long tract signs had resolved. Mild bilateral trochlear nerve paresis persisted with a 4- PD right hypertropia in primary gaze, although the patient no longer re­quired the Fresnel prism. Magnetic resonance im­aging ( MRI) showed resolution of the hydroceph­alus. Case 2 A 16- year- old boy complained of headaches and transient visual obscurations for 3 weeks. An en­larged head circumference had facilitated the diag­nosis of hydrocephalus when he was 1.5 years of age, although this was conservatively managed. Neuro- ophthalmic examination revealed visual acuity of 20/ 30 in the right eye and 20/ 20 in the left eye. The pupils were 4 mm and briskly reactive to light. An afferent defect was absent. Goldmann visual fields revealed an incongruous left inferior homonymous quadranopsia. Motility examination disclosed the absence of a vertical deviation in primary gaze; however, in right gaze there was a 12 PO left hypertropia. In left gaze, a 9 PO right hypertropia was seen. With right head tilt, a 6 PO right hypertropia was present; with left head tilt, a 5 PO left hypertropia was elicited. These measurements were consistent with bilateral trochlear nerve paresis. An 8 PD es­otropia was also present in all positions of gaze. Eye movements were full, although upward sac­cades and convergence- retraction nystagmus were not elicited with downward movement of an OKN tape. Ophthalmoscopy revealed bilateral optic atro­phy and confirmed the excyclotorsion of haplo­scopic testing ( Fig. 2). Neurologic examination dis­closed a left hemiparesis and bilateral extensor plantar responses. CT scans showed dilation of the lateral and lllrd ventricles ( Fig. 3) but no intrinsic striate nor para­striate lesion to account for the left inferior hom­onymous quadranopsia. While cytologic examina­tion of the CSF revealed the absence of malignant cells and microorganisms, the remainder of the CSF analysis was not documented in the patient's medical records. One week after placement of a ventriculoperitoneal shunt, the transient visual ob­scurations had resolved, although the patient's neuro- ophthalmic examination was unchanged. He failed to return for follow- up examinations. Case 3 A 23- year- old woman complained of diplopia, nausea, vomiting, vertigo, and ataxia for 3 weeks. TROCHLEAR NERVE PARESIS IN HYDROCEPHALUS 107 FIG. 2. Optic atrophy involving the temporal sectors of both the right ( A) and left ( 8) eyes of case 2. Excyclotorsion is also evident. Headaches were absent. After a bout of meningi­tis, communicating hydrocephalus had been treated with a ventriculoperitoneal shunt 3 years earlier. Neuro- ophthalmic examination revealed that vi­sual acuity was 20/ 20 in each eye. The pupils, mea­suring 7 mm, were sluggishly reactive to light, contracting to 5 mm, but briskly reactive to accom-modation, contracting to 3 mm. Papilledema was absent. Eye movements showed bilateral limitation of upgaze to 10% of normal and a right abduction deficit to 90% of normal ( Fig. 4). Upgaze was ac­companied by bursts of convergence- retraction nystagmus. Lancaster red- green testing revealed a right hypertropia in left gaze and right head tilt, AG. 3. Coronal magnetic resonance imaging o, f case ~ sh? wing enlarge. ment of anterior ~ A) ( arrow) and posterior IIlrd ventricle ( arrow) in proximity to the superior colhcuh ( arrowhead) In the rostral bralnstem ( Sr) ( 8). I Ct/ ll Nturo · ophtlUllnwl, Vol. 9, No. 2. 1989 108 f. R. GUY ET AL. FIG. 4. Eye movements of case 3 showing limitation of upgaze. bilateral trochlear nerve paresis. and a right abducens paresis. Bagolini lenses demonstrate excyclotorsion. but a left hypertropia in right gaze and left head tilt, consistent with bilateral superior oblique pare­sis ( Fig. 5). Bagolini lenses oriented with the ver­tical streak at 90°, and when the right lens was rotated until the patient perceived the two lenses to be paraJlel, a combined excyclotorsion of 30° was revealed. Neurologic examination showed truncal ataxia, a mild left hemiparesis, and a left Babinski sign. Communicating hydrocephalus with enlargement of the lateral, IIIrd, and IVth ventricles was imaged on CT scanning. Two months after a shunt revision, full abduc­tion and supraduction returned ( Fig. 6). Although improved, bilateral trochlear nerve paresis did not resolve untiJ 5 months after surgery. DISCUSSION Bilateral paresis of the trochlear nerves was clearly associated with nonneoplastic hydrocepha­lus in this series of patients. The criteria necessary for diagnoqjq of trllchlear nerv paresis, e tab­!.. ~ ., • '. .: "',' I~~.:,. l. ( 4,10) were fulfilled by all patients. While a skew deviation may be responsible for a hypertropia with lesions involv­ing the brainstem ( 3,11- 16), skew is a diagnosis of exclusion. A vertical deviation that does not con­form to a pattern resembling paresis of a particular ocular motor nerve or extraocular muscle ( 17) and the absence of cyclodeviation are characteristics of skew deviation ( 18). Moreover, alternating hyper­tropias that increase in abduction are usually ob­served with skews ( 14-- 16). This is in contrast to the hypertropias of superior oblique paresis, which increase in adduction. The motility pattern, head tilt, and excyclodeviation of our patients best conformed with paresis of the trochlear nerves. While all of our cases had signs and symptoms attributable to elevation of intracranial pressure, only the first had papilledema. It is unlikely that trochlear nerve paresis is a nonspecific effect of increased intracranial pressure, since it rarely ac­companies pseudotumor cerebri ( 19,20), a nonlo­calizing etiology of abducens paresis. The incongruous left inferior homonymous quadranopsia of our second case suggested com­pression of the right optic tract by the enlarged TROCHLEAR NERVE PARESIS IN HYDROCEPHALUS 109 os FIX B H _ 0 __•. _ DIACNOIII - ----: r......,..--,......""-; 0=------- TILT RIGHT ' SUMMAI't Of flNO. fIIGS 20 I I II I ' 0 . to- - I I ~ '- . I 12 I : , fT 8 , I 0 I4 II , . 2, 20- j8- 16- 14- 1' 2- - 1- 6- 4- 2- 0- 1- 4- 0- 1- -' 2- 10- 10- 18- 20 I 2, 0 " 1- - ..,.. I l- ~ .. 8 . , I 12, 10, 10 , ,. I 20 OS F I X A H , ~ _ 0 1' _ 00 _ ..' --.:,-,;;----;:;:-;_ • ..- _ NO TILT 20 I" , ' 6 I -'" ' 0 I I -. 12 - I · -~.. ~ I -'-. I 6, ; 0 , . 2 · I ~ 20- 11- r- · 0 - 11 - - 1- 6- 0- 2-?- 2- 0,6- 1- - 11-'.- 16- 11-' 20 I 2I I 0 · I . 6 . ... I! I -,- 1 , I r-..,~ _ . ' 0 I ' 6 I " I 20 00 FI X D H _ 0 _ OfAOI< tOSII_ ----.,-;--;--;;;;---, C--...... c=------ TILT LEFT 20 , II, 16, _ 10- 0 -~ 1\ 12 1... 1,000 .- , 1\ 1\. .,... -<- .- .- . I 1 " · , 0I I 0 ~ : \ ~, I r l~ " lO- IB- 16- 14- 12- IP • - 6-. - ' 2 - 0 - ' 2-" - 6- '- r-' 2 0-' 0- 18- 20 • ~ !. ool I ~ ......~ I.- iooo'" , · 1\ ~~~, I 1 :-. I · ~ 8- .,... , 1- . 11 I 10, 10 , I. I 20 00 FI X c O. A(; ItIfOSt5" .....-:;;:-_-=~'~~------- NO TILT SUMM". 1 Of "' NOINGS H ~_ o ~ _ 20 I II I 16, 10 I L. oo~ .- .... 1' 2. ~ .... I ......~ · L. o-' .... , -, 6 . , I 0 I , • 2 ' 20- 18- 16- 1.- 12-'~- 8- 6 I .. - 2- 0- 1- 4- 6- 1- 1 - 12- - 1. - 18- 20 - j • ~ j I0 • I · 0 ....... 1 ~- • I ~ -~ - .~ l; Io"~ ~ .... I 10 I 10 I 18 I 20 FIG. S. Lancaster red- green of case 3 demonstrating right hypertropia in left gaze ( A) that increases with right head tilt ( B) and demonstrating left hypertropia in right gaze ( C) that increases with left tilt ( 0). IIlrd ventricle ( 4). The lack of intrinsic striate or parastriate lesions on CT scanning and the oph­thalmoscopic absence of bowtie atrophy excluded a congenital etiology of the visual field defect. The neuro- ophthalmic signs associated with ros­tral involvement of the midbrain ( 1,2,4,21- 28), suggesting periaqueductal dysfunction, accompa­nied bilateral trochlear nerve paresis in two of our cases with hydrocephalus. Supranuclear paresis of upgaze, sluggishly reactive pupils to light, and convergence- retraction nystagmus improved after revision of the ventricular shunts in these two I Clin N, uro- ophtluzlmol, Vol. 9, No. 2. 1989 110 J. R. GUY ET AL. FIG. 6. Two months after revision of the shunt, full abduction and elevation returned, accompanied by improve­ment of the bilateral trochlear nerve paresis in case 3. cases. In the other, upward saccades-- absent with the OKN tape moving down- indicated subtle su­pranuclear upgaze involvement, although supra­duction was normal. While hydrocephalic dilation of the sylvian aqueduct may affect the adjacent pupillary and vertical gaze centers in this region of the mesencephalon, only our third case, with com­municating hydrocephalus, had this radiographic finding ( Table 1). Consequently, an alternative mechanism may be involved. In this series, the presence of bilateral trochlear nerve paresis associated with nonneoplastic hy­drocephalus suggested involvement of the supe­rior medullary velum, the anatomic site of decus­sation of the trochlear nerves. The presence of uni-lateral or bilateral trochlear nerve dysfunction ( and accompanying signs, if any) and plausible mecha­nisms were not discussed in the three cases with hydrocephalus listed in Rush and Younge's series of 172 cases of trochlear nerve paresis ( 7) or in the single case of hydrocephalus in Ellis and Helveston's review of 130 cases of trochlear nerve paresis ( 8) ( Table 2). Cobbs and co- workers pointed out the relationship of hydrocephalus to trochlear nerve paresis ( 2). They believed the mechanism to be compression of the superior TABLE 2. Literature summary of trochlear paresis and hydrocephalus Bilateral Improved Number trochlear Other after Series of cases paresis signs shunting TABLE 1. Summary of bilateral trochlear paresis and hydrocephalus Ellis & Unknown Unknown Unknown Helveston Case Enlarged Parinaud's Improved ( 8) Rush & 3 Unknown Unknown Unknown number sylvian aqueduct syndrome after shunting Younge ( 7) 1 No Yes Yes Cobbs et aL 4 Yes Parinaud'S Yes 2 No No Unknown ( 2) ( 4) .: Yp. s Yes Yes Guayndetparle. sent stUdy 3 Yes Pa( r2i) naud's Yes ( 2) TROCHLEAR NERVE PARESIS IN HYDROCEPHALUS 111 REFERENCES Acknowledgment: Supported in part by an unre­stricted departmental grant from Research to Prevent Blindness, Inc. FIG. 7. Dilation of the suprapineal recess of the IlIrd ventricle ( large curved arrow) may exert downward pressure on the superior medullary velum ( arrowhead) at the level of the inferior colliculus. 3. Cogan OJ. Convergence nystagmus. Arch Ophthalmol 1959; 62: 295-- 9. 4. Osher RH, Corbett Jj, Schatz NJ, Savino PJ, Orr lS, Neuro­ophthalmic complications of the third ventricle. Br 1 Oph­tha/ mol 1978: 62: 536- 42, 5. Murray RS, Ajax ET. 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Sylvian aqueduct syndrome as a sign of acute obstructive hydrocephalus in children. 1Neu­rot Nellrosllr.~ PiOychiatr 1975; 38: 288- 97. Callie Ius .. , ~.,.. .:. Y ;.,. r' \ 1. Shallat RF, Parol RP, lerva MJ. Significance of upward gaze palsy ( Parinaud's syndrome) in hydrocephalus due to shunt malfunction. j Neurosurg 1973; 38: 717-:- 21. . . 2. Cobbs WH, Schatz NJ, Savino Pl · Midbram eye signs m hydrocephalus [ Abstractl. Ami Neurol 1978; 4: 172. medullary velum by the dilated suprapineal recess of the ITlrd ventricle ( this rostral pressure on the dorsal mesencephalon is illustrated in Fig. 7). However, Cobbs et al. noted the appearance of neuro- ophthalmic signs prior to ventricular en­largement on CT scanning. Dilation of the sylvian aqueduct may have con­tributed to the signs of periaqueductal dysfunction ( 1) and bilateral trochlear nerve paresis in our third case. However, aqueductal stenosis in the others suggested that rostral compression of the dorsal midbrain, including the superior medullary ve­lum, by the downward force exerted with expan­sion of the suprapineal recess of the IIIrd ventricle may be the alternative mechanism ( 1,2). I CIiTl NeuTa- ophtha/ mol, Vol. 9. No. 2. 1989