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Show Journal of Nemo- Ophthalmology 14( 1): 52- 54, 1994. 1994 Raven Press, Ltd., New York Isolated Trochlear Nerve Palsy Secondary to Dural Carotid- Cavernous Sinus Fistula Aki K. Selky, M. D., and Valerie A. Purvin, M. D. Ophthalmoplegia associated with dural carotid- cavernous sinus fistula typically involves the third, fourth, and sixth cranial nerves. Occasionally, isolated palsy of the oculomotor or abducens nerve is noted. We report a patient with bilateral dural carotid- cavernous sinus fistulas who presented with an isolated trochlear nerve palsy. Key Words: Trochlear nerve palsy- Ophthalmoplegia- Carotid- cavernous sinus fistula- Cavernous sinus. Common ophthalmic manifestations of dural carotid- cavernous sinus fistulas include episcleral venous distension and tortuosity, conjunctival and lid edema, proptosis, elevated intraocular pressure, and ophthalmoplegia. Isolated oculomotor nerve or isolated abducens nerve palsy has rarely been reported as the sole clinical finding of a symptomatic dural carotid- cavernous sinus fistula ( 1- 3). We describe a patient whose initial presentation of a dural carotid- cavernous sinus fistula was a painful superior oblique palsy, which spontaneously improved over several weeks. We believe this is the first reported case of an isolated trochlear nerve palsy due to a dural carotid- cavernous sinus fistula. From the Midwest Eye Institute, Methodist Hospital of Indiana, and Departments of Ophthalmology and Neurology, Indiana University Medical Center, Indianapolis, Indiana, U. S. A. Address correspondence and reprint requests to Dr. Aki K. Selky, Midwest Eye Institute, 1800 N. Capitol Avenue, Indianapolis, IN 46202, U. S. A. CASE REPORT A 52- year- old woman experienced sudden onset of severe, bifrontal headaches. These headaches were unlike her " monthly migraine" headaches which typically resolved with sleep. Three weeks later, she noted vertical diplopia. Examination by her local ophthalmologist revealed a 6 prism diopter left hypertropia, which on three- step testing was consistent with a left superior oblique palsy. A head computed tomography scan was negative. Over the next 3 weeks, the patient's vertical diplopia cleared spontaneously. Her headache also decreased in severity and became localized to the left periorbital area. A head magnetic resonance scan was negative. The patient was referred to Midwest Eye Institute for further evaluation and management of her left periorbital pain. Past medical history was significant for menstrual migraine and borderline hypertension. There was no history of trauma. Current medications were Lodine and acetominophen. On examination, visual acuity was 20/ 20 OU. Pseudoisochromatic plates, Goldmann perimetry, 52 TROCHLEAR NERVE PALSY 53 brightness comparison, and funduscopy were normal in both eyes. Pupils were 7 mm OU and briskly reactive with no afferent pupillary defect. There was no proptosis. Biomicroscopy was unremarkable. Intraocular pressures were 21 mm OU. A 1 prism diopter hyperphoria in the primary position was detected by Maddox rod and increased to 2 prism diopters on right gaze and on left head tilt. Ductions and versions were full, pursuit was smooth, saccades were brisk and accurate. There was 2.5 degrees left excyclotorsion by double Maddox rod testing. No bruits were auscultated and the remainder of the neurologic examination was normal. One week later, the patient reported the appearance of a spontaneous " bruise" under her left eye and a self- audible bruit. Repeat examination confirmed a small subcutaneous ecchymosis along the lateral margin of the left lower lid as well as mild left periorbital soft tissue swelling and mild conjunctival injection. There was now 3 mm of left proptosis by Hertel measurements and intraocular pressures of 21 mm OD and 26 mm OS. Motility was unchanged. No objective bruit was auscultated. Orbital computed tomography showed enlargement of the left superior ophthalmic vein. Cerebral angiography demonstrated bilateral dural carotid- cavernous sinus fistulas supplied by both cavernous internal carotid artery branches. Venous drainage was primarily via the ophthalmic veins, pterygoid plexus, and petrosal sinuses bilaterally. Coil embolization into the left cavernous sinus via the inferior petrosal sinus resulted in immediate resolution of the patient's left eye pain, proptosis, and subjective bruit. However, 1 month later, she complained of new right retro- orbital pain and pulsatile tinnitus in her right ear. There was no ocular congestion or ophthalmoplegia, but a right orbital bruit was audible. Intraocular pressures were 24 mm OD and 17 mm OS. A similar embolization was successfully performed for the newly symptomatic right dural carotid- cavernous sinus fistula. DISCUSSION A dural carotid- cavernous sinus fistula becomes symptomatic when its fistular flow is predominantly shunted into the superior ophthalmic vein. This leads to orbital venous engorgement and subsequent soft tissue congestion ( 1). A fulminant carotid- cavernous sinus fistula syndrome is easily recognized by the severe periorbital swelling, massive chemosis, proptosis, objective bruit, distended " corkscrew" episcleral veins, raised intraocular pressure and ophthalmoplegia. Because of the slow- flow, low- pressure nature of dural carotid- cavernous sinus fistulas, these classic manifestations may be present in lesser and varying degrees. Occasionally, the only finding is an oculomotor or abducens palsy in a patient with nonspecific head or eye pain ( 1- 3). An isolated trochlear nerve palsy due to a dural carotid-cavernous sinus fistula has not been previously reported. Our patient with bilateral dural carotid- cavernous sinus fistula presented with headache and a unilateral transient fourth nerve palsy. Symptomatic diplopia cleared in 2 weeks, and by 3 weeks only a minimal vertical phoria was demonstrated. A dural carotid- cavernous sinus fistula may cause ophthalmoplegia secondary to engorgement of extraocular muscles; however, this mechanism seems unlikely in our patient's case. Signs and symptoms of ocular congestion were just emerging as the superior oblique palsy was improving, and an orbital computed tomography scan showed no muscle enlargement at any time during her clinical course. The sudden onset and subsequent spontaneous recovery of our patient's trochlear nerve palsy does resemble " garden-variety" vasculopathic fourth nerve palsy. However, the severe persistent headaches that preceded her diplopia and rapid resolution of her vertical deviation would be highly atypical for this entity. The exact mechanism of fourth nerve palsy in dural carotid- cavernous sinus fistula is unclear. Compromise of the nerve within the cavernous sinus is typically accompanied by paresis of oculomotor and abducens nerves. Nevertheless, isolated trochlear nerve palsy due to other disorders of the cavernous sinus has been previously reported. Slavin ( 4) described a patient with an isolated fourth nerve palsy secondary to a cavernous sinus meningioma. Arruga and colleagues ( 5) reported a patient with an isolated fourth nerve palsy secondary to an intracavernous carotid artery aneurysm and cited two other cases from the literature. These authors postulated the mechanism of injury to be either direct, long- standing compression causing a chronic fourth nerve palsy or an ischemic insult, resulting in a transient fourth nerve palsy. We suggest an alternative mechanism of injury for a transient isolated trochlear nerve palsy due to carotid- cavernous sinus fistula. We speculate there is intermittent compression of the trochlear nerve / Neuw- Ophtlmlmol, Vol. 14, No. 1, 1994 54 A. K. SELKY AND V. A. PURVIN against the tentorial edge by a distended superior petrosal vein engorged from the additional flow burden of a posteriorly draining carotid- cavernous sinus fistula. A comparable mechanism has been proposed by Leonard and colleagues ( 3) to explain transient sixth nerve paresis in carotid- cavernous sinus fistula. In their model the abducens nerve is intermittently compressed against the pet-roclinoid ligament by an enlarged inferior petrosal sinus. Dural carotid- cavernous sinus fistula should be included in the differential diagnosis of isolated superior oblique palsy, especially if accompanied by ipsilateral head or eye pain. Addendum. After this paper was accepted for publication, the authors became aware of a prior similar case described by Kosmorsky and colleagues in their series entitled " Carotid- Cavernous Fistulae Presenting as Painful Ophthalmoplegia Without External Ocular Signs." Reference: / Clin Neuro- ophthalmol 1988; 8: 131- 135. The clinical course and outcome of their patient was not described. REFERENCES 1. Hawke SHB, Mullie MA, Hoyt WF, Hallinan JM, Halmagyi GM. Painful oculomotor nerve palsy due to dural-cavernous sinus shunt. Arch Neurol 1989; 46: 1252- 5. 2. Sempere AP, Menendez BM, Alvarez CC, Hoenigsfeld LC. Isolated oculomotor nerve palsy due to dural cavernous sinus fistula. Eur Neurol 1991; 31: 186- 7. 3. Leonard TJK, Moseley IF, Sanders MD. Ophthalmoplegia in carotid cavernous sinus fistula. Br / Ophthalmol 1984; 68: 128- 34. 4. Slavin ML. Isolated trochlear nerve palsy secondary to cavernous sinus meningioma. Am / Ophthalmol 1987; 104: 433- 4. 5. Arruga J, De Rivas P, Espinet HL, Conesa E. Chronic isolated trochlear nerve palsy produced by intracavernous internal carotid artery aneurysm: report of a case. / Clin Neuro- ophthalmol 1991; 11: 104- 8. / Neuro- Ophthalmol, Vol. 14, No. 1, 1994 |
