Journal of Neuro-Ophthalmology, December 1994, Volume 14, Issue 4

Hemifacial spasm. An unusual manifestation of idiopathic intracranial hypertension.

Increased intracranial pressure may produce a variety of clinical manifestations, some common and others rare. We present a patient with idiopathic intracranial hypertension whose initial symptom was hemifacial spasm. All signs and symptoms of intracranial hypertension resolved with acetazolamide.

Journal of Neuro- Ophthalmology 14( 4): 196- 198, 1994. 1994 Raven Press, Ltd., New York Hemifacial Spasm An Unusual Manifestation of Idiopathic Intracranial Hypertension Aki K. Selky, M. D., and Valerie A. Purvin, M. D. Increased intracranial pressure may produce a variety of clinical manifestations, some common and others rare. We present a patient with idiopathic intracranial hyper­tension whose initial symptom was hemifacial spasm. All signs and symptoms of intracranial hypertension re­solved with acetazolamide. Key Words: Hemifacial spasm- Idiopathic intracranial hypertension- Pseudotumor cerebri. Idiopathic intracranial hypertension also known as pseudotumor cerebri, is a clinical syndrome of increased intracranial pressure in the absence of a mass or hydrocephalus and with normal spinal fluid constituents. Symptoms typically associated with elevated intracranial pressure include head­ache ( 94%), transient visual obscurations ( 68%), in­tracranial noises ( 58%), photopsias ( 54%), diplopia ( 38%), and visual blur or field loss ( 30%) ( 1). Round and Keane ( 2) profiled some of the less common clinical manifestations of elevated intra­cranial pressure among 101 patients with idio­pathic intracranial hypertension. These included paresthesias ( 22%), arthralgias ( 13%), back or leg pain ( 5%), and ataxia ( 4%). Involvement of cranial nerves other than optic and abducens nerves is another uncommon man­ifestation of intracranial hypertension. There are sporadic reports of oculomotor, trochlear, trigem­inal, facial, and hypoglossal nerve palsies that re­solved with lowering of the elevated intracranial pressure ( 3- 9). In this paper, we describe a patient whose presenting symptom of idiopathic intracra­nial hypertension was transient facial nerve dys­function. However, unlike previously reported cases, our patient had hemifacial spasm, a syn­drome of facial nerve hyperexcitability, rather than facial nerve palsy. From the Division of Neuro- ophthalmology, Midwest Eye Institute, Methodist Hospital of Indiana ( A. K. S., V. P.) and the Departments of Ophthalmology ( A. K. S., V. P.) and Neurology ( V. P.), Indiana University of Medicine, Indianapolis, Indiana, U. S. A. Address correspondence to Dr. Aki Selky, Midwest Eye In­stitute, 1800 N. Capital Avenue, Indianapolis, IN 46202, U. S. A. CASE REPORT A 46- year- old woman was referred for papille­dema. Two months previously, she had developed intermittent twitching and " drawing- up" of the right side of her face with sustained closure of the right eye lasting 1- 2 minutes. This occurred sev­eral times daily and was unassociated with other involuntary movements. Hemifacial spasm was observed and diagnosed by her local physician, 196 HEMIFACIAL SPASM 197 who did not find any evidence of facial numbness, paresthesias, or palsies between episodes of hemi­facial spasm. An electroencephalogram ( EEG) and magnetic resonance imaging ( MRI) of the head were normal. Specifically, no vertebrobasilar ar­tery tortuosity or ectasia was noted. She was then started on carbamazepine with significant reduc­tion in the frequency of her right hemifacial spasm. One month later, she noticed decreased visual field interiorly in the left eye and complained of severe headaches and intermittent pulsatile tinni­tus. She was referred for neuro- ophthalmologic evaluation. Her last episode of hemifacial spasm was 3 days prior to our evaluation. Past medical history was unremarkable except for chronic obesity with a recent 10- lb weight gain. She had not ingested vitamin A or antibiotics. Cur­rent medications were carbamazepine and Pre-marin. On examination, visual acuity was 20/ 20 OD and 20/ 25 OS. Pupils were 5 mm OU with a 1 + left afferent defect. Kinetic perimetry on a Goldmann perimeter demonstrated peripheral inferior con­striction in the right eye and an inferior altitudinal defect in the left eye. Intraocular pressures were 18 mm Hg OU. Funduscopy revealed moderate bilat­eral disc edema with hyperemia. The remainder of the ophthalmologic and neurologic examination was normal. No facial muscle spasms were seen. There was no underlying facial weakness or syn­kinesis. Serum chemistries and serologies were normal. Lumbar puncture showed an opening pressure of 350 mm H20. Spinal fluid analysis was normal. Acetazolamide 500 mg three times daily was be­gun, and the patient reported marked improve­ment of her headaches and resolution of tinnitus after 1 week. Carbamazepine was discontinued without recurrence of hemifacial spasm. At 9 months follow- up, the patient remained asymptomatic. She had lost a total of 30 lb and was maintained on acetazolamide 500 mg twice daily. Her neuro- ophthalmologic examination was nor­mal, and serial kinetic perimetry on a Goldmann perimeter disclosed no progression of the visual defects. Several months later, acetazolamide was decreased to 500 mg once daily, but recurrence of headaches and a " funny sensation" around her eyes prompted a return to twice daily dosage. DISCUSSION Idiopathic intracranial hypertension typically af­fects the optic nerves by transmission of increased cerebrospinal fluid pressure to the retrolaminar subarachnoid space. Axoplasmic stasis then leads to papilledema with or without associated visual loss. Involvement of other cranial nerves has been described in idiopathic intracranial hypertension, most commonly abducens palsy in 24% of cases ( 10). Various mechanisms for sixth nerve palsy as a remote effect of intracranial hypertension have been proposed. They include traction from brain­stem shifts of the longitudinal segment of the sixth nerve, stretching of its transverse segment across the bony skull base, grooving of the pontine sur­face, compression/ constriction of the sixth nerves as they exit the brainstem by the anterior inferior cerebellar and internal auditory arteries and tran­sient nuclear or neural ischemia due to poor blood-flow associated with spontaneous, periodic rises of intracranial pressure ( Lundberg a waves) ( 11- 13). Because of the frequent association of abducens palsy and increased intracranial pressure with or without an intracranial mass, it has been called a " false localizing sign." The mechanism of other cranial nerve palsies due to idiopathic intracranial hypertension re­mains even more speculative. Nevertheless, a pop­ular theory for any cranial nerve palsy associated with idiopathic intracranial hypertension invokes pressure- induced intracranial structural shifts which pull and stretch the extra- axial segment of the involved cranial nerve. At sites where cranial nerves traverse bone and arteries, it is hypothe­sized that progressive stretching of the nerve fibers might temporarily paralyze axonal function. Once intracranial pressure is lowered, the cranial nerves can " relax" and function is immediately restored. For example, Kiwak and Levine ( 8) detailed the clinical course of a patient with idiopathic intracra­nial hypertension and bilateral facial palsies which remitted and recurred as intracranial pressure was lowered then rose again. Permanent recovery of the facial diplegia was secured after lumboperito-neal shunt placement. These authors hypothe­sized a mechanism of stretch injury to the facial nerves within the facial canal as there was no con­comitant eighth nerve dysfunction. The rapidity of recovery implied that significant demyelination or axonal disruption did not occur. However, we have seen a patient with idiopathic intracranial hy­pertension who had persistent facial diplegia with eventual facial nerve synkinesis from aberrant re­generation despite lowering of her intracranial pressure with medical and surgical modalities. Our patient is noteworthy because her initial symptom of idiopathic intracranial hypertension was hemifacial spasm, not facial palsy. We believe her hemifacial spasm was a manifestation of intra- / Neuro- Ophthalmol, Vol. 14, No. 4, 1994 198 A. K. SELKY AND V. A. PURVIN cranial hypertension because of the close temporal relationship between its appearance and the onset of more typical symptoms of elevated intracranial pressure ( headache, tinnitus, visual field loss). Furthermore, there was no reemergence of our pa­tient's hemifacial spasm when carbamazepine was stopped and the other symptoms of idiopathic in­tracranial hypertension were being effectively con­trolled with acetazolamide. A well- documented mechanism for some cases of hemifacial spasm is compression of the facial nerve by an adjacent blood vessel as the nerve emerges from the brainstem ( 14). The utility of noninvasive neuroimaging in identifying dolicho-ectasia of the vertebrobasilar artery as a cause of hemifacial spasm was recently investigated in 37 patients with hemifacial spasm by Bernardi and colleagues ( 15). Routine magnetic resonance imag­ing was positive for abnormal brainstem vascula­ture in 27% of patients, 51% with magnetic reso­nance angiography and 65% with magnetic reso­nance tomographic angiography. Our patient had routine magnetic resonance imaging that did not show evidence of vertebrobasilar artery tortuosity or ectasia. Why compressive injury sometimes acts to irritate a nerve and at other times acts to disable a nerve is not clear. We propose that elevated in­tracranial pressure shifted our patient's facial nerve to a more intimate position against adjacent brainstem vascular structures, which triggered an irritative, hyperexcitable response from the nerve. Perhaps if left untreated, eventual facial nerve palsy would have developed from progressive compression and stretching of the facial nerve. REFERENCES 1. Guiseffi V, Wall M, Siegel PZ, Rojas PB. Symptoms and disease associations in idiopathic intracranial hypertension ( pseudotumor cerebri): a case- control study. Neurology 1991; 41: 239- 44. 2. Round R, Keane JR. The minor symptoms of increased in­tracranial pressure: 101 patients with benign intracranial hypertension. Neurology 1988; 38: 1461- 4. 3. Baker RS, Baumann RJ, Buncic JR. Idiopathic intracranial hypertension ( pseudotumor cerebri) in pediatric patients. 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