Grand Prize: Facial Spasm Signals Sixth-Nerve Palsy
Stephanie D. Pulpan, Jade S. Schiffman, M.D., Gina G. Wong, O.D., Houston

A 48-year-old white male complaining of double vision and a facial tic on the left side presented for a neuro-ophthalmological evaluation. His optometrist and general physician referred him.

Top: MRI identified a 2x4cm lesion in the left petrous apex. Middle: The fifth cranial nerve was stretched over part of the mass, and the growth encroached on the left cerebellopontine angle. Bottom: A large bony shelf compressed the seventh nerve where it entered into the brainstem.

His ocular history was eventful. At 21 he was diagnosed with an isolated left abducens palsy. Blood testing, spinal tap and head X-ray were normal and revealed no systemic disease. The physician determined that the patient's condition was idiopathic. Over the next two years, the palsy partially resolved, but the left eye never fully abducted.

The patient continued to report diplopia in left gaze over the next 25 years, but had no subsequent workup. In 1995 he began to experience involuntary, forceful blinking of the left eyelid. His optometrist noted the abducens palsy and blepharospasm, and prescribed glasses. The O.D. told him the blepharospasm was probably stress-related, but advised him to consult his physician if it persisted or worsened.

The patient later presented to his family physician, who reassured him that it was stress-related and prescribed alprazolam. During the next two years, the condition progressed to a left hemifacial spasm. The physician now prescribed carbamazepine. Both medications proved ineffective.

When the patient presented to us in 1997, the left hemifacial spasm was almost constant, and he had persistent diplopia on left gaze. He denied any headache, hearing problems, loss of vision, numbness, or transient weakness of his face or extremities. He reported taking glipizide for diabetes mellitus and atenolol-chlorthalidone for hypertension since 1990.

Diagnostic Data
Best corrected visual acuity was 20/20. Pupil exam was normal, and visual fields were full to confrontation. Motility exam revealed a moderate left lateral rectus weakness, which we graded as -2, and the patient reported diplopia in all gazes to the left. There was no nystagmus. Biomicroscopy and funduscopy were unremarkable, and there was no papilledema in either eye.

Examination of his facial nerve revealed frequent left hemifacial spasm. The patient had slight frontalis weakness and orbicularis oris weakness. However, the orbicularis oculi function was normal on both sides. Trigeminal function, hearing and cerebellar function were all normal.

Diagnosis
We diagnosed left sixth nerve palsy of long duration and left hemifacial spasm with mild seventh nerve weakness. We also ordered a brain MRI, MR angio- gram and blood tests to rule out a lesion in the petrous apex or cerebellopontine (CP) angle. The MRI identified a 2x4cm space-occupying lesion centered in the left petrous apex. The lesion extended into the clivus and CP angle.

Treatment and Follow-up
We referred the patient for removal of the lesion. Additional MRI and CT scans showed that the mass was eroding the left petrous apex and that it extended down the clivus. The fifth cranial

Left: Lagophthalmos, orbicularis oculi and paralytic ectropion are common ocular signs of seventh nerve palsy. Right: Facial expressions such as smiling (orbicularis oris) and lifting the brow (frontalis) are easy to assess in the optometric office.

nerve was stretched over a portion of the mass, and the growth encroached on the left CP angle, where it exerted mass effect on the left seventh-eighth nerve complex. The left cavernous sinus was mildly involved, as was the left internal carotid artery in the petrous carotid canal. A large bony shelf compressed the seventh nerve at its site of entry into the brainstem.

The patient underwent two brain surgeries to remove the tumor and decompress the seventh nerve. The pathology report identified the tumor as a cholesteatoma.

Following surgery, the left abducens palsy remained. The patient also suffered left sensorineural hearing loss and a left facial palsy, for which he underwent tarsorrhaphy. An MRI showed that the tumor was significantly debulked. The patient was followed for ocular management of his facial palsy and diplopia.

Discussion
Mass lesions of the petrous apex region can present with isolated signs and symptoms or as a fully developed clinical syndrome.1-3 Cranial nerves V, VI, VII and VIII and the cerebellum all intersect at this anatomical region, so a tumor could cause ocular symptoms from any one or a combination of these structures.4-8
Intracranial tumors of the petrous apex region may involve these areas:

• The abducens. The sixth is the most commonly involved cranial nerve that results from intracranial tumor, particularly one at the skull base.8-10 The most common presentation of sixth nerve palsy is a partial or complete abduction deficit. This results in horizontal diplopia that worsens on gaze toward the involved side.1-3,11 You can detect the abduction deficit with a motility exam and cover test in the nine cardinal positions. Testing may reveal a noncomitant esotropia or esophoria, depending on severity.1-3,8 

The palsy, which may be partial or complete, can spontaneously remit and recur.12 The compressive palsy is often unilateral, but may present bilaterally if the tumor crosses the midline or causes downward displacement of the brainstem due to increased intracranial pressure. In that case, papilledema or nonspecific headache may develop.8

• Facial nerve. A mass that extends into the CP angle frequently involves the facial, or seventh, nerve.8,9 The first signs often are spasm or twitching of the ipsilateral eyelid or half of the face.8 In later stages, a peripheral facial palsy may develop.8,13,14 Lagophthalmos is a common ocular sign of seventh nerve palsy, as are orbicularis oculi weakness and paralytic ectropion.8 Ocular symptoms may include a bothersome lid twitch, irritated and dry feeling in one eye, or difficulties in closing one eye.

To evaluate orbicularis oculi function, try to open the patient's forcefully closed eyelid. Facial expressions such as smiling (orbicularis oris) or lifting the brow (frontalis) are also reasonably easy to assess in the optometric office.

• The trigeminal nerve. The fifth cranial nerve is very susceptible to lesions of the petrous apex, as it drapes directly over the ridge just prior to the trigeminal ganglion. It, too, often presents as an early sign of CP angle involvement.
Trigeminal symptoms usually first manifest as paresthesia and later as neuralgia.8 The corneal reflex is often diminished before sensory disturbance of the skin.8 You can use cotton wisp testing to evaluate the presence and severity of corneal anesthesia. Be sure to rule out corneal anesthesia, since this leaves the eye subject to serious injury and infection, and is especially dangerous when combined with a seventh nerve palsy.8,9,15

• Vestibular and cerebellar involvement. Patients whose tumors involve the eighth nerve often present with hearing deficits. Nystagmus may also be present, due to disruption of the vestibular portion of the nerve. These patients may complain of tinnitus or vertigo.16-18 The nystagmus may also be related to cerebellar disruption. Both etiologies may result in jerking and horizontal nystagmus, often with greater amplitude in gaze toward the side of the tumor.8

These tumors rarely result in visual field changes and decreased acuity. If these conditions are present, they are most likely related to increased intracranial pressure and post-papilledema optic atrophy.8

Always be suspicious of isolated palsy in a young, healthy patient. Any acquired, long-standing neurological symptom warrants a thorough work-up.8,9,12 Even when these symptoms are long-standing, they are not necessarily benign, especially when they result from slow-growing tumors as in this patient. Cases of long-standing or chronic palsy may warrant periodic imaging until an etiology can be determined.

Be sure to investigate any presentation that involves one or more cranial nerves, unless it's a classic presentation.8-12 One study reported that 69% of cases that involved two or more cranial nerves resulted from a tumor.12

Any multiple cranial neuropathies or a chronic isolated palsy strongly suggest a compressive etiology. Isolated palsies are not uncommon in slow-growing tumors such as those that involve the skull base because they slowly increase compression or displacement of proximal structures. When tumors in this region occur, they are likely to have ocular manifestations. Timely diagnosis can spare cranial nerve function and significantly decrease morbidity.

Ms. Pulpan is a fourth-year student at the University of Houston College of Optometry. Dr. Schiffman is a research associate professor at the college and director of neuro-ophthalmology and telemedicine at the University Eye Institute. Dr. Wong is a second-year resident in neuro-ophthalmology at the University Eye Institute.

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