A 45-year-old woman comes to the office to discuss her facial asymmetry. For the past 6 weeks, the right side of her face has been progressively weakening. The patient notices there are fewer wrinkles on the right side of her forehead than on the left, and the fold in front of her cheek seems less deep. Sometimes she has "spasms" of the right side of her face, and her right eye feels "gritty, like there is sand in it." The patient has no chronic medical conditions and takes no medications. Vital signs are within normal limits. On examination, the ears are clear with no lesions. She is unable to hear a finger rub on the right side. Extraocular movements are intact; there is edema and erythema of the conjunctiva on the right, and normal conjunctiva on the left. Pupils are equal and reactive to light. There is asymmetry between the left and right sides of the face at rest. When asked to move her face, there is a little movement of right-sided parts of the face, including the forehead. There is incomplete eye closure of the right eye; the left eye closes fully. Which of the following is the most appropriate next step in diagnosis?
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This patient has unilateral hemifacial weakness with several concerning associated features. Progression over several weeks and facial spasms are concerning for neoplastic growth with ongoing irritation of the facial nerve (CN VII). Ipsilateral hearing loss is concerning for dysfunction of the vestibulocochlear nerve (CN VIII). Therefore, this presentation is likely due to a tumor at the cerebellopontine angle (eg, acoustic neuroma) and should be evaluated with an audiogram and an MRI of the head, specifically evaluating the internal auditory canal.
In general, the most common cause of unilateral facial weakness is Bell palsy. Although classic cases of Bell palsy require no further workup (Choice E), other, more serious causes of facial nerve weakness must be excluded with a thorough history and physical examination. If red flags (eg, sparing of the upper face, rash, hearing loss) are found, imaging and/or laboratory testing may be required, as in this patient.
Patients with facial weakness (from any cause) often have incomplete eye closure, which can lead to exposure keratitis (as seen in this patient with a red, irritated eye). Therefore, eyelid closure should be evaluated and eye-protection strategies (eg, lubrication drops, taping the eye closed at night) should be performed in patients unable to fully close the eye.
(Choice A) CT angiography is helpful for diagnosing aneurysms. Aneurysms are usually asymptomatic until they burst, leading to hemorrhagic stroke. Although very large aneurysms can very rarely present with facial weakness, they would affect the motor cortex or descending tracts and result in only lower facial weakness (ie, sparing of the forehead muscles).
(Choice B) HIV patients are at risk for sensory peripheral neuropathy. Isolated motor mononeuropathy is an extremely uncommon presentation of HIV; accompanying hearing loss and facial spasms would not be expected. Therefore, HIV screening is not recommended.
(Choice C) Lumbar puncture is typically performed in patients with suspected Guillain-Barré syndrome (GBS), which can cause facial weakness. In addition, it typically presents with symmetric ascending weakness with decreased or absent deep tendon reflexes usually over a few days (vs 6 weeks in this patient). Autonomic dysfunction, pain, or paresthesia is more likely to accompany GBS than the hearing loss and muscle spasms seen in this patient.
Educational objective:
Slowly progressive facial weakness associated with hearing loss and facial twitching is concerning for a tumor at the cerebellopontine angle (eg, acoustic neuroma).