Review Question - QID 214615

This patient is most likely presenting with left-sided Bell palsy, as evidenced by hyperacusis (i.e., intolerance to ordinary sounds), taste abnormalities, and unilateral facial weakness (e.g., eyebrow sagging and nasolabial fold absence). These symptoms would be caused by an insult to the 7th (facial) cranial nerve.

Bell palsy is defined as palsy of the facial nerve of unknown origin. Its pathogenesis is inflammation and edema leading to compression of the cranial nerve, causing an ischemic insult. The classical Bell palsy presentation is sudden unilateral facial paralysis (e.g., sagging eyebrows, inability to close one’s eye, and nasolabial fold disappearance). Other symptoms include hyperacusis, loss of taste sensation on the anterior 2/3 of the tongue, and decreased tearing. Herpes simplex reactivation is believed to be the most likely cause, but there is currently no established clinical method of confirmation. Facial nerve palsy can also be caused by herpes zoster, neoplasm compression, and Lyme disease. Patients should be treated early with oral glucocorticoids like prednisone.

Incorrect Answers:
Answer 1: Cranial nerve 3, the oculomotor, is involved in most ocular movements, eyelid elevation, as well as parasympathetic constriction and accommodation. Although the patient has a drooping eyebrow, he does not have any ocular problems. Damage to the oculomotor nerve classically presents with ptosis, mydriasis, and a “down-and-out” pointing pupil.

Answer 2: Cranial nerve 5, the trigeminal, is involved in facial sensation and the muscles of mastication, which are not affected in the patient. A specific trigeminal disorder is trigeminal neuralgia, which causes intense, chronic pain along the trigeminal nerve branches.

Answer 4: Cranial nerve 9, the glossopharyngeal, supplies the stylopharyngeus and both taste/sensation of the posterior 1/3 of the tongue. Although the patient has issues with taste, a glossopharyngeal palsy would not explain the other symptoms. Damage to the glossopharyngeal nerve can be ascertained by testing the gag reflex.

Answer 5: Cranial nerve 10, the vagus, is a key player in the parasympathetic nervous system and also innervates some pharynx muscles (e.g., cricothyroid, palatoglossal, etc.). Symptoms of vagus nerve damage could include abnormal heart rate or blood pressure and difficulty speaking. The patient does not have these symptoms. Anatomically, the vagus nerve can be found in the carotid sheath with the common carotid and internal jugular vein.

Bullet Summary:
Hyperacusis, an intolerance to ordinary sounds, can present with Bell palsy and is caused by damage to the 7th (facial) cranial nerve.