A 55-year-old man comes to the clinic due to headache and progressive facial weakness. The patient's headaches began 2 months ago and are characterized as throbbing. They are typically worse in the morning and when he bears down or coughs. He has had no recent head trauma or loss of consciousness. The patient has a history of hypertension for which he takes lisinopril. He does not use tobacco, alcohol, or illicit drugs. Vital signs are normal. On physical examination, there is flattening of the left nasolabial fold and drooping of the left lower lip. The patient cannot fully close his left eye. MRI of the brain reveals a well-circumscribed homogenously enhancing mass in the posterior fossa that is compressing the left facial nerve root. Which of the following additional findings is most likely present on this patient's neurologic examination?

Question

A 55-year-old man comes to the clinic due to headache and progressive facial weakness.  The patient's headaches began 2 months ago and are characterized as throbbing.  They are typically worse in the morning and when he bears down or coughs.  He has had no recent head trauma or loss of consciousness.  The patient has a history of hypertension for which he takes lisinopril.  He does not use tobacco, alcohol, or illicit drugs.  Vital signs are normal.  On physical examination, there is flattening of the left nasolabial fold and drooping of the left lower lip.  The patient cannot fully close his left eye.  MRI of the brain reveals a well-circumscribed homogenously enhancing mass in the posterior fossa that is compressing the left facial nerve root.  Which of the following additional findings is most likely present on this patient's neurologic examination?

Quizplus · Accepted Answer

This patient has facial nerve (CN VII) palsy, likely due to nerve compression by a meningioma (eg, well-circumscribed, homogenously enhancing mass) in the posterior fossa. Space-occupying intracranial lesions classically present with a headache that is worse in the morning and with Valsalva (eg, bearing down, coughing) due to increased intracranial pressure. The facial nerve exits the brainstem at the pontomedullary junction and subsequently enters the internal auditory meatus and facial canal in the temporal bone. Here, it gives off branches that supply the stapedius muscle (reduces volume by dampening ossicle movement in middle ear), salivary glands (eg, sublingual, submandibular), and lacrimal glands. It also provides taste from the anterior two thirds of the tongue via the chorda tympani nerve. After exiting the skull through the stylomastoid foramen, the facial nerve courses within the parotid gland and its terminal branches innervate the muscles of facial expression. Facial nerve palsy presents with ipsilateral facial paralysis (eg, flattening of the nasolabial fold, drooping of the lower lip, inability to close the eye). There is also loss of the corneal reflex (efferent limb) due to denervation of the orbicularis oculi muscle. Paralysis of the stapedius muscle may lead to increased sensitivity to sound (hyperacusis). Since the nerve to the stapedius is one of the first branches of the facial nerve, hyperacusis indicates that the facial nerve is injured near its brainstem origin. Other features of facial nerve palsy include decreased lacrimation, salivation, and loss of taste in the anterior two thirds of the tongue. (Choice A) Oculomotor nerve (CN III) palsy causes "down and out" eye deviation, ptosis (due to levator palpebrae superioris paralysis), and a fixed dilated pupil (due to parasympathetic fiber injury). (Choice B) Vagus nerve (CN X) injury causes paralysis of the soft palate (eg, loss of efferent limb of the gag reflex), pharyngeal muscles (eg, dysphagia), and laryngeal muscles (eg, hoarseness). Sensory loss in the larynx and pharynx may also lead to impaired cough reflex. (Choice D) Trigeminal nerve (CN V) damage causes ipsilateral facial anesthesia, loss of the corneal reflex (afferent limb), weakness of the muscles of mastication, and jaw deviation toward the side of the lesion (due to unopposed action of the opposite pterygoid muscle). (Choice E) Vestibulocochlear nerve (CN VIII) injury (eg, due to vestibular schwannoma) causes sensorineural hearing loss, tinnitus, and vertigo. (Choices F and G) Glossopharyngeal nerve (CN IX) damage causes loss of sensation and taste in the posterior one third of the tongue, and loss of the gag reflex (afferent limb). (Choice H) Hypoglossal nerve (CN XII) injury causes tongue weakness and deviation toward the side of the lesion. Educational objective: Hyperacusis (increased sensitivity to sound) is an indication of damage to the facial nerve (CN VII) close to its origin from the brainstem. __________ References: Hyperacusis. (http://www.ncbi.nlm.nih.gov/pubmed/14645606) Seventh cranial neuropathy. (http://www.ncbi.nlm.nih.gov/pubmed/19214928)

A 55-Year-Old Man Comes to the Clinic Due to Headache