A 34-year-old woman is evaluated for several months of moderate hearing loss. She has also noticed a ringing in her left ear. The patient has had no recent ear infections or cold symptoms, does not use cotton ear swabs, and has no history of head trauma. Her father has bilateral hearing loss attributed to old age. On physical examination, the auditory canals are patent and tympanic membranes appear gray with a well-visualized light reflex. Hearing is diminished on the left side. Neurologic examination shows left-sided facial numbness, an asymmetric smile, and diminished corneal reflex response in the left eye. This patient's condition suggests an intracranial mass in which of the following locations?

Question

A 34-year-old woman is evaluated for several months of moderate hearing loss.  She has also noticed a ringing in her left ear.  The patient has had no recent ear infections or cold symptoms, does not use cotton ear swabs, and has no history of head trauma.  Her father has bilateral hearing loss attributed to old age.  On physical examination, the auditory canals are patent and tympanic membranes appear gray with a well-visualized light reflex.  Hearing is diminished on the left side.  Neurologic examination shows left-sided facial numbness, an asymmetric smile, and diminished corneal reflex response in the left eye.  This patient's condition suggests an intracranial mass in which of the following locations?

Quizplus · Accepted Answer

11ec160b_35cf_1df4_9249_fbae55d818af_MD0001_00 This patient's unilateral hearing loss with associated facial numbness and weakness, is highly suggestive of a vestibular schwannoma, the most common cause of cerebellopontine angle (ie, between the cerebellum and lateral pons) tumors in adults. Vestibular schwannomas most often arise from the vestibular portion of the vestibulocochlear nerve (CN VIII). Spontaneous vestibular schwannomas are usually unilateral, whereas bilateral vestibular schwannomas are associated with neurofibromatosis type 2. The facial nerve (CN VII) and trigeminal nerve (CN V) are in proximity to CN VIII at the cerebellopontine angle and may be compressed by vestibular schwannomas. Symptoms can vary based on the pattern of nerve involvement: Impairment of the cochlear portion of CN VIII leads to ipsilateral sensorineural hearing loss and tinnitus (ringing in the ear), and damage to the vestibular portion causes unsteadiness and disequilibrium. Compression of CN V may cause loss of ipsilateral facial sensation with interruption of the afferent limb of the corneal reflex. CN VII compression can result in ipsilateral facial muscle paralysis (eg, asymmetric smile). (Choice A) Craniopharyngiomas arise from remnants of Rathke's pouch and are typically located in the suprasellar region. Patients usually have hypothalamic or pituitary dysfunction and changes in vision due to disruption of the optic chiasm (eg, bitemporal hemianopia), none of which are evident in this patient. (Choices B and E) Meningiomas are most commonly found in the falcine/parasagittal region or over the convexities of the cerebral hemispheres. Most are discovered incidentally, but some patients may have seizures, headaches, or focal neurologic deficits. This patient's findings are localized to CN V, CN VII, and CN VIII, making vestibular schwannoma more likely. (Choice D) Germ cell tumors frequently arise from the pineal gland in the dorsal midbrain. Pineal tumors can cause obstructive hydrocephalus with symptoms of increased intracranial pressure (eg, headache, vomiting, altered mental status) and Parinaud syndrome (eg, upward gaze palsy). Educational objective: Vestibular schwannomas arise from the vestibulocochlear nerve (CN VIII) and are usually located at the cerebellopontine angle. These tumors can cause a range of symptoms by damaging the vestibulocochlear nerve (unsteadiness and ipsilateral sensorineural hearing loss with tinnitus), trigeminal nerve (ipsilateral facial paresthesia and diminished corneal reflex), and facial nerve (ipsilateral facial paresis). Bilateral acoustic neuromas are associated with neurofibromatosis type 2. __________ References: Epidemiology and natural history of vestibular schwannomas. (http://www.ncbi.nlm.nih.gov/pubmed/22483814)

A 34-Year-Old Woman Is Evaluated for Several Months of Moderate