Review Question - QID 216405

This patient presenting with tinnitus, dizziness, and hearing loss has characteristic signs of a vestibular schwannoma (acoustic neuroma). Vestibular schwannoma is a benign tumor of the vestibulocochlear nerve (CN VIII) that arises from Schwann cells and is typically found in the internal acoustic meatus.

Vestibular schwannomas classically present with non-pulsatile tinnitus and gradual hearing loss. Vestibular schwannoma is typically found in the internal acoustic meatus, and extension into the cerebellopontine angle is possible. Compression of CN VIII in the internal acoustic meatus leads to vestibular symptoms (dizziness, gait ataxia) and hearing symptoms (tinnitus, hearing loss). Upon extension to the cerebellopontine angle, the tumor can compress the trigeminal nerve (CN V) or facial nerve (CN VII), leading to additional symptoms such as weakness of the muscles of mastication or facial expression. Magnetic resonance imaging (MRI) is used to diagnose vestibular schwannoma, which can appear solid or cystic on imaging. A small fraction of vestibular schwannomas also presents with intratumoral hemorrhage.

Carlson and link review vestibular schwannomas. They note the prevalence is roughly 1 per 500 individuals. The recommend a personalized workup and close attention to symptoms and anatomy given treatments and management available are controversial.

Incorrect Answers:
Answer 2: Enhancing cerebellar mass with extension into the 4th ventricle describes medulloblastoma, a malignant tumor derived from the granule cells of the cerebellum. Medulloblastoma often causes hydrocephalus and presents with symptoms of elevated intracranial pressure, such as headache, nausea, ataxia, and vomiting. Medulloblastoma typically presents in children and is first noticed as a cause of a headache and ataxia.

Answer 3: Intradural isointense tumor with compression of the medial cerebellum describes meningioma, a tumor of the arachnoid cells that can compress intracranial structures. Although a meningioma at the cerebellopontine angle could compress CN VIII and cause the vestibular and hearing symptoms observed, it would additionally affect adjacent cranial nerves (CN V-XII). Since this patient's symptoms are limited to a purely CN VIII distribution, meningioma is less likely. A meningioma is typically seen in young or middle-aged women and may present with headache and seizures.

Answer 4: Ring-enhancing butterfly-shaped cortical tumor in the cerebellopontine angle describes glioblastoma, the most common primary malignant central nervous system (CNS) tumor in adults. Glioblastoma, which is a grade IV glioma, typically presents in the cortex, and cerebellar gliomas are rare. Cerebellar glioma can present with headache, visual disturbance, gait ataxia, and vomiting, but is unlikely to cause the hearing symptoms observed in this patient.

Answer 5: Suprasellar sub-centimeter non-enhancing mass with cerebellar extension describes pituitary adenoma, which can cause headache, visual symptoms (bitemporal hemianopsia), and increased secretion of certain pituitary hormones. Cerebellar extension could lead to gait ataxia or truncal instability, but would not cause tinnitus or hearing loss. The initial presentation in women often is amenorrhea from a prolactin-secreting tumor.

Bullet Summary:
Vestibular schwannoma is a benign CNS tumor that grows in the internal acoustic meatus and can present with vestibular and hearing symptoms.