Skull Base and Cranial Nerve Disorders
Core concepts
Know the anatomy of the cranial nerves and skull base compartments, and the classic syndromes: trigeminal neuralgia, hemifacial spasm, vestibular schwannoma (acoustic neuroma), and pituitary tumors. Understand the surgical approaches (transsphenoidal, retrosigmoid, middle fossa, translabyrinthine) and their indications and risks. Know the presentation of vestibular schwannoma (unilateral sensorineural hearing loss, tinnitus, imbalance) and the role of observation, radiosurgery, and microsurgery. Understand trigeminal neuralgia treatment (carbamazepine, microvascular decompression, percutaneous procedures). Recognize the risks of skull base surgery (CSF leak, cranial nerve deficits, vascular injury).
Traps
A frequent trap is missing a vestibular schwannoma in a patient with unilateral hearing loss and treating it as presbycusis. Another is confusing trigeminal neuralgia (paroxysmal, electric-shock pain) with atypical facial pain. Questions may test that microvascular decompression is the definitive treatment for classic trigeminal neuralgia when medication fails. Watch for CSF leak after transsphenoidal surgery.
Worked rule of thumb
Unilateral sensorineural hearing loss warrants MRI to evaluate for vestibular schwannoma. Classic trigeminal neuralgia: carbamazepine first-line; microvascular decompression for refractory cases. After transsphenoidal surgery, watch for CSF rhinorrhea and diabetes insipidus.