Trochlear nerve schwannomas occurring in patients without neurofibromatosis: case report and review of the literature.
OBJECTIVE
Despite their predilection for sensory nerves, intracranial schwannomas have been reported in a number of mixed and purely motor cranial nerves, especially in association with Type 2 neurofibromatosis. We report the rare occurrence of a trochlear nerve schwannoma in a patient without neurofibromatosis and review 17 other case reports from the literature.


METHODS
A 35-year-old woman presented with an 8-week history of evolving left hemiparesis, bilateral bulbar paresis, and out-of-character emotional lability.


METHODS
She underwent a left temporal craniotomy and a subtemporal, transtentorial approach to the tentorial hiatus, with complete excision of a cisternal trochlear nerve schwannoma.


CONCLUSIONS
Postoperative complications included temporary oculomotor and abducens nerve palsies and temporary right hemiparesis and mild expressive dysphasia, which were resolved at 23-month follow-up. Preoperative symptoms and signs completely resolved, but a postoperative complete trochlear nerve palsy required inferior oblique myectomy for correction of diplopia. A review of the literature showed no preoperative trochlear nerve involvement in at least 45% of cases. The tumor is isointense on T1- and T2-weighted magnetic resonance images and enhances brightly with gadolinium. The most frequently used approach for surgical excision is the subtemporal approach, and the tumor is almost always totally excised. Long-term follow-up suggests recovery of preoperative deficit, and persisting or new trochlear nerve palsy is the rule.
Santoreneos
S
S
Department of Surgery, Queen Elizabeth Hospital, Adelaide, Australia.
Hanieh
A
A
Jorgensen
R E
RE
D000328:Adult; D003390:Cranial Nerve Neoplasms / Q000175:diagnosis / Q000473:pathology / Q000601:surgery*; D003399:Craniotomy; D005260:Female; D006801:Humans; D009442:Neurilemmoma / Q000175:diagnosis / Q000473:pathology / Q000601:surgery*; D016518:Neurofibromatosis 2 / Q000175:diagnosis / Q000473:pathology; D009460:Neurologic Examination; D011183:Postoperative Complications / Q000175:diagnosis; D014321:Trochlear Nerve / Q000473:pathology / Q000601:surgery*