Gamma Knife surgery and trigeminal schwannoma: is it possible to preserve cranial nerve function?
OBJECTIVE
The current study was undertaken to evaluate the tumor control rate and functional outcome after Gamma Knife surgery (GKS) in patients with a trigeminal schwannoma. The conditions associated with the development of cranial neuropathies after radiosurgery were scrutinized.


METHODS
The authors reviewed the clinical records and radiological data in 22 consecutive patients who received GKS for a trigeminal schwannoma. The median tumor volume was 4.1 ml (0.2-12.0 ml), and the mean tumor margin dose was 13.3 +/- 1.3 Gy at an isodose line of 49.9 +/- 0.6% (mean +/- standard deviation). The median clinical follow-up period was 46 months (range 24-89 months), and the median length of imaging follow-up was 37 months (range 24-79 months).


RESULTS
Tumor growth control was achieved in 21 (95%) of the 22 patients. Facial pain responded best to radiosurgery, with two thirds of patients showing improvement. However, only one third of patients with facial hypesthesia improved. Six patients (27%) experienced new or worsening cranial neuropathies after GKS. Ten patients (46%) showed tumor expansion after radiosurgery, and nine of these also showed central enhancement loss. Loss of central enhancement, tumor expansion, and a tumor in a cavernous sinus were found to be significantly related to the emergence of cranial neuropathies.


CONCLUSIONS
The use of GKS to treat trigeminal schwannoma resulted in a high rate of tumor control and functional improvement. Cranial neuropathies are bothersome complications of radiosurgery, and tumor expansion in a cavernous sinus after radiosurgery appears to be the proximate cause of the complication. Loss of central enhancement could be used as a warning sign of cranial neuropathies, and for this vigilant patient monitoring is required.
Phi
Ji Hoon
JH
Department of Neurosurgery, Seoul National University College of Medicine, Korea.
Paek
Sun Ha
SH
Chung
Hyun-Tai
HT
Jeong
Sang Soon
SS
Park
Chul-Kee
CK
Jung
Hee-Won
HW
Kim
Dong Gyu
DG
D000328:Adult; D000368:Aged; D003390:Cranial Nerve Neoplasms / Q000473:pathology / Q000601:surgery*; D005157:Facial Pain / Q000601:surgery; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008499:Medical Records; D008875:Middle Aged; D009442:Neurilemmoma / Q000473:pathology / Q000601:surgery*; D011183:Postoperative Complications; D016634:Radiosurgery; D016896:Treatment Outcome; D014276:Trigeminal Nerve / Q000502:physiology* / Q000601:surgery*