A multicenter, prospective pilot study of gamma knife radiosurgery for mesial temporal lobe epilepsy: seizure response, adverse events, and verbal memory.
OBJECTIVE
The safety, efficacy, and morbidity of radiosurgery (RS) must be established before it can be offered as an alternative to open surgery for unilateral mesial temporal lobe epilepsy. We report the 3-year outcomes of a multicenter, prospective pilot study of RS.


METHODS
RS was randomized to 20 or 24Gy targeting the amygdala, hippocampus, and parahippocampal gyrus. Seizure diaries evaluated the final seizure remission between months 24 and 36. Verbal memory was evaluated at baseline and 24m with the Wechsler Memory Scale-Revised (WMS-R) and California Verbal Learning Test (CVLT). Patients were classified as having "significant improvement," "no change," and "significant impairment" based on relative change indices.


RESULTS
Thirteen high-dose and 17 low-dose patients were treated. Both groups showed significant reductions in seizures by 1 year after treatment. At the 36-month follow-up evaluation, 67% of patients were free of seizures for the prior 12 months (high dose: 10/13, 76.9%; low dose: 10/17, 58.8%). Use of steroids, headaches, and visual field defects did not differ by dose or seizure remission. The prevalence of verbal memory impairment was 15% (4/26 patients); none declined on more than one measure. The prevalence of significant verbal memory improvements was 12% (3/26).


CONCLUSIONS
RS for unilateral mesial temporal lobe epilepsy offers seizure remission rates comparable with those reported previously for open surgery. There were no major safety concerns with high-dose RS compared with low-dose RS. Additional research is required to determine whether RS may be a treatment option for some patients with mesial temporal lobe epilepsy.
Barbaro
Nicholas M
NM
Department of Neurological Surgery, University of California at San Francisco, 94143, USA. barbaron@neurosurg.ucsf.edu
Quigg
Mark
M
Broshek
Donna K
DK
Ward
Mariann M
MM
Lamborn
Kathleen R
KR
Laxer
Kenneth D
KD
Larson
David A
DA
Dillon
William
W
Verhey
Lynn
L
Garcia
Paul
P
Steiner
Ladislau
L
Heck
Christine
C
Kondziolka
Douglas
D
Beach
Robert
R
Olivero
William
W
Witt
Thomas C
TC
Salanova
Vicenta
V
Goodman
Robert
R
D000328:Adult; D004307:Dose-Response Relationship, Radiation; D004833:Epilepsy, Temporal Lobe / Q000503:physiopathology* / Q000601:surgery*; D005260:Female; D006261:Headache / Q000209:etiology; D006801:Humans; D008297:Male; D008568:Memory / Q000502:physiology*; D009483:Neuropsychological Tests; D010865:Pilot Projects; D011446:Prospective Studies; D016634:Radiosurgery / Q000009:adverse effects / Q000379:methods*; D013997:Time Factors; D016896:Treatment Outcome; D014706:Verbal Learning / Q000502:physiology*; D014794:Visual Fields