Gamma knife surgery of superficially located meningioma.
OBJECTIVE
The authors analyzed tumor control rates and complications in patients with superficially located meningiomas after gamma knife surgery (GKS).


METHODS
Between 1998 and 2003, GKS was performed in 23 patients with 26 lesions in whom follow-up imaging for 1 year or more was available. The male/female ratio was 1:22. The mean age was 59 years. The median tumor volume was 4.7 cm3, and the mean margin dose was 16 Gy at the 50% isodose line. Peritumoral edema was revealed on magnetic resonance (MR) imaging in four patients before GKS. Magnetic resonance imaging and clinical examinations were performed every 6 months after GKS. The mean follow-up duration was 32 months. The tumor shrank in eight cases, was stable in 17, and enlarged in one; thus 25 (95%) of 26 tumors were controlled. A peritumoral high signal on T2-weighted MR images was found in eight lesions and preexisting edema was aggravated in three lesions after GKS. Ten of these 11 patients complained of severe headache, and three patients experienced neurological deficits at the same time after a mean latency of 3 months; however, high signal was not demonstrated on imaging before 6 months on average. Steroid agents, when required, gave relief to all patients. The complication rate was 43% (10 of 23 cases). High signal disappeared in nine patients and decreased in the remaining two. High signal was associated with a high integral dose and a large tumor volume. Tumor shrinkage at the last follow-up examination was more prominent in the patients with symptomatic high signal (p = 0.03).


CONCLUSIONS
There was a good tumor control rate with a high complication rate. Longer follow up of more patients is needed. Adjusting the dose-volume relationship should be considered to reduce complications.
Kim
Dong Gyu
DG
Department of Neurosurgery, Seoul National University College of Medicine, Seoul, Korea. gknife@plaza.snu.ac.kr
Kim
Ch Heon
ChH
Chung
Hyun-Tai
HT
Paek
Sun Ha
SH
Jeong
Sang Soon
SS
Han
Dae Hee
DH
Jung
Hee-Won
HW
D000328:Adult; D000368:Aged; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008577:Meningeal Neoplasms / Q000473:pathology / Q000601:surgery*; D008579:Meningioma / Q000473:pathology / Q000601:surgery*; D008875:Middle Aged; D011829:Radiation Dosage; D016634:Radiosurgery / Q000295:instrumentation* / Q000379:methods; D047368:Tumor Burden / Q000528:radiation effects