BMET-21NEUROLOGICAL CHANGE AFTER GAMMA KNIFE RADIOSURGERY FOR BRAIN METASTASES INVOLVING THE MOTOR CORTEX

Abstract

Although gamma knife radiosurgery (GKRS) can provide beneficial therapeutic effects for patients with brain metastases, lesions involving the eloquent areas carry a higher risk of neurologic deterioration after treatment, compared to those located in the non-eloquent areas. We aimed to investigate neurological change of the patients with brain metastases involving the motor cortex (MC) and the relevant factors related to neurological deterioration after GKRS. We retrospectively reviewed clinical, radiological and dosimetry data of 42 patients who underwent GKRS for 50 brain metastases involving the MC. Prior to GKRS, motor deficits existed in 22 patients (52.4%). The mean target volume was 3.2 cc (range 0.001-14.1) at the time of GKRS, and the mean prescription dose was 18.4 Gy (range 12-24 Gy). The actuarial median survival time from GKRS was 14.7 ± 5.2 months. The calculated local tumor control rates at 6 and 12 months after GKRS were 87.9% and 83.3%, respectively. During the median clinical follow-up duration of 14.7 ± 2.4 months (range 1.0-43.7 months), 18 patients (42.9 %) experienced new or worsened neurologic deficits with a median onset time of 2.5 ± 0.8 months (range 0.2-7.2 months) after GKRS. Among various factors, prescription dose (> 20 Gy) (p =0.028), and new metastases involving the MC (p = 0.015) were significant factors for the new or worsened neurologic deficits in multivariate. The managements of 18 patients were steroid medication (n = 13), boost radiation therapy (n =3), and surgery (n =2), and neurological improvement was achieved in 10 (55.6%). In our series, prescription dose (>20 Gy) and new metastases involving the MC were significantly related to neurological deterioration after GKRS for brain metastases involving the MC. Therefore, we suggest that careful dose adjustment would be required for lesions involving the MC to avoid neurological deterioration requiring additional treatment after GKRS.