title: Neurological Change after Gamma Knife Radiosurgery for Brain Metastases Involving the Motor Cortex.
abstract: BACKGROUND
  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.
  
  
  METHODS
  We retrospectively reviewed clinical, radiological and dosimetry data of 51 patients who underwent GKRS for 60 brain metastases involving the MC. Prior to GKRS, motor deficits existed in 26 patients (50.9%). The mean target volume was 3.2 cc (range 0.001-14.1) at the time of GKRS, and the mean prescription dose was 18.6 Gy (range 12-24 Gy).
  
  
  RESULTS
  The actuarial median survival time from GKRS was 19.2±5.0 months. The calculated local tumor control rates at 6 and 12 months after GKRS were 89.7% and 77.4%, respectively. During the median clinical follow-up duration of 12.3±2.6 months (range 1-54 months), 18 patients (35.3%) experienced new or worsened neurologic deficits with a median onset time of 2.5±0.5 months (range 0.3-9.7 months) after GKRS. Among various factors, prescription dose (>20 Gy) was a significant factor for the new or worsened neurologic deficits in univariate (p=0.027) and multivariate (p=0.034) analysis. The managements of 18 patients were steroid medication (n=10), boost radiation therapy (n=5), and surgery (n=3), and neurological improvement was achieved in 9 (50.0%).
  
  
  CONCLUSIONS
  In our series, prescription dose (>20 Gy) was 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 in the patients with limited life expectancy.
authors.affiliation: Department of Neurosurgery, Gamma Knife Center, Ajou University School of Medicine, Suwon, Korea.
authors.forename: Chang-Yong
authors.initials: CY
authors.lastname: Park
authors.affiliation: Department of Neurosurgery, Winjin Green Hospital, Seoul, Korea.
authors.forename: Hyun-Yong
authors.initials: HY
authors.lastname: Choi
authors.affiliation: Department of Neurosurgery, Gamma Knife Center, Ajou University School of Medicine, Suwon, Korea.
authors.forename: Sang-Ryul
authors.initials: SR
authors.lastname: Lee
authors.affiliation: Department of Neurosurgery, Gamma Knife Center, Ajou University School of Medicine, Suwon, Korea.
authors.forename: Tae Hoon
authors.initials: TH
authors.lastname: Roh
authors.affiliation: Department of Neurosurgery, Gamma Knife Center, Ajou University School of Medicine, Suwon, Korea.
authors.forename: Mi-Ra
authors.initials: MR
authors.lastname: Seo
authors.affiliation: Department of Neurosurgery, Gamma Knife Center, Ajou University School of Medicine, Suwon, Korea.
authors.forename: Se-Hyuk
authors.initials: SH
authors.lastname: Kim
keywords: Motor cortex; Neoplasm metastasis; Neurologic deficits; Radiation dosage; Radiosurgery