Evaluation of mini-mental status examination score after gamma knife radiosurgery as the first radiation treatment for brain metastases.

This study evaluated the mini-mental status examination (MMSE) scores of patients with brain metastases after gamma knife radiosurgery (GKS) without whole-brain radiation therapy (WBRT). Between January 2009 and June 2011, 119 consecutive patients with new brain metastases were treated with a single session of GKS without WBRT. MMSE scores were determined for all patients before GKS and for surviving patients every 3 months after GKS. We evaluated 76 patients (63.9 %) after GKS. The median pre-GKS MMSE score was 28 (range 3-30). The median age, number of brain metastases, and total volume of brain metastases were 65.5 years (range 40-92 years), 2 (range 1-18), and 4.17 ml (range 0.04-27.0 ml), respectively. The median marginal dose was 22.0 Gy (range 14-24 Gy). Thirty-nine patients (51.3 %) developed new distant lesions. The median MMSE follow-up time was 5.8 months (range 0.9-21.6 months). In 16 of 37 patients (43.2 %) with pre-GKS MMSE scores ≤27, the MMSE scores improved by ≥3 points, whereas 15 of all patients (19.7 %) experienced deteriorations of ≥3 points. The incidences of 3-point drops due to new distant lesions and adverse radiation effects were 2.6 and 1.3 %, respectively. The 12-month rate of 3-point drops of the MMSE score due to these 2 causes was 4.2 % (1 of 24 patients). A larger tumor volume was a better prognostic factor for an improvement. GKS has a mild effect on neurocognitive function. Mental deterioration of patients with large symptomatic metastatic tumors tended to improve after GKS.