1. Hemispherectomy is a neurosurgical procedure used as a last resort for treating severe epilepsy.
（半脑切除术是一种作为最后手段治疗严重癫痫的神经外科手术。）
2. After the hemispherectomy, the patient's seizures significantly decreased in frequency and severity.
（在半脑切除术后，患者的癫痫发作频率和严重程度明显减少。）