Operative Strategies during Awake Surgery Affect Deterioration of Paresis a Month after Surgery for Brain Lesions in the Primary Motor Area.

Introduction We analyzed factors associated with worsened paresis at 1-month follow-up in patients with brain tumors located in the primary motor area (M1) to establish protocols for safe awake craniotomy for M1 lesions. Methods Patients with M1 brain tumors who underwent awake surgery in our hospital (n = 61) were evaluated before, during, and immediately and 1 month after surgery for severity of paresis, tumor location, extent of resection, complications, preoperative motor strength, histology, and operative strategies (surgery stopped or continued after deterioration of motor function). Results Worsened paresis at 1-month follow-up was significantly associated with worsened paresis immediately after surgery and also with operative strategy. Specifically, when motor function deteriorated during awake surgery and did not recover within 5 to 10 minutes, no deterioration was observed at 1-month follow-up in cases where we stopped surgery, whereas 6 of 13 cases showed deteriorated motor function at 1-month follow-up in cases where we continued surgery. Conclusion Stopping tumor resection on deterioration of motor function during awake surgery may help prevent worsened paresis at 1-month follow-up.