To investigate the efficacy and influencing factors of gamma knife radiosurgery (GKRS) for the treatment of drug-refractory trigeminal neuralgia (TN).

A retrospective analysis was conducted on the clinical data of 91 patients with drug-refractory TN who were treated with GKRS for the first time at the Department of Neurosurgery, Zhongshan Hospital of Xiamen University from October 2014 to December 2018. After treatment, all patients were followed up in outpatient clinics or by telephone. The content of follow-up included evaluation of the patient′s pain relief, complications and recurrence. According to the Barrow Neurology Institute (BNI) pain intensity scale, the patient′s pain relief was evaluated. Among them, grades Ⅰ-Ⅲ indicated effectiveness of treatment, and grades Ⅳ, Ⅴ indicated ineffectiveness. Univariate analysis and multivariate Cox regression analysis were used to determine the risk factors that affected the effectiveness of GKRS treatment in patients with drug-refractory TN.

The median follow-up time of 91 patients was 32 months (10-60 months). During the follow-up period, 19 patients (20.9%) relapsed; 14 cases (15.4%) had facial numbness, 1 case (1.1%) had masticatory muscle weakness, 2 cases (2.2%) had herpes labialis, 1 case (1.1%) had dry eye and corneal ulcer, 3 cases (3.3%) had paresthesia, and 2 cases (2.2%) had masseter muscle weakness. At the last follow-up, 78 of 91 patients achieved effectiveness (treatment-effective group) and 13 patients reported ineffectiveness (treatment-ineffective group); the pain relief rate was 85.7% (78/91). The median effective time for pain relief in 91 patients was 7 months (1-36 months). Compared with the treatment-ineffective group, the treatment-effective group had a lower proportion of patients with a history of hypertension and a preoperative BNI pain intensity scale rating of grade Ⅴ (both P<0.05). There were no significant differences in gender, age, course of disease, pain involvement of trigeminal nerve branches, pain side or central radiation dose between the two groups (all P>0.05). Multivariate Cox regression analysis showed that history of hypertension (HR=1.83, 95%CI: 1.35-2.34) and preoperative BNI pain intensity scale rating of grade Ⅴ (HR=2.13, 95%CI: 1.54-2.66) were risk factors that affected the effectiveness of GKRS treatment in TN patients (both P<0.05).

GKRS for the first treatment of drug-refractory TN has a relatively high pain relief rate, a relatively low postoperative recurrence rate and a relatively low incidence of complications. However, patients with a history of hypertension and preoperative BNI pain intensity scale rating of grade Ⅴ have a lower pain relief rate following GKRS treatment.

Radiosurgery; Trigeminal neuralgia; Treatment outcome; Factor analy-sis, statistical