Relative Pain Reduction and Duration of Nerve Block Response Predict Outcomes in Headache Surgery- A prospective cohort study.

Overview

abstract

BACKGROUND: Experts agree that nerve block (NB) response is an important tool in headache surgery screening. However, the predictive value of NBs remains to be proven in a prospective fashion. METHODS: Pre- and post- NB visual analogue pain scores (0- 10) as well as duration of NB response were recorded prospectively. Surgical outcomes were recorded prospectively by calculating the Migraine Headache Index (MHI) preoperatively and postoperatively at 3 months, 12 months, and every year thereafter. RESULTS: The study population included 115 patients. The chance of achieving MHI percent improvement of ≥80% was significantly higher in subjects who reported relative pain reduction of >60% following NB versus ≤60% (63/92, 68.5% versus 10/23, 43.5%; p= 0.03). Patients were more likely to improve their MHI ≥50% with relative pain reduction of >40% versus ≤40% (82/104, 78.8% versus 5/11, 45.5%; p= 0.01). In subjects with NB response of >15 days, 10 of 13 patients (77.0%) experienced MHI improvement of ≥80%. Notably, all of these patients (100%) reported MHI improvement of ≥50% with mean MHI improvement of 88%. Subjects with a NB response of ≥24 hours achieved significantly better outcomes than patients with a shorter response (72.7± 37.0% vs. 46.1± 39.7%; p= 0.02). However, of 14 patients reporting NB response of <24 hours, 4 patients had MHI improvement of ≥80% and 7 of ≥50%. CONCLUSIONS: Relative pain reduction and duration of NB response are predictors of MHI improvement after headache surgery. NBs are a valuable tool to identify patients who will benefit from surgery.