Long-term prognostic factors for microvascular decompression for trigeminal neuralgia.

The purpose of this retrospective study was to identify preoperative imaging characteristics and surgical findings that predict pain relief after microvascular decompression (MVD) for trigeminal neuralgia (TN). This study included 141 patients with follow-up ranging from 6 months to 10 years (mean follow-up=26.3 months). Preoperative images were assessed in 90 patients who were evaluated with constructive interference in steady-state (CISS) MRI in the last 6 years. These findings were compared with the severity of neurovascular conflict (NVC) found at operation to identify imaging findings useful for prognosis. Using Kaplan-Meier analysis, we found that the success rate of MVD was 91.1 ± 2.5% at 1 year and was 76.3 ± 7.5% after 5 years. A higher degree of NVC at operation (p=0.000), no vein compression (p=0.049) and single vessel compression (p=0.000) were good prognostic factors for pain relief. Two meaningful positive MRI findings, specifically, the "cerebrospinal fluid rim sign" and the "deviation sign" were statistically significantly associated with the severity of NVC at operation and MVD success (p=0.000). In this study, 34 patients (24.1%) complained of facial numbness postoperatively, and the oral herpes simplex virus was reactivated in 19 patients (13.4%). The involvement of a single arterial offender in NVC is the most important prognostic factor for MVD in TN, and the positive MRI findings described in this report may be helpful in selecting patients for MVD.