An individual patient data meta-analysis on vagal nerve stimulation for recovery from disorders of consciousness

Disorders of consciousness (DoC), including vegetative state (VS), unresponsive wakefulness syndrome (UWS), and minimally conscious state (MCS), are characterized by impaired consciousness and have limited therapeutic options. We aimed to perform a systematic review and meta-analysis of individual participant data (IPD) on the efficacy of vagal nerve stimulation (VNS) for DoC. A systematic literature search identified studies on the use of VNS in patients with DoC. IPD were extracted from included studies and pooled for analysis. The primary outcome was improvement in consciousness, assessed clinically using the Coma Recovery Scale-Revised (CRS-R). A total of 10 studies including 112 patients were identified. VNS was associated with significant improvements in consciousness, with a mean increase of 2.78 (95% CI 1.62 to 3.94) in CRS-R. 40.2% of patients demonstrated an improvement in CRS-R score above the minimal clinically important difference (MCID) of 3 or more. Patients in MCS improved more than those in coma or VS/UWS. This IPD meta-analysis provides early evidence for the efficacy of VNS in improving consciousness in patients with DoC. Our results imply the need for high-quality randomized controlled trials for both invasive and non-invasive VNS to better inform its role in DoC neuro-recovery.