Central thalamic deep brain stimulation for disorders of consciousness: an individual participant data meta-analysis

OBJECTIVE: Severe traumatic brain injury, cerebral hemorrhage, or cardiac arrest can lead to disorders of consciousness, such as coma, unresponsive wakefulness syndrome, and minimally conscious state (MCS). Deep brain stimulation (DBS) of central thalamic nuclei has been used as therapy to restore consciousness and promote neurological recovery for these patients. It is difficult to evaluate the effectiveness of this emerging therapy given the small sample sizes of published studies and their methodological limitations. METHODS: An individual participant data (IPD) meta-analysis was performed to assess neurological outcomes after central thalamic DBS for chronic disorders of consciousness. The authors systematically reviewed the existing literature in accordance with PRISMA guidelines. The lead authors for every published case or cohort receiving DBS for disorders of consciousness were contacted; data that included the clinical diagnosis and pre- and postoperative neurological status according to the JFK Coma Recovery Scale-Revised (CRS-R) were requested for the individual cases included in their papers. The results were pooled, and the influence of different factors (preoperative consciousness status, age, time from injury to DBS implantation, and anatomical target) on the neurological outcome after DBS implantation was analyzed. RESULTS: IPD of 49 patients who underwent implantation with central thalamic DBS for chronic disorders of consciousness (37 in a vegetative state and 12 in MCS) from 7 distinct centers were analyzed. Overall, 7 of 49 patients significantly recovered awareness after DBS implantation, all of whom underwent implantation ≤ 12 months after neurological injury. The main predictors of greater CRS-R improvement were age at the time of surgery and the delay between injury and DBS implantation. CONCLUSIONS: In patients with severe impairments of consciousness, cyclic DBS of the central thalamus has acutely improved daytime awareness and could increase the potential for readaptation and recovery. However, in this IPD meta-analysis, insufficient data were found to suggest that central thalamic DBS significantly improves the natural history of neurological recovery in patients with chronic disorders of consciousness.