Introduction: Traumatic Brain Injury (TBI) can lead to vegetative state (VS) or minimally conscious state (MCS) in affected patients. Deep brain stimulation (DBS) and repetitive transcranial magnetic stimulation (rTMS) are modalities that are being explored as treatment options for VS and MCS. The safety, efficacy, and outcomes of DBS and rTMS for the treatment of MCS and VS in the setting of TBI are reported in this systematic review.
Methods: A literature search was performed using Pubmed and Google Scholar according to PRISMA guidelines. The following search terms were used: TBI, Neurostimulation, DBS, rTMS, VS, MCS. The following variables were analyzed; number of patients, type of disorder of consciousness, preoperative and postoperative scales and presentation, target region, clinical outcomes, parameters of stimulation, and complications. A Z-proportions test was used to determine clinical improvement in each modality.
Results: Nine studies revealed 39 patients diagnosed with VS or MCS who underwent DBS or rTMS treatment or were part of a control group. Five of the nine studies involved treatment with DBS while the other 4 studies investigated treatment with rTMS. 6 out of 13 patients showed clinical improvement in 3 out of 5 studies investigating DBS. The criterion included strong arousal responses, eye opening with dilated pupils, or communicating with vocalizations. The Coma/Near Coma Scale and Coma Recovery Scale-revised (CRS-R) were used. A Z-proportions test revealed no significant difference in clinical improvement (p=0.78). 8 out of 18 patients showed clinical improvement in 2 out of 4 studies investigating rTMS. 1 patient progressed to minimal but definite awareness of self and environment. 7 VS patients turned MCS with a 3- 4-point increase in CRS-R. A Z-proportions test revealed no significant difference in clinical improvement (p=0.64).
Conclusion : Neurostimulation modalities including DBS and rTMS are safe treatments in TBI with moderate evidence. Long-term outcomes and side-effects merit further investigation.
