Non-pharmacologic approaches to neurological stimulation in patients with severe brain injuries: a systematic review

This review aimed to evaluate and summarize the current knowledge about the non-pharmacological neurological stimulation (NPNS) in patients with severe brain injuries (SBI). The approaches we analyzed included sensory stimulation, music therapy, virtual reality, transcranial direct current stimulation (tDCS) and transcranial magnetic stimulation (TMS).

We performed a review following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) standards. The key words used for the search across electronic databases such as PubMed and the Cochrane Library were "brain injury" or "coma" or "vegetative state" and "neurological stimulation" or "sensory stimulation" or "music therapy" or "virtual reality" or "transcranial direct current stimulation" or "transcranial magnetic stimulation".

38 studies matched the inclusion criteria. These articles were categorized into five clusters: sensory stimulation, music therapy, virtual reality, transcranial direct current stimulation and transcranial magnetic stimulation. Hence, a concise summary of each study was made up, including study population characteristics, type of non-pharmacological neurological stimulation, neurological clinical outcomes or neuroimaging outcomes.

Overall, all the non-pharmacological approaches to neurological stimulation in patients with SBI seem to be innovative and promising. Further randomized clinical trials, including a wide range of patients, will be necessary to definitely validate these methods and develop standardized protocols shared in the scientific community.