Systematic review and meta-analysis of noninvasive cranial nerve neuromodulation for nervous system disorders.

Objective: To systematically review the medical literature and comprehensively summarize clinical research done on rehabilitation with a novel portable and noninvasive electrical stimulation device called the cranial nerve noninvasive neuromodulator in patients suffering from nervous system disorders.

Data Sources: PubMed, MEDLINE, and Cochrane Database of Systematic Reviews from 1966 to March 2013.

Study Selection: Studies were included if they recruited adult patients with peripheral and central nervous system disorders, were treated with the cranial nerve noninvasive neuromodulator device, and were assessed with objective measures of function.

Data Extraction: After title and abstract screening of potential articles, full texts were independently reviewed to identify articles that met inclusion criteria.

Data Synthesis: The search identified 12 publications: 5 were critically reviewed, and of these 5, 2 were combined in a meta-analysis. There were no randomized controlled studies identified, and the meta-analysis was based on pre-post studies. Most of the patients were individuals with a chronic balance dysfunction. The pooled results demonstrated significant improvements in the dynamic gait index postintervention with a mean difference of 3.45 (95% confidence interval, 1.75-5.15; P<.001), Activities-specific Balance Confidence scale with a mean difference of 16.65 (95% confidence interval, 7.65-25.47; P<.001), and Dizziness Handicap Inventory with improvements of -26.07 (95% confidence interval, -35.78 to -16.35; P<.001). Included studies suffered from small sample sizes, lack of randomization, absence of blinding, use of referral populations, and variability in treatment schedules and follow-up rates.

Conclusions: Given these limitations, the results of the meta-analysis must be interpreted cautiously. Further investigation using rigorous randomized controlled trials is needed to evaluate this promising rehabilitation tool for nervous system disorders.