Effect of right median nerve electric stimulation on brain electrical activity of traumatic coma patients

Abstract

Objective To investigate the effect of right median nerve electric stimulation on brain electrical activity of traumatic coma patients, and the possible mechanism. Methods Forty-five coma patients (28 males and 17 females) after traumatic brain injury (TBI) were included in this study, with age ranging from 26 to 64 years [(41.6±5.5)years]. Glasgow Coma Score (GCS) was ≤8 points [(6.2±0.9)points] 2 weeks after injury. Electroencephalogram was acquired pre-stimulation and 1 d, 3 d, 7 d and 14 d after right median nerve electric stimulation. Power spectrum was analyzed based on fast Fourier transformation. Frequency spectrum was divided in δ(1.0-4.0 Hz), θ(4.1-8.0 Hz), α(8.1-13.0 Hz) and β(13.1-35.0 Hz) bands. Absolute and relative powers of each frequency band were calculated. Changes in spectral measures were compared before and after the electric stimulation. Results Electroencephalogram showed diffuse slow waves in traumatic coma patients before the electric stimulation. Patients demonstrated a notably decrease in slow-wave activity and increase in fast-wave activity after the electrical stimulation. Electrical activity in the left parietal-occipital lobes displayed the most significant changes. Overall trend of electric activity in other brain parts was in line with the left parietal-occipital region, but the change amplitude and time serial of brain electric activity was different. Conclusions Right median nerve electric stimulation results in brain electrical activity variation from slow waves to fast waves. The change is consistent with the brain electric activity while consciousness improved, which provides evidence for coma awakening by right median nerve electric stimulation. Key words: Craniocerebral trauma; Coma; Electroencephalography; Right median nerve stimulation