Electrical stimulation (ES) of injured peripheral nerves accelerates axonal 
regeneration in laboratory animals. However, clinical applicability of this 
intervention has never been investigated in human subjects. The aim of this 
pilot study was to determine the effect of ES on axonal regeneration after 
surgery in patients with median nerve compression in the carpal tunnel causing 
marked motor axonal loss. A randomized control trial was conducted to provide 
proof of principle for ES-induced acceleration of axon regeneration in human 
patients. Carpel tunnel release surgery (CTRS) was performed and in the 
stimulation group of patients, stainless steel electrode wires placed alongside 
the median nerve proximal to the surgical decompression site for immediate 1 h 
20 Hz bipolar ES. Subjects were followed for a year at regular intervals. Axonal 
regeneration was quantified using motor unit number estimation (MUNE) and 
sensory and motor nerve conduction studies. Purdue Pegboard Test, Semmes 
Weinstein Monofilaments, and Levine's Self-Assessment Questionnaire were used to 
assess functional recovery. The stimulation group had significant axonal 
regeneration 6-8 months after the CTRS when the MUNE increased to 290+/-140 
(mean+/-SD) motor units (MU) from 150+/-62 MU at baseline (p<0.05). In 
comparison, MUNE did not significantly improve in the control group (p>0.2). 
Terminal motor latency significantly accelerated in the stimulation group but 
not the control group (p>0.1). Sensory nerve conduction values significantly 
improved in the stimulation group earlier than the controls. Other outcome 
measures showed a significant improvement in both patient groups. We conclude 
that brief low frequency ES accelerates axonal regeneration and target 
reinnervation in humans.