Multielectrode Array-Based Percutaneous Nerve Stimulation Strategy With Ultrasound Guidance for Ulnar Nerve Injury

Studies have shown that percutaneous nerve stimulation can promote repair of ulnar neuropathy. However, this approach requires further optimization. We evaluated multielectrode array-based percutaneous nerve stimulation for treatment of ulnar nerve injury. The optimal stimulation protocol was determined using a multi-layer model of the human forearm using the finite element method. We optimized the number and distance between electrodes, and used ultrasound to aid in electrode placement. Six electrical needles in series along the injured nerve at alternating distances of five and seven centimeters. We validated the model in a clinical trial. Twenty-seven patients were randomly assigned to a control group (CN) and an electrical stimulation with finite element group (FES). The results showed that disability of arm shoulder and hand (DASH) scores decreased and grip strength increased to a greater extent in the FES group than those in the CN group following treatment ( $\text{P}< 0.05$ ). Furthermore, the amplitudes of compound motor action potentials (cMAPs) and sensory nerve action potentials (SNAPs) improved in the FES group to a greater extent than those in the CN group. The results showed that our intervention improved hand function and muscle strength, and aided in neurologic recovery, as shown using electromyography. Analysis of blood samples indicated that our intervention may have promoted conversion of the precursor form of brain-derived neurotrophic factor (pro-BDNF) to mature brain-derived neurotrophic factor (BDNF) to promote nerve regeneration. Our percutaneous nerve stimulation regimen for ulnar nerve injury has potential to become a standard treatment option.