High-Intensity Peripheral Magnetic Stimulation in Traumatic Peripheral Nerve Injury

This is a prospective, randomized, double-blind, sham-controlled clinical trial conducted at a single center. Adults aged 18-65 years with unilateral traumatic peripheral nerve injury confirmed by electromyography, with symptom onset at least 3 months prior, neuropathic pain (DN4 ≥ 4), pain severity (VAS ≥ 4), and reduced muscle strength (MRC < 5) will be enrolled.

Participants will be randomly allocated using computer-generated randomization to one of two groups: (1) active high-intensity PMS plus a standardized therapeutic exercise program, or (2) sham PMS plus the same exercise program. Active stimulation will be delivered using a high-intensity magnetic stimulation system with a predefined neuropathy protocol (approximately 10 minutes per session, variable frequencies 1-60 Hz) applied over the injured peripheral nerve, for a total of 9 sessions over 3 weeks (3 sessions per week). In the sham group, the applicator coil will be reversed to prevent effective delivery of the magnetic field, while device screen and audible feedback are maintained. Both groups will receive an individualized exercise program (active range of motion, strengthening, stretching, proprioception and balance exercises, and occupational therapy) for 20 minutes per day, 5 days per week, over 3 weeks.

Participants and outcome assessors will be blinded to group allocation. The physiotherapist delivering the intervention will be aware of allocation but will not participate in assessments. Electrophysiological evaluations will be performed by a blinded electroneurophysiologist.

The primary outcome is pain severity measured by the Visual Analog Scale (VAS). Secondary outcomes include the Douleur Neuropathique 4 (DN4) questionnaire, the Brief Pain Inventory (BPI), the Nottingham Health Profile (NHP), Manual Muscle Testing (MRC scale), and electrophysiological parameters including compound muscle action potential (CMAP) amplitude, distal latency, nerve conduction velocity (NCV), and quantitative motor unit potential (MUP) analysis. Assessments will be performed at baseline (week 0), week 4, and week 8. A total of 40 participants (20 per group) is planned based on an a priori sample size calculation.

Inclusion criteria

• Age between 18 and 65 years
• Traumatic peripheral nerve injury
• Unilateral traumatic peripheral neuropathy confirmed by electromyography (EMG)
• Nerve injury occurring at least 3 months prior
• Douleur Neuropathique 4 (DN4) score ≥ 4
• Visual Analog Scale (VAS) score ≥ 4
• Manual Muscle Testing score < 5
• No analgesic use, or stable analgesic therapy for the past month (no dose changes)

Exclusion criteria

• Active infection or malignancy
• Metal implant or shrapnel in the application area
• Electronic implants (e.g., cardiac pacemaker, spinal cord stimulator, deep brain stimulator)
• Central nervous system diseases
• Non-traumatic causes of neuropathy (e.g., radiculopathy, diabetic neuropathy, entrapment neuropathies, HIV-related neuropathy, trigeminal neuralgia)
• Complete nerve injury
• Injury involving three or more peripheral nerves or plexus injury
• History of peripheral nerve surgery or injection within the past 3 months
• Active psychiatric illness
• Coagulopathy