Monitoring Reinnervation and Neuroplasticity After Neurotization Using Needle Electromyography.

Abstract

Purpose: Brachial plexus injuries show variable outcomes after nerve transfer surgery. Recovery depends not only on axonal regeneration but also on cortical plasticity. Although neuroimaging can detect such changes, its clinical utility is limited. Needle electromyography offers a reproducible, low-cost method to assess reinnervation and synkinetic activity as potential markers of neuroplasticity.

Methods: We conducted a longitudinal observational study of 21 patients who underwent 34 proximal nerve transfers (2012-2020) to restore shoulder and elbow function after traumatic brachial plexus injury. Serial electromyography was performed at 3- to 9-month intervals over ≥36 months, using dual-channel recordings to assess spontaneous activity, motor unit potentials, and synkineses. Functional outcomes were measured using the MRC scale, goniometry, modified Mallet scale, and DASH questionnaire.

Results: Mean age was 36.1 years; 86% were male. Root avulsions occurred in 43%, panavulsion in 10%. Median time from trauma to surgery was 147 days. Functional success (MRC ≥3/5 with adequate ROM) was achieved in 58.8% of transfers. Early reinnervation (<6 months) occurred in 53% and correlated with greater muscle strength (Rs = 0.53, p < 0.01). Synkineses resolution occurred in 29% and correlated negatively with time to surgery (Rs = -0.50, p = 0.005). Absence of synkineses was associated with better outcomes (60 vs. 40%, p = 0.07).

Conclusions: Needle electromyography enables systematic, accessible tracking of reinnervation and synkineses. Resolution of synkineses may indicate functional cortical reorganization and support improved recovery. This approach warrants further prospective validation.