Nerve Transfer After Cervical Spinal Cord Injury: Who Has a “Time Sensitive” Injury Based on Electrodiagnostic Findings?

Michael J. Berger, Jana Dengler, Amanda Westman, Armin Curt, Martin Schubert, Rainer Abel, Norbert Weidner, Frank Röhrich, Ida K. Fox

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


Objective: To use the ulnar compound muscle action potential (CMAP) to abductor digiti minimi (ADM) to identify the proportion of individuals with cervical spinal cord injury (SCI) who have lower motor neuron (LMN) abnormalities involving the C8-T1 spinal nerve roots, within 3-6 months, and thus may influence the response to nerve transfer surgery. Design: Retrospective analysis of prospectively collected data. Data were analyzed from European Multicenter Study About SCI database. Setting: Multi-center, academic hospitals. Participants: We included 79 subjects (age=41.4±17.7, range:16-75; 59 men; N=79), who were classified as cervical level injuries 2 weeks after injury and who had manual muscle strength examinations that would warrant consideration for nerve transfer (C5≥4, C8<3). Interventions: None. Main Outcome Measures: The ulnar nerve CMAP amplitude to ADM was used as a proxy measure for C8-T1 spinal segment health. CMAP amplitude was stratified into very abnormal (<1.0 mV), sub-normal (1.0-5.9 mV), and normal (>6.0 mV). Analysis took place at 3 (n=148 limbs) and 6 months (n=145 limbs). Results: At 3- and 6-month post-injury, 33.1% and 28.3% of limbs had very abnormal CMAP amplitudes, respectively, while in 54.1% and 51.7%, CMAPs were sub-normal. Median change in amplitude from 3 to 6 months was 0.0 mV for very abnormal and 1.0 mV for subnormal groups. A 3-month ulnar CMAP <1 mV had a positive predictive value of 0.73 (95% CI 0.69-0.76) and 0.78 (95% CI 0.75-0.80) for C8 and T1 muscle strength of 0 vs 1 or 2. Conclusion: A high proportion of individuals have ulnar CMAPs below the lower limit of normal 3- and 6-month post cervical SCI and may also have intercurrent LMN injury. Failure to identify individuals with LMN denervation could result in a lost opportunity to improve hand function through timely nerve transfer surgeries.

Original languageEnglish
Pages (from-to)682-689
Number of pages8
JournalArchives of Physical Medicine and Rehabilitation
Issue number4
StatePublished - Apr 2024


  • Compound muscle action potential
  • Nerve conduction study
  • Nerve transfer
  • Rehabilitation
  • Spinal cord injury
  • Ulnar nerve


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