Berger MJ, Dengler J, Westman A, Curt A, Schubert M, Abel R, Weidner N, Röhrich F, Fox IK. Nerve Transfer After Cervical Spinal Cord Injury: Who Has a "Time Sensitive" Injury Based on Electrodiagnostic Findings?
Arch Phys Med Rehabil 2024;
105:682-689. [PMID:
37979641 DOI:
10.1016/j.apmr.2023.11.003]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 11/06/2023] [Accepted: 11/07/2023] [Indexed: 11/20/2023]
Abstract
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.
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