Clinical electrodiagnostic evaluation for nerve transfer surgery in spinal cord injury: a new indication and clinical pearls

Abstract

In this review, we highlight the important role of the clinical electrodiagnostic (EDX) evaluation after cervical spinal cord injury (SCI). Our discussion focuses on the need for timely, frequent and accurate EDX evaluations in the context of nerve transfer surgery to restore critical upper limb functions, including elbow extension, hand opening and hand closing. The EDX evaluation is crucial to define the extent of lower motor neuron lesions and determine candidacy for surgery. We also discuss the important role of the post-operative EDX evaluation in determining prognosis and supporting rehabilitation. We propose a practical framework for EDX evaluation in this clinical setting.

Segmental infralesional pathological spontaneous activity in subacute traumatic spinal cord injury

“…Data were pooled for the C8‐T1 myotomes, which were caudal to the neurological level of injury for all individuals included in the study. The rationale for examining the pooled data at the C8‐T1 myotomes is that nerve transfer recipients to restore grasp function are innervated by these segments, making them the most clinically relevant segments to evaluate 17 . The frequency of PSA observed for each injury level is depicted in Table 2.…”

“…The reason for performing the EMG examination was to determine whether potential donor and recipient muscle groups demonstrated signs of pathological spontaneous activity (PSA; the presence of fibrillation potentials and/or positive sharp waves) that might preclude delaying a decision regarding nerve transfer surgery. 17 The EMG protocol was at the discretion of the physiatrist and tailored to each individual patient, but generally included needle EMG screen of representative muscles innervated by the C5-T1 nerve roots, as well as nerve conduction studies to rule out intercurrent peripheral nervous system conditions when indicated clinically. For this reason, not all those included had the complete battery of electrodiagnostic testing to definitively rule out intercurrent plexopathy, polyradiculopathy or polyneuropathy, as the exams were tailored toward the specific question of nerve transfer candidacy.…”

“…Subjects were included if they underwent needle electromyography (EMG) examination in at least one upper limb, within 6 months of their injury. The reason for performing the EMG examination was to determine whether potential donor and recipient muscle groups demonstrated signs of pathological spontaneous activity (PSA; the presence of fibrillation potentials and/or positive sharp waves) that might preclude delaying a decision regarding nerve transfer surgery 17 . The EMG protocol was at the discretion of the physiatrist and tailored to each individual patient, but generally included needle EMG screen of representative muscles innervated by the C5‐T1 nerve roots, as well as nerve conduction studies to rule out intercurrent peripheral nervous system conditions when indicated clinically.…”

“…The rationale for examining the pooled data at the C8-T1 myotomes is that nerve transfer recipients to restore grasp function are innervated by these segments, making them the most clinically relevant segments to evaluate. 17 The frequency of PSA observed for each injury level is depicted in Table 2. Not all participants had all relevant segments evaluated and the number of observations for each myotome is listed in parentheses.…”

“…There are now two clinical expert recommendations regarding the suggested electrodiagnostic evaluation in SCI and future studies are required to determine whether distal peripheral nervous system lesions explain the high frequency of PSA observed in this analysis. 17,19…”