Nerve Transfer Surgery in Acute Flaccid Myelitis: Long-Term Follow-up and Role of Electrodiagnostic Testing
Jesse A Stokum, MD, PhD1, Glenn Rivera, MD2, Matthew Elrick, MD2 and Allan Belzberg, MD3, 1University of Maryland School of Medicine, Baltimore, MD, 2Johns Hopkins University, Baltimore, MD, 3Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, MD
Acute flaccid myelitis (AFM) is a syndrome of weakness in one or more limbs associated with the non-polio enterovirus D68, and often results in incomplete recovery. The efficacy of nerve transfer surgery, the role of preoperative electromyography, and ideal surgical timing remains unclear. Here, we conducted a single-center retrospective review of 10 patients who underwent 19 total nerve transfers. The study cohort was comprised of patients of age 0-21 with AFM defined by the AFM working group criteria, who were treated with nerve transfer surgery between 2013 and 2020, and that included work-up with EMG/nerve conduction study (NCS) and at least 6 months of postoperative follow-up. Control muscles were comprised of severely affected proximal muscles that did not receive nerve transfer surgery. Mean age of onset of AFM was 3.8 years (range 2-7 years), with mean duration of follow-up of 2.5 years (range 1.3-4.5 years). For muscles with preoperative medical research council (MRC) grade 0 strength, muscles receiving nerve transfer performed better on follow-up than those that did not, with postoperative MRC grade 2.17 ± 0.42 vs 0 ± 0 (p < 0.0001). Preoperative EMG/NCS indicated worse outcomes in recipient muscles that exhibited the most abundant acute denervation potentials (p=0.0098), but otherwise outcomes did not stratify based on time-to-surgery, preoperative recipient strength, EMG/NCX spontaneous activity, recruitment pattern, or donor compound muscle action potential amplitude. Overall, our results indicate that nerve transfer surgery effectively improves strength in patients with persistent weakness from AFM and indicates that partially affected donor nerves can still serve as viable donors.
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