American Society for Peripheral Nerve

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Nerve Decompression Alone Can Restore Motor Function in Patients with Acute Flaccid Myelitis
Elspeth J R Hill, MD PhD MRes, Washington University School of Medicine, St Louis, MO, Jana Dengler, MD, Washington University School of Medicine, St. Louis, MO and Amy M Moore, MD, Department of Surgery, Division of Plastic and Reconstructive Surgery, Washington University School of Medicine, Saint Louis, MO

Introduction: Acute Flaccid Myelitis (AFM) is a rare but devastating disorder resulting in mixed-pattern motor weakness in previously healthy children, with proximal muscles more severely affected than distal muscles. While much remains to be understood, the condition is known to attack the anterior horn cell causing lower motor neuron injury, with highly variable patterns of recovery. Early results from our group have shown the successful restoration of function using a combination of nerve decompression, intra-operative stimulation and motor nerve transfers. Here, we present the striking recovery of motor function in a select group of patients following nerve decompression alone.


Materials & Methods: We present three distinct cases of AFM who underwent decompression neurolysis by a single surgeon. We retrospectively collected data regarding demographics, history of illness and electrodiagnostic studies. We reviewed pre-operative physical examination, response to intra-operative stimulation and immediate post-operative physical examination.



Results: We present three cases of AFM who underwent decompression neurolysis with immediate post-operative recovery of motor function. Case 1: a previously-healthy 15 year-old male, who developed AFM with persistent left leg weakness at 8 months, underwent combined transfer-decompression procedures. Preoperative Medical Research Council (MRC) quadriceps strength of 1/5 improved to 4/5. Case 2: a 9 year-old female with AFM with persistent right leg weakness underwent combined transfer-decompression procedures. Pre-operative toe flexion MRC 1/5 improved to 3/5. Case 3: a 2-year-old female with severe AFM requiring tracheostomy and mechanical ventilation, with persistent left leg weakness, right arm flaccidity, left arm proximal weakness and preservation of some hand function underwent decompressions alone. Left deltoid strength improved from MRC 2/5 to 3/5 by post-operative day 1. In all cases, post-operative findings correlated to intra-operative stimulation following decompression. Further outcomes and data collection is ongoing.



Conclusions: Though much is still not understood about AFM, these cases demonstrate a role for surgical decompression neurolysis in the treatment of AFM. The immediate improvement in motor function from decompression alone suggests a component of compressive-ischemic conduction block underlying motor deficits in this condition, which can be reversed with removal of the thick perineural scar, and provide immediate improved function for these children. Further work is needed to identify the exact etiology, disease process, and best management for children with this debilitating condition. Early referral to a nerve surgeon for these children is warranted.


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