The Motor Neuron Response to SMN1 Deficiency in Spinal Muscular Atrophy

Overview

Journal Muscle Nerve

Date 2013 Jul 30

PMID 23893312

Citations 18

Authors

Peter B Kang

Clifton L Gooch

Michael P McDermott

Basil T Darras

Richard S Finkel

Michele L Yang

Douglas M Sproule

Wendy K Chung

Petra Kaufmann

Darryl C De Vivo

Affiliations

Soon will be listed here.

Abstract

Introduction: The purpose of this study was to measure and analyze motor unit number estimation (MUNE) values longitudinally in spinal muscular atrophy (SMA).

Methods: Sixty-two children with SMA types 2 and 3 were observed prospectively for up to 42 months. Longitudinal electrophysiological data were collected, including compound motor action potential (CMAP), single motor unit action potential (SMUP), and MUNE.

Results: Significant motor neuron loss and compensatory collateral reinnervation were noted at baseline. Over time, there was a significant mean increase in MUNE (4.92 units/year, P = 0.009), a mean decrease in SMUP amplitude (-6.32 μV/year, P = 0.10), and stable CMAP amplitude.

Conclusions: The unexpected longitudinal results differ from findings in amyotrophic lateral sclerosis studies, perhaps indicating that compensatory processes in SMA involve new motor unit development. A better understanding of the mechanisms of motor unit decline and compensation in SMA is important for assessing novel therapeutic strategies and for providing key insights into disease pathophysiology.

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