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The motor neuron response to SMN1 deficiency in spinal muscular atrophy
Author(s) -
Kang Peter B.,
Gooch Clifton L.,
McDermott Michael P.,
Darras Basil T.,
Finkel Richard S.,
Yang Michele L.,
Sproule Douglas M.,
Chung Wendy K.,
Kaufmann Petra,
Vivo Darryl C.
Publication year - 2014
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/mus.23967
Subject(s) - sma* , spinal muscular atrophy , amyotrophic lateral sclerosis , compound muscle action potential , motor neuron , motor unit , smn1 , reinnervation , medicine , neuroscience , anterior horn cell , electrophysiology , physical medicine and rehabilitation , cardiology , psychology , spinal cord , disease , mathematics , combinatorics
: 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. Muscle Nerve 49 : 636–644, 2014