Dissociated lower limb muscle involvement in amyotrophic lateral sclerosis

Simon, Neil G, Lee, Michael, Bae, Jong Seok, Mioshi, Eneida, Lin, Cindy S-Y, Pfluger, Casey M, Henderson, Robert D, Vucic, Steve, Swash, Michael, Burke, David and Kiernan, Matthew C (2015) Dissociated lower limb muscle involvement in amyotrophic lateral sclerosis. Journal of Neurology, 262 6: 1424-1432. doi:10.1007/s00415-015-7721-8

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Author Simon, Neil G
Lee, Michael
Bae, Jong Seok
Mioshi, Eneida
Lin, Cindy S-Y
Pfluger, Casey M
Henderson, Robert D
Vucic, Steve
Swash, Michael
Burke, David
Kiernan, Matthew C
Title Dissociated lower limb muscle involvement in amyotrophic lateral sclerosis
Journal name Journal of Neurology   Check publisher's open access policy
ISSN 1432-1459
0340-5354
Publication date 2015-06
Year available 2015
Sub-type Article (original research)
DOI 10.1007/s00415-015-7721-8
Open Access Status Not Open Access
Volume 262
Issue 6
Start page 1424
End page 1432
Total pages 9
Place of publication Heidelberg, Germany
Publisher Springer Medizin
Collection year 2016
Language eng
Abstract t has been suggested that corticomotoneuronal drive to ankle dorsiflexors is greater than to ankle plantar flexor muscles, despite the finding that plantar flexors are no less active than TA during walking and standing. The present study was undertaken to determine whether there was differential involvement of distal lower limb muscles in amyotrophic lateral sclerosis (ALS), to elucidate pathophysiological mechanisms of selective muscle involvement. Prospective studies were undertaken in 52 ALS patients, including clinical assessment, disease staging (revised ALS functional rating scale), Medical Research Council sum score, and a scale of upper motor neurone (UMN) dysfunction. Motor unit number estimates (MUNE) and compound muscle action potentials (CMAP) from ankle dorsiflexors and plantar flexors were used to provide objective measures. A novel ‘split leg index’ was calculated as follows: SLI = CMAPDF ÷ CMAPPF. In ALS, there was significantly greater reduction of MUNE and CMAP amplitude recorded from plantar flexors when compared to dorsiflexors, suggesting preferential involvement of plantar flexor muscles, underpinning a ‘split leg’ appearance. The SLI correlated with clinical plantar flexor strength (R= −0.56, p < 0.001). In no patient did the SLI suggest preferential dorsiflexor involvement. In subgroup analyses, mean SLI was greatest in lower limb-onset ALS. In conclusion, the present study has established dissociated involvement of muscles acting around the ankle in ALS. We suggest this reflects underlying differences in cortical, descending or local spinal modulation of these muscles.
Keyword Amyotrophic lateral sclerosis
Clinical phenotype
Disease spread
Pathophysiology
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: UQ Centre for Clinical Research Publications
Official 2016 Collection
School of Medicine Publications
 
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