jnnp-2018-319894.full.pdf (398.75 kB)
Relative preservation of triceps over biceps strength in upper limb-onset ALS: the 'split elbow'
Version 2 2023-06-07, 08:22
Version 1 2023-06-07, 06:30
journal contribution
posted on 2023-06-07, 08:22 authored by Roaya Khalaf, Sarah Martin, Cathy Ellis, Rachel Burman, Jemeen Sreedharan, Christopher Shaw, Nigel LeighNigel Leigh, Martin R Turner, Ammar Al-ChalabiOBJECTIVE Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease of the motor system. The split hand sign in ALS refers to observed preferential weakness of the lateral hand muscles, which is unexplained. One possibility is larger cortical representation of the lateral hand compared with the medial. Biceps strength is usually preserved relative to triceps in neurological conditions, but biceps has a larger cortical representation and might be expected to show preferential weakness in ALS. METHODS Using the South-East England Register for Amyotrophic Lateral Sclerosis, we performed a retrospective longitudinal cohort study and extracted the modified Medical Research Council (MRC) muscle strength score for biceps and triceps in patients with a diagnosis of upper limb-onset ALS in the 19-year period 1996-2015. A Wilcoxon signed-rank test was used to assess the relative strength of the muscles within the total sum of the upper limbs involved in the study. RESULTS There were 659 people with upper limb onset of weakness. In 215 there were insufficient data to perform the analysis, and a further 33 were excluded for other reasons, leaving 411 for analysis. Biceps was stronger than triceps in 87 limbs, and triceps was stronger than biceps in 258 limbs, with no difference seen in the remaining 477. Triceps strength scores (mean rank=186.1) were higher than ipsilateral biceps strength scores (mean rank=134.2), Z=-10.1, p<0.001 (two-tailed). CONCLUSION Triceps strength is relatively preserved compared with biceps in ALS. This is consistent with a broadly corticofugal hypothesis of selective vulnerability, in which susceptibility might be associated with larger cortical representation.
History
Publication status
- Published
File Version
- Published version
Journal
Journal of Neurology, Neurosurgery and PsychiatryISSN
0022-3050Publisher
BMJ Publishing GroupExternal DOI
Department affiliated with
- BSMS Neuroscience Publications
Full text available
- No
Peer reviewed?
- Yes
Legacy Posted Date
2019-04-24First Open Access (FOA) Date
2019-04-24First Compliant Deposit (FCD) Date
2019-04-24Usage metrics
Categories
No categories selectedKeywords
Licence
Exports
RefWorks
BibTeX
Ref. manager
Endnote
DataCite
NLM
DC