Abstract Details

Title The Split Leg in Amyotrophic Lateral Sclerosis

Topic Anterior Horn

Presentation(s) P07 - (-)

Poster/Presentation
Number 083

Objective

Background BACKGROUND: Thenar muscles are preferentially affected in ALS, and a cortical mechanism of this 'split hand' pattern has been suggested. However, thenar muscles have both relatively greater direct corticospinal input and higher physical demands than hypothenar muscles. TA and soleus have relatively equal physical demands but relatively high (TA) and low (soleus) direct cortciospinal projections and hence allow the cortical hypothesis to be tested.

Design/Methods DESIGN/METHODS: 24 patients (33 LLs) with clinically probable or definite ALS were prospectively studied with the revised ALS Functional Rating Scale, Medical Research Council Sum Score, Addenbrooke's Cognitive Examination revised, and quantitative scales of clinical lower motor neurone (LMN) and upper motor neurone (UMN) involvement. Compound muscle action potentials (CMAPs) from TA and soleus, and the Split Hand Index were recorded. Neurophysiological values were compared with 15 age-matched controls.

Results RESULTS: There were significant reductions of CMAP amplitudes from TA (p<0.05) and soleus (p<0.0001) in ALS patients. The TA/soleus CMAP ratio was significantly increased in clinically involved limbs when compared with clinically uninvolved and control limbs (p<0.001), suggesting preferential involvement of the soleus muscle or a 'split leg'. The split leg pattern was identified irrespective of the clinical region of onset. The split hand pattern was identified in 73% of patients, with 63% of those also demonstrating the split leg pattern. LL neurophysiological findings were supported by results of clinical muscle strength testing. In addition, the TA/soleus CMAP ratio was negatively correlated with clinical UMN dysfunction (r=-0.352, p<0.05).

Conclusions CONCLUSIONS: Findings of the present study suggest that local spinal factors are important determinants of the propagation of LMN degeneration in ALS. However, concomitant UMN factors may partially influence the pattern of LMN degeneration.

Authors/Disclosures
Neil G. Simon, MD PRESENTER	No disclosure on file
Robert Zivadinov, MD, PhD, FAAN (Buffalo Neuroimaging Analysis Center)	The institution of Dr. Zivadinov has received personal compensation in the range of $500-$4,999 for serving as a Consultant for BMS. The institution of Dr. Zivadinov has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Omnicuris. The institution of Dr. Zivadinov has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Myrobalan. Dr. Zivadinov has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Sanofi. Dr. Zivadinov has received personal compensation in the range of $10,000-$49,999 for serving on a Speakers Bureau for EMD Serono. Dr. Zivadinov has received personal compensation in the range of $5,000-$9,999 for serving on a Speakers Bureau for Bristol Myers Squibb. The institution of Dr. Zivadinov has received personal compensation in the range of $5,000-$9,999 for serving on a Speakers Bureau for Biogen.
	No disclosure on file
	No disclosure on file
	No disclosure on file
	No disclosure on file
Matthew C. Kiernan, MBBS, PhD, FRACP (Neuroscience Research Australia)	The institution of Prof. Kiernan has received personal compensation in the range of $50,000-$99,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for British Medical Journal Publishers (UK).

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