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Higher Sympathetic Activity In Amyotrophic Lateral Sclerosis
A DGReview of :"Subtle involvement of the sympathetic nervous system in amyotrophic lateral sclerosis"
Muscle and Nerve
03/05/2002
By Anne MacLennan
The sympathetic nervous system shows subtle abnormalities, predominantly sympathetic overactivity, in amyotrophic lateral sclerosis.
This is one finding of an investigation of autonomic function in patients with this disease, undertaken by P. Liam Oey and colleagues from the University Medical Center Utrecht, Utrecht, and Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
Study results also point to the involvement of the preganglionic sympathetic column as the cause of the higher sympathetic activity and the absence of sympathetic skin response (SSR).
The authors postulate the higher sympathetic activity is due to changes in modulation of the sympathetic system, whereas the absence of the SSR is probably caused by disruption of the reflex pathway. The literature on the involvement of the autonomic nervous system (ANS) in amyotrophic lateral sclerosis (ALS) is conflicting though.
Participants were 16 patients with sporadic ALS and 12 age-matched healthy volunteers, and they were tested both at rest and during sympathoexcitatory stimulation. Researchers measured muscle sympathetic nerve activity (MSNA) by provoking venous pooling during short-lasting lower body negative pressure (LBNP) and during the cold pressor test (CPT). To assess the vagal (baroreflex) control of heart rate (HR), spontaneous baroreflex sensitivity (BRS) was measured; to assess involvement of the ANS beyond the cardiovascular system, SSR was measured.
The study found the stand-up test showed none of the subjects had orthostatic intolerance. In comparison with the control group, the ALS patients had an increased HR and a decreased BRS at rest, and a reduced MSNA response to LBNP.
Patient CPT response was normal, and the total MSNA at rest did not differ significantly from that of controls. The latencies of the palmar and plantar SSR were prolonged, and in three ALS patients there was no plantar SSR.
Muscle and Nerve 25: 2002.
"Subtle involvement of the sympathetic nervous system in amyotrophic lateral sclerosis"
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