Correlations between slow-rate repetitive nerve stimulation and characteristics associated with amyotrophic lateral sclerosis in Chinese patients.
Yan Wang, Zheman Xiao, Hong Chu and 5 others
PMID 28533621WHAT IT FOUND
Slow repetitive nerve stimulation showed abnormal electrical drops in 54% of ALS patients, mostly in neck muscles.
Those with these drops progressed faster. However, the test was less sensitive than in myasthenia gravis, limiting its standalone diagnostic value.
Key findings
01Positive decrements in compound muscle action potentials were observed in 54% of ALS patients using a >5% threshold, and in 43% using a >10% threshold.
02ALS patients with positive decrements had a significantly faster rate of disease progression compared to those without decrements.
03Decremental responses were significantly more frequent in the proximal trapezius muscle (67%) than in distal hand muscles (12-20%).
STILL TO COME
How it was doneWhat they foundWhat it means for PTsWhat it means for OTsWhat it means for SLPs
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What it does not show
The study was retrospective and single-center, which increases the risk of bias and limits generalizability. The sample size was small (54 patients per group). The population was exclusively Chinese, so results may not apply to other ethnic groups. RNS was less sensitive in ALS than in myasthenia gravis, reducing its utility as a standalone diagnostic marker.
Declared interests
The authors report no conflicts of interest.
The easy way to misread this
Do not conclude that RNS is a reliable standalone diagnostic test for ALS based on this study. The sensitivity was low compared to myasthenia gravis, and the authors state it should only be considered a potential assistant index, not a definitive marker.