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Nerve conduction studies in amyotrophic lateral sclerosis
Author(s) -
Cornblath David R.,
Kuncl Ralph W.,
Mellits E. David,
Quaskey Shirley A.,
Clawson Lora,
Pestronk Alan,
Drachman Daniel B.
Publication year - 1992
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/mus.880151009
Subject(s) - amyotrophic lateral sclerosis , nerve conduction velocity , medicine , compound muscle action potential , atrophy , abnormality , cardiology , latency (audio) , anatomy , electrophysiology , disease , psychiatry , electrical engineering , engineering
Nerve conduction studies (NCS) are an integral part of the evaluation of amyotrophic lateral sclerosis (ALS) patients and are useful in distinguishing ALS from disorders that mimic it. The question often arises whether in the presence of severe atrophy and reduction of the compound muscle action potential amplitude, abnormal conduction velocity (CV), distal latency (DL), of F‐wave latency (F) exceeds what can be expected from ALS alone. To determine the limits of abnormality in classic ALS, we prospectively evaluated NCS data from 61 patients who met a strict clinical definition of ALS. We ralated CV, DL, and F to distal evoked amplitude (AMP) in peroneal ( n = 63 observations), median ( n = 50), and ulnar ( n = 52) nerves. In nerves with reduced AMP, CV rarely fell to less than 80% of the lower limit of normal, and DL and F rarely exceeded 1.25 times the upper limit of normal. Utilizing the entire data set and regression analyses, 95% confidence limits for expected values for CV, F, and DL as a function of AMP were calculated. These limits thus derived suggest criteria for NCS abnormalities in ALS and may by useful in differentiating ALS from other illnesses. © 1992 John Wiley & Sons, Inc.