Upper leg conduction time distinguishes demyelinating neuropathies
Related Experiment Video
Updated: Jun 4, 2026

Screening of Axonal Degeneration in Carpal Tunnel Syndrome Using Ultrasonography and Nerve Conduction Studies
Published on: January 11, 2019
Paul J Maccabee1, Larry P Eberle, Ian A G Stein
1Department of Neurology, Robert F. Furchgott Center for Neural and Behavioral Science, SUNY Downstate Medical Center, 450 Clarkson Avenue, Brooklyn, New York 11203, USA. paul.maccabee@downstate.edu
Background:
The objective of this study was to determine whether differentiation between demyelinating and axonal neuropathies could be enhanced by comparing conduction time changes in defined segments of the total peripheral nerve pathway.
Methods:
Compound muscle action potentials (CMAPs) were elicited by cathodal stimulation of the tibial nerve at the ankle and popliteal fossa, and by paravertebral neuromagnetic stimulation at proximal and distal cauda equina while recording from muscles of the foot, shin, and thigh. Segmental conduction times were calculated in normal subjects; in patients with lumbosacral radiculopathy, distal symmetric diabetic neuropathy, amyotrophic lateral sclerosis, acute and chronic inflammatory demyelinating polyneuropathy; and in patients with anti-myelin-associated glycoprotein, myelomatous, and Charcot-Marie-Tooth type 1a polyneuropathies.
Results:
Distal cauda equina latency and CMAP duration and segmental conduction times in upper leg and cauda equina facilitated differentiation of demyelinating from axonal neuropathies, even in the presence of a range of reduced amplitude CMAPs.
Conclusions:
Within the demyelinating neuropathy spectrum, it was further possible to distinguish subtypes.
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