Motor nerve conduction study in cauda equina with high-voltage electrical stimulation in multifocal motor neuropathy and amyotrophic lateral sclerosis.
In this study we aim to establish a motor nerve conduction study (NCS) for the cauda equina and examine its usefulness in multifocal motor neuropathy (MMN) and amyotrophic lateral sclerosis (ALS). NCS of the tibial nerve proximal to the knee was performed with an optimized high-voltage electrical stimulation (HV-ES) method in 21 normal subjects, 5 with MMN, and 11 with ALS. HV-ES, but not magnetic stimulation, could supramaximally stimulate the cauda equina. Cauda equina motor conduction time determined by HV-ES, but not that with F-waves, correlated well with cauda equina length on magnetic resonance imaging. HV-ES revealed proximal lesions in 4 MMN patients but in none of the ALS patients. Importantly, 1 patient with "MMN without conduction block (CB)" had a CB in the cauda equina. Cauda equina motor conduction is better evaluated by HV-ES than with F-wave study or magnetic stimulation. HV-ES can help to distinguish MMN and "MMN without CB" from ALS.
Department of Neurology and Neurological Science, Tokyo Medical and Dental University Graduate School, Tokyo 113-8519, Japan.
Miho
M
Akaza
Tadashi
T
Kanouchi
Akira
A
Inaba
Yoshiyuki
Y
Numasawa
Takashi
T
Irioka
Hidehiro
H
Mizusawa
Takanori
T
Yokota
D000200:Action Potentials / Q000502:physiology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000690:Amyotrophic Lateral Sclerosis / Q000628:therapy*; D000842:Ankle / Q000294:innervation; D002420:Cauda Equina / Q000502:physiology* / Q000503:physiopathology; D004558:Electric Stimulation; D004576:Electromyography / Q000379:methods; D005260:Female; D006615:Hip / Q000294:innervation; D006801:Humans; D007717:Knee / Q000294:innervation; D008280:Magnetics; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000503:physiopathology; D009431:Neural Conduction / Q000502:physiology*; D011115:Polyneuropathies / Q000628:therapy*; D013979:Tibial Nerve / Q000503:physiopathology*; D055815:Young Adult