Muscle fiber conduction abnormalities in early diabetic polyneuropathy.
OBJECTIVE
Diabetic polyneuropathy (PNP) has been proposed to be a primary disorder of sensory nerves. At an early stage motor nerve conduction velocity (MNCV) and muscle strength remain preserved due to compensatory mechanisms (axonal sprouting, reinnervation). We evaluated the use of invasive muscle fiber conduction velocity (MFCV) measurements as a method to detect muscle fiber denervation atrophy, as an early sign of motor axonal loss in diabetes mellitus (DM).


METHODS
Twelve selected male patients (8 type 1, 4 type 2; mean age 35.8 years, SD 10.6), without any sign of micro- or macroangiopathy, were studied by systematic clinical and neurophysiological testing including MFCV estimation.


RESULTS
Hand-held dynamometry was normal in all subjects. There were no signs of recent denervation by concentric needle EMG in any of the patients. Sensory nerve conduction velocity (SNCV) was abnormal in 6 subjects, MFCV in 6 subjects (5 had also low SNCV). The ratio of fastest/slowest muscle fibers in MFCV was correlated to SNCV of sural nerve (-.59, p < .05), but not to MNCV.


CONCLUSIONS
Half of the clinically asymptomatic DM subjects showed sensory involvement together with MFCV abnormalities, despite normal needle EMG and force.


CONCLUSIONS
MFCV estimation offers a sensitive method in detecting early signs of motor axonal dysfunction in DM.
Meijer
J W G
JW
Rehabilitation Centre Tolbrug/Jeroen Bosch Hospital, 's-Hertogenbosch, The Netherlands. J.W.G.Meijer@umcutrecht.nl
Lange
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Links
T P
TP
van der Hoeven
J H
JH
D000328:Adult; D003928:Diabetic Nephropathies / Q000150:complications*; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation / Q000379:methods; D004568:Electrodiagnosis; D004576:Electromyography; D006801:Humans; D008297:Male; D008875:Middle Aged; D018485:Muscle Fibers, Skeletal / Q000502:physiology*; D053581:Muscle Strength Dynamometer; D009133:Muscular Atrophy / Q000209:etiology* / Q000473:pathology*; D009431:Neural Conduction / Q000502:physiology