Strength-duration properties of sensory and motor axons in alcoholic polyneuropathy.
OBJECTIVE
The strength-duration time constant (SDTC) is a measure of axonal excitability and depends on the biophysical properties of the axonal membrane. The strength-duration time constant can provide information about Na+ channel function. We aimed to examine changes in the SDTCs of motor and sensory fibers in the median nerves in patients with alcoholic polyneuropathy.


RESULTS
We measured the SDTCs of motor and sensory fibers in 17 patients with alcoholic polyneuropathy (15 men and two women) after stimulating the right median nerve at the wrist. The results were compared with ten healthy age-matched subjects (six men and four women). In patients, the SDTC and rheobase for the motor fibers were 370.8+/-97.4 micros and 3.9+/-1.7 mA; for the sensory fibers, the SDTC and rheobase were 464.7+/-104.3 micros and 3.3+/-1.9 mA. In controls, the SDTC and rheobase for the motor fibers were 359.3+/-103.5 micros and 3.5+/-1.9 mA; for the sensory fibers, the SDTC and rheobase were 478.9+/-113.9 micros and 2.1+/-1.5 mA. Sensory fibers had significantly longer SDTCs and lower rheobase than motor fibers in patients and controls. However, when the values of the patients and controls were compared, a statistically significant difference was only found for the rheobase of sensory fibers (p=0.037).


CONCLUSIONS
Although alcoholic neuropathy corresponds to the pattern of axonopathy, it did not act on the SDTC of the median nerve, which depends on the biophysical properties of the axonal membrane at the node of Ranvier. The process causing axonal degeneration in alcoholic neuropathy may affect internodal channels other than nodal channels or the Na+ -K+ ATP pump.
Yerdelen
Deniz
D
Department of Neurology, Baskent University of Medicine, Adana, Turkey. yerdelend@gmail.com
Koc
Filiz
F
Uysal
Hilmi
H
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000328:Adult; D020269:Alcoholic Neuropathy / Q000175:diagnosis / Q000503:physiopathology*; D001369:Axons / Q000187:drug effects* / Q000473:pathology; D002462:Cell Membrane / Q000187:drug effects / Q000473:pathology; D002492:Central Nervous System Depressants / Q000009:adverse effects; D004568:Electrodiagnosis / Q000379:methods; D000431:Ethanol / Q000009:adverse effects*; D005260:Female; D006801:Humans; D008297:Male; D008475:Median Nerve / Q000187:drug effects / Q000473:pathology / Q000503:physiopathology; D009046:Motor Neurons / Q000187:drug effects / Q000473:pathology / Q000502:physiology; D009186:Myelin Sheath / Q000187:drug effects / Q000473:pathology; D009431:Neural Conduction / Q000187:drug effects* / Q000502:physiology; D010525:Peripheral Nerves / Q000187:drug effects* / Q000473:pathology / Q000503:physiopathology*; D011901:Ranvier's Nodes / Q000187:drug effects / Q000473:pathology; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology; D011984:Sensory Receptor Cells / Q000187:drug effects / Q000473:pathology / Q000502:physiology; D013997:Time Factors; D014855:Wallerian Degeneration / Q000139:chemically induced / Q000175:diagnosis / Q000503:physiopathology
D002492:Central Nervous System Depressants; D000431:Ethanol