[Dynamic changes in abnormal afferent activities following peripheral nerve injury].

Peripheral nerve injury by chronic compression caused a decrease in conductive velocity or a delay in the transmission of the action potential, later blocking it completely following demyelination of the damaged nerve region. Abnormal firing activities were recorded from the injured peripheral nerve fibers after the 6-7th postoperative day. There were different patterns of abnormal firing from fibers. Regular tonic ectopic firings with high frequency were always recorded from A beta fibers. A delta/C fibers, however, had burst or irregular spikes. A single antidromic shock to the damaged region sometimes induced ectopic spikes following the expected one. The demyelinated region of the damaged nerve was very sensitive to both tetraethylammonium, a K+ channel blocker, and noradrenaline. The authors suggest that new ion channels or receptors, absent in normal, form in the damaged region.