Spontaneous discharge of afferents in a neuroma reflects original receptor tuning

doi:10.1016/0006-8993(90)91033-D

Brain Research

Volume 517, Issues 1–2, 28 May 1990, Pages 245-250

https://doi.org/10.1016/0006-8993(90)91033-D Get rights and content

Abstract

Injured afferent axons trapped in chronic nerve-end neuromas frequently generate spontaneous discharge. We asked whether the patterns of discharge originating at such sites of ectopic electrogenesis bear a consistent relationship to the patterns of discharge characteristic of the corresponding intact afferent types before injury. Nerve-end neuromas were created in electrosensory lateral line nerves in 3 species of weakly electric Gymnotiform fish. Species were chosen in which normal afferent activity occurs at highly characteristic, non-overlapping, species-specific frequencies. Afferent impulse discharge was recorded in vivo from lateral line nerve end neuromas using the nerve-teasing technique. The distribution of firing frequencies of spontaneously active neuroma afferents was relatively uniform within a given fish species, and differed significantly from species to species. Mean values were somewhat lower than for corresponding intact afferents, but the rank order of frequencies across the species was preserved. These data indicate that differential membrane remodelling after axotomy tends to reestablish normal afferent fiber tuning despite failure of regeneration, and in the absence of peripheral electroreceptor reinnervation.

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Citation Excerpt :
Previous studies have shown that injury to peripheral nerves associated with trauma, amputation, compression, or surgery can lead to painful neuromas (Devor and Govrin-Lippmann, 1983; Lindqvist et al., 2000; Kryger et al., 2001; Black et al., 2008), which have a morphology similar to the neuroma-like structures observed in the present tumor-bearing mouse bones. In humans, these non-malignant neuromas frequently cause chronic and severe pain (Lindqvist et al., 2000; Devor, 2001; Black et al., 2008), produce spontaneous ectopic discharges (Nystrom and Hagbarth, 1981; Devor and Govrin-Lippmann, 1983; Devor et al., 1990) in part by up-regulation of sodium channels (Devor et al., 1993; England et al., 1996; Black et al., 2008), and are largely refractory to medical treatment (Black et al., 2008). Whether these neuroma-like structures in the tumor-bearing bone also show an up-regulation of sodium channels and produce spontaneous discharges is unknown, but these structures could partially explain the phenomenon of spontaneous breakthrough cancer pain, as movement would not be required for these spontaneous ectopic and painful discharges to occur.
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Spontaneous discharge of afferents in a neuroma reflects original receptor tuning

Abstract

Neurosci. Lett.

TINS

Brain Research

Pain

Neuroscience

Neurosci. Lett.

Exp. Neurol.

Mechanisms of electroreception

An electrophysiological tuning mechanism in turtle cochlear hair cells

J. Physiol. (Lond.)

Pathophysiology of damaged peripheral nerve

Axoplasmic transport block reduces ectopic impulse generation in injured peripheral nerves

Pain

Temporal and spatial characteristics of the voltage responses of rods in the retina of the snapping turtle

J. Physiol. (Lond.)

Squid axon K conduction: admittance and noise during short- versus long-duration step clamps