The effect of delayed nerve repair on the properties of regenerated fibres in the chorda tympani.
The characteristics of regenerated fibres in the chorda tympani have been investigated in cats after nerve section without repair or after section followed by nerve repair twelve weeks later. In the unrepaired group the animals were allowed to recover for twenty four weeks and after delayed repair there was a further recovery period of twelve or twenty four weeks. The properties of gustatory, thermosensitive and mechanosensitive units and the return of vasomotor and secretomotor responses were then investigated and data compared with that from normal controls and from animals which had undergone immediate nerve repair. After nerve section, integrated whole-nerve activity recorded from the chorda tympani during gustatory or thermal stimulation of the tongue was reduced when compared to controls, but there were only small differences between the repaired and unrepaired groups. Recordings made from single units in the chorda tympani revealed that more units were spontaneously active after repair (P < 0.05) and the gustatory units produced more impulses when stimulated (P < 0.005). Twelve weeks after delayed repair the units had slower conduction velocities than those in the unrepaired nerves (P < 0.001), but by twenty four weeks after repair they were significantly faster (P < 0.05). There was little difference in the level of recovery twelve weeks after immediate or delayed repair. We conclude that delayed nerve repair results in better recovery than leaving the nerve unrepaired and that a twelve week delay before repair has little effect.
Smith
K G
KG
Department of Oral and Maxillofacial Surgery, University of Sheffield, School of Clinical Dentistry, Claremont Crescent, Sheffield, UK.
Robinson
P P
PP
D000818:Animals; D002415:Cats; D002814:Chorda Tympani Nerve / Q000502:physiology*; D004558:Electric Stimulation; D005071:Evoked Potentials / Q000502:physiology; D009412:Nerve Fibers / Q000502:physiology*; D009416:Nerve Regeneration / Q000502:physiology*; D009474:Neurons / Q000502:physiology; D011930:Reaction Time / Q000502:physiology; D013649:Taste / Q000502:physiology; D013696:Temperature; D014666:Vasomotor System / Q000502:physiology