STRUCTURAL NERVE CHANGES AT WRIST LEVEL IN WORKERS EXPOSED TO VIBRATION

Objectives--To analyse the character of morphological changes occurrin g in a well defined peripheral nerve in humans exposed to vibration fr om hand held tools. Methods--Biopsies of the dorsal interosseus nerve just proximal to the wrist were taken from 10 men exposed to vibration and from 12 male age matched necropsy controls. The nerve was resecte d for pain relief either as the sole procedure or in conjunction with carpal tunnel release. All specimens were sectioned and examined by li ght microscopy in standard sections, thin epon sections, and teasing p reparations. Results--The combined results of the analyses showed path ological changes in all 10 patients dominated by breakdown of myelin a nd by interstitial and perineurial fibrosis. All but one of the 12 con trols were normal. Conclusion--These findings often show severe nerve injury previously not described at this level. They indicate that demy elination may be the primary lesion in neuropathy induced by vibration followed by fibrosis associated with incomplete regeneration or with organisation of oedema. Vibration can induce structural changes in per ipheral nerves just proximal to the wrist and such changes may constit ute a structural component in carpal tunnel syndrome among people expo sed to vibration. This may help to explain the poor results achieved b y carpal tunnel release in these patients.