Nerve growth factor inhibition prevents traumatic neuroma formation in therat

Nerve growth factor (NGF) is thought to play a role in the pathogenesis of neuroma formation as well as in the development of neuropathic pain. In thi s study we attempted to antagonize NGF by using trkA-IgG, an inhibitor of N GF, consisting of the NGF receptor linked to an immunoglobulin. It was deli vered by an implanted osmotic pump directly to the site of a sciatic nerve transection in 16 rats for 30 days. The animals were monitored daily for th e first 2 weeks for evidence of auto-cannibalization (autotomy) of the dene rvated foot (a sign of neuropathic pain). Four (25%) of the 16 rats receivi ng trkA-IgG exhibited such cannibalization compared with 9 of 15 control ra ts (60%) that underwent an identical procedure but were not treated with th e trkA-IgG solution. One month after surgery the sciatic nerves and represe ntative dorsal root ganglia (DRG) from these rats were evaluated histologic a[ly. Six of the 16 experimental rats (38%) demonstrated histological evide nce of neuroma formation compared with 12 of the 15 controls (80%). There w ere no histological differences between the DRG from the two groups. These results support the notion that inhibiting NGF following peripheral nerve i njury in the rat can reduce neuroma formation and neuropathic pain without damaging the cell bod ies of the transected neurons. Copyright (C) 2001 by the American Society for Surgery of the Hand.