A PROSPECTIVE-STUDY OF PAINFUL SYMPTOMS, SMALL-FIBER FUNCTION AND PERIPHERAL VASCULAR-DISEASE IN CHRONIC PAINFUL DIABETIC NEUROPATHY

Fifty diabetic patients with chronic painful sensorimotor neuropathy w ere studied prospectively to clarify the natural history of this condi tion and the roles of small-fibre damage and concomitant peripheral va scular disease (PVD). Initially, 30 patients had no significant PVD (a nkle:brachial Doppler ratio > 1.0). Pain was assessed using a visual a nalogue scale (0-10 cm), and small-fibre function by thermal limen (TL ), heat-pain threshold (HPT), and weighted pinprick threshold (PPT). A t follow-up, on average 3.6 years later (range 3.0-4.1), 11 patients h ad died (6 with PVD) and contact had been lost with 6. Pain scores fel l in subjects without PVD (n = 24; median (range), from 4.8 (0.5-1 0.0 ) to 2.0 (0.0-9.2) cm, p < 0.001) and also in those with PVD (n = 9; f rom 5.1 (2.0-8.2) to 2.1 (0.0-8.0) cm, p < 0.05). Seven patients (5 wi thout PVD) became pain-free; at presentation, these 7 patients had exp erienced pain for a shorter period of time. Despite this symptomatic i mprovement, small-fibre function generally deteriorated in both groups , with significant worsening (p < 0.05) of HPT and PPT in patients wit hout PVD, and in HPT and TL in patients with PVD. Neuropathic pain the refore tends to improve with time and can resolve completely. By contr ast, small-fibre function continues to deteriorate, indicating that th ese peripheral measures do not predict the evolution of painful sympto ms. The presence or absence of PVD does not appear to affect the natur al history of neuropathic pain or its symptomatology.