Delayed recovery of nerve conduction and vibratory sensibility after ischaemic block in patients with diabetes mellitus

Abstract

Objectives - To determine if the recovery of nerve function after ischaemic block is impaired in patients with diabetes mellitus relative to healthy controls. Methods - Median nerve impulse conduction and vibratory thresholds in the same innervation territory were studied in patients with diabetes mellitus (n = 16) and age matched controls (n = 10) during and after 30 minutes of cuffing of the forearm. Results - Cuffing caused a 50% reduction of the compound nerve action potential (CNAP) after 21.9 (SEM 1.6) minutes in patients with diabetes mellitus and after 10.6 (0.7) minutes in controls. After release of the cuff the half life for CNAP recovery was 5.13 (0.45) minutes in patients with diabetes mellitus and < 1 minute in controls. At seven minutes after release of the cuff CNAP was fully restored in the controls whereas in patients with diabetes mellitus CNAP had only reached 75.1 (4.1)% of its original amplitude. After onset of ischaemia it took 14.6 (1.9) minutes in patients with diabetes mellitus before the vibratory threshold was doubled, whereas this took 5.8 (0.8) minutes in controls. After release of the cuff half time for recovery of vibratory threshold was 8.8 (1.0) minutes in patients with diabetes mellitus and 2.6 (0.3) minutes in controls. Ten minutes after the cuff was released the threshold was still raised (2.0 (0.3)-fold) in the diabetes mellitus group, whereas it was normalised in controls. Among patients with diabetes mellitus the impaired recovery correlated with older age, higher HbA1c, and signs of neuropathy, but not with blood glucose. Conclusion - After ischaemia there is a delayed recovery of nerve conduction and the vibratory sensibility in patients with diabetes mellitus. Impaired recovery after ischaemic insults may contribute to the high frequency of entrapment neuropathy in patients with diabetes mellitus.