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Item #15 

Evidence For Denervation In Painful Neuropathy

Difference in plasma norepinephrine was significantly less in patients with painful neuropathy.

A group of researchers led by Dr Cees Tack from the University Medical Center Nijmegen, Netherlands, evaluated sympathetic nerve function in patients with diabetes and painful neuropathy of the feet. The researchers used neurochemical techniques to quantify the rate of spillover of norepinephrine into the local venous plasma and neuroimaging techniques to visualize sympathetic innervation and local perfusion. Results from nine patients with diabetes and painful peripheral neuropathy were compared with those from healthy volunteers, patients with diabetes without neuropathy, patients with diabetes with painless neuropathy and those with unilateral complex regional pain syndrome (CRPS).

The researchers found that the local arteriovenous difference in plasma norepinephrine was significantly less in patients with painful neuropathy than in other groups. The rate of norepinephrine spillover also tended to be lower in patients with painful neuropathy. Positron emission tomography scanning showed that these patients had decreased sympathetic innervation compared with healthy volunteers and patients with CRPS. The local arteriovenous difference in plasma norepinephrine was similar in patients with diabetes without neuropathy and in those without diabetes. Patients with diabetes and painless neuropathy showed a partial loss of sympathetic innervation. The researchers conclude that painful neuropathy of the feet in patients with diabetes is associated with regionally selective sympathetic denervation.  Diabetes 2002;51:3545-53