Polyneuropathy of different etiologies is often associated with pain. The standard treatment of this pain is anticonvulsants or antidepressants, but none of these treatment are effective or tolerable for all patients. Levetiracetam is a newer anticonvulsant and it is the hypothesis is that it could relieve neuropathic pain in polyneuropathy. This is a randomised, double-blind, placebo-controlled, cross-over trial on the effect of levetiracetam 3.000 mg/day on pain in polyneuropathy