Cutaneous thermal thresholds in patients with painful burning feet.

Small nerve fibre sensory function was assessed by psychophysical estimates of cutaneous thermal thresholds in 30 patients who presented with the symptoms of painful burning feet. Thresholds were abnormal in 12 and normal in 18 patients although symptoms in the two groups were very similar. Various hypotheses for the mechanism of pain in small fibre neuropathy have been proposed previously and these are discussed, but the cause of symptoms in patients with normal thresholds, is unknown. The possibility exists that these patients have a neuropathic disorder which affects only those unmyelinated fibres involved with pain.