Exposure to
sauna heat during
sauna bathing raises the skin temperature of the bather near the hot pain perception threshold and enhances sympathetic activity. Self-reports provided by regular bathers of changes in intensity of their ongoing
pain might, therefore, add novel information on the effect of intense heat on various
pain conditions. We interviewed consecutive patients attending our pain clinic over a period of 1 year about their
pain-related responses to
sauna bathing and controlled the results by quantitated somatosensory tests. There were 61 patients with chronic
neuropathic pain of peripheral origin, 13 patients with central
pain and 59 patients with rheumatoid
pain.
Allodynia and
hyperalgesia to heat were relatively infrequent in all groups (10%, 15% and 8%, respectively). Three out of 17 patients with postinjury
nerve pain reported similar exacerbation. By contrast,
mechanical allodynia was present in 48% of patients with peripheral
neuropathic pain and in 54% of patients with central
pain. The results speak against an important role for C-afferent or sympathetic postganglionic fibres in most subclasses of
neuropathic pain. Animal models of
neuropathic pain should be critically viewed against this finding.