Hypersensitivity and hyperalgesia in somatoform pain disorders.

OBJECTIVE In psychiatry, pain disorders not explained by structural lesions have been classified for decades as somatoform pain disorders, the underlying concept being somatization. In a parallel move, somatic medicine has defined an expanding group of similar pain disorders, known as functional pain syndromes. Functional pain syndromes are characterized by enhanced pain sensitivity. The aim of our study was to investigate the proportion of patients with somatoform pain disorders who also meet the criteria of functional pain syndromes and the extent to which patients with somatoform pain disorders also show enhanced pain sensitivity. METHODS Data on pain sensitivity in 120 hospitalized patients were obtained by means of two algometric methods. The group of patients with somatoform pain disorders was further divided into two subsets: patients with and those without a co-diagnosis of a functional pain syndrome. Patients with nociceptive pain served as control group. RESULTS Of the 120 in-patients selected, 67 fulfilled the criteria of a somatoform pain disorder of which 41 (61%) also met the co-diagnosis of a functional pain syndrome. Patients with somatoform pain disorder differed from controls in that they showed enhanced pain sensitivity, irrespective of whether a functional pain syndrome was concomitantly present (P<.001). CONCLUSIONS Somatoform pain disorders show considerable overlap with functional pain syndromes, including enhanced pain sensitivity. This suggests the relevance of integrating somatosensory aspects of pain into a modified understanding of somatoform pain disorders.