Elevated cerebrospinal fluid levels of substance P in patients with the fibromyalgia syndrome.

OBJECTIVE: To measure, and seek clinical correlates with, levels of substance P (SP) in the cerebrospinal fluid (CSF) of fibromyalgia syndrome (FMS) patients. METHODS: CSF from 32 FMS patients and 30 normal control subjects was tested for SP by radioimmunoassay. Clinical measures included tender point examination and standardized questionnaires. RESULTS: CSF SP levels were 3-fold higher in FMS patients than in normal controls (P < 0.001), but they correlated only weakly with tenderness found on examination. CONCLUSION: SP is significantly elevated in FMS CSF, but other abnormalities must exist in FMS to more fully explain the symptoms.