Low calcitonin gene-related, peptide-like immunoreactivity in cerebrospinal fluid from chronic pain patients.

Cerebrospinal fluid (CSF) levels of calcitonin gene-related peptide-like activity (CGRP-LI), were determined in 35 patients with painful orthopaedic disorders and the activity was compared to that of 12 healthy controls without pain. Fourteen patients had pain from osteoarthritis of the hip or the knee, 11 had rhizopathic pain due to a herniated lumbar disc and 10 had pain from a hip fracture. In all patients, decreased CGRP-LI was observed in CSF compared to the controls. The lowest values were found in the patients with osteoarthritis, while there was less, but still significant, reduction of CGRP-LI in the patients with herniated lumbar disc and those with a hip fracture. In most of the patients, CGRP-LI was also analysed at a second lumbar puncture after operative treatment, when pain had subsided or was reduced. However, the CGRP-LI remained low after treatment, which may suggest the influence of factors other than pain.