How Does Pain Happen?

Between elevated intrinsic (resting-state) brain connectivity and spontaneous pain intensity in patients with fibromyalgia (FM)there is a link, and evidence for this has been produced in a new study.

The study by researchers at Massachusetts General Hospital and University of Michigan shows an interaction of multiple brain networks, offering greater understanding of how pain arises.

The National Institute of Arthritis and Musculoskeletal and Skin Diseases estimates that FM affects 5 million American 18 years of age or older, occurring more often in women (80 percent-90 percent).

In the current study, Vitaly Napadow, Ph.D. and colleagues enrolled 36 female subjects -18 FM patients and 18 healthy control subjects with a mean age of 38.9 and 36.1 years of age, respectively.

FM study subjects had a disease-duration of at least 1 year, self-reported pain for more than 50 percent of each day, and were willing to limit introduction of new medications or treatment strategies to control FM symptoms.

Prior to undergoing the MRI scan, participants were asked to rate the intensity of their FM pain on a scale of 0, where 0 is equivalent to "no pain present" and 10 is equivalent to "the worst pain they could imagine." The pain scores ranged widely, from 0 to 8.1.

"Our results clearly show that individuals with FM have greater connectivity between multiple brain networks and the insular cortex, which is a brain region previously linked with evoked pain processing and hyperexcitability in FM," said Dr. Napadow.

The research team found that patients with FM had greater intrinsic connectivity within the right EAN, and between the DMN and the insular cortex-a brain region linked to evoked pain processing.

"In patients with FM, our findings strongly implicate the insular cortex as being a key node in the elevated intrinsic connectivity," added Dr. Napadow.

"Patients demonstrated greater DMN connectivity to the left anterior, middle, and posterior insula."

In the right EAN, FM patients demonstrated greater intra-network connectivity within the right intraparietal sulcus (iPS). Researchers found no differences between the FM and healthy control groups for the left EAN or the MVN.

Details of the study appear online and in the August issue of Arthritis and Rheumatism, a journal published by Wiley-Blackwell on behalf of the American College of Rheumatology.

Source: ANI