Participants

Individuals with FM and HC were recruited from the North Central Florida area. FM participants fulfilled the 1990 and 2011 ACR Fibromyalgia Criteria.^33,34 Informed written consent for all study procedures was obtained prior to data collection. All procedures were approved by the Medical Institutional Review Board of the University of Florida (IRB-01) and the study protocol conformed to the ethical guidelines of the 2013 Declaration of Helsinki.

Inclusion criteria for participants were (1) adults over the age of 18; (2) the ability to give informed consent; and (3) FM patients had to fulfill the 1990 and 2011 American College of Rheumatology Criteria for FM; (4) Normal neurological examination.

Exclusion criteria were (1) a relevant medical condition besides FM; (2) significant mental illness, including major depression; (3) the inability to give informed consent; (4) current use of analgesic drugs, anxiolytic drugs, anti-depressants, or cough suppressants, (5) presence of spontaneous pain or numbness in any of the body areas used for CPM testing. All subjects taking analgesic drugs or antidepressants before enrollment were asked to complete a wash-out phase (5 half-lives) prior to testing. Medications used for non-pain conditions (i.e., hypertension, hypothyroidism) could be continued.

All prospective subjects had a pre-session screening with one of the investigators who consented the subject and performed a comprehensive history. If the subject met the study criteria, the investigator explained the nature of the study and provided a copy of the informed consent form.