SAN FRANCISCO — Physicians think of fibromyalgia as a disorder of central sensitization, but thinking of it in terms of subsets of tender points may improve understanding and speed diagnosis, suggest findings from two small studies.
The 1990 American College of Rheumatology's diagnostic criteria for fibromyalgia rely heavily on patients' reports of pain, and require that a patient feel pain at a minimum of 11 out of 18 tender points. An analysis of data on 748 patients with fibromyalgia identified subsets of tender points that might be used to speed diagnosis, Dr. Terence W. Starz said in a poster presentation at the college's annual meeting.
Clinicians conducted the Manual Tender Point Survey (MTPS) on the 18 standard tender points and 3 control points on patients enrolled in a separate treatment trial. Through a principal components factor analysis, they described three key body regions with tender point subsets: the neck/shoulders, the gluteal and trochanteric tender points, and extremity points on the lateral epicondyle and knee.
Examining two tender points from each of those regions may suffice to diagnose fibromyalgia, but further research is needed to validate this strategy and to identify the most useful tender points, reported Dr. Starz, a rheumatologist at the University of Pittsburgh Medical Center, and his associates.
“I think we can get it down to around six tender points” for diagnosis, he said at the poster session.
Patients in the study averaged 50 years in age, and 95% were women.
Dr. Starz also was an investigator in a separate study led by Dr. Molly T. Vogt, also of the university, that reinforces the idea of thinking about fibromyalgia pain in regional body areas instead of as widespread pain.
A total of 50 patients with fibromyalgia who were seen in a community rheumatology practice completed a questionnaire to localize the musculoskeletal pain they experienced during daily life, and to rate their pain severity on a scale of 0-10. Clinicians performed the MTPS on 18 tender points, 3 control points, and 5 additional sites on the head, then averaged the 18 tender point scores to get a Fibromyalgia Intensity Score (FIS).
Certain areas–the posterior neck, shoulders, low back, hip girdle, and knees–were more intensely symptomatic, Dr. Starz and his associates reported in a separate poster presentation.
The diffuse pain of fibromyalgia seldom was reported by patients or clinicians in some body areas that have the largest sensory cortical representation: the lips, tongue, ears, nose, and thumb. Both the patients' subjective pain measures and the clinician measures yielded similar results.
“Is every place tender in fibromyalgia? No,” Dr. Starz said. The findings suggest that it may be important to investigate local pain generators, especially in the cervical and lumbar spine, the investigators concluded.
The severest pain most often was reported in the low back, outer hips, shoulders, back of the neck, and knees (each reported by more than 90% of patients with severe pain on FIS). Patients with higher-intensity pain were more likely to report pain in peripheral body sites than were patients with less-intense pain.
In the total cohort, 61% had no pain in the ears, either in patient reports or on clinical exam; 69% had no pain in the nose; 80% had no pain in the tongue; 81% had no pain in the lips; and 76% had no pain in fingernails.
Pain was present in the neck and back, the shoulders, and the outer hip in 94% of patients, in the knees in 92%, in the buttocks in 62%, and in the front of the neck in 60%, Dr. Starz reported.