The new research may shed light on fibromyalgia, a condition that is characterized by chronic widespread pain.
However, lead author Nathaniel Watson, MD, emphasizes that the findings are preliminary and should be used more as a hypothesis to be explored in future research, rather than as proof of a distinct neurological cause for fibromyalgia.
“I don’t think these findings are significant enough to suggest we should change the way fibromyalgia should be evaluated or managed,” says Dr. Watson, who performed the blinded neurological exams in the study. “But it’s a starting point.”
In addition to chronic pain, people with fibromyalgia may have symptoms such as fatigue, insomnia, depression or anxiety, and numbness and tingling of the limbs. About 2% of Americans have the condition, which is often debilitating and more common in women than in men.
Dr. Watson and his colleagues at the University of Washington Medicine Sleep Institute, in Seattle, compared a group of 166 adults with fibromyalgia with 66 people who did not have any pain problems. Compared to their pain-free counterparts, the people with fibromyalgia were more likely to have neurological abnormalities, including greater cranial nerve dysfunction and more sensory, motor, and gait problems, according to the study in the September 2009 issue of Arthritis and Rheumatism. The doctors performing the exams were not aware if the patients had fibromyalgia or not.
In addition, the fibromyalgia patients’ self-reported neurologic symptoms often correlated with the results of the physical exam. In fact, they had more symptoms in 27 of the 29 categories. In particular, light sensitivity (70% versus 6%) was more common in those with fibromyalgia, as were poor balance, weakness, and tingling in the arms and legs.
The results support the possibility that fibromyalgia might be related to a neurological or anatomical problem in the head or neck. Some possibilities include the narrowing of the spinal canal or Arnold-Chiari type I malformation, a genetic defect that affects the brain.
Dr. Watson also says that some of the neurological results could be caused by pain sensations themselves and not other neurological or anatomical issues.
Cleveland Clinic pain management specialist Phil Berenger, MD, does not believe that the neurological exam itself can yield purely objective findings, as the responses patients give during the exam are still subjective. “The exam depends upon what the patient tells you he or she is experiencing, like ‘I can’t feel that pin prick,’ so it’s really hard to say that these findings are totally objective,” says Dr. Berenger, who was not involved in the study.
Dr. Berenger also notes that fibromyalgia patients could be experiencing symptoms from other undiagnosed conditions—such as rheumatoid arthritis, lupus, hypothyroidism, or Parkinsonism—highlighting the difficulty doctors face in accurately diagnosing fibromyalgia. Since its symptoms often overlap with those of various ailments, people may be diagnosed with fibromyalgia if they have widespread pain and symptoms that are not explained by other diseases. People with chronic pain lasting more than three months should see a doctor and undergo a thorough neurological exam, Dr. Berenger says.
Although the precise cause of fibromyalgia remains at large, recent research points to possible central-nervous-system functioning problems that might amplify normal pain signals. Several hormonal abnormalities have been associated with the condition, including unusual levels of a chemical known as substance P, circulating growth hormone, and serotonin. Still, none of the potential explanations have gained widespread acceptance or been proven conclusively.
Fibromyalgia can be treated in a number of ways. The U.S. Food and Drug Administration has approved the anti-epileptic Lyrica as the first drug to treat the condition. Some other types of drugs, such as antidepressants, tricyclic compounds, and dual reuptake inhibitors, can also be effective, along with alternative therapies such as massage. Regular exercise, relaxation techniques, and a regular sleeping pattern can be beneficial for patients as well.
The National Institute of Arthritis and Musculoskeletal and Skin Diseases funded the study.