Up To 50% of Fibromyalgia Cases Affected
“I would not say that small fiber polyneuropathy causes all cases of fibromyalgia. However, we now have enough confirmation from independent groups, using different research techniques, to say that SFPN is found in close to 50% of people with fibromyalgia,” Anne Louise Oaklander, MD, PhD, from Harvard Medical School in Boston, told Clinical Pain Advisor.
In a study conducted at Massachusetts General Hospital5, Dr. Oaklander and colleagues used leg skin biopsies to show that 41% of 27 patients with fibromyalgia had undiagnosed SFPN.
In contrast with the nebulous syndrome known as fibromyalgia, SFPN is a disease associated with objective evidence of pathology and pathophysiology that can be included in a differential diagnosis, Dr. Oaklander pointed out.
SFPN Linked To Other Fibromyalgia Symptoms
Although some fibromyalgia patients have symptoms of neuropathic pain, others report widespread pain, deep tenderness, insomnia, cognitive dysfunction, and fatigue.2
Research is clarifying that SFPN causes more symptoms than first thought. Abnormal small-fiber control of muscle microcirculation appears to cause deep tenderness and exercise intolerance4, while poor perfusion of the brain from neurogenic orthostatic hypotension can produce cognitive dysfunction or fibromyalgia “brain fog,” Dr. Oaklander said.
Fibromyalgia often begins after a period of physical or emotional stress. “We propose that stress causes sympathetic sprouting in dorsal root ganglions leading to changes in sodium channel gate keeping. A sodium channelopathy may be the underlying mechanism for some cases of fibromyalgia and small fiber neuropathy,” Dr. Martinez-Lavin explained.
“The major clinical implication [of the findings] is that fibromyalgia is real,” Dr. Martinez-Lavin said.