Chap. 43. These symptomatic forms have led some experts to question whether erythromelalgia is a type of neuropathy (Davis et al).
The familial form of erythromelalgia has been traced to a mutation in a sodium channel (NaV 1.7) that is selectively expressed in dorsal root ganglia nociceptive neurons. In addition to its inherent value in explaining the manifestations of this disease, the discovery of this channelopathy has evinced interest in novel ways to treat pain by manipulating sodium channels.
Treatment According to Abbott and to Mitts and others, aspirin is useful in the treatment of paroxysms of secondary erythromelalgia and of some primary cases as well; others had recommended methysergide, which has fallen out of use because of retroperitoneal and cardiac valvular fibrosis. Even small doses of aspirin provide relief within an hour, lasting for several days, a feature that is diagnostic. Sano and colleagues report that cyclosporine was of great benefit in a case of familial erythromelalgia that had not responded to other medications.
A similar condition, restricted in topography to the region of an acquired single nerve or skin injury, has been described by Ochoa under the term ABC syndrome (angry, backfiring C-nociceptors). Episodes of pain and cutaneous vasodilatation were induced by mechanical or thermal stimulation and relieved by cooling. There may be persistent hyperalgesia over the affected area. Lance has suggested that a similar mechanism is operative in the “red ear syndrome” as a result of irritation of the third cervical root.
A confusing problem in the differential diagnosis of neck and limb pain is posed by the patient with pains that are clearly musculoskeletal in origin but are not attributable to a disease of the spine, articular structures, or nerves. The pain is localized to certain vague points in skeletal muscles, particularly the large muscles of the neck and shoulder girdle, arms, and thighs. We have been unable to corroborate the ill-defined tender nodules or cords (trigger points) that have been reported as an essential element of this illness. Excision of such nodules has not revealed any sign of inflammation or other disease process. The currently fashionable terms myofascial pain syndrome, fibromyalgia, and fibrositis have been attached to the syndrome. Many of the patients are middle-aged women, who also have the equally vague chronic fatigue syndrome (myalgic encephalopathy). Some relief is afforded by interventions such as local anesthetic injection, administration of local coolants, stretching of underlying muscles (“spray and stretch”), and massage, but the results in any given individual are unpredictable and the status of the disorder is not settled.
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