causalgia

   The term causalgia comes from the Greek words kaiein (to heat, to set on fire) and algos (pain). It was introduced in 1867 by the American neurologist Silas Weir Mitchell (1829-1914) to denote a specific painful condition following injury to one of the major peripheral nerves. Although various definitions of causalgia exist, today the term is used to denote an intolerable, burning pain, usually located in the palm of the hand, the palmar face of the fingers, or the dorsum of the foot, which is accompanied by severe * hyperaesthesia of the affected region. Causalgia is typically located along the efferent trajectory of a peripheral nerve containing sensory fibres, at some distance removed from a skin lesion or wound that has healed. It can be accompanied by autonomic dysfunction in the form of sudomotor, vasomotor, and trophic skin changes. Although Mitchell recognizes that causalgic pain can also present in the form of a mild burning sensation, he emphasizes its predilection for causing "a state of torture which can hardly be credited". As he asserts, "Perhaps few persons who are not physicians can realize the influence which long-continued and unendurable pain may have on both body and mind... Under such torments the temper changes, the most amiable grow irritable, the bravest soldier becomes a coward, and the strongest man is scarcely less nervous than the most hysterical girl. Nothing can better illustrate the extent to which these statements may be true than the cases of burning pain, or, as I prefer to term it, Causalgia, the most terrible of all tortures which a nerve wound may inflict." Traditionally causalgia has been divided into two forms, referred to as causalgia major and causalgia minor. The term causalgia major has been used to denote a form of peripheral nerve injury, accompanied by electrophysiological cross-activation, and severe hyperactivity of the sympathetic nervous system. This condition can be complicated by * hyperpathia, vasoconstriction, and movement disorders. Etiologically, causalgia major is associated with injuries caused by a high-velocity sharp object such as a razor knife, a vibratory-component major trauma (caused by a bullet, for instance), or a high-voltage nerve lesion (as in electrocution). The term causalgia minor has traditionally been used to denote a somewhat similar, but milder symptom complex. The difference between the two forms of causalgia is essentially a question of degree. The incidence rate of causalgia among victims of nerve injuries has been reported as lying between 2 and 20%. Causalgia can be classified as a severe form of reflex sympathetic dystrophy (RSD). In 1993 the International Association for the Study of Pain proposed the new term complex regional pain syndrome (CRPS) as an umbrella term for RSD and causalgia, in order to better reflect the possible nature of these painful conditions. Causal-gia, RSD, and CRPS should not be confused with otherpain syndromes such as *allodynia, * central pain, * hyperalgesia, hyperpathia, * phantom pain, *topalgia, and *hallucinated pain. The question of whether pain can also be experienced in a hallucinated form is a knotty philosophical issue.

   References

   Mitchell, S.W. (1867). On the diseases of nerves, resulting from injuries.In: Contributions relating to the causation and prevention of disease, and to camp diseases. Edited by Flint, A. New York, NY: Hurd and Houghton.

   Richards, R.L. (1967). Causalgia. A centennial review. Archives of Neurology, 16, 339-350.

   Stanton-Hicks, M., Janig, W., Hassenbusch, S., Haddox, J.D., Boas, R., Wilson, P. (1995). Reflex sympathetic dystrophy: Changing concepts and taxonomy. Pain, 63, 127-133.