Congenital Insensitivity to Pain with Anhydrosis: A Unique Syndrome in Two Male Siblings

Introduction  The syndrome of congenital indifference to noxious stimuli (congenital universal indifference to pain, congenital indifference to pain, congenital insensitivity to pain, congenital pure analgesia, congenital analgia) consists of failure to react to ordinarily painful stimuli and usually occurs as an isolated sensory abnormality. Most observers have attributed the syndrome to an abnormal affective response rather than to defective perception. Therefore the term, "indifference to pain" is generally applied. However, Kunkle¹ recently has emphasized that some patients manifest signs indicating faulty transmission of pain signals. He comments that insensitivity to pain is a more appropriate term if evidence for defective transmission is demonstrated.While indifference to pain is usually considered congenital, Ervin's report of a family with dominant inheritance² is the only well-documented case of familial occurrence. One-third of the 36 patients reported in the literature were over 25 years of age when studied, and the congenital nature