Spontaneous cure of popliteal aneurysm of syphilitic aetiology.

The two principal causes of aneurysm of the arteries in human beings are arteriosclerosis and syphilis. Arteriosclerotic aneurysms usually develop after the age of 60, while syphilitic aneurysms develop earlier between the third and the fifth decade of life. The common sites of the former are the abdominal aorta and the popliteal artery, while in 70 to 85 per cent. of cases, the sites of involvement of syphilitic aneurysms are the thoracic aorta and its principal branches. Complete rupture is less frequent in arteriosclerotic aneurysms than in syphilitic aneurysms. Mural thrombosis occurs in both types, but complete thrombosis is often associated with the arteriosclerotic type. There is little information in the literature on the incidence of syphilitic aneurysms involving the peripheral vasculature. Stokes, Beerman, and Ingraham (1944) stated that syphilis of the arteries of the extremities was comparatively uncommon, and Allen, Barker, and Hines (1955) specifically stated that syphilis as a cause of aneurysm in the lower extremities was rare. Gifford, Hines, and Janes (1953), in a follow-up study of 100 popliteal aneurysms from 1913 to 1951, reported that the diagnosis of syphilis as the cause of aneurysm was made only in three patients (aged 37, 54, and 57 years) and that two others (aged 37 and 76) had a positive serological test for syphilis besides clinical evidence of occlusive arterial disease presumably arteriosclerotic in nature. An attempt has been made to obtain some figures on aneurysms from the surgical records of the Government General Hospital, Madras, for the 10-year period 1947-1956. The total number of aneurysms dealt with on the surgical side was 86 (thirty abdominal, 34 thoracic, and 22 peripheral). Traumatic, mycotic, arterio-venous, cirsoid, and intracranial aneurysms were excluded. Among the 22 aneurysms affecting the peripheral arteries, there