19. Proctalgia Fugax / W.G. Thompson 

Proctalgia fugax is a sudden severe pain in the anus lasting several seconds or minutes and then disappearing completely.

The pathophysiology of proctalgia fugax is uncertain. Although some observations (under obviously fortuitous circumstances) suggest a rectal motility disorder, the symptom appears more likely to result from spasm of the skeletal muscle of the pelvic floor (specifically, the puborectalis). 

Proctalgia fugax occurs in about 14% of adults and is somewhat more common in females than males. The pain may be excruciating, but since it is so short-lived patients seldom report it to their physician. In 90% of instances it lasts less than five minutes and in many cases less than a minute. About one-third of patients suffer attacks following defecation. A small minority report attacks following sexual activity. There are no physical signs. 

Perianal disease may cause pain but it usually accompanies, rather than follows, defecation. One should be particularly careful to exclude the presence of an anal fissure, which may be difficult to see on anal inspection. Pain originating from the coccyx may be accompanied by coccygeal tenderness both externally and from within the rectum. An acute attack of anal pain lasting several hours may indicate a thrombosed hemorrhoid. However, constant pain for many months or years is unlikely to have an organic explanation. 

Beyond reassurance there is no treatment.