[Management of priapism in sickle-cell diseases with alpha-adrenergic agonists]

Priapism is a common complication of sickle cell anemia. Two different patterns are described: acute priapism, a prolonged painful erection generally lasting more than 6 hours, and stuttering priapism, which consist of brief repeated self-resolving episodes. Until 1990, priapism in sickle-cell patients has relied on measures aimed at lowering blood viscosity and acidosis and reducing the level of circulating hemoglobin S (alcalinization, hyperhydration, exsanguinotransfusion). But these means are not consistently successful. Surgical cavernous-venous shunt was proposed after 12 to 24 hours when conservative treatment failed. These therapeutic modalities are based on the pathophysiology of sickle-cell priapism. Priapism in sickle-cell disease may be due to sequestered sickled red cells in the corpus cavernosum with venous outflow obstruction. For some years, the treatment of priapism in sickle-cell anemia was changed by the use of alpha-adrenergic agonists. These therapeutics (mainly etilefrine and epinephrine) were first reserved for priapism resulting from intrapenile injections of vasoactive drugs which are used for the treatment of impotence. In acute priapism, alpha-adrenergic agonists are used in intracavernous injections (ICI). In stuttering priapism, treatment consists in an oral administration associated, if necessary, with self-administered ICI. ICI results mainly depend on when treatment occurs. Detumescence is achieved in patients treated within 30 hours, as opposed to the few patients treated beyond this delay. This finding is in agreement with experimental findings demonstrating histological evidence of necrosis of endothelial cells and cavernous smooth muscle fibers after 24 hours. Surgery is only used after failure of ICI. The result of oral treatment is not very satisfactory because many patients do not respond well or are dependent on ICI. However, self-administered ICI associated with the oral treatment protects patients with stuttering priapism against acute strokes. The safety of alpha-adrenergic agonists is good as both oral and ICI have few side-effects. The excellent efficacy of ICI in sickle-cell priapism leads to suggest that the pathogenic mechanism could involve a neuromuscular dysfunction.