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Sunday, February 1, 2009

Priapism

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Priapism is the presence of a persistent, usually painful, erection of the penis unrelated to sexual stimulation or desire. It is a true urologic emergency that may lead to permanent erectile dysfunction and penile necrosis if left untreated. Priapism is frequently idiopathic in etiology but is associated with a number of important medical conditions and pharmacologic agents.

Pathophysiology

Priapism is the result of persistent engorgement of the corpora cavernosa of the penis, originating from a disturbance in the mechanisms that control normal penile detumescence. In most cases, the ventral corpora spongiosum and glans penis remain flaccid.
Two types of priapism are generally described. Arterial high-flow priapism usually is secondary to a rupture of a cavernous artery and unregulated flow into the lacunar spaces. This rare type of priapism is usually not painful and results from penetrating penile trauma or a blunt perineal injury. Low-flow priapism is usually due to full and unremitting corporeal veno-occlusion where venous stasis and deoxygenated blood pools within the cavernous tissue. Prolonged veno-occlusive priapism results in fibrosis of the penis and a loss of the ability to achieve an erection. Significant changes at the cellular level are noted within 24 hours in veno-occlusive priapism, whereas arterial priapism is not associated with fibrotic change.

Frequency

The overall incidence of priapism is 1.5 cases per 100,000 person-years, which increases to 2.9 cases per 100,000 person-years for men older than 40 years. In one study, 38-42% of adult patients with sickle cell disease reported at least one episode of priapism.

Mortality/Morbidity

Deaths have been reported in patients with sickle cell disease presenting with priapism, but the cause of death usually is not related to the priapism per se but to complications from the underlying disease process.
Morbidity is related to long-term impotence, primarily with veno-occlusive priapism, when diagnosis and therapy have been delayed.

Race
No racial predilection exists. Sickle cell disease, which predisposes to the development of priapism, occurs more frequently in the African American population.

Sex
Priapism is primarily a disease of males. Priapism of the clitoris has been reported but is extremely rare.

Age
Priapism has been described at nearly all ages, from infancy through old age. A bimodal distribution between 5 and 10 years in children and 20-50 years in adults is noted.
Younger groups are more often associated with sickle cell disease, while older groups tend to be secondary to pharmacologic agents.


History

-History of thromboembolic (eg, sickle cell disease) or neoplastic disease
-Drug history, including injectable medications used for erectile dysfunction such as papaverine, phentolamine, and prostaglandin E1; antipsychotic oral medications use (eg, trazodone)
-Recent illicit drug use (Cocaine, ecstasy, and marijuana use have been associated.)
-History of trauma or activities that may result in the formation of an arterial-venous fistula or shunt (eg, bicycle riding)
-Degree of pain may help to differentiate between high and low flow varieties of priapism.
-Arterial high-flow priapism
Priapism secondary to arterial causes also may be significantly less painful than venous priapism.
Onset of priapism may be delayed after the acute injury. The delay may be due to vessel spasm initially or to the formation of a clot that is gradually reabsorbed over a period of days.
Priapism secondary to arterial causes usually is less tumescent when compared with venous priapism.
-Veno-occlusive priapism
Patients with veno-occlusive priapism present with a painful erection.
Erection may have been present for hours to days.

Physical
-Presence of priapism should be confirmed by the finding of an erect or semierect penis. The ventral glans and corpus spongiosum are rarely rigid.
-Carefully examine for evidence of trauma or unreported injection sites to the genital region.
-Examine the patient for evidence of an underlying condition that may predispose to priapism.
-Piesis sign - Perineal compression with thumb in young children causes prompt detumescence in high-flow priapism.

Causes

-Medications
Only rare case reports of selective cyclic guanosine monophosphate (cGMP) inhibitors such as sildenafil have been associated with priapism. In fact, several case reports suggest sildenafil as a means to treat priapism and may be able to prevent full-blown episodes from occurring in patients with sickle cell disease.
Some patients may use injectable medications to induce an erection. In these patients, excessive use may produce priapism. Examples of agents used to induce an erection include papaverine, phentolamine, and prostaglandin E1.
Many psychotropic medications such as chlorpromazine, trazodone, quetiapine, and thioridazine have been associated with priapism. The newer agents are not immune to this complication. Priapism has been described with citalopram, a selective serotonin reuptake inhibitor.
Rebound hypercoagulable states with anticoagulants such as heparin and warfarin have been associated. Hydralazine, metoclopramide, omeprazole, hydroxyzine, prazosin, tamoxifen, and androstenedione for athletic performance enhancement.
Cocaine, marijuana, and ethanol abuse - Recently, the complication has been described in patients using ecstasy.

-Thromboembolic
Sickle cell disease and thalassemia
Leukemia and multiple myeloma

-Trauma (pelvic, genital, or perineal)

-Neoplastic (may be primary or metastatic)

-Neurologic
Spinal cord injury and anesthesia
Cauda equina compression syndrome

-Infection
Recent infection with Mycoplasma pneumoniae (Mechanism is thought to be a hypercoagulable state induced by the infection.)
Malaria

Other causes
Fabry disease (rare association, occasionally noted to be priapism of the high-flow type) and amyloidosis
Carbon monoxide poisoning, black widow spider bites, and vigorous sexual exercise have been implicated.
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