Priapism

Classification

Priapism is classified into three groups: ischemic (low-flow), nonischemic (high-flow), and recurrent ischemic. The majority of cases (19 out of 20) are ischemic in nature.

Some sources give a duration of four hours as a definition of priapism, but others give six: "The duration of a normal erection before it is classifiable as priapism is still controversial. Ongoing penile erections for more than 6 hours can be classified as priapism."

Complications

Because ischemic priapism causes the blood to remain in the penis for unusually long periods of time, the blood becomes deprived of oxygen and can cause damage to the penile tissue itself. Should the penile tissue become damaged, it can result in erectile dysfunction or disfigurement of the penis. In extreme cases, if the penis develops severe vascular disease, the priapism can result in penile gangrene.

Causes

Priapism may be associated with haematological disorders, especially sickle-cell disease, sickle-cell trait, and other conditions such as leukemia, thalassemia, and Fabry's disease, and neurologic disorders such as spinal cord lesions and spinal cord trauma (priapism has been reported in people who have hanged; see death erection).

Priapism may also be associated with glucose-6-phosphate dehydrogenase deficiency, which leads to decreased NADPH levels. NADPH is a co-factor involved in the formation of nitric oxide, which may result in priapism.

Sickle cell disease often presents special treatment obstacles. Hyperbaric oxygen therapy has also been used with success in some patients. Priapism is also found to occur in extreme cases of rabies.

Medications

Priapism can also be caused by reactions to medications. The most common medications that cause priapism are intra-cavernous injections for treatment of erectile dysfunction (papaverine, alprostadil). Other groups reported are antihypertensives, antipsychotics (e.g., chlorpromazine, clozapine), antidepressants (most notably trazodone), anti-convulsant and mood stabilizer drugs such as sodium valproate, anticoagulants, cantharides (Spanish Fly) and recreational drugs (alcohol, heroin and cocaine). Priapism is also known to occur from bites of the Brazilian wandering spider and the black widow spider.

Mechanism

The mechanisms are poorly understood but involve complex neurological and vascular factors.

Diagnosis

The diagnosis is often based on the history of the condition and the physical exam.

Blood gas testing the blood from the cavernosa of the penis can help in the diagnosis. If the low flow type of priapism is present the blood typically has a low pH while if the high flow type is present the pH is typically normal. Color doppler ultrasound may also help differentiate the two. Testing a person to make sure they do not have a hemoglobinopathy may also be reasonable.

Treatment

Medical evaluation is recommended for erections that last for longer than four hours. Pain can often be reduced with a dorsal penile nerve block or penile ring block. For those with nonischemic priapism cold packs and pressure to the area may be sufficient.

Aspiration

For those with ischemic priapism the initial treatment is typically aspiration of blood from the corpus cavernosum. This is done on either side. If this is not sufficiently effective than cold normal saline may be injected and removed.

Medications

If aspiration is not sufficient a small dose of phenylephrine may be injected into the corpus cavernosum. Side effects of phenylephrine may include low blood pressure, slow heart rate, and arrhythmia. If this medication is used, it is recommended that people be monitored for at least an hour after. For those with recurrent ischemic priapism diethylstilbestrol (DES) or terbutaline may be tried.

Surgery

Distal shunts, such as the Winter's, involve puncturing the glans (the distal part of the penis) into one of the cavernosa, where the old, stagnant blood is held. This causes the blood to leave the penis and return to the circulation. This procedure can be performed by a urologist at the bedside. Winter's shunts are often the first invasive technique used, especially in hematologically induced priapism, as it is relatively simple and repeatable.

Proximal shunts, such as the Quackel's, are more involved and entail operative dissection in the perineum to where the corpora meet the spongiosum, making an incision in both, and suturing both openings together. Shunts created between corpora cavernosa and saphenous vein called Grayhack shunt can be done though this technique is rarely used.

As the complication rates with prolonged priapism are high, early penile prosthesis implantation may be considered. As well as allowing early resumption of sexual activity, early implantation can avoid the formation of dense fibrosis and hence a shortened penis.

Sickle cell anemia

In sickle-cell anemia treatment is initially with intravenous fluids, pain medication, and oxygen therapy. The typical treatment of priapism may be carried out as well. Blood transfusions are not usually recommended as part of the initial treatment but if other treatments are not effective exchange transfusion may be done.

History

Persistent semi-erections or intermittent states of prolonged erections have historically been sometimes called semi-priapism.

Terminology

The name comes from the Greek god Priapus (Ancient Greek: Πρίαπος), a fertility god often represented with a disproportionately large and permanent erection. Priapism in females (continued, painful erection of the clitoris) is known as clitoral priapism or clitorism. Relentless, persistent or continuous erections that lack any Complications are sometimes referred to as a "permaboner" in slang terms.