Priapism is a pathological penile erection that persists in the absence of sexual stimulation. It is a relatively poorly understood condition and is a medical emergency if ischemic, because of its attendant pain and the associated complication of permanent erectile dysfunction (ED). Despite significant advances in the understanding of the physiology of normal erection and pathophysiology of ED, the infrequent occurrence of this condition, the paucity of basic research, and the lack of controlled trials of therapeutic options has led to priapism being considered an enigma.
Management of low-flow priapism
Therapeutic goals in the management of priapism are to alleviate pain and fear, abort the erection, maintain detumescence, and prevent long-term complications, particularly ED. These goals are achieved through attempts at reducing the arterial inflow and increasing the outflow from the corpora. Local measures within the corpora should be accompanied by definitive therapy for the underlying medical condition. The American Urologic Association (AUA) guidelines on the management of priapism stress the importance of concurrent systemic and local management in patients with underlying systemic diseases. They note a resolution rate of only up to 37 % in sickle cell patients with priapism who did not receive local therapy.
Management of ischemic priapism must proceed in a step-wise fashion depending upon the degree of response to each intervention.
Conservative measures for the erection include ice compresses and ejaculation. However, these are sufficient in only a minority of patients. In fact, Burnett believes that‘ lack of ejaculation ’ as a cause of priapism is only a myth. Pain management may be achieved through either local penile or systemic analgesia. This could include dorsal nerve block, penile block, or oral conscious sedation in children.
Primary medical management involves corporeal aspiration to remove the collected blood and achieve detumescence, and instillation of an alpha-adrenergic agonist drug to induce smooth muscle contraction and maintain the detumescence. Aspiration can be performed using a 21- or 22-gauge butterfly needle inserted into the corpora. A pure alpha-adrenergic stimulant such as phenylephrine is diluted to a concentration of about 0.5mg/ml and 0.5 – 1ml of this solution is administered repeatedly at intervals of 5 – 7 minutes for up to 1 hour through the butterfly needle to achieve detumescence. Alternatives to phenylephrine include epinephrine (10 – 20 µg per dose) and ephedrine (50 – 100 mg per dose). Despite their alpha-selectivity, use of these agents should be accompanied by cardiac monitoring. These agents may induce release of endogenous norepinephrine with consequent cardiac and vascular side-effects. This mandates a close watch for features such as headache, bradycardia, hypertension, and cardiac arrhythmia. Resolution rates following the use of these agents is higher (43 – 81 %) than with aspiration or irrigation alone (24–36%).
Failure of aspiration and drug instillation would be an indication to begin a more extensive cross-irrigation using a second 21-gauge needle in the opposite corpora for efflux of the irrigant solution and alpha-adrenergic agonist drugs may be added to the irrigant solution or instilled after achievement of detumescence.
Oral terbutaline, a beta-adrenergic agonist, has been used to induce detumescence in patients who develop an erection during anesthesia. This observation led to its use in priapism and was found to be successful in up to a third of patients with early presentation, particularly those with intracorpo-real prostaglandin-induced priapism. Priyadarshi reported that 42 % of patients with a pharmacologically induced erection had detumescence with oral terbutaline compared with 15 % of patients receiving a placebo. However, in a prospective, blind, controlled trial of 24 patients with prolonged erections, Govier et al. found no benefit of terbutaline over placebo.
Methylene blue is an inhibitor of cGMP and may induce smooth muscle contraction. It has been used in the management of priapism as a replacement for alpha-adrenergic agonist drugs. Hubler et al. described five patients in whom intracavernosal injection of methylene blue 100 mg helped to achieve detumescence. Methylene blue may be specifically useful in patients with priapism secondary to intracavernosal drug therapy.
First-line therapies such as aspiration and irrigation are found to be most effective if used early, ideally within the first 12 hours of the initiation of the erection. If these are initiated beyond 72 hours, they have limited efficacy, and while they may relieve pain, they do not help preserve potency.
If conservative and medical management measures fail to achieve detumescence, surgical procedures may be needed. The principle behind these procedures is to create a shunt between the corpora cavernosa, and the corpora spongiosa since in most cases, priapism affects only the corpora cavernosa, and the venous drainage from the spongiosa is intact. Creation of a shunt diverts the blood from the cavernosa into the spongiosa, causing detumescence.
The Winter procedure is one of the simplest first-line surgical interventions used for patients in whom medical management fails. It creates a shunt between the glans penis and the corpora cavernosa using a tru-cut needle. The needle is passed through the glans and fired into the cavernosa, thus excising a small length of the two tissues to create a shunt. An alternative to this is the Ebbehoj procedure, in which a similar shunt is obtained using a sharp triangular scalpel blade. Another, more formal, distal shunt is the El-Ghourab procedure, in which, through an incision at the corona, the tips of the two corpora are excised to create a communication.
Proximal shunts are more formidable surgical procedures. The Quakles shunt is a cavernospongiosal shunt in which an anastomosis is created between the cavernosal bodies and the spongiosum. It is important to place these shunts carefully so as to avoid urethral injury. Venous drainage may also be enhanced by creating direct cavernovenous anastomosis. The Grayhack shunt drains the corpora into the saphenous vein while the cavernopenile dorsal vein shunts it to the dorsal vein of the penis.
There are no clear data on the efficacy of one shunting procedure over the other. The distal shunts are easier to perform and should be attempted first before progressing to the proximal shunts. The AUA panel found success rates varying from 66 % to 77 % for these procedures. Common complications of these procedures are erectile dysfunction and urethral injury. erectile dysfunction may result from the corporal ischemia-induced fibrosis or as a result of excessive shunting if the shunt remains patent for a prolonged period. Urethral injuries are more likely to occur in the proximal shunts.
The term ‘priapism’ is derived from Priapus, one of the many mythological characters in Greek history. Modern medical awareness of the condition can be safely attributed to Hinman, who, in an article in 1914, described the condition as a thrombosis of the corporal veins and further attempted to describe the etiology as arising out of mechanical or nervous causes. He believed the majority of cases were due to mechanical causes resulting either from local factors (such as pelvic infections, perineal injuries and penile tumors), or from blood dyscrasias. These descriptions remain valid even today.
Sickle cell disease
Patients with underlying sickle cell disease should be hydrated, alkalinized, and started on oxygen therapy along with local measures for priapism. These are general measures for sickling crises at any site and help to increase the arterial oxygen saturation and decrease the tendency of the red blood cells to sickle. Additional therapeutic options include hyper-transfusion in an attempt to increase the hemoglobin concentration and reduce the levels of hemoglobin S.
Patients with sickle cell hemoglobinopathies may suffer from recurring episodes of priapism. A Jamaican study found recurrent (stuttering) priapism in 42 % of men with sickle cell anemia. Recurrent episodes of ischemic priapism are likely to predispose to corporeal fibrosis. Levine et al. reported this form of priapism in six men with no hemoglobinopathy and no other underlying abnormality. They believe that even one episode of ischemic priapism may lead to an abnormality in the normal regulation of tumescence and detumescence, predisposing to recurrent episodes of ischemic priapism. One of the potential reasons for this dysregulation may be depletion in the expression of the PDE-5 enzyme.
Stuttering or recurrent priapism may recur multiple times during the same day or once every few months. Each episode needs to be evaluated and treated independently. Additionally, a number of preventive strategies have been attempted for these patients.
Oral therapies to prevent recurrence have been based on hormonal manipulation to suppress endogenous testosterone action. The hormonal agents used include diethylstilbesterol, antiandrogens, and gonadotropin-releasing hormone agonists. While these agents show a variable degree of success, they cause significant side-effects such as loss of libido, gyneco-mastia, and premature closure of epiphyseal plates in children. An alternative to hormonal agents is the self-administration of injectable alpha-adrenergic agonist drugs. The patient is taught the injection technique and is instructed to self-inject when a priapism episode begins. This is particularly useful in children, in whom hormonal manipulation is contraindicated. Levine et al. used oral phenylpropanolamine and found that it significantly reduced both the incidence of recurrences as well as the need for repeated use of injectable phenylephrine during the acute episode.
Bivalacqua and Burnett describe an interesting therapeutic option for the prevention of recurrent priapism based on their experimental data on the pathogenesis of priapism. They believe that constant administration of PDE-5 inhibitors to men with an episode of priapism may help to restore the activity of PDE-5 in deficiency of this enzyme. This deficiency may have been the primary reason for these men’s predisposition to priapism, and restoration of normal activity may prevent recurrent episodes. The authors validated their theory while using PDE-5 inhibitors as oral preventive therapy in four patients with recurrent priapism, refractory to standard therapy. One patient had hemoglobin SS disease, two had hemoglobin SC disease, and one had no major medical problems. All four used either sildenafil citrate or tadalafil at varying doses and noted a decreased incidence of recurrent episodes, and all retained their erectile function.
Management of high-flow priapism
The majority of patients with high-flow priapism present with a varying degree of delay after the initial trauma. Early presentation can often be treated with ice compresses, which may induce a spasm of the ruptured vessel, resulting in spontaneous resolution. Occasionally, conservative measures may also work in patients with a typical, delayed-onset priapism. Aspiration and irrigation or use of alpha-adrenergic agonist drugs has no role in achieving detumescence.
Most patients with delayed-onset, high-flow priapism will not have a spontaneous resolution and require intervention.
Arteriography with selective embolization of the internal pudendal artery branches may be necessary. This therapy, though minimally invasive, is associated with a risk of arte-riogenic impotence. Steers and Selby described injection of methylene blue followed by embolization as a successful option for such patients. The use of bioabsorbable material, such as autologous blood clot and gels, may be preferable to permanent embolization coils as these may result in a higher incidence of permanent ED. In patients where a pseudo-aneurysm has formed and is visible using a trans-perineal Doppler probe, a direct puncture of the pseudoaneurysm with injection of embolizing material may also be attempted.
Direct surgical exploration with excision or ligation of the aneurysm or fistula is a choice of last resort, with a high risk of ED.
Priapism represents an acute state. Prompt diagnosis and differentiation between ischemic and non-ischemic priapism is indicated since treatment strategies are different, and ischemic priapism represents an emergency state. Patients and partners should be counseled since long-term sequelae may occur.
Selections from the book: “Textbook of Erectile Dysfunction”, 2009