Treatment of persistent penile erection and priapism using terbutaline

The recent finding of terbutaline as the treatment of choice to manage intraoperative penile tumescence with the patient under anesthesia (general and regional) has prompted us to use this beta-2 agonist (5 mg. orally) for persistent penile erection and priapism resulting from injection of pharmacological agents, such as phentolamine, phenoxybenzamine and papavarine, into the penis for erectile impotence. The drug also has been used successfully (0.25 to 0.5 mg. intravenously or subcutaneously) to treat priapism developing despite a cavernosum-spongiosum shunt procedure. This and other pure beta 2 agonists will have an important role in the treatment of undesirable and painful penile erection, alone or in association with other invasive and noninvasive intervention.     

The physiology of penile erection. I. Hemodynamics of penile erection

Arterial and venous flow and pressure studies of the corpora cavernosa were performed to elucidate the hemodynamics of canine penile erection. Being able to induce erection by electrical stimulation we were able to study the functionally relevant parameters at different stages of penile erection. From our results we conclude that penile erection can be subdivided in 5 phases: (1) latent-, (2) tumescence-, (3) erection-, (4) rigidity- and (5) detumescence phase. Furthermore, a differentiation of these subdivisions is made by observing at the mechanism of the 5 different stages: phase 1 to 4 is an active phenomenon, the detumescence phase is passive only.     

The physiology of penile erection. II. Neurophysiology of penile erection

Selective cavernous and pudendal nerve stimulation enabled us to study the neurophysiologic-/neurovascular mechanisms of penile erection in 6 monkeys. Corporeal pressure recordings during different neurostimulation patterns demonstrated that tumescence and erection are controlled by the autonomic nervous system (Nn. cavernosi) and has to be understood as the vascular phase of erection. However, rigidity is related to the muscle tone of the striated bulbospongiosus and ischiocavernosus muscles which are innervated by somatomotoric fibers of the pudendal nerve. This mechanism is defined as the muscular phase of penile erection.     

Pathophysiology of prolonged penile erection associated with trazodone use

Treatment with the antidepressant trazodone has been associated with the occurrence of prolonged penile erection and priapism. To evaluate the effect of trazodone on erection we monitored the periodic physiological sleep-related erections in 6 healthy volunteers in a double-blind crossover study comparing the effect of trazodone, trimipramine (a tricyclic antidepressant) and placebo. In addition, to determine the effects of trazodone on the neurovascular control of penile smooth muscle we performed in vitro studies on corpus cavernosum tissue obtained from patients undergoing penile prosthesis implantation. Trazodone significantly increased the total interval of nocturnal erectile activity, while trimipramine had no effect. During the high dose treatment (nights 4 and 5) the average duration of erectile activity per night with placebo was 158 +/- 41 minutes (mean +/- standard deviation) for night 4 and 177 +/- 21 minutes for night 5. During trazodone treatment the erectile activity per night was significantly prolonged to 285 +/- 115 minutes during night 4 and 232 +/- 86 during night 5 (p less than 0.01). Analysis of the erectile activity in relation to the rapid eye movement sleep period during which erectile activity usually occurs revealed that the detumescence phase of erection, under sympathetic control, was significantly prolonged an average of 2.4 times by trazodone compared to placebo (p less than 0.05). In vitro, trazodone at concentrations comparable to those reached in plasma significantly impaired corporeal smooth muscle contractions elicited by electrical stimulation of adrenergic nerves and antagonized contractions induced by exogenous norepinephrine. We conclude that trazodone can enhance penile erection in man and propose a mechanism related to the alpha-adrenoceptor blocking properties of trazodone by interference with the sympathetic control of penile detumescence.     

Role of hydrogen sulfide in the physiology of penile erection

Hydrogen sulfide (H(2)S), which is a well-known toxic gas, has recently been recognized as a biological messenger that plays an important role in physiological and pathophysiological conditions. Relatively high levels of H(2)S have been discovered in mammalian tissues. It is mainly synthesized by 2 enzymes, including cystathionine β-synthase and cystathionine γ-lysase, which utilize L-cysteine as substrate to produce H(2)S. H(2)S has been demonstrated to exhibit potent vasodilator activity both in vitro and in vivo by relaxing vascular smooth muscle. Recently, H(2)S has been discovered in penile tissue with smooth muscle relaxant effects. Furthermore, other effects of H(2)S could play a role in the physiology of erection. Understanding H(2)S in the physiology of erection might provide alternative erectile dysfunction strategies for those patients with poor or no response to type 5 phosphodiesterase inhibitors. This review intends to present the H(2)S pathway in penile tissue and the potential role of H(2)S in the physiology of erections.     

General use of animal models for investigation of the physiology of erection

In review, animal models have accounted significantly for the amazing strides made in the field of sexual dysfunction research. Fundamentally, they have offered a unique experimental approach to test many hypotheses regarding sexual function. Since their early use for sexual physiology research, there has been increasing sophistication using animals involving techniques for stimulating and monitoring sexual responses. One specific area that has been advanced is the use of conscious animal models to obtain a better sense of the natural contexts for sexual physiology and to avoid pharmacological interference associated with anesthetics. Another area of interest is the increasing use of simple but valid techniques to record and assess sexual responses. Efforts to develop and evaluate animal models that replicate disorders of sexual function have also been most advantageous. In the future, animal models will remain useful. The expanded applications of animal models include the study of predisposing disease states associated with sexual dysfunction and the study of all aspects of sexual dysfunction, in both male and female subjects. Continued judgment must be applied, understanding the advantages of one or another animal model, to explore questions and provide answers that are most scientifically relevant to the human condition. The promise of advancing therapies in this field indicates the additional prominent role for animals for the purposes of drug development.     

High-flow priapism as a complication of a veno-occlusive priapism: two case reports

The presentation of two cases of veno-occlusive priapism, in patients of 36 and 58 years, in whom the different medical and surgical techniques employed, failed. The suspicion that high-flow priapism had been provoked by said surgical intervention was confirmed by bilateral arteriographs of the pudendal artery. The treatment, selective embolisation of the affected cavernosal artery with reabsorbable material, led to a rapid return of penile detumescence.     

Recurrent prolonged erections and priapism as a sequela of priapism: pathophysiology and management

Veno-occlusive priapism may be associated with prolonged corporeal ischemia, subsequent fibrosis of the corpora and impotence. We report on 6 patients who presented with an unusual sequela of veno-occlusive priapism, recurrent episodes of prolonged erections or priapism. In all cases the subsequent episodes were idiopathic and veno-occlusive, occurred with a frequency ranging from several times per day to once per month and were symptomatically disabling. Pharmacocavernosometry ruled out mechanical occlusion of corporeal venous drainage by demonstrating elevated flows to maintain intracavernosal pressures following smooth muscle contraction and markedly decreased flow rates following smooth muscle relaxation. Treatment of the recurrent episodes with intracavernous self-injection of phenylephrine resulted in successful detumescence. The use of oral phenylpropanolamine reduced the frequency and duration of the recurrences, and markedly reduced the need for adrenergic self-injection. It is proposed that this syndrome may develop secondary to the initial ischemic episode, resulting in a functional alteration of the adrenergic and/or endothelial-mediated mechanisms that control penile tumescence and maintain penile flaccidity.     

Insights of priapism mechanism and rationale treatment for recurrent priapism

Priapism is defined as abnormal prolonged penile erection occurring beyond or unrelated to sexual interest. The disorder is enigmatic yet devastating because of its elusive etiology, irreversible erectile tissue damage, and resultant erectile dysfunction （ED）. Current management strategies suffer from a poor understanding of the pathophysiology, especially at the molecular level. The traditional treatments are based more on empirical rather than evidence-based knowledge. The outcomes for restoration of normal erectile function are poor, especially for stuttering priapism. Therefore, it is critical to understand priapism from a molecular level, to formulate treatment strategies and to establish rational prevention strategies for high-risk populations, such as sickle cell disease （SCD） patients and cases of the stuttering variant. This review focuses on the recent advances at the molecular level in priapism and penile erection, and applies the recent knowledge to the treatment of stuttering priapism.     

Papaverine-induced priapism: 2 case reports

Intracorporeal papaverine injection therapy for impotence has been reported recently as a therapeutic option with low morbidity. We report 2 cases of papaverine-induced priapism that required surgical intervention.     

阴茎异常勃起的治疗

目的探讨阴茎异常勃起的治疗方法,降低勃起功能障碍（ED）的发生。方法回顾性分析28例阴茎异常勃起病历资料及随访记录。结果3例高流量型阴茎异常勃起经保守治疗后完全消退。19例病程≤48h低流量型阴茎异常勃起病人均经镇静冷敷及阴茎海绵体内注射阿拉明、冲洗并连续硬膜外微量注入麻醉药物治疗,14例症状消失,5例无效行分流术;随访出现勃起功能障碍者分别为1例、2例。6例病程〉48h者3例保守治疗3例手术治疗痊愈后随访出现勃起功能障碍者分别为2例、1例。结论高流量型阴茎异常勃起一般行保守治疗,低流量型阴茎异常勃起病程≤48h尽可能行充分的保守治疗,如无效或病程〉48h应尽可能考虑分流术。     

Shunt surgery for priapism: review of results

In a review of the literature on shunt operations for priapism, 100 case reports were found. The over-all result in terms of potency is 61 per cent. In general there is little difference in outcome between the cavernosus-saphenous vein and cavernosus-spongiosum shunts. If the former surgical procedure is to be performed, a unilateral operation appears to yield better results than a bilateral one. Various causes of priapism are noted in relation to results of surgery, and the complications of shunt procedures are discussed. Equally good results are noted whether the operation is performed early or relatively late in the disease.