Insights of priapism mechanism and rationale treatment for recurrent priapism

Priapism in a 31-Year-Old Male With Paranoid Schizophrenia

Priapism is a painful and emergent side effect that has been linked to some antipsychotics and other psychiatric medications, most often trazodone. This is thought to be due to some level of alpha-1 adrenergic blockade by these medications. Aripiprazole is an atypical antipsychotic with notably weak alpha-1 adrenergic antagonism. Thus, we report on a unique case of aripiprazole-induced priapism in a patient with schizophrenia and recurrent episodes of antipsychotic-induced priapism. This study offers insight into the potential mechanism of aripiprazole-induced priapism and offers alternative medications, such as olanzapine and lumateperone, to treat the patient's ongoing psychotic disorder.

Treatment of Refractory Ischemic Priapism: A Case Report and Literature Review

Recurrent priapism is a rare and poorly known entity. It is defined by recurrent episodes of painful erections that last less than four hours. The etiology is similar to that of ischemic priapism. Episodes lasting more than four hours require immediate intervention to prevent penile fibrosis and subsequent erectile dysfunction. A 42-year-old male with no significant chronic-degenerative history was referred to our medical center from his second-level medical unit after a 56-hour history of ischemic priapism with the persistence of tumescence despite medical and surgical treatment. Upon interrogation, the patient reported stuttering (recurrent) episodes of painful erections lasting approximately three to four hours, not associated with sexual activity or arousal, in the past two years, with spontaneous resolution. He denied the use of psychotropics or drugs for erectile dysfunction. As a palliative measure, a left saphenous-cavernous (Grayhack) bypass was performed, with a 90% decrease in tumescence and total resolution of pain during the first 12 hours. There is little information and treatment recommendations for patients with recurrent priapism, and even less for patients who are refractory to conventional medical and surgical treatment. Recurrent or stuttering priapism is a condition with a low incidence and a pathophysiology compatible with low-flow priapism. It is difficult to treat and has a poor prognosis in terms of erectile function. Likewise, it is mostly associated with the use of psychotropic drugs such as cocaine and marijuana, medications for erectile dysfunction such as phosphodiesterase inhibitors, prostaglandin E1 analogues, and hematological malignancies such as sickle cell anemia and multiple myeloma. The aim of this article is to share our experience with a patient refractory to multiple medical and surgical treatments.

Stuttering Priapism in a Dog—First Report

Simple Summary

A 5-year-old recently castrated male Doberman dog presented for prolonged erection of one week’s duration with associated pain and dysuria. This was the fourth episode within a year. Each episode was associated with an unusual event, which was stressful for the dog. Castration performed two months prior to the final episode did not prevent recurrence. Due to tissue necrosis, penile amputation and urethrostomy had to be performed. To our knowledge, this case is the first report of a stuttering priapism in a dog. Stuttering priapism, also called recurrent or intermittent priapism, is a particular type of ischemic priapism described in humans that is characterized by repeated episodes of prolonged erections.

Abstract

A 5-year-old recently castrated male Doberman dog presented for prolonged erection of one week’s duration with associated pain and dysuria. This was the fourth episode within a year. Each episode was associated with an unusual event, which was stressful for the dog. Castration performed two months prior to the final episode did not prevent recurrence. Due to tissue necrosis, penile amputation and urethrostomy had to be performed. The dog recovered fully. Prolonged erection that persists beyond or that is unrelated to sexual stimulation is called “priapism”. This term refers to the Greek god Priapus, a god of fertility, memorialized in sculptures for his giant phallus. In humans, depending on the mechanism involved, priapism is classified as nonischemic or ischemic. Because prognosis and treatment are different, priapism must be determined to be nonischemic or ischemic. Nonischemic priapism is a rare condition observed when an increase in penile arterial blood flow overwhelms the capacity of venous drainage; it is often associated with penile trauma, and does not require medical intervention. Ischemic priapism is associated with decreased venous return. In humans, ischemic priapism accounts for 95% of cases, the majority of which are idiopathic. Ischemic priapism is a urological emergency; simple conservative measures such as aspiration of blood from the corpora cavernosa and intracavernosal injection of an adrenergic agent are often successful. Stuttering priapism, also called recurrent or intermittent priapism, is a particular form of ischemic priapism reported in humans that is characterized by repetitive episodes of prolonged erections. Management consists of treating each new episode as an episode of acute ischemic priapism, and preventing recurrence with oral medications such as dutasteride and/or baclofen, gabapentin, or tadalafil. To the authors’ knowledge, this case is the first report of stuttering priapism in a dog.

An update on the management algorithms of priapism during the last decade

Priapism is a persistent penile erection lasting longer than 4 hours, that needs emergency management. This disorder can induce irreversible erectile dysfunction. There are three subtypes of priapism: ischemic, non-ischemic, and stuttering priapism. If the patient has ischemic priapism (IP) of less than 24-hours (h) duration, the initial management should be a corporal blood aspiration followed by instillation of phenylephrine into the corpus cavernosum. If sympathomimetic fails or the patient has IP from 24 to 48h, surgical shunts should be performed. It is recommended that distal shunts should be attempted first. If distal shunt failed, proximal, venous shunt, or T-shunt with tunneling could be performed. If the patient had IP for 48 to 72h, proximal and venous shunt or T-shunt with tunneling is indicated, if those therapies failed, a penile prosthesis should be inserted. Non-ischemic priapism (NIP) is not a medical emergency and many patients will recover spontaneously. If the NIP does not resolve spontaneously within six months or the patient requests therapy, selective arterial embolization is indicated. The goal of the management of a patient with stuttering priapism (SP) is the prevention of future episodes. Phosphodiesterase type 5 (PDE5) inhibitor therapy is considered an effective tool to prevent stuttering episodes but it is not validated yet. The management of priapism should follow the guidelines as the future erectile function is dependent on its quick resolution. This review briefly discusses the types, pathophysiology, and diagnosis of priapism. It will discuss an updated approach to treat each type of priapism.

Short Sleep Duration and Erectile Dysfunction: A Review of the Literature

The meaning of sleep has puzzled people for millennia. In modern society, short sleep duration is becoming a global problem. It has been established that short sleep duration can increase the risk of several diseases, such as cardiovascular and metabolic diseases. Currently, a growing body of research has revealed a possible link between sleep disorders and erectile dysfunction (ED). However, the mechanisms linking short sleep duration and ED are largely unknown. Thus, we provide a review of clinical trials and animal studies. In this review, we propose putative pathways connecting short sleep duration and ED, including neuroendocrine pathways and molecular mechanisms, aiming to pave the way for future research. Meanwhile, the assessment and improvement of sleep quality should be recommended in the diagnosis and treatment of ED patients.

Effect of lysyl oxidase (LOX) on corpus cavernous fibrosis caused by ischaemic priapism

Penile fibrosis caused by ischemic priapism (IP) adversely affects patients’ erectile function. We explored the role of lysyl oxidase (LOX) in rat and human penes after ischemic priapism (IP) to verify the effects of anti‐LOX in relieving penile fibrosis and preventing erectile dysfunction caused by IP in rats. Seventy‐two rats were randomly divided into six groups: control group, control + β‐aminopropionitrile (BAPN) group, 9 hrs group, 9 hrs + BAPN group, 24 hrs group, and 24 hrs + BAPN group. β‐aminopropionitrile (BAPN), a specific inhibitor of LOX, was administered in the drinking water. At 1 week and 4 weeks, half of the rats in each group were randomly selected for the experiment. Compared to the control group, the erectile function of IP rats was significantly decreased while the expression of LOX in the corpus cavernosum was significantly up‐regulated in both 9 and 24 hrs group. Proliferated fibroblasts, decreased corpus cavernosum smooth muscle cells/collagen ratios, destroyed endothelial continuity, deposited abnormal collagen and disorganized fibers were observed in IP rats. The relative content of collage I and III was not obviously different among the groups. β‐aminopropionitrile (BAPN) could effectively improve the structure and erectile function of the penis, and enhance recovery. The data in this study suggests that LOX may play an important role in the fibrosis of corpus cavernosum after IP and anti‐LOX may be a novel target for patients suffering with IP.

Contemporary best practice in the evaluation and management of stuttering priapism

Stuttering priapism is rare and under-investigated clinical entity. Although it shares similarities with ischaemic priapism, by definition, stuttering priapism has distinct characteristics that advocate for a different management in the clinical setting. Therefore, the management of stuttering priapism aims primarily to prevent recurrence rather than the resolution of spontaneous attacks. A multimodal approach and the individualization of each case are essential because of the diversity of the condition and the plethora of proposed therapeutic strategies. Understanding the underlying pathophysiology and familiarity with contemporary, past and emerging future agents and therapeutic options are required in order to provide an optimal solution for each patient. In addition, patient counselling and the option to combine therapeutic strategies and challenge second-line therapies are essential weapons in the armament of the urologist. Although further clinical trials and studies are mandatory in order to obtain solid data and provide recommendations, all therapeutic options are analysed, with specific interest in the potential advantages and disadvantages. A structured evaluation procedure is also described.

Clinical and preclinical treatment of urologic diseases with phosphodiesterase isoenzymes 5 inhibitors: an update

Phosphodiesterase isoenzymes 5 inhibitors (PDE5-Is) are the first-line therapy for erectile dysfunction (ED). The constant discoveries of nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) cell-signaling pathway for smooth muscle (SM) control in other urogenital tracts (UGTs) make PDE5-Is promising pharmacologic agents against other benign urological diseases. This article reviews the literature and contains some previously unpublished data about characterizations and activities of PDE5 and its inhibitors in treating urological disorders. Scientific discoveries have improved our understanding of cell-signaling pathway in NO/cGMP-mediated SM relaxation in UGTs. Moreover, the clinical applications of PDE5-Is have been widely recognized. On-demand PDE5-Is are efficacious for most cases of ED, while daily-dosing and combination with testosterone are recommended for refractory cases. Soluble guanylate cyclase (sGC) stimulators also have promising role in the management of severe ED conditions. PDE5-Is are also the first rehabilitation strategy for postoperation or postradiotherapy ED for prostate cancer patients. PDE5-Is, especially combined with α-adrenoceptor antagonists, are very effective for benign prostatic hyperplasia (BPH) except on maximum urinary flow rate (Q max ) with tadalafil recently proved for BPH with/without ED. Furthermore, PDE5-Is are currently under various phases of clinical or preclinical researches with promising potential for other urinary and genital illnesses, such as priapism, premature ejaculation, urinary tract calculi, overactive bladder, Peyronie's disease, and female sexual dysfunction. Inhibition of PDE5 is expected to be an effective strategy in treating benign urological diseases. However, further clinical studies and basic researches investigating mechanisms of PDE5-Is in disorders of UGTs are required.

Nitrergic Mechanisms for Management of Recurrent Priapism

INTRODUCTION

Priapism is a condition involving prolonged penile erection unrelated to sexual interest or desire. The ischemic type, including its recurrent variant, is often associated with both physical and psychological complications. As such, management is of critical importance. Ideal therapies for recurrent priapism should address its underlying pathophysiology.

AIM

To review the available literature on priapism management approaches particularly related to nitrergic mechanisms.

METHODS

A literature review of the pathophysiology and management of priapism was performed using PubMed.

MAIN OUTCOME MEASURE

Publications pertaining to mechanisms of the molecular pathophysiology of priapism.

RESULTS

Nitrergic mechanisms are characterized as major players in the molecular pathophysiology of priapism. PDE5 inhibitors represent an available therapeutic option with demonstrated ability in attenuating these underlying nitrergic derangements. Several additional signaling pathways have been found to play a role in the molecular pathophysiology of priapism and have also been associated with these nitrergic mechanisms.

CONCLUSION

An increasing understanding of the molecular pathophysiology of priapism has led to the discovery of new potential targets. Several mechanism-based therapeutic approaches may become available in the future.

How I treat priapism

Priapism is a disorder of persistent penile erection unrelated to sexual interest or desire. This pathologic condition, specifically the ischemic variant, is often associated with devastating complications, notably erectile dysfunction. Because priapism demonstrates high prevalence in patients with hematologic disorders, most commonly sickle cell disease (SCD), there is significant concern for its sequelae in this affected population. Thus, timely diagnosis and management are critical for the prevention or at least reduction of cavernosal tissue ischemia and potential damage consequent to each episode. Current guidelines and management strategies focus primarily on reactive treatments. However, an increasing understanding of the molecular pathophysiology of SCD-associated priapism has led to the identification of new potential therapeutic targets. Future agents are being developed and explored for use in the prevention of priapism.

Erectile dysfunction after sickle cell disease-associated recurrent ischemic priapism: profile and risk factors

INTRODUCTION

Risk factors associated with erectile dysfunction (ED) that results from recurrent ischemic priapism (RIP) in sickle cell disease (SCD) are incompletely defined.

AIM

This study aims to determine and compare ED risk factors associated with SCD and non-SCD-related "minor" RIP, defined as having ≥2 episodes of ischemic priapism within the past 6 months, with the majority (>75%) of episodes lasting <5 hours.

METHODS

We performed a retrospective study of RIP in SCD and non-SCD patients presenting from June 2004 to March 2014 using the International Index of Erectile Function (IIEF), IIEF-5, and priapism-specific questionnaires.

MAIN OUTCOME MEASURES

Prevalence rates and risk factor correlations for ED associated with RIP.

RESULTS

The study was comprised of 59 patients (40 SCD [mean age 28.2 ± 8.9 years] and 19 non-SCD [15 idiopathic and four drug-related etiologies] [mean age 32.6 ± 11.7 years]). Nineteen of 40 (47.5%) SCD patients vs. four of 19 (21.1%) non-SCD patients (39% overall) had ED (IIEF <26 or IIEF-5 <22) (P = 0.052). SCD patients had a longer mean time-length with RIP than non-SCD patients (P = 0.004). Thirty of 40 (75%) SCD patients vs. 10 of 19 (52.6%) non-SCD patients (P = 0.14) had "very minor" RIP (episodes regularly lasting ≤2 hours). Twenty-eight of 40 (70%) SCD patients vs. 14 of 19 (73.7%) non-SCD patients had weekly or more frequent episodes (P = 1). Of all patients with very minor RIP, ED was found among 14 of 30 (46.7%) SCD patients vs. none of 10 (0%) non-SCD patients (P = 0.008). Using logistic regression analysis, the odds ratio for developing ED was 4.7 for SCD patients, when controlling for RIP variables (95% confidence interval: 1.1-21.0).

CONCLUSIONS

ED is associated with RIP, occurring in nearly 40% of affected individuals overall. SCD patients are more likely to experience ED in the setting of "very minor" RIP episodes and are five times more likely to develop ED compared with non-SCD patients.

Management of priapism: an update for clinicians

Priapism is a prolonged erection that persists beyond or is unrelated to sexual stimulation. It is associated with significant morbidity: psychological, socioeconomic, and physical, including pain and potentially irreversible compromise of erectile function. There are three major types of priapism: ischemic, nonischemic, and stuttering. Establishing the type of priapism is paramount to safely and effectively treating these episodes. Ischemic priapism represents a urological emergency. Its treatment may involve aspiration/irrigation with sympathomimetic injections, surgical shunts, and as a last resort, penile prosthesis implantation. Nonischemic priapism results from continuous flow of arterial blood into the penis, most commonly related to penile trauma. This is not an emergency and may be managed conservatively initially, as most of these episodes are self-limiting. Stuttering priapism involves recurrent self-limiting episodes of ischemic priapism. The primary goal of therapy is prevention, but acute episodes should be managed in accordance with guidelines for ischemic priapism. In this paper we review the diagnosis and treatment of the three priapism variants, as well as discuss future targets of therapy and novel targets on the horizon.

Is testosterone deficiency a possible risk factor for priapism associated with sickle-cell disease?

PURPOSE

The purpose of this study was to determine the association of testosterone deficiency and priapism in adult men with sickle cell disease (SCD).

METHODS

A cross-sectional study of 50 adult men with SCD (hemoglobin SS) was performed. All patients had early morning blood taken for total and free testosterone, FSH, LH, prolactin, lipid levels, LDH and hematological indices. Patients completed an interviewer-administered questionnaire regarding priapism frequency, duration and treatment. Testosterone deficiency was defined as a serum total testosterone<12 nmol/L (346 ng/dL).

RESULTS

The mean age of the study population was 34.2±8.9 years. Priapism was noted in 24 (48%) patients and was most frequently seen in men between ages 18-25 years. Testosterone deficiency was observed in 11 of the 50 (22%) patients, particularly in 6 of 24 (25%) patients with histories of priapism. There was no difference in mean total testosterone levels in patients with and without a history of priapism (16.7±4.9 nmol/L and 15.4±5.9 nmol/L, respectively) (p=0.43). Similarly, there was no difference in serum LH and FSH levels based on history of priapism.

CONCLUSION

Testosterone deficiency is prevalent in patients with SCD; however, we did not identify an association based on a history of priapism. Larger, prospectively gathered data are needed to define the priapism profile of SCD patients with testosterone deficiency.

Priapism associated with the use of stimulant medications and atomoxetine for attention-deficit/hyperactivity disorder in children

OBJECTIVE

To review the association of priapism with stimulant medications and atomoxetine commonly used in the treatment of attention-deficit/hyperactivity disorder (ADHD).

DATA SOURCES

A comprehensive literature search was conducted through PubMed (1966-May 15, 2014) using the search terms priapism, methylphenidate, amphetamine, atomoxetine, attention-deficit disorder with hyperactivity, and pediatrics. Google Scholar, Scopus, and the Food and Drug Administration (FDA) Web site were also searched. References from identified literature were also reviewed.

STUDY SELECTION AND DATA EXTRACTION

All identified literature focused on ADHD treatment. Literature regarding priapism caused by methylphenidate, amphetamines, and atomoxetine were included.

DATA SYNTHESIS

Stimulant medications and atomoxetine have been linked to the occurrence of priapism in children. Specifically, methylphenidate has been implicated in a recent FDA safety announcement warning as a result of 15 case reports (mean age = 12.5 years), and thus, the drug label and medication guides have been updated to reflect this concern. Prolonged erections and priapism occurred with immediate- and long-acting products, dose increases, and drug withdrawal periods. Priapism has also occurred in 4 patients taking amphetamines and one 11-year-old patient taking atomoxetine for ADHD.

CONCLUSIONS

Priapism has been associated with stimulants, amphetamines, and atomoxetine use for ADHD in children. Providers and health care practitioners should educate male patients prescribed these ADHD medications as well as caregivers regarding the signs, symptoms, and complications with priapism. Discontinuation and evaluation of the medication is warranted if this adverse drug reaction occurs. Depending on the priapism subtype, other products may be initiated or medications not associated with priapism may be utilized.

Opiorphin is a master regulator of the hypoxic response in corporal smooth muscle cells

Men with sickle cell disease (SCD) risk developing priapism. Recognizing that SCD is a disease of hypoxia, we investigated the effect of hypoxia on gene expression in corporal smooth muscle (CSM) cells. Rat CSM cells in vitro were treated with CoCl2 or low oxygen tension to mimic hypoxia. Hypoxic conditions increased expression of genes previously associated with priapism in animal models. Variable coding sequence a1 (Vcsa1; the rat opiorphin homologue, sialorphin), hypoxia-inducible factor 1a (Hif-1a), and A2B adenosine receptor (a2br) were increased by 10-, 4-, and 6-fold, respectively, by treatment with CoCl2, whereas low oxygen tension caused increases in expression of 3-, 4-, and 1.5-fold, respectively. Sialorphin-treated CSM cells increased expression of Hif-1a and a2br by 4-fold, and vcsa1-siRNA treatment reduced expression by ∼50%. Using a Hif-1a inhibitor, we demonstrated up-regulation of a2br by sialorphin is dependent on Hif-1a, and knockdown of vcsa1 expression with vcsa1-siRNA demonstrated that hypoxic-up-regulation of Hif-1a is dependent on vcsa1. In CSM from a SCD mouse, there was 15-fold up-regulation of opiorphin at a life stage prior to priapism. We conclude that in CSM, opiorphins are master regulators of the hypoxic response. Opiorphin up-regulation in response to SCD-associated hypoxia activates CSM "relaxant" pathways; excessive activation of these pathways results in priapism.

Priapism in children: a comprehensive review and clinical guideline

OBJECTIVE

We review the English literature between 1980 and 2013 and summarize the clinical classification, aetiology, physiology, and pathophysiology of paediatric priapism. We propose a clinical guideline for the management of priapism in children.

PATIENTS

Male patients aged ≤ 18 years.

RESULTS

Priapism, a prolonged penile erection lasting >4 h, is a rare condition in childhood. There are 3 widely accepted types of priapism: 1) ischaemic priapism, the commonest type seen in children; 2) stuttering priapism, recurrent, self-limiting prolonged erections; and 3) non-ischaemic priapism, rare in children, usually due to trauma. Neonatal priapism has also been described. Ischaemic priapism is a urological emergency causing fibrosis of the corpora cavernosa, subsequent erectile dysfunction and penile disfigurement. The commonest causes of priapism in children are sickle cell disease (65%), leukaemia (10%), trauma (10%), idiopathic (10%), and pharmacologically induced (5%).

CONCLUSIONS

Priapism in children must be assessed urgently. Rapid resolution of ischaemic priapism prevents permanent cavernosal structural damage and is associated with improved prognosis for potency later in life. Stuttering priapism requires careful counselling for episodic management. Chronic prophylaxis may be obtained using α-adrenergic sympathomimetics, phosphodiesterase type 5 inhibitors and, in sickle cell disease, hydroxyurea. Non-ischaemic and neonatal priapism may generally be treated less urgently.

Priapism in homozygous sickle cell patients: important clinical and laboratory associations

OBJECTIVE

To evaluate the relationship between the occurrence of priapism and important steady-state clinical and laboratory parameters in homozygous sickle cell disease (SCD).

SUBJECTS AND METHODS

Steady-state clinical and laboratory data were obtained from the medical records of 126 male patients seen in the clinic over a 7-year period. Estimated prevalence rates, correlation coefficients and independent t tests were calculated to assess the relationship between priapism and several important clinical and laboratory indices. Patient data on age, haemoglobin concentrations, the frequency of crises per annum, leucocyte counts, platelet counts, serum bilirubin and aspartate transaminase were evaluated.

RESULTS

The prevalence of priapism was determined to be 21.4%, and 22.2% of those affected had erectile dysfunction. There was a significant positive correlation between priapism and older age (p = 0.049) and lower leucocyte counts (p = 0.008). There was no significant relationship with other clinical or laboratory indices.

CONCLUSION

About 1 in 4 of all homozygous older SCD patients had priapism, and an approximately similar ratio developed erectile dysfunction; they also had lower steady-state leucocyte counts. Other clinical and laboratory indicators of disease severity in SCD did not positively correlate with the occurrence of priapism, and this may imply an alternative pathogenetic mechanism.

Second pathways in the pathophysiology of ischemic priapism and treatment alternatives

OBJECTIVE

To evaluate the early therapeutic alternatives such as bosentan, an endothelin receptor blocker, theophylline, an adenosin receptor blocker, and a nonselective phosphodiesterase enzyme inhibitor, zinc protoporphyrin (ZnPP), a heme oxygenase 1 inhibitor, for the therapy of ischemic priapism in the rat models.

METHODS

Twenty-four Sprague-Dawley rats were randomly divided into 4 equal groups: control group, ZnPP group, bosentan group, and theophylline group. Erection was provided by vacuum constriction method and maintained for 4 hours for achieving the priapism in all groups. The rats in the control group were administered 1 mL/kg saline intraperitoneally (ip). The rats in group 2 were administered 25 mg/kg ZnPP ip. The rats in group 3 were administered 0.25 mg/kg bosentan ip. The rats in group 4 were administered 100 mg/kg theophylline ip. Six rats from each group were decapitated after 6 hours of drug administration. Then endothelin 1, adenosine deaminase, heme oxygenase 1 enzymatic activity, and apoptosis index in the cavernous tissues were estimated.

RESULTS

Cavernous tissue endothelin 1, adenosine deaminase, heme oxygenase 1 enzymatic activity levels, and apoptosis index were significantly decreased in bosentan, theophylline, and ZnPP-treated rats compared with the controls.

CONCLUSION

Inhibition of priapism induced apoptosis with bosentan, theophylline, and ZnPP seems promising on preserving erectile function.

Priapism associated with lumbar stenosis in a dog

Priapism, a persistent long-lasting involuntary erection of the penis, is uncommon in dogs. In this report, the case of a 13-year-old male Pointer, referred to our services due to persistent exposition of the penis, is described. This condition was consecutive to an intermittent priapism situation lasting for several days, which has been initially attributed to the inflammation and haematoma associated with a perianal bite. The owners became unable to retract the penis into the prepuce. At presentation, the dog was anorectic for 48 h, intolerant to manipulation, and showed poor body condition and unsteady locomotion. During physical evaluation, a marked engorgement of the local vessels in the prepuce and penis was found. An abdominal X-ray was asked under the suspicion of a neurogenic origin for the clinical situation, which showed evidences of spondylosis. After discussion of the clinical condition, the owners asked for euthanasia. The necropsy confirmed the engorgement of the regional vessels deriving from the pudendal arteries and blood accumulation within all the cavernous spaces, accompanied by congestion and thrombosis within the erectile structures of the penis. No significant changes were observed in the pelvic organs that could be at the origin of priapism. The lumbar-sacral spinal regions were carefully inspected and evidenced signs of L7-S1 stenosis due to spondylosis. The case presented herein is a rare situation of priapism of neurogenic origin in a dog. Necropsy findings suggest that it was consecutive to cauda equina compression due to lumbar spinal stenosis.

Priapism: pathophysiology and the role of the radiologist

Priapism is defined as a penile erection that persists for 4 h or longer and is unrelated to sexual activity. Its identification is important as lack of timely treatment (particularly of the low flow/ischaemic subgroup) can result in persisting erectile dysfunction as a consequence of irreversible corporal fibrosis. This review describes the physiology and anatomy of the normal erection, the aetiology and pathophysiology of the different types of priapism, and the role of the radiologist in the management of the condition. The treatment of iatrogenic priapism following intracavernosal injection of pharmacostimulant is discussed.

Priapism is associated with sleep hypoxemia in sickle cell disease

PURPOSE

We assessed penile rigidity during sleep and the relationship of sleep abnormalities with priapism in adults with sickle cell disease.

MATERIALS AND METHODS

This was a case-control study of 18 patients with sickle cell disease and a history of priapism during the previous year, and 16 controls with sickle cell disease. Participants underwent overnight polysomnography and RigiScan® Plus recording to detect penile rigidity oscillations.

RESULTS

The priapism group (cases) showed a higher apnea-hypopnea index and oxyhemoglobin desaturation parameters than controls. A lower positive correlation between the apnea-hypopnea index and oxyhemoglobin desaturation time was observed in cases than in controls (Spearman coefficient ρ = 0.49, p = 0.05 vs ρ = 0.76, p <0.01), suggesting that desaturation events occurred independently of apnea. Two controls and 14 cases had a total sleep time that was greater than 10% with oxyhemoglobin saturation less than 90% but without CO(2) retention. Penile rigidity events were observed during rapid eye movement sleep and during stage 2 of nonrapid eye movement sleep, particularly in cases. The duration of penile rigidity events concomitant to respiratory events was higher in cases than in controls. Regression analysis revealed that the periodic limb movement and desaturation indexes were associated with priapism after adjusting for rapid eye movement sleep and lung involvement. Finally, oxyhemoglobin saturation less than 90% was associated with priapism after adjusting for lung involvement, hyperhemolysis and the apnea-hypopnea index.

CONCLUSIONS

Oxyhemoglobin desaturation during sleep was associated with priapism history. It may underlie the distribution pattern of penile rigidity events during sleep in these patients.

Medical management of ischemic stuttering priapism: a contemporary review of the literature

Priapism is defined as a prolonged and persistent erection of the penis without sexual stimulation. This is a poorly understood disease process with little information on the pathophysiology of this erectile disorder. Complications from this disorder are devastating due to the irreversible erectile damage and resultant erectile dysfunction (ED). Stuttering priapism, though relatively rare, affects a high prevalence of men with sickle-cell disease (SCD) and presents a challenging problem with guidelines for treatment lacking or resulting in permanent ED. The mechanisms involved in the development of priapism in this cohort are poorly characterized; therefore, medical management of priapism represents a therapeutic challenge to urologists. Additional research is warranted, so we can effectively target treatments for these patients with prevention as the goal. This review gives an introduction to stuttering priapism and its clinical significance, specifically with regards to the patient with SCD. Additionally, the proposed mechanisms behind its pathophysiology and a summary of the current and future targets for medical management are discussed.

Propofol and priapism

Propofol-induced priapism in a 25-year-old male confirmed by rechallenge is reported for its rarity and to create awareness among practitioners, because propofol is used frequently in India for the induction and maintenance of anesthesia or sedation. The probable mechanisms are highlighted. Because propofol causes low-flow priapism, early alleviation is essential to minimize and/or avert the long-term complications.

Experimental priapism is associated with increased oxidative stress and activation of protein degradation pathways in corporal tissue

Priapism is a debilitating disease for which there is at present no clinically accepted pharmacologic intervention. It has been estimated that priapism lasting more than 24 hours in patients is associated with a 44–90% rate of erectile dysfunction (ED). In this investigation we determined in two animal models of priapism (opiorpin-induced priapism in the rat and priapism in a mouse model of sickle cell disease) if there is evidence for an increase in markers of oxidative stress in corporal tissue. In both animal models we demonstrate that priapism results in increased levels of lipid peroxidation, glutathione S-transferase activity, and oxidatively damaged proteins in corporal tissue. Using Western blot analysis we demonstrated there is up regulation of the ubiquitination ligase proteins, Nedd-4 and Mdm-2, and the lysososomal autophage protein, LC3. The anti-apoptotic protein, Bcl-2, was also up regulated. Overall, we demonstrate that priapism is associated with increased oxidative stress in corporal tissue and the activation of protein degradation pathways. Since oxidative stress is known to mediate the development of ED resulting from several etiologies (for example ED resulting from diabetes and aging) we suggest that damage to erectile tissue resulting from priapism might be prevented by treatments targeting oxidative stress.

In vitro and in vivo animal models in priapism research

INTRODUCTION

Priapism is an enigmatic yet devastating clinical phenomenon. In the last two decades, the use of various animal models to study this disorder has dramatically advanced our understanding of this mysterious disorder.

AIM

This report reviews various animal models used to study ischemic priapism and informs basic science researchers the broad view of priapism research.

METHODS

Retrospective review of pertinent literature from the last two decades via PubMed search using the keywords "ischemic priapism" and "priapism model."

MAIN OUTCOME MEASURES

  Findings on the animal models used in ischemic priapism research and its advantages and limitations.

RESULTS

In vitro and in vivo animal models varying from dogs, cats, rabbits, rats to mice were used in priapism research. In vitro models included: (i) corpora cavernosa smooth muscle (CCSM) strip in organ bath; (ii) corporal tissue binding assay; (iii) CCSM cell culture under hypoxia/anoxia. In vivo models could be categorized as: (i) pharmacologically induced by corpus cavernosum medicine injection; (ii) ventilation induced by tidal volume control; (iii) mechanical induced by a constrictor band placed around the base of the penis combined with induced erection; (iv) genetic engineered by intracorporal gene transfer, transgenic, or gene knock-out.

CONCLUSIONS

The ischemic priapism animal models are shifting from pharmaceutically or mechanically induced to genetically engineered. The knowledge generated by those models is enhancing our understanding and management of this clinical challenge.

Priapism associated with antipsychotics: role of alpha1 adrenoceptor affinity

Case reports indicate that antipsychotics can cause priapism, a persistent penile erection possibly leading to erectile dysfunction. The mechanism of antipsychotic-induced priapism is thought to be related to blockade of alpha1 adrenergic receptors, but clinical data supporting this hypothesis are lacking. The aim of this study was to investigate if the presence of safety signals for antipsychotics and priapism is associated with their alpha1 affinity. Spontaneous reports of adverse drug reactions contained in the US Adverse Event Reporting System database were used to calculate reporting odds ratios (RORs) of priapism for antipsychotics. In total, 426 cases of priapism with 144 of them attributed to antipsychotics were identified. For antipsychotics with high alpha1 affinity, the adjusted ROR was markedly elevated (ROR = 9.9; 95% CI, 7.9-12.4), whereas a weaker signal was observed for antipsychotics with low/medium alpha1 affinity (ROR = 3.6; 95% CI, 2.4-5.2). Signals were present for chlorpromazine, quetiapine, risperidone, ziprasidone, and aripiprazole. After restricting the analysis to cases with medical intervention or disability, the safety signal remained evident only for antipsychotics with high but not for those with low/medium affinity. The observed pattern of signals indicates a relationship between alpha1 affinities of antipsychotics and the occurrence of priapism.

Metastatic tumors to the penis: a report of 17 cases and review of the literature

This study presents clinicopathologic and outcome features of 17 patients with metastatic tumor to the penis. Primary sites and histological types were as follows: 6 urothelial carcinomas of urinary bladder, 4 prostatic carcinomas (2 adenocarcinomas and 2 adenosquamous carcinomas), 2 colorectal adenocarcinomas, 2 pulmonary carcinomas (1 squamous cell carcinoma and 1 small cell carcinoma), 1 squamous cell carcinoma of base of the tongue, 1 cutaneous malignant melanoma, and 1 acute myeloid leukemia. Literature review revealed similar distribution of organ sites in 437 cases. Most of our tumors were metachronous. Interval between primary and penile metastasis ranged from 3 to 60 months (mean 16 months). Most of the patients presented with a penile mass. Priapism was observed in 4 patients. The shaft was the commonest anatomical site involved (12 cases). Tumor emboli were usually found in the erectile tissues (14 cases), mainly corpora cavernosa. A total of 14 patients died of disseminated disease. Time interval between primary tumor and penile metastasis ranged from 3 to 60 months (mean 19 months) and between diagnosis of penile metastasis and death ranged from 0.25 to 18 months (mean 6 months), significantly shorter (P = .0058). Patients presented a median survival of 18 months from primary treatment and 5 months after diagnosis of penile metastasis. None of the patients who died of disseminated cancer lived more than 18 months after pathological diagnosis. Clinical evidence of penile involvement in a patient with a known malignancy is an ominous sign and should alert the clinicians to the dismal prognosis.

The mechanism of opiorphin-induced experimental priapism in rats involves activation of the polyamine synthetic pathway

Intracorporal injection of plasmids encoding opiorphins into retired breeder rats can result in animals developing a priapic-like condition. Microarray analysis demonstrated that following intracorporal gene transfer of plasmids expressing opiorphins the most significantly upregulated gene in corporal tissue was the ornithine decarboxylase gene (ODC). Quantitative RT-PCR confirmed the upregulation of ODC, as well as other genes involved in polyamine synthesis, such as arginase-I and -II, polyamine oxidase, spermidine synthase, spermidine acetyltransferase (SAT), and S-adenosylmethionine decarboxylase. Western blot analysis demonstrated upregulation of arginase-I and -II, ODC, and SAT at the protein level. Levels of the polyamine putrescine were upregulated in animals treated with opiorphin-expressing plasmids compared with controls. A direct role for the upregulation of polyamine synthesis in the development of the priapic-like condition was supported by the observation that the ODC inhibitor 1,3-diaminopropane, when added to the drinking water of animals treated with plasmids expressing opiorphins, prevented experimental priapism. We also demonstrate that in sickle cell mice, another model of priapism, there is increased expression of the mouse opiorphin homologue in corporal tissue compared with the background strain at a life stage prior to evidence of priapism. At a life stage when there is onset of priapism, there is increased expression of the enzymes involved in polyamine synthesis (ODC and arginase-I and -II). Our results suggest that the upregulation of enzymes involved in the polyamine synthetic pathway may play a role in the development of experimental priapism and represent a target for the prevention of priapism.

Structural analysis of the corpora cavernosa in patients with ischaemic priapism

STUDY TYPE

Therapy (case series).

LEVEL OF EVIDENCE

4.

OBJECTIVE

To evaluate, using quantitative and qualitative methods, the changes in the corpora cavernosa of patients with ischaemic priapism.

PATIENTS AND METHODS

We obtained samples of corpora cavernosa from seven patients with ischaemic priapism (mean age 38 years, range 28-44) who had a cavernous-glandular shunt. The control tissues were fragments of corpora cavernosa obtained from autopsies of seven age-matched men who died from causes unrelated to the urogenital tract. Histochemical and immunohistochemical techniques were used to assess and quantify the extracellular matrix and smooth muscle fibres. The volumetric density of smooth muscle, elastic fibres and collagen were determined in corpora cavernosa.

RESULTS

From the stereological analysis the mean (sd) values of volumetric density were: for collagen, control 34.76 (4.64), priapism 39.64 (2.91) (P = 0.002); elastic system fibres, controls 28.10 (2.85), priapism 36.10 (3.06) (P = 0.001); smooth muscle fibres, controls 43.37 (4.96), priapism 26.48 (5.00) (P < 0.001). There were significantly more fibrous elements of the connective tissue and significantly fewer smooth muscle fibres in the corpora cavernosa of patients with ischaemic priapism than in controls.

CONCLUSION

Ischaemic priapism is associated with early and significant changes in the components of the extracellular matrix and smooth muscle fibres of the corpora cavernosa. This could explain the frequent occurrence of erectile dysfunction found in patients with ischaemic priapism.