Priapism in sickle-cell disease: a hematologist's perspective

Clinical Vignettes Part I

Patients with sickle cell disease and/or (rarely) trait are at increased risk for developing recurrent episodes of priapism, also known as stuttering priapism, and major ischemic priapism. Treatment of acute ischemic priapism is reactive; whereas ideal management consists of preventative approaches to ultimately promote the best improvement in patient's quality of life. Leg ulcers in patients with sickle cell disease (SCD) are quite common, with ∼20 % of patients with HBSS reporting either having an active or a past ucler. They can be confused with venous ulcers, with lower extremity hyperpigmentation confounding further the diagnosis. Several factors believed to contribute to the development of leg ulcers in patients with SCD are discussed in this article. Sickle cell liver disease (SCLD) occurs because of a wide variety of insults to the liver that happen during the lifetime of these patients. SCLD includes a range of complications of the hepatobiliary system and is increasing in prevalence with the aging adult sickle population. Liver nodular regenerative hyperplasia (NRH) is more common than realized and underappreciated as a diagnosis and requires liver biopsy with reticulin staining. Undiagnosed, the insidious damage from liver NRH can lead to noncirrhotic portal hypertension or cirrhosis.

Haptoglobin treatment contributes to regulating nitric oxide signal and reduces oxidative stress in the penis: A preventive treatment for priapism in sickle cell disease

Background: In sickle cell disease (SCD), reduced bioavailability of endothelial NO and cGMP results in reduced expression of phosphodiesterase type 5 (PDE5), thus impairing the penile erection control mechanism and resulting in prolonged penile erection (priapism). In SCD, reduced NO bioavailability is associated with excess plasma hemoglobin due to intravascular hemolysis and increased oxidative stress. Haptoglobin is the plasma protein responsible for reducing plasma hemoglobin levels, but in SCD, haptoglobin levels are reduced, which favors the accumulation of hemoglobin in plasma. Therefore, we aimed to evaluate the effects of haptoglobin treatment on functional and molecular alterations of erectile function, focusing on the contractile and relaxant mechanisms of corpus cavernosum (CC), as well as oxidative stress.

Methods: SCD mice were treated with haptoglobin (400 mg/kg, subcutaneous) or vehicle of Monday, Wednesday and Friday for a period of 1 month. Corpus cavernosum strips were dissected free and placed in organ baths. Cumulative concentration-response curves to the acetylcholine, sodium nitroprusside, phenylephrine and KCL, as well as to electrical field stimulation (EFS), were obtained in CC. Protein expressions of eNOS, phosphorylation of eNOS at Ser-1177, nNOS, PDE5, ROCK1, ROCK2, gp91^phox, 3-nitrotyrosine, and 4-HNE were measured by western blot in CC.

Results: Increased CC relaxant responses to acetylcholine, sodium nitroprusside and electrical-field stimulation were reduced by haptoglobin in SCD mice. Reduced CC contractile responses to phenylephrine and KCl were increased by haptoglobin in SCD mice. Haptoglobin prevented downregulated eNOS, p-eNOS (Ser-1177), PDE5, and ROCK2 protein expressions and reduced protein expressions of reactive oxygen species markers, NADPH oxidase subunit gp91phox, 3-nitrotyrosine and 4-HNE in penises from SCD mice. Haptoglobin treatment did not affect ROCK1 and nNOS protein expressions in penises from SCD mice. Basal cGMP production was lower in the SCD group, which was normalized by haptoglobin treatment.

Conclusion: Treatment with haptoglobin improved erectile function due to up-regulation of eNOS-PDE5 expression and down-regulation of the gp91phox subunit of NADPH oxidase and oxidative/nitrosative stress in the penises of SCD mice. Treatment with haptoglobin also increased contractile activity due to up-regulation of ROCK2. Therefore, haptoglobin treatment may be an additional strategy to prevent priapism in SCD.

Exploring the Use of Exchange Transfusion in the Surgical Management of Priapism in Sickle Cell Disease: A Population-Based Analysis

INTRODUCTION

Priapism is a urologic emergency that may require surgical intervention in cases refractory to supportive care. Exchange transfusion (ET) has been previously used to manage sickle cell disease (SCD), including in priapism; however, its utilization in the context of surgical intervention has not been well-established.

AIM

To explore the utilization of ET, as well as other patient and hospital-level factors, associated with surgical intervention for SCD-induced priapism METHODS: Using the National Inpatient Sample (2010-2015), males diagnosed with SCD and priapism were stratified by need for surgical intervention. Survey-weighted regression models were used to analyze the association of ET to surgical intervention. Furthermore, negative binomial regression and generalized linear models with logarithmic transformation were used to compare ET vs surgery to length of hospital stay (LOS) and total hospital charges, respectively.

MAIN OUTCOME MEASURES

Predictors of surgical intervention among patients with SCD-related priapism RESULTS: A weighted total of 8,087 hospitalizations were identified, with 1,782 (22%) receiving surgical intervention for priapism, 484 undergoing ET (6.0%), and 149 (1.8%) receiving combined therapy of both ET and surgery. On multivariable regression, pre-existing Elixhauser comorbidities (e.g. ≥2 Elixhauser: OR: 2.20; P < 0.001), other forms of insurance (OR: 2.12; P < 0.001), and ET (OR: 1.99; P = 0.009) had increased odds of undergoing surgical intervention. In contrast, Black race (OR: 0.45; P < 0.001) and other co-existing SCD complications (e.g. infectious complications OR: 0.52; P < 0.001) reduced such odds. Compared to supportive care alone, patients undergoing ET (adjusted IRR: 1.42; 95% CI: 1.10-1.83; P = 0.007) or combined therapy (adjusted IRR: 1.42; 95% CI: 111-1.82; P < 0.001) had a longer LOS vs. surgery alone (adjusted IRR: 0.85; 95% CI: 0.74-0.97; P = 0.017). Patients receiving ET (adjusted Ratio: 2.39; 95% CI: 1.52-3.76; P < 0.001) or combined therapy (adjusted Ratio: 4.42; 95% CI: 1.67-11.71; P = 0.003) had higher ratio of mean hospital charges compared with surgery alone (adjusted Ratio: 1.09; 95% CI: 0.69-1.72; P = 0.710).

CONCLUSIONS

Numerous factors were associated with the need for surgical intervention, including the use of ET. Those receiving ET, as well as those with combined therapy, had a longer LOS and increased total hospital charges. Ha AS, Wallace BK, Miles C, et al. Exploring the Use of Exchange Transfusion in the Surgical Management of Priapism in Sickle Cell Disease: A Population-Based Analysis. J Sex Med 2021;18:1788-1796.

Priapism in sickle cell disease: Associations between NOS3 and EDN1 genetic polymorphisms and laboratory biomarkers

Priapism is a urologic emergency characterized by an uncontrolled, persistent and painful erection in the absence of sexual stimulation, which can lead to penile fibrosis and impotence. It is highly frequent in sickle cell disease (SCD) associated with hemolytic episodes. Our aim was to investigate molecules that may participate in the regulation of vascular tone. Eighty eight individuals with SCD were included, of whom thirty-seven reported a history of priapism. Priapism was found to be associated with alterations in laboratory biomarkers, as well as lower levels of HbF. Patients with sickle cell anemia using hydroxyurea and those who received blood products seemed to be less affected by priapism. Multivariate analysis suggested that low HbF and NOm were independently associated with priapism. The frequency of polymorphisms in genes NOS3 and EDN1 was not statistically significant between the studied groups, and the presence of the variant allele was not associated with alterations in NOm and ET-1 levels in patients with SCD. The presence of the variant allele in the polymorphisms investigated did not reveal any influence on the occurrence priapism. Future studies involving larger samples, as well as investigations including patients in priapism crisis, could contribute to an enhanced understanding of the development of priapism in SCD.

Metabolomic and molecular insights into sickle cell disease and innovative therapies

Sickle cell disease (SCD) is an autosomal-recessive hemolytic disorder with high morbidity and mortality. The pathophysiology of SCD is characterized by the polymerization of deoxygenated intracellular sickle hemoglobin, which causes the sickling of erythrocytes. The recent development of metabolomics, the newest member of the "omics" family, has provided a powerful new research strategy to accurately measure functional phenotypes that are the net result of genomic, transcriptomic, and proteomic changes. Metabolomics changes respond faster to external stimuli than any other "ome" and are especially appropriate for surveilling the metabolic profile of erythrocytes. In this review, we summarize recent pioneering research that exploited cutting-edge metabolomics and state-of-the-art isotopically labeled nutrient flux analysis to monitor and trace intracellular metabolism in SCD mice and humans. Genetic, structural, biochemical, and molecular studies in mice and humans demonstrate unrecognized intracellular signaling pathways, including purinergic and sphingolipid signaling networks that promote hypoxic metabolic reprogramming by channeling glucose metabolism to glycolysis via the pentose phosphate pathway. In turn, this hypoxic metabolic reprogramming induces 2,3-bisphosphoglycerate production, deoxygenation of sickle hemoglobin, polymerization, and sickling. Additionally, we review the detrimental role of an impaired Lands' cycle, which contributes to sickling, inflammation, and disease progression. Thus, metabolomic profiling allows us to identify the pathological role of adenosine signaling and S1P-mediated erythrocyte hypoxic metabolic reprogramming and hypoxia-induced impaired Lands' cycle in SCD. These findings further reveal that the inhibition of adenosine and S1P signaling cascade and the restoration of an imbalanced Lands' cycle have potent preclinical efficacy in counteracting sickling, inflammation, and disease progression.

Clinical and laboratory parameters, risk factors predisposing to the development of priapism in sickle cell patients

Although sickle cell disease is very common in Oman, priapism is a relatively rare complication of this disease. This study was aimed to identify the clinical and laboratory risk factors that predispose sickle cell disease patients to priapism. In a retrospective, case-control study, data on 21 male sickle cell disease patients, with priapism, were compared to 20 age and sex-matched sickle cell disease patients without priapism from the hospital medical records. Specifically, the demographical, hematological, biochemical, and clinical parameters including complications attributable to priapism were studied. Means for continuous measures and independent t-test were used to evaluate the association between the parameter studied and the occurrence of priapism. Priapism occurrence was associated with low basal hemoglobin (Hb), along with an increase in other parameters such as white blood cell count (WBC) ( P = 0.010), platelet count ( P = 0.001), reticulocyte count ( P < 0.001), mean corpuscular volume (MCV) ( P < 0.001), and mean corpuscular hemoglobin (MCH) ( P < 0.001). Biochemical laboratory parameters revealed an association with an increased total bilirubin ( P < 0.001). Patients with priapism were more likely to have acute chest syndrome, stroke, pulmonary hypertension, asplenia ( P = 0.006), gallbladder stones, and consequently cholecystectomy. Blood exchange and Penile aspiration were the most frequent medical therapies ( P = 0.010 and P < 0.001 respectively). Patients with sickle cell disease who presented with priapism were young adults with low Hb, high WBC’s, platelets, reticulocytes, MCV, MCH, bilirubin, and LDH. These findings suggest an association of priapism with increased hemolysis.

Impact statement

Sickle cell disease is prevalent throughout the world with a 5.8% incidence of sickle cell trait among the Omani population, yet priapism was a relatively rare complication. Penile erection and detumescence are complex physiological processes, which require a delicate neurohormonal and cardiovascular response. In this cohort, young SCD patients developed priapism with a low incidence of complications. These patients had high WBCs, platelets, bilirubin, LDH, and reticulocytes with low hemoglobin as compared to controls, suggesting an increased hemolytic process. Favorable outcome was dependent on early intervention, with almost half of these patients needing surgical intervention.

Differential role of adenosine signaling cascade in acute and chronic pain

Adenosine is a signaling molecule induced under stress such as energy insufficiency and ischemic/hypoxic conditions. Adenosine controls multiple physiological and pathological cellular and tissue function by activation of four G protein-coupled receptors (GPCR). Functional role of adenosine signaling in acute pain has been widely studied. However, the role of adenosine signaling in chronic pain is poorly understood. At acute levels, adenosine can be beneficial to anti-pain whereas a sustained elevation of adenosine can be detrimental to promote chronic pain. In recent years, extensive progress has been made to define the role of adenosine signaling in chronic pain and to dissect molecular new insight underlying the development of chronic pain. In this review, we summarize the differential role of adenosine signaling cascade in acute and chronic pain with a major focus on recent studies revealing adenosine ADORA2B receptor activation in the pathology of chronic pain. We further provide a therapeutic outlook of how multiple adenosine signaling components can be useful to treat chronic pain.

Resolution of Acute Priapism in Two Children With Sickle Cell Disease Who Received Nitrous Oxide

BACKGROUND

Nitrous oxide (N O) is an inhalational medication that has anxiolytic, amnestic, potent venodilatory and mild-to-moderate analgesic properties commonly used in the emergency department (ED) setting. N₂ O has a rapid onset of action (<5 minutes) and recovery (<5 minutes) and can be quickly titrated to effect without the need for IV access. It has few side effects, does not require renal or hepatic metabolism for excretion and has no reports of allergic reaction. Priapism is a serious complication of sickle cell disease (SCD) affecting approximately 35% of males, with an adverse impact on quality of life. Treatment options are limited and not evidence based, including hydration, alkalization, analgesia, oxygenation to prevent further sickling, and exchange transfusion. Patients who do not respond within 4 hours often require a painful invasive procedure that includes aspiration of blood from the corpus cavernosum and phenylephrine injections. Case reports have described a therapeutic benefit from oral pseudoephedrine, sildenafil, and intravenous (IV) arginine, however controlled clinical trials are lacking. Although a 50:50 nitrous oxide/oxygen mix is commonly used in France to enhance analgesia in patients with SCD and vasoocclusive pain events (VOE) not sufficiently responding to IV morphine, there are no reports of its use to treat priapism. We describe the effects of N₂ O for the treatment of acute priapism associated with SCD in a pediatric ED.

METHODS

This is a case series of two adolescent boys with Hb-SS who on 3 separate occasions presented to the ED with acute priapism that failed oral therapy (pseudoephedrine and opioids). N₂ O gas was utilized to help facilitate IV catheter placement.

RESULTS

In each presentation (at ages 8 and 10 years for patient 1; age 15 years for patient 2), the patient experienced complete resolution of the priapism within 4-15 min of receiving N₂ O (max 60%). The patients were discharged from the ED following each presentation and had no recurrence during the subsequent week.

CONCLUSIONS

Priapism is a challenging complication of SCD associated with long-term morbidity and a paucity of treatment options. Opioids are commonly used. Given the risks and inconsistent results of current recommended therapy, N₂ O may represent a potential opioid-sparing treatment option for priapism presenting to the ED that warrants further investigation. Although anecdotal, N₂ O inhalation is an intervention to consider during a time when a treating ED physician may have few alternatives.

Self-care of men with priapism and sickle cell disease

ABSTRACT Objective: To identify self-care demands of men with sickle cell disease and priapism and describe self-care measures in light of Orem's Self-Care Theory. Method: This is a descriptive exploratory study with qualitative approach conducted with nine men with a history of sickle cell disease and priapism. Data were analyzed using Orem's Self-Care Theory. Results: Some demands were identified: from universal self-care - difficulty in social interaction and solitude, changes in self-image, self-esteem and sexual activity; from development - the experience with priapism and little knowledge about the pathophysiology of the disease; regarding health deviations - pain crises. Conclusion: Orem's theory allowed to identify self-care demands, which are essential for the nursing care provided for men with priapism. Nursing has an essential role in the measures for the different demands presented.

Priapism due to essential thrombocythaemia: a rare causation

Priapism is rarely caused by essential thrombocytosis, a disorder characterised by increased number of megakaryocytes. We report a case of a 21-year-old man who presented with priapism and on investigation was found to have essential thrombocytosis as the cause.

Efficacy and Safety of Manual Partial Red Cell Exchange in the Management of Severe Complications of Sickle Cell Disease in a Developing Country

Introduction

The realization of red cell exchange (RCE) in Africa faces the lack of blood, transfusion safety, and equipment. We evaluated its efficacy and safety in severe complications of sickle cell disease.

Patients and Method

Manual partial RCE was performed among sickle cell patients who had severe complications. Efficacy was evaluated by clinical evolution, blood count, and electrophoresis of hemoglobin. Safety was evaluated on adverse effects, infections, and alloimmunization.

Results

We performed 166 partial RCE among 44 patients including 41 homozygous (SS) and 2 heterozygous composites SC and 1 S/β0-thalassemia. The mean age was 27.9 years. The sex ratio was 1.58. The regression of symptoms was complete in 100% of persistent vasoocclusive crisis and acute chest syndrome, 56.7% of intermittent priapism, and 30% of stroke. It was partial in 100% of leg ulcers and null in acute priapism. The mean variations of hemoglobin and hematocrit rate after one procedure were, respectively, +1.4 g/dL and +4.4%. That of hemoglobin S after 2 consecutive RCE was −60%. Neither alloimmunization nor viral seroconversion was observed.

Conclusion

This work shows the feasibility of manual partial RCE in a low-resource setting and its efficacy and safety during complications of SCD outside of acute priapism.

Pediatric sickle cell disease: past successes and future challenges

Once a fatal disease of childhood, more than 95% of patients born today with sickle cell disease (SCD) in developed countries are expected to survive into adulthood, largely because of improvements in supportive and preventive care (newborn screening, penicillin prophylaxis, transcranial Doppler (TCD) screening). Hydroxyurea (HU) therapy, the only oral medication currently available to prevent SCD complications, has become more widespread over the past 20 y. The NHLBI recommends that HU be offered to all patients with HbSS beginning at 9 mo of age, and the recently published Abnormal TCD with Transfusions Changing to HU (TWiTCH) trial has shown HU as an acceptable alternative to transfusion therapy for patients at high risk of stroke. While hematopoietic stem cell transplant (HSCT) is a curative option for SCD, less than 25% of patients have a suitable donor. Alternative stem cell sources from unrelated donors and haplo-identical donors are currently under investigation as are gene therapy trials. This review will focus on early efforts to elucidate SCD pathophysiology as well as supportive and preventive care improvements. Findings from recent multi-center studies (Silent Infarct Transfusion (SIT) Trial and TWiTCH) will be summarized. Finally, HSCT trials and gene therapy will be reviewed.

Beneficial Effect of the Nitric Oxide Donor Compound 3-(1,3-Dioxoisoindolin-2-yl)Benzyl Nitrate on Dysregulated Phosphodiesterase 5, NADPH Oxidase, and Nitrosative Stress in the Sickle Cell Mouse Penis: Implication for Priapism Treatment

Patients with sickle cell disease (SCD) display priapism, and dysregulated nitric oxide (NO) pathway may contribute to this condition. However, current therapies offered for the prevention of priapism in SCD are few. The 3-(1,3-dioxoisoindolin-2-yl)benzyl nitrate (compound 4C) was synthesized through molecular hybridization of hydroxyurea and thalidomide, which displays an NO-donor property. This study aimed to evaluate the effects of compound 4C on functional and molecular alterations of erectile function in murine models that display low NO bioavailability, SCD transgenic mice, and endothelial NO synthase and neuronal NO synthase double gene-deficient (dNOS^-/) mice, focusing on the dysregulated NO-cGMP- phosphodiesterase type 5 (PDE5) pathway and oxidative stress in erectile tissue. Wild-type, SCD, and dNOS^-/- mice were treated with compound 4C (100 μmol/kg/d, 3 weeks). Intracavernosal pressure in anesthetized mice was evaluated. Corpus cavernosum tissue was dissected free and mounted in organ baths. SCD and dNOS^-/- mice displayed a priapism phenotype, which was reversed by compound 4C treatment. Increased corpus cavernosum relaxant responses to acetylcholine and electrical-field stimulation were reduced by 4C in SCD mice. Likewise, increased sodium nitroprusside-induced relaxant responses were reduced by 4C in cavernosal tissue from SCD and dNOS^-/- mice. Compound 4C reversed PDE5 protein expression and reduced protein expressions of reactive oxygen species markers, NADPH oxidase subunit gp91^phox, and 3-nitrotyrosine in penises from SCD and dNOS^-/- mice. In conclusion, 3-week therapy with the NO donor 4C reversed the priapism in murine models that display lower NO bioavailability. NO donor compounds may constitute an additional strategy to prevent priapism in SCD.

Priapism in Homozygous Sickle Cell Disease: A 40-year Study of the Natural History

OBJECTIVES

To describe the incidence, pattern, and outcome of priapism in homozygous sickle cell (SS) disease.

METHODS

Regular review, for periods up to 40 years, was done of all 162 males with SS disease detected during the screening of 100 000 consecutive non-operative deliveries at the main government maternity hospital in Kingston, Jamaica, between June 1973 and December 1981.

RESULTS

Priapism occurred in 52 (32.7%) patients overall, the incidence rising steeply in late adolescence to 32% by age 20 years and a cumulative incidence of nearly 60% of patients by age 40 years. Many cases were elicited only on direct questioning because of embarrassment and the lack of realization that priapism complicates SS disease. Initial events were recurrent stuttering episodes in 39 patients, a single short-term event in six patients and a major attack (more than six hours) in seven patients. Erectile function was preserved in almost all patients with simple stuttering or single events. Major attacks (> 6 hours) occurred in 17 patients, preceded by stuttering episodes in nine, by a single event in one, and occurring de novo in seven. In these, erectile function was unknown in five, deemed satisfactory in five (sometimes improving over three years), weak in three and impotence persisted in four (two with major attacks three and six months previously).

CONCLUSION

A history of stuttering priapism should be routinely enquired and prophylactic measures used if attacks exceed once weekly. Major events generally result in short-term impotence, but the late recovery of erectile function cautions against the early insertion of penile prostheses.

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.

Management of sickle cell disease: a review for physician education in Nigeria (sub-saharan Africa)

Sickle cell disease (SCD) predominates in sub-Saharan Africa, East Mediterranean areas, Middle East, and India. Nigeria, being the most populous black nation in the world, bears its greatest burden in sub-Saharan Africa. The last few decades have witnessed remarkable scientific progress in the understanding of the complex pathophysiology of the disease. Improved clinical insights have heralded development and establishment of disease modifying interventions such as chronic blood transfusions, hydroxyurea therapy, and haemopoietic stem cell transplantation. Coupled with parallel improvements in general supportive, symptomatic, and preventive measures, current evidence reveals remarkable appreciation in quality of life among affected individuals in developed nations. Currently, in Nigeria and other West African states, treatment and control of SCD are largely suboptimal. Improved knowledge regarding SCD phenotypes and its comprehensive care among Nigerian physicians will enhance quality of care for affected persons. This paper therefore provides a review on the aetiopathogenesis, clinical manifestations, and management of SCD in Nigeria, with a focus on its local patterns and peculiarities. Established treatment guidelines as appropriate in the Nigerian setting are proffered, as well as recommendations for improving care of affected persons.

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.

Priapism: current updates in clinical management

Priapism is a persistent penile erection that continues for hours beyond, or is unrelated to, sexual stimulation. Priapism requires a prompt evaluation and usually requires an emergency management. There are two types of priapism: 1) ischemic (veno-occlusive or low-flow), which is found in 95% of cases, and 2) nonischemic (arterial or high-flow). Stuttering (intermittent or recurrent) priapism is a recurrent form of ischemic priapism. To initiate appropriate management, the physician must decide whether the priapism is ischemic or nonischemic. In the management of an ischemic priapism, resolution should be achieved as promptly as possible. Initial treatment is therapeutic aspiration with or without irrigation of the corpora. If this fails, intracavernous injection of sympathomimetic agents is the next step. Surgical shunts should be performed in cases involving failure of nonsurgical treatment. The first management of a nonischemic priapism should be observation. Selective arterial embolization is recommended for the management of nonischemic priapism in cases that request treatment. The goal of management for stuttering priapism is prevention of future episodes. This article provides a review of recent clinical developments in the medical and surgical management of priapism and an investigation of scientific research activity in this rapidly developing field of study.

Sustained nitric oxide (NO)-releasing compound reverses dysregulated NO signal transduction in priapism

We evaluated the therapeutic potential of a sustained nitric oxide (NO)-releasing compound to correct the molecular hallmarks and pathophysiology of priapism, an important but poorly characterized erectile disorder. 1,5-Bis-(dihexyl-N-nitrosoamino)-2,4-dinitrobenzene (C6') and an inactive form of the compound [1,5-bis-(dihexylamino)-2,4-dinitrobenzene (C6)] were tested in neuronal cell cultures and penile lysates for NO release (Griess assay) and biological activity (cGMP production). The effect of local depot C6' or C6 was evaluated in mice with a priapic phenotype due to double neuronal and endothelial NO synthase deletion (dNOS(-/-)) or human sickle hemoglobin transgenic expression (Sickle). Changes in NO signaling molecules and reactive oxygen species (ROS) surrogates were assessed by Western blot. The physiological response after C6' treatment was assessed using an established model of electrically stimulated penile erection. C6' generated NO, increased cGMP, and dose dependently increased NO metabolites. C6' treatment reversed abnormalities in key penile erection signaling molecules, including phosphodiesterase type 5, phosphorylated endothelial nitric oxide synthase, and phosphorylated vasodilator-stimulated phosphoprotein. In Sickle mice, C6' also attenuated the increased ROS markers gp91(phox), 4-hydroxynonenal, and 3-nitrotyrosine. Finally, C6' corrected the excessive priapic erection response of dNOS(-/-) mice. Exogenous sustained NO release from C6' corrects pathological erectile signaling in mouse models of priapism and suggests novel approaches to human therapy.

A pathophysiology-based approach to the management of early priapism

Priapism is a rare condition that involves persistent penile erection for greater than 4 h. Distinct variants exist, each with unique characteristics. Ischemic priapism is a painful medical emergency that may occur as a result of veno-occlusion leading to hypoxia and tissue death. Recurrent bouts of ischemic priapism, or stuttering priapism, require treatment for individual attacks as well as long-term prevention. Non-ischemic priapism is associated with trauma and may be managed conservatively. Recent advances into the pathophysiology of priapism have allowed the development of treatment algorithms that specifically target the mechanisms involved. In this review, we outline the basics of smooth muscle contraction and describe how derangement of these pathways results in priapism. A pathophysiological approach to the treatment of priapism is proposed with duration-based algorithms presented to assist in management.

Beyond the definitions of the phenotypic complications of sickle cell disease: an update on management

The sickle hemoglobin is an abnormal hemoglobin due to point mutation (GAG → GTG) in exon 1 of the β globin gene resulting in the substitution of glutamic acid by valine at position 6 of the β globin polypeptide chain. Although the molecular lesion is a single-point mutation, the sickle gene is pleiotropic in nature causing multiple phenotypic expressions that constitute the various complications of sickle cell disease in general and sickle cell anemia in particular. The disease itself is chronic in nature but many of its complications are acute such as the recurrent acute painful crises (its hallmark), acute chest syndrome, and priapism. These complications vary considerably among patients, in the same patient with time, among countries and with age and sex. To date, there is no well-established consensus among providers on the management of the complications of sickle cell disease due in part to lack of evidence and in part to differences in the experience of providers. It is the aim of this paper to review available current approaches to manage the major complications of sickle cell disease. We hope that this will establish another preliminary forum among providers that may eventually lead the way to better outcomes.

Drug repurposing in pediatrics and pediatric hematology oncology

Drug 'repurposing', that is, using old drugs for new indications, has been proposed as a more efficient strategy for drug development than the current standard of beginning with novel agents. In this review, we explore the scope of drug repurposing in pediatric hematology oncology and in pediatrics in general. Drugs commonly used in children were identified using the Harriet Lane Handbook (HLH) and searched in PubMed for different uses. Additional drugs were identified by searching PubMed and Google.com for 'drug repurposing' or 'drug repositioning'. Almost 10% of drugs with primary uses in pediatrics have been repurposed in pediatric hematology oncology or pediatrics. The observant clinician, pharmacologist and translational bioinformatician, as well as structural targeting, will have a role in discovering new repurposing opportunities.

Sickling cells, cyclic nucleotides, and protein kinases: the pathophysiology of urogenital disorders in sickle cell anemia

Sickle cell anemia is one of the best studied inherited diseases, and despite being caused by a single point mutation in the HBB gene, multiple pleiotropic effects of the abnormal hemoglobin S production range from vaso-occlusive crisis, stroke, and pulmonary hypertension to osteonecrosis and leg ulcers. Urogenital function is not spared, and although priapism is most frequently remembered, other related clinical manifestations have been described, such as nocturia, enuresis, increased frequence of lower urinary tract infections, urinary incontinence, hypogonadism, and testicular infarction. Studies on sickle cell vaso-occlusion and priapism using both in vitro and in vivo models have shed light on the pathogenesis of some of these events. The authors review what is known about the deleterious effects of sickling on the genitourinary tract and how the role of cyclic nucleotides signaling and protein kinases may help understand the pathophysiology underlying these manifestations and develop novel therapies in the setting of urogenital disorders in sickle cell disease.

Acute management of priapism in men

What's known on the subject? and What does the study add? Priapism is a rare event. However, various medications and medical conditions may increase the risk. Priapism can be ischaemic, non-ischaemic or stuttering. It is paramount to distinguish the type of priapism, as misdiagnosis may lead to significant morbidity. Ischaemic priapism represents a compartment syndrome of the penis and is therefore a medical emergency. A delay in management may significantly affect future erectile function. Stuttering priapism represents recurrent subacute episodes of ischaemic priapism, which may lead to erectile dysfunction. Thus episodes must be minimised. Non-ischaemic priapism is not a medical emergency. However, misdiagnosis and injection with sympathomimetic agents can result in system absorption and toxicity. This review article provides a summary of the evaluation and management of priapism. Furthermore, a step by step flow chart is provided to guide the clinician through the assessment and management of this complex issue.

OBJECTIVES

To review the literature regarding ischaemic, non-ischaemic and stuttering priapism. To provide management recommendations.

PATIENTS AND METHODS

A Medline search was carried out to identify all relevant papers with management guidelines for priapism.

RESULTS

Ischaemic priapism represents a compartment syndrome of the penis and urgent intervention is required to decrease the risk of erectile dysfunction. Non-ischaemic priapism is not a medical emergency; however, it can result in erectile dysfunction. The treatment objective for stuttering priapism is to reduce future episodes with systemic treatments, whilst treating each ischaemic episode as an emergency.

CONCLUSIONS

Priapism is a complex condition that requires expert care to prevent complications and irreversible erectile dysfunction.