Priapism high-flow

The overall incidence ofpriapismis 1.5 per 100000 person-year [1]. Priapism is broadly classified as high-flow and low-flow. Arterial high-flow priapism (HFP) is usually secondary to the laceration of a cavernous artery with unregulated flow into the lacunar spaces. This type of priapism is most of the times not painful because there is no ischemia. HFP is rare and only 200 cases have been reported in the literature. Nonetheless, because it is painless, it is possible that HFP is under reported. The other type is veno-occlusive priapism which is usually caused by corporeal veno-occlusion, and can be very painful due to ischemia. 

The clinical presentation of these two types of priapism is different. HFP is often seen after an acute injury, and the onset can be delayed. This delayed onset may be due to initial vessel spasm, hemostasis with clot formation or a compressing hematoma. Reabsorption of this clot or hematoma is the mechanism for the late onset. The HFP is often less tumescent when compared with venous priapism. Priapism secondary to arterial causes maybe, as mentioned before, significantly less painful than venous priapism and is not considered as an emergency. The major etiology of HFP is trauma, especially in children or young adults in older men, HFP is a rare event mainly caused by malignancy [2]. High-flow priapism in acute lymphatic leukaemia has also been reported [3]. 

Penile ultrasound and Doppler testing may be necessary to differentiate high-flow from low-flow priapism. In HFP, ultrasound reveals an hypoechoic, well-circumscribed region in the corpus caverno-sum. The Doppler will show an increased flow in the penile artery, uni-or bilateral, and an arterio-cavernosal fistula (Fig. 13.1). In patients with high-flow priapism, selective penile angiography may be required in order to identify the site of the fistula. Angiography should however not be done as a diagnostic procedure, but always in combination with a planned therapeutic embolization. 

Kuefer R, Bartsch G Jr, Herkommer K, Kramer SC, Klein-schmidt K, Volkmer BG (2005) Changing diagnostic and therapeutic concepts in high-flow priapism. Int J Impot Res 17 109-113... 

Mentzel HJ, Kentouche K, Doerfel C, Vogt S, Zintl F, Kaiser WA High-flow priapism in acute lymphatic leukaemia. Pediatr Radiol 34 560-563... 

Savoca G, Pietropaolo F, Scieri F, Bertolotto M, Mucelli FP, Belgrano E (2004) Sexual function after highly selective embolization of cavernous artery in patients with high flow priapism long-term followup. J Urol 172 644-647... 

Treatment of Priapism 74 Treatment of Low-Flow Priapism 74 Treatment of High-Flow Priapism 76... 

The etiology of priapism has been traditionally divided into primary or idiopatic and secondary to some other condition or disease process. However, in accordance with Pryor (2004), for the purposes of clinical management, it is appropriate to distinguish between high-flow, low-flow, and recurrent or stuttering priapism. 

Trauma to the perineum, penis or groin, while usually resulting in high-flow priapism, can result in venous compression secondary to penile hematoma or edema. 

The onset of a post-traumatic, high-flow priapism may occur up to 72 h after the injury. Pain is never as severe as in an ischemic priapism the penis is often not maximally rigid and pulsation may be recognized. 

A mechanism for the pathophysiology of high-flow priapism is described by Bastuba et al. (1994). Unlike a traditional arteriovenous fistula, the condition is described as an arterial-lacunar fistula where the helicine arteries are bypassed, and the blood passes directly into the lacunar spaces. The high-flow in the lacunar space creates shear stress in adjacent areas, leading to increased nitric oxide release, activation of the cGMP pathway, smooth muscle relaxation and trabecular dilatation. These authors also postulate that the delay in onset of high-flow priapism may be secondary to a delay in the complete necrosis of the arterial wall after the initial trauma or secondary to clot formation at the site of injury followed by the normal lytic pathway, which progresses in a few days. 

A rare condition associated with high-flow priapism is Fabry s disease, which may be caused by an unregulated high arterial inflow (Foda et al. 1996). 

Low-flow priapism is suggested by finding low oxygen tension, high carbon dioxide and low pH in the blood gas analysis of the aspirate. When a high-flow state is suspected based on the bright red appearance or blood gas analysis of the corporal aspirate, color Doppler ultrasound is indicated to identify the arterial sinusoidal fistula. 

A thorough history and physical examination are prerequisites to diagnostic accuracy. The fundamental aim of the initial phase of assessment is to distinguish arterial from ischemic priapism. The sexual and medical history should especially focus on medications, trauma and predisposing comorbidities. Presence or absence of pain is a fairly reliable predictor oflow-flow versus high-flow priapism, respectively. Absence of pain in arterial priapism frequently results in less patient anxiety and discomfort as compared with veno-occlusive priapism. Consequently, patients with arterial priapism may present days or even weeks after the original injury (Ricciardi et al. 1993). 

Ricciardi R, Jr., Bhatt GM, Cynamon J et al (1993) Delayed high flow priapism pathophysiology and management. J Urol 149 119-121... 

Steers WD, Selby JB,Jr (1991) Use of methylene blue and selective embolization of the pudendal artery for high flow priapism refractory to medical and surgical treatments. J Urol 146 1361-1363... 

As described in Chapter 9, priapism is an uncommon medical condition defined as persistent tumescence or erection not associated with sexual desire or stimulation (Pautler and Brock 2001). Different pathophysiologies have been described. Low-flow or ischemic priapism is characterized by complete painful erection secondary to inadequate venous outflow leading to hypoxia, acidosis and pain (Lue et al. 1986 Pautler and Brock 2001). High-flow priapism is usually associated with penile or perineal blunt trauma and cavernosal artery tear (Pautler and Brock 2001). Patients... 

Recently, recurrent or stuttering priapism has been described as a poorly understood condition that may present clinically with low-flow or, more frequently, with high-flow episodes, alternatively (Pautler and Brock 2001 Pryor et al. 2004). 

Color Doppler ultrasonography is currently considered the imaging modality of choice for the diagnosis of high-flow priapism since it is sensitive, non-invasive and widely available (Hakim et al. 1996 Bertolotto et al. 2003). No cavernosal injection of vasoactive drugs is required. 

In about 23% of patients with high-flow priapism and apparently successful embolization of the lacer-... 

Fig. 10.4a,b. High-flow priapism. Color Doppler appearance of the fistula before and after embolization, a Sagittal color Doppler image of the right crus shows extravasation of blood from the cavernosal artery (arrowheads), b Duplex Doppler ultrasound image obtained soon after angiography shows that the fistula is still patent, but reduced in size. The fistula closed spontaneously within 5 days... 

In patients with high-flow priapism and complex traumas undergoing contrast-enhanced CT with state-of-the-art multiple detector-row systems, the arterial-sinusoidal fistula can he identified (Fig. 10.8). This examination, however, cannot replace angiography, because interventional maneuvers cannot be performed. In malignant priapism contrast-enhanced CT is indicated to evaluate the perineal and pelvic extent of the disease. In patients with priapism secondary to aortocaval fistula contrast-enhanced CT reveals the communication between the aorta and the inferior vena cava and congestion of the pelvic vessels (Abela et al. 2003 Gordon et al. 2004). Poor enhancement of the kidneys reveals renal hypoperfusion. 

During the follow-up of high-flow priapism, magnetic resonance imaging is able to document persistent closure or recanalization of the embolized cavernosal artery (Park et al. 2001). Color Doppler ultrasonography, however, usually provides enough clinically useful information in these patients. 

Ankem MK, Gazi MA, Ferlise VJ et al (2001) High-flow priapism a novel way of lateralizing the lesion in radiologi-cally inapparent cases. Urology 57 800... 

Arango 0, Castro R, Dominguez J, Gelabert A (1999) Complete resolution of post-traumatic high-flow priapism with conservative treatment. Int 1 Impot Res 11 115-117... 

Fig. 10.8a,b. Postraumatic high-flow priapism. Imaging features with multidetector-row CT angiography, a Coronal image showing iodinated contrast extravasation within the right corpus cavernosum (arrowhead), b 3D reconstruction of the vascular supply to the penis on the right side, from the pudendal artery to the cavernosal artery tear (arrowhead)... 

Engin G, Tunaci M, Acunas B (1999) High-flow priapism due to cavernous artery pseudoaneurysm color Doppler sonography and magnetic resonance imaging findings. Eur Radiol 9 1698-1699... 

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