Priapism is a persistent erection of the penis that occurs without sexual arousal and lasts for more than four hours. It is often accompanied by pain and requires prompt medical attention. This condition can affect individuals with spinal cord injury (SCI), presenting unique challenges due to neurological changes.
Understanding Priapism in Spinal Cord Injury
Priapism in the context of spinal cord injury falls into two main categories: ischemic (low-flow) and non-ischemic (high-flow). Ischemic priapism, the more common, urgent type, results from blood becoming trapped in the penile erectile tissues, unable to drain. This leads to tissue oxygen deprivation, causing pain and potential permanent damage if not addressed quickly.
Non-ischemic priapism is less common and less painful. It occurs due to uncontrolled arterial blood flow into the penis, often due to trauma creating an abnormal connection (fistula) between an artery and erectile tissue. Distinguishing these types is important for individuals with SCI, as their causes and treatments differ significantly.
How Spinal Cord Injury Leads to Priapism
Spinal cord injury can lead to priapism through disruptions in the autonomic nervous system, which controls involuntary functions, including penile blood flow. The sympathetic nervous system normally maintains penile flaccidity by restricting blood flow, while the parasympathetic nervous system promotes erection by increasing blood flow. Following a spinal cord injury, especially those above the T6 level, there can be a sudden loss of sympathetic tone to the pelvic vasculature.
This loss of sympathetic input results in an unchecked increase in parasympathetic activity, leading to uncontrolled arterial blood flow into the penile sinusoidal spaces, the sponge-like tissues that fill with blood for an erection. This dysregulation causes a prolonged erection unrelated to sexual stimulation. While priapism often occurs immediately after acute SCI and may resolve spontaneously, recurrent episodes in individuals with chronic SCI can be unpredictable and may require intervention. The exact proportion of SCI patients experiencing priapism is not well-established due to rare reported cases.
Identifying and Treating Priapism
Diagnosing priapism in individuals with spinal cord injury involves clinical assessment and diagnostic tests. A healthcare provider evaluates the patient’s history and performs a physical examination of the genitalia and perineum. A penile blood gas analysis, drawing a blood sample from the penis, is performed to differentiate between ischemic and non-ischemic priapism. Ischemic priapism shows blood that is dark, acidic, and low in oxygen, while non-ischemic priapism reveals normal arterial blood values.
Doppler ultrasound of the penis is another diagnostic tool. For ischemic priapism, the ultrasound shows absent or significantly reduced blood flow in the penile arteries. In contrast, non-ischemic priapism is characterized by normal or increased arterial flow, and the ultrasound can identify the arteriovenous fistula causing the condition.
Treatment for ischemic priapism, a medical emergency, follows a stepwise approach to restore blood flow and preserve erectile function. Initial interventions include aspiration, drawing excess blood from the penis, often with saline irrigation. This may be followed by intracavernosal injections of alpha-agonists (e.g., phenylephrine), which constrict blood vessels and reduce penile blood flow. If unsuccessful, surgical shunting procedures may create new pathways for blood to drain from the penis.
Non-ischemic priapism, being less urgent, can be managed conservatively, with many cases resolving spontaneously. If the condition persists or requires intervention, selective arterial embolization is a common treatment. This procedure blocks the artery or fistula causing uncontrolled blood flow, typically using a catheter-based approach.
Potential Complications and Outlook
If left untreated, priapism can lead to serious complications, especially with the ischemic type. Lack of oxygen to penile tissues due to trapped blood can cause significant damage and scarring. This tissue damage can result in long-term erectile dysfunction (ED), where an individual cannot achieve or maintain an erection for sexual activity. In severe cases, prolonged ischemia can lead to fibrosis, or scar tissue formation within the penis, further impairing function.
The long-term outlook for individuals with SCI who experience priapism depends on the type of priapism and timeliness of intervention. For ischemic priapism, prompt treatment within four to six hours improves the chances of preserving erectile function. If ischemic priapism lasts for more than 36 hours, there is a high likelihood of permanent erectile dysfunction and scarring. Non-ischemic priapism carries a better prognosis for erectile function, as it does not involve the same degree of oxygen deprivation. Early diagnosis and appropriate management are important for minimizing complications and preserving penile health and function in individuals with spinal cord injury.