Priapism and Spinal Cord Injury: Causes and Treatments

Priapism after a spinal cord injury is caused by an abrupt disruption of the nerve signals that control blood flow to the penis, and it typically appears within moments of the injury itself rather than developing days or weeks later. In most cases tied to acute spinal cord trauma, the erection is driven by uncontrolled arterial inflow and tends to resolve on its own, but the condition can sometimes become an emergency that threatens permanent damage to erectile tissue. Understanding which type of priapism is occurring shapes every treatment decision that follows.

How a Spinal Cord Injury Triggers Priapism

Normal erections depend on a careful balance between three sets of nerve pathways that converge in the pelvis: somatic nerves (voluntary motor control), sympathetic nerves from the thoracolumbar spine (which constrict blood vessels and help end an erection), and parasympathetic nerves from the sacral spine (which relax blood vessels and promote erection). The brain coordinates all three through descending signals that can both excite and inhibit the process.¹

When the spinal cord is suddenly damaged, especially at the cervical or upper thoracic level, the sympathetic nerve supply to the pelvic blood vessels drops out. The sacral parasympathetic nerves, which sit below most injury sites, often keep working. The result is a lopsided situation: the “open the floodgates” signal persists while the “close them” signal disappears. Blood rushes into the erectile tissue and stays there because nothing is telling the vessels to constrict.² This is why priapism in spinal cord injury patients tends to happen right away, during the phase of “spinal shock” when reflexes below the injury level are still sorting themselves out.

Ischemic Versus Non-Ischemic Priapism

Not all priapism is the same, and the distinction matters enormously for treatment. Ischemic priapism, sometimes called “low-flow” priapism, involves trapped, deoxygenated blood that cannot drain from the erectile tissue. It is painful, the penis is typically rigid, and the blood inside is dark and acidotic. Left untreated, the oxygen-starved tissue begins to die. Non-ischemic priapism, or “high-flow” priapism, involves excessive arterial blood flowing in. The penis is usually only partially rigid, the condition is often painless, and the blood inside remains well-oxygenated.³

After acute spinal cord injury, the priapism that develops is usually the non-ischemic, high-flow type. A study of six patients with spinal cord injury-related priapism found that all cases were non-ischemic and could be managed conservatively because of the high likelihood of spontaneous resolution.⁴ That said, ischemic priapism can also follow spinal cord injury, particularly in cervical or upper thoracic injuries where the loss of sympathetic inhibition is more complete. A 2025 narrative review found that priapism following these higher-level injuries typically reflected abrupt loss of sympathetic output with preserved sacral parasympathetic outflow, resulting in sustained reflexogenic or, less commonly, ischemic priapism.⁵

The practical takeaway: if someone develops priapism immediately after a spinal cord injury, it is not safe to assume it is harmless. Clinicians need to determine the type before deciding on a treatment plan.

Timing, Injury Level, and Clinical Patterns

Priapism in spinal cord injury follows a recognizable pattern. It appears at the moment of complete motor and sensory loss, not after a delay, and it typically accompanies spinal shock.⁶ In practice, emergency responders and trauma teams may notice it during the initial evaluation of a patient with a new spinal cord injury. Its presence can actually serve as a clinical sign that suggests the cord injury is complete, since it points to total disruption of descending sympathetic control.

Cervical injuries account for a disproportionate share of cases. In the six-patient series mentioned earlier, four had injuries between C5 and C7, one at C5-C6, and one at T12.⁴ This makes physiological sense: cervical injuries knock out sympathetic outflow more completely than lower injuries because the sympathetic chain begins at T1. An injury above that level severs essentially all sympathetic signaling to the pelvis.

Most episodes in the acute setting are self-limiting, resolving within hours. One case report documented resolution within about 30 hours.² During that window, clinical teams monitor the situation and watch for signs that it might be transitioning from non-ischemic to ischemic, which would demand urgent intervention.

Diagnosing the Type

Because treatment for ischemic and non-ischemic priapism is fundamentally different, getting the diagnosis right is the first priority. Ischemic priapism is characterized by little or no blood flow through the erectile tissue, and a blood sample drawn from the penis will show the hallmarks of trapped venous blood: low oxygen, high carbon dioxide, and acidic pH.⁷ Non-ischemic priapism, by contrast, shows bright red, well-oxygenated arterial blood. Doppler ultrasound can also help by visualizing whether blood is flowing freely through the penile arteries or whether it is stagnant.

In a spinal cord injury patient who cannot feel pain below the injury, the usual symptom of ischemic priapism (severe penile pain) is absent, which makes the blood gas test even more critical. A painless erection in a patient with a new cervical injury could be benign high-flow priapism that will resolve on its own, or it could be a painless ischemic emergency that the patient simply cannot feel. Clinicians cannot rely on symptoms alone to tell the difference.

First-Line Treatments for Ischemic Priapism

Ischemic priapism is a urological emergency regardless of its cause.⁸ The immediate goal is to drain the trapped blood and restore circulation before the tissue sustains irreversible damage. Treatment follows a stepwise approach.

The first step is corporal aspiration and irrigation: a needle is inserted into the erectile tissue to drain the dark, deoxygenated blood, and saline is flushed through to wash out the stagnant material. If that alone does not resolve the erection, the next step is injection of a sympathomimetic drug, most commonly phenylephrine. Phenylephrine causes the smooth muscle in the blood vessel walls to contract, squeezing the excess blood out and mimicking the sympathetic signal that the damaged spinal cord can no longer deliver. One institutional protocol used phenylephrine at a concentration of 100 micrograms per milliliter, injected directly into the erectile tissue, with repeat doses as needed up to a maximum of 1,000 micrograms.⁹

For priapism lasting less than about 24 hours, these bedside procedures are often enough to resolve the problem.¹⁰ The urgency comes from the clock: the longer ischemic priapism persists, the more the smooth muscle inside the erectile tissue deteriorates. After a certain point, the tissue begins to scar, and that fibrosis becomes irreversible.

Conservative Management of Non-Ischemic Priapism

Non-ischemic priapism after spinal cord injury often does not need aggressive treatment. Because arterial blood is flowing in rather than venous blood being trapped, the tissue is getting oxygen and is not at immediate risk of dying. Many cases resolve as the autonomic nervous system stabilizes in the hours and days after injury.⁴ Clinical teams typically observe the patient, perform serial assessments, and intervene only if the priapism persists or shows signs of converting to an ischemic pattern.

When non-ischemic priapism does persist or recur, especially if it stems from a traumatic arterial injury such as a laceration to one of the pudendal arteries, selective arterial embolization becomes an option. In this procedure, an interventional radiologist threads a catheter into the offending artery and blocks it with tiny particles or coils. Case reports have documented successful embolization without subsequent erectile dysfunction or recurrence.¹¹ ¹² The procedure is targeted enough that the unaffected arteries continue to supply the penis normally.

Surgical Options for Refractory Ischemic Cases

When aspiration, irrigation, and phenylephrine injections fail to resolve ischemic priapism, surgical shunting is the next step. Shunt procedures create an artificial drainage pathway between the rigid erectile tissue and the spongy tissue of the glans or the veins nearby, allowing trapped blood to escape. Several techniques exist, ranging from simple needle-based shunts to open surgical approaches. Newer tunneling methods, including a technique called the “corporal snake maneuver,” have shown early promise not only in resolving the priapism but potentially in preserving some erectile function afterward.¹⁰

The challenge with any surgical intervention for ischemic priapism is that by the time surgery becomes necessary, the tissue has usually been oxygen-deprived for a long time. The more time that passes, the more fibrosis sets in, and the less likely it is that normal erectile function will return. This reality puts enormous pressure on the treatment timeline.

Long-Term Damage and Erectile Function

Priapism’s most feared consequence is permanent erectile dysfunction. The mechanism is straightforward: prolonged oxygen deprivation causes the smooth muscle inside the erectile tissue to be replaced by fibrous scar tissue. Once that happens, the tissue loses the ability to relax and expand with blood flow, which is the fundamental requirement for a normal erection. Prompt treatment aims to prevent this fibrosis and preserve the smooth muscle.¹³

For spinal cord injury patients, the stakes are layered. Many already face changes to sexual function because of their underlying neurological injury. Priapism-related fibrosis on top of that can remove options that might otherwise remain available, such as the ability to achieve reflex erections or respond to medications like phosphodiesterase inhibitors. Penile shortening from fibrosis is another documented outcome that compounds the functional and psychological impact.

The likelihood of preserving erectile function depends heavily on how long the ischemic episode lasted before treatment. Episodes that resolve within a few hours carry much better odds than those persisting for a day or more. Non-ischemic priapism, because it does not starve the tissue of oxygen, carries a substantially lower risk of permanent damage.

Penile Prosthesis After Priapism-Related Damage

When ischemic priapism causes severe fibrosis and permanent erectile dysfunction, a penile prosthesis (implant) becomes the primary option for restoring the ability to have intercourse. But the timing of implantation presents a dilemma. Placing a prosthesis during the acute episode, while the tissue is still inflamed, is associated with a higher risk of infection and can cause psychological distress in a patient already coping with a traumatic injury. Waiting, on the other hand, allows fibrosis to worsen, which makes the surgery harder, increases the risk of needing downsized implants, and leads to greater loss of penile length.¹⁴

Implanting a prosthesis in a scarred penis is one of the more technically difficult procedures in urological surgery. The fibrotic tissue that replaces the normal spongy erectile bodies is tough and resistant to dilation. Surgeons sometimes have to use downsized cylinders to fit within the scarred space, which limits the cosmetic and functional outcome.¹⁵ Despite these challenges, penile prostheses remain a viable path to restoring sexual function after priapism-related damage, and satisfaction rates in the broader prosthesis literature are generally high.

Preventing Recurrent Episodes

Some spinal cord injury patients experience recurrent priapism rather than a single acute episode. In the chronic setting, the autonomic imbalance that caused the initial event can continue to trigger unwanted erections that are prolonged and difficult to control. Several preventive strategies have been tried, though the evidence base for each is limited.

Oral medications that have been used to prevent recurrent priapism include beta-agonists like terbutaline, which have shown success rates of roughly 60% or higher in adults, though the exact mechanism remains unclear.¹⁶ Hormonal approaches, including drugs that lower testosterone, have also been tried in adults with recurrent priapism, though these carry their own side effects and are generally reserved for cases that do not respond to other measures.

Baclofen has a particularly interesting role in the spinal cord injury population. It is already widely used to treat spasticity after spinal cord injury, and it has been reported to reduce priapism episodes as well. One study followed nine men with spinal cord injury or multiple sclerosis who received intrathecal baclofen via an implanted pump. After an average follow-up of about three and a half years, eight of the nine reported decreased erection rigidity and duration.² That dual benefit makes baclofen appealing for patients who need spasticity management anyway, though side effects like drowsiness and the risk of reducing wanted erectile function limit its enthusiasm as a first-line option.¹⁶

Priapism as a Clinical Sign in Trauma

In the emergency setting, priapism has a role that goes beyond being a complication requiring its own treatment. When paramedics or emergency physicians encounter a male trauma patient with a sustained erection, it serves as a red flag for spinal cord injury. Because priapism appears at the moment of complete cord disruption and not after a delay, its presence during initial assessment can help localize the injury and gauge its severity.⁶ In a chaotic trauma bay with multiple competing injuries, a clinical sign that points directly at the cord can help prioritize imaging and stabilization.

Clinicians also use the resolution of priapism as one indicator during the monitoring of spinal shock. As sympathetic tone gradually returns over hours to days, the erection subsides. If it does not, or if the clinical picture shifts toward a more rigid, painful presentation, the concern shifts from “this is part of spinal shock” to “this may be becoming ischemic and needs intervention.” The evolving nature of the condition means that even initially reassuring cases warrant close observation.

Why Spinal Cord Injury Priapism Is Understudied

Despite being a recognized complication, priapism after spinal cord injury has not attracted the same research attention as priapism from other causes like sickle cell disease or medication side effects. The published literature consists largely of case reports and small case series rather than large prospective trials. There are good reasons for this: spinal cord injury itself is relatively uncommon, priapism occurs in only a fraction of those patients, and the acute trauma setting makes controlled studies extremely difficult to design. Patients are often critically ill with polytrauma, and priapism understandably takes a back seat to life-threatening concerns.

The result is that much of the management guidance for spinal cord injury-related priapism is borrowed from the broader priapism literature, which is dominated by hematological causes and drug-induced cases. The 2021 AUA/SMSNA guideline on acute ischemic priapism, for instance, provides a general treatment framework that applies regardless of cause, emphasizing the time-dependent and progressive nature of the condition.⁷ But spinal cord injury patients have unique considerations, including impaired sensation that masks pain, ongoing autonomic instability, and a rehabilitation trajectory that intersects with sexual function recovery in complex ways. More targeted research would help clinicians tailor their approach rather than applying a one-size-fits-all protocol to a population with distinct physiological circumstances.

1
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