Abstract
Priapism in children after a black widow spider bite is a rare phenomenon with only a few case reports noted in the literature. Black widow bites are commonly associated with pain, muscle cramping, hypertension, and tachycardia. Initial treatment includes pain control with opiate or opioid medications and benzodiazepines, with antivenom reserved for severe cases of envenomation manifested by uncontrolled pain or hypertension. Treatment with antivenom for priapism is not well described; however, it has been noted to resolve priapism in the few cases that have been reported. We present a case of a 3-year-old boy who was bitten by a black widow and presented with abdominal cramping and priapism.
Case Report
A 3-year-old boy with no prior medical problems was bitten on the dorsum of his left foot at 7:30
As a result of the priapism, he was then transferred to the Loma Linda University Medical Center Pediatric Emergency Division for further management. His initial vital signs after transfer were remarkable for a heart rate of 151 beats/min and blood pressure of 125/73 mm Hg. On examination it was noted that his abdomen was diffusely tender with rigidity and he had an erect penis without full tumescence. There were no color changes to the penis, and it was painless. A 2- to 3-mm punctate lesion to the dorsum of the patient’s left foot was also present. He was again treated with opioids and benzodiazepines without resolution of the priapism.
It was then decided to treat the patient with Black Widow Spider Antivenin, Equine Origin (Merck, Whitehouse Station, NJ). Urology was consulted and agreed to see the patient if his priapism did not resolve after antivenom. After pretreatment with solumedrol and diphenhydramine, one 2.5-mL vial of antivenom was administered over 15 minutes. He was admitted to the emergency department observation unit after administration of the antivenom. The patient’s abdominal pain resolved almost immediately, and his priapism gradually resolved during the next few hours. Overall, the patient had priapism for more than 6 hours. During observation he had no recurrence of pain or priapism and did not require any additional doses of morphine or lorazepam after the administration of the antivenom. The patient was discharged from the emergency department at 11:20 in the morning of the day after his bite in stable condition with normal vital signs.
Discussion
Despite black widow bites being a fairly common event, only 3 prior cases of priapism after black widow spider bites were noted in the literature. 1 –7 Each case, including our case, involved children who were eventually treated with black widow antivenom and had gradual resolution of priapism. 5 –7 In addition to the priapism, the patients also demonstrated more classic symptoms of latrodectism, including a painful abdomen, hypertension, and tachycardia.
Priapism is considered a nonphysiologic, persistent erection that is not related to sexual stimulation. It is usually divided into 2 classes: high-flow or low-flow. High-flow priapism is usually a painless erection caused by increased arterial flow to the cavernosal sinusoids. Low-flow, caused by decreased venous outflow, is generally painful and can lead to penile ischemia and compartment syndrome. 8 –10 Based on the painless priapism seen in our case and the preceding case reports, priapism from black widow envenomation is most likely high-flow. The mechanism behind priapism in latrodectism is likely complex but is thought to be mediated through the neurotransmitters norepinephrine (NE) and acetylcholine. Norepinephrine is involved in penile detumescence, and black widow venom may cause a local depletion of NE at the vasculature and smooth muscle, preventing detumescence. Increases in acetylcholine leading to smooth muscle relaxation also play a role in increased blood flow to the sinusoids and priapism.7,11
Treatment of bites with antivenom is generally reserved for patients with hypertensive emergencies or uncontrolled pain after using benzodiazepines and opioids. 3 The hesitancy to treat bites initially with antivenom may be from the reactions that are associated with antivenom, including anaphylaxis and serum sickness. Some physician experts, such as those at our institution, pretreat patients before receiving this particular antivenom with steroids and antihistamines. Clark 12 has demonstrated that treatment with antivenom can be safe and effective when administered in the proper manner and environment, ie, a closely monitored emergency department or intensive care unit setting; however, serious, even fatal, adverse events have been reported in association with black widow spider antivenom. Risk factors for allergic reaction to antivenom may include asthma, allergy to horse serum, or atopy. In all 4 case reports of priapism after a bite, including our own, antivenom was administered with immediate resolution of pain and no reports of adverse events. Priapism was slower to resolve than pain in each case, sometimes lasting a few more hours before complete detumescence.
It is possible that the priapism might have resolved spontaneously, even without antivenom, which limits the conclusions that can be drawn from this case report.
We present a case of priapism after a black widow spider bite that resolved after the administration of antivenom. This is the fourth case presented in the literature, suggesting a pattern of effectiveness of antivenom in treating priapism caused by latrodectism.