Prolonged, reversible neurologic symptoms after carpet sea anemone envenomation in a pet store worker

To the Editor:

Neuromuscular toxicity due to marine envenomation from the phylum Cnidaria has been well documented, though most frequently following exposure to jellyfish venom.¹ We report a case of prolonged, reversible neurologic symptoms in a pet store worker who experienced giant carpet sea anemone (Stichodactyla gigantea) envenomation.

A 25-year-old right–hand-dominant woman presented to the Emergency Department (ED) for evaluation one hour after a giant carpet sea anemone envenomation while at work. She was retrieving the anemone from an aquarium tank when its tentacles curled around her right second and third fingers. She noted immediate onset of severe pain, swelling, and numbness to her hand, particularly over the affected fingers. No immediate decontamination was done on site prior to arrival. In the ED she was found to be very uncomfortable. Her vital signs were within normal limits except for sinus tachycardia with a rate of 110 beats per min. She was treated with hot water immersion (45°C for 10 min), diphenhydramine: 50 milligrams (mg), oral opioid analgesics (oxycodone and acetaminophen: 5 mg/325 mg), and prednisone: 60 mg. After these interventions, she reported significant pain reduction and her tachycardia resolved. She was discharged home with a prescription for four additional days of prednisone: 60 mg, as well as diphenhydramine and ibuprofen as needed. Upon follow-up two months later, she noted that the swelling and pain decreased, but she had persistent numbness and paresthesias to her right second and third fingers. She reported subjective associated weakness in those fingers as well. On examination, she had no objective motor weakness or tenderness in her right hand. Sensation was decreased to light touch and pinprick in the distribution of the common palmar and proper palmar branches of the median nerve on the right hand. Electromyography (EMG) done two months after her initial injury revealed reduced recruitment of motor units at lower firing frequencies. The patient was subsequently treated conservatively with non-steroidal anti-inflammatory medication and occupational therapy. Six months after the injury, she was asymptomatic and had regained full function of her right hand. Repeat EMG was not done as the patient stated that she was able to return to work without difficulty.

The giant carpet anemone is a species of sea anemone native to the Indo-Pacific area. Their care is notoriously difficult. They are large, spanning up to meter in diameter. Like other cnidarians, carpet anemones contain nematocysts contained in finger-like projections. Anemone venom contains multiple components, including neuromuscular toxins. The most common effects of Cnidaria envenomation include immediate local reactions such as burning pain, swelling, pruritis, and tissue inflammation, though rare cases of systemic toxicity have been reported.^2–4 Few studies have examined the neurotoxic components of anemone venom, but effects are thought to at least in part be due to enhancement of sodium currents in dorsal root ganglia.⁵ This case uniquely demonstrates the seldom-reported neurologic toxicity which may occur after sea anemone envenomation, and to our knowledge is the first such report occurring in a pet store employee.

Funding source

None.

Declaration of interest

The authors report no declarations of interest. The authors alone are responsible for the content and writing of the paper.