Isolated severe median mononeuropathy caused by a jellyfish sting.

Neuropathies caused by jellyfish stings are extremely rare and poorly studied. A 20-year-old female patient was stung on the volar aspect of the right forearm by an unidentified species of jellyfish. Local cutaneous reaction was followed within few days by severe median mononeuropathy, involving the motor and sensory branches to the hand and forearm but sparing the palmar branch. The patient had neuropathic pain relieved by pregabaline. Electrodiagnostic studies confirmed a demyelinating lesion. Ultrasound and magnetic resonance imaging of the median nerve revealed uniform swelling with mild uptake of contrast along the forearm. Within 2 months, strength improved significantly, pain subsided, and numbness partially resolved. Literature review and discussion of the possible mechanisms and implications of this rare effect of marine animal envenomation is presented. Jellyfish sting may cause focal mononeuropathies most probably because of the local effects of the toxins.