Neurological Considerations of Envenomation by Flower Sea Urchin (Toxopneustes pileolus): A Review

The flower sea urchin (Toxopneustes pileolus) sting is characterised by severe pain, followed by a brief paralysis of facial muscles that may create confusion with the diagnosis of similar clinical conditions like facial palsy and an episode of myasthenia gravis (MG), at the first glance. The epidemiological history, paralysis of face muscles occurring in scuba divers, following a sting, by the sea urchin, distinguishes the venomation by the flower sea urchin, from the other conditions. Its awareness to the medical professionals, assumes paramount importance in avoiding misdiagnosis. Another distinguishing feature of the envenomation, is its self limiting nature and the sting's effect wears of within a few minutes to hours besides being nonreccurent. Though two toxins, contractin and Pedixin are identified, the possible mechanisms involved in the sting paralysis are not clearly elucidated. The similarity of symptomatology with MG suggests a possible mechanism of action of the sea urchin toxin, similar to that of MG involving the myonueral junction. The various mechanisms disrupting the signal transmission at the myoneural junction are explored. The article is aimed at creating awareness among the medical profession about the sting paralysis, its transient and reversible nature and also suggest possible mechanisms that may be involved in the sting paralysis,to give impetus to future research, in this direction.