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The video is frightening, I did never see seizures like that but I suppose they are possible. Acetilsalicilic acid can cause sudden death, and allergic reactions to simple things like nuts kill people every year. You cannot live without taking risks.
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The Transverse Myelitis one? I take it more as an expression of pain than a 'seizure' per-se. In an interview I saw with the guy, he described the sensation during the acute phase as having a total body muscle spasm which would not go away.
Unlike with lots of neurological issues with are dysfunctions in part of the brain which is responsible for peripheral nerve signal processing, it sounds like TM really is impacting large portions of the peripheral nervous system in some very real ways as the myelin sheath of the nerves are eaten away. It is not hard to imagine it causing intense pain.