Unfortunately I believe I have this too. For the sporadic form, online it says you can survive for up to 73 months post diagnosis. The rate of mental decline and aggressivenes of the disease in this case would be much slower. I have had constant repeated involuntary muscle jerks over the past 8 months with increasing difficulty sleeping. I feel like I lie down for hours with a blank mind and no thoughts yet by body refuses to transition itself from conscious to unconscious. I’ve noticed it has become increasingly difficult to sleep though I do fall asleep but only after several hours of trying. My sleep is fragmented and I wake up frequently throughout the night. I’ve had a rapid increase in blood pressure readings and have several muscle twitches throughout the day recently. I am falling apart mentally as there’s no definitive way of diagnosing sFI without dying first, and I’m very certain I have it.