SOS - 2 year old baby involuntary entire body shakes 9 episodes in 19hours

[yishanchenrui]

My son is born at 32 weeks had subependymal hemorrhage diagnosed at 4weeks, in NICU for 4 weeks, did well after and never had seizure in the past. Recently had high grade fever 39.8C for 48h, given regular Tylenol which reduces the fever. Last fever was at 5pm and have not recurred since. There’s no specific source for the fever, such as cough, rhinorrhea, vomiting, diarrhea, etc. Ears look normal.  Then at midnight, had sudden episode where his entire body froze, he couldn’t move, fell backwards from standing height, hit his head on hardwood floor, and entire body shaked for 20-30s with increased tone. He was conscious and crying, no eye rolling or tongue biting. We took him to ER, he got discharged without any investigations and thought to have a temper tantrum. Then he had 8 more episodes within the past 18 hours, 2 episodes happened during sleep, the subsequent ones became more frequent almost hourly and lasted a bit longer. He was very calm prior to these episodes, not upset or in pain or crying. But right before he becomes stiff, he loses control of his body, collapses to one side while sitting in baby high chair or stroller. After the episodes resolve spontaneously, he feels tired, and have mild difficulty standing or walking, which then become normal within 30-60min. We are really concerned and don’t know what’s the cause. The doctors also don’t know what is going on, and think his presentations are not typical of seizure. They are reluctant to do further investigations, so he is just being monitored for now but getting progressively worse and having more frequent episodes every hour to the point that he is no longer safe to stand or walk. We also have videos of these episodes we are happy to share. Thank you and we welcome any comments or suggestions in terms of differential diagnosis, investigations, etc.