Case 1. Eleven-year-old boy presented with long-standing intellectual disability (ID), including speech and cognitive delay since age 3 years, Hashimoto’s thyroiditis, and abnormal EEG. Six months prior to presentation, the patient developed aggression and impulsivity 1 week after starting azithromycin for mycoplasma. He was diagnosed with PANDAS by Cunningham panel. Rage gradually resolved but continued to have ID and impulsivity. Stimulant medications were not helpful. He had no clinical seizure events but routine electroencephalography (EEG) showed frontally predominant generalized spike and slow-wave complexes with moderate background slowing for which valproic acid was started. MRI brain was unremarkable. Thyroid peroxidase antibodies were previously elevated to 193 IU/mL but improved to 103 IU/ml without immunotherapy. Epilepsy gene panel resulted a pathogenic c916C>T;pR306C heterozygous mutation in the KCNB1 gene, which can cause seizures and encephalopathy.
Case 2. Thirteen-year-old girl with autism and two previous admissions for altered mental status, motor impairment, and dysarthria presented to hospital for five days of regurgitation, odd behaviors, language regression, agitation, affection, and biting. She was started on multiple psychotropic medications without improvement and had two psychiatric admissions for aggression. One year later, she reported weeklong episodes of insomnia followed by loss of cognitive, emotional, and activities of daily living skills. Prior evaluations over two years included cerebrospinal fluid, neuroimaging, and EEG that were unremarkable. Chromosomal microarray showed 22q13.3 deletion, consistent with Phelan-McDermid Syndrome, which includes SHANK3 deletion and developmental regression.