A 7 year old white male presents with 4 day history of nausea, vomiting, headache and altered mental status. Initially thought to be infectious meningoencephalitis, an extensive infectious workup was negative. MRI showed diffuse enhancement of the meninges. Lumbar puncture showed lymphocytic pleocytosis and mildly elevated protein. His clinical state worsened to a near catatonia. He was started on empiric high-dose steroids with minimal improvement. He was soon after started on IVIG therapy. A serum encephalopathy panel returned positive for VGKC antibodies, with negative LGI1 and CSPR2 antibodies. His remaining symptoms consist of decreased attention and emotional lability.
Two years later, his 7-year-old younger brother presented with a two-day history of acute onset paranoid behaviors with tactile, auditory and visual hallucinations. Initial studies including MRI, EEG, LP, infectious work-up were unrevealing. He was empirically started on IVIG and high-dose steroids due to concern for autoimmune encephalitis, as his brother had. His serum encephalopathy panel returned positive for VGKC, negative LGI1 and CSPR2. Patient showed improvement with steroids and IVIG, although has had several relapses and was recently started on rituximab.