We report a series of four of 12 patients observed at our children's hospital between 2011 and 2013 that we chose as particularly representative examples of two distinct clinical features.
In these individuals with anti-N-methyl-D-aspartate receptor antibody encephalitis, we note a very rapid on–off state between responsiveness and nonresponsiveness and/or insomnia accompanied by extreme irritability. We describe the abrupt mental status shift as “light switch” because the patients can awaken in seconds from a completely nonresponsive state. The insomnia noted in our patients was also impressive and often present early in the patients' courses.
Light switch mental status changes and irritable insomnia are important early features of anti-N-methyl-D-aspartate receptor antibody encephalitis that can signal the presence of this disorder. The exact pathophysiology of these two symptoms has not been fully elucidated, and we feel that presence of one or both of these symptoms early in the disease course should prompt immediate concern for this disorder.