Transient extreme spindles in a case of subacute Mycoplasma pneumoniae encephalitis.

We describe a 4-year-old boy with delirium including somnolence, irritability, agitation and visual hallucination, associated with Mycoplasma pneumoniae (MP) encephalitis. The MP encephalitis was diagnosed from increased MP-antibody (> 1:1280). Electroencephalography during sleep revealed continuous 9 Hz fast wave activity over the bilateral frontocentral regions, which was thought to represent extreme spindles. These extreme spindles were in parallel with the degree of delirium. Transient extreme spindles have not previously been reported in MP or other encephalitis.