FAST-WAVE PERIODIC COMPLEXES IN A MENTALLY-RETARDED CHILD WHO LATER DEVELOPED SUBACUTE SCLEROSING PANENCEPHALITIS - A MODIFICATION OF A CLASSIC EEG BY PREEXISTING BRAIN-DAMAGE

The EEG of a 12-year-old girl with stage II subacute sclerosing panenc ephalitis (SSPE), who had also suffered from a non-progressive mental retardation of unknown aetiology since early childhood, revealed perio dic generalised stereotyped fast wave bursts synchronous with myocloni c jerks, The background activity was nearly normal, The diagnosis of S SPE was established by raised serum and measles antibody titres, raise d CSF IgG, and brain biopsy, This rare type of periodic complex has on ly once been described in the literature, again in a mentally retarded child who had developed SSPE, We suggest a mechanism of origin of thi s type of periodic complex drawn from observations in these two cases, anti discuss its significance.