Abnormal patterns

Abnormal electroencephalogram wave patterns include:

• theta 8-12 Hz in parietal and occipital regions
• delta less than 4 Hz - any slow wave pattern suggests acute problems - any acute insult
• epilepsy: paroxysmal sharp high-voltage waves, e.g. the spike and wave pattern at rate of 3Hz seen in petit mal
• brain death is indicated by absence of activity in normothermic patients not exposed to sedative drugs
• periodic complexes - seen in Creutzfeldt-Jakob disease, subacute sclerosing panencephalitis, herpes simplex encephalitis and hepatic coma.
• diffuse slowing of rhythms - seen in progressive multi - focal leukoencephalopathy

Reference

1. Britton JW, Frey LC et al. Electroencephalography (EEG): An Introductory Text and Atlas of Normal and Abnormal Findings in Adults, Children, and Infants American Epilepsy Society 2016 (online).