The Breach Rhythms

The breach rhythm or breach effect in EEG is most part a benign pattern caused by focal skull defect due to craniotomy and occasionally by burr hole.This pattern is not caused by an abnormality in the brain but is due to skull defect. The skull bone attenuates the fast frequencies of the electrical signal of the brain by providing resistance between the cortical tissue and scalp electrodes.

The brain signal recorded from an area of missing bone flap or damaged skull bone shows irregular but higher voltage alpha, beta and mu rhythms. The breach rhythms pattern is focal, spiky, irregular and of high voltage with frequencies ranging from 6 to 11 Hz, persists in sleep and produces high voltage sleep spindles.

Due to the morphology of the pattern, it becomes hard to differentiate it from ictal or interictal activity and may lead to misinterpretation of the EEG signal and under or overdiagnosis of epilepsy. Breach rhythm has no direct relationship to epilepsy unless sporadic epileptiform activity is present. The slower frequencies in theta range in breach rhythm increases the risk of sporadic epileptiform activity as compared to presence of alpha and beta rhythms.

This webinar will shed light on various aspects of breach rhythms, its association with certain conditions and tips to recognize breach rhythms and differentiating it from epileptiform activity