breach rhythm
Increased amplitude and altered morphology of EEG rhythms over areas where the skull is defective or thinned.
Full Definition
Breach rhythm refers to the characteristic alteration of EEG activity that occurs over regions where the skull has been surgically removed, fractured, or congenitally defective. The absence or thinning of bone reduces the electrical resistance between the brain and recording electrodes, resulting in increased amplitude of normal rhythms and enhanced visibility of underlying brain activity. Breach rhythm typically manifests as higher amplitude beta or mu rhythms with sharper morphology than normal. This finding is important to recognize as it represents a benign consequence of skull defects rather than pathological brain activity, though it may make detection of subtle abnormalities more challenging.
Usage
Usage note: Always correlate with surgical history and skull imaging when reporting.
In Context
- "High-amplitude breach rhythm was noted over the left frontoparietal craniotomy site." — Post-surgical EEG report
- "The increased beta activity represented breach rhythm rather than epileptiform discharges." — EEG interpretation note