Kadian Renu, Vemireddy Lalitha Padmanabha, Lui Forshing, Kumar Anil
Great Plains Health
Rosalind Franklin University
The breach rhythm, also known as the breach effect, is a benign electroencephalogram (EEG) pattern with high voltage, often spiky and irregular morphology that can resemble an epileptiform morphology caused by a focal skull abnormality. A focal skull defect, such as after a craniotomy, can cause an increase in the amplitude of alpha, beta, and mu rhythms, leading to the breach effect. Breach rhythm and epileptiform activity in the same area can be challenging to differentiate. Breach rhythm typically has sharp contours and irregular morphology and usually has a frequency of 6 to 11 Hz but may be associated with faster or slower wave activity. It may sometimes be hard to differentiate from actual epileptiform activity in the same area, which can lead to under- or overdiagnosis of epilepsy and thus can have significant clinical consequences. An EEG is a noninvasive test for providing neurophysiological activity of the brain. It is usually done by placing electrodes over the scalp to measure the activity of cortical neurons. The EEG waveforms are the summation of EPSP and IPSP of cortical neurons. It is essential to understand how to differentiate between normal/benign variants of EEG vs pathological variants of EEG. The benign variants of EEG are considered normal but can be confused with epileptiform activity. Accurate recognition of benign variants in the EEG is crucial to avoid an errant diagnosis of epilepsy. Breach rhythm typically is a focal, asymmetrical, high-voltage EEG activity. It often has arch-like waveforms, sometimes having spiky morphology. It can manifest as an irregular rhythm, sometimes associated with sharp activity. Breach rhythm is most prominent when recorded over central and temporal regions. Breach rhythm can be identified easily when it occurs in serial trains. Single, spike-like, or sharp-contoured waveforms are more likely to be mistaken for epileptiform activity. These waveforms should be compared with waveforms of the rhythmic activity constituting breach rhythm to determine if these are distinct waveforms or similar to those constituting the breach rhythm. The absence of after-coming slow-wave components and lack of spread to other areas is characteristic of breach rhythm. Brain damage should be suspected if breach rhythm is associated with polymorphic delta activity. If the breach rhythm is located over the central region, it can be blocked by physical movement due to the presence of an underlying normal mu activity. Breach rhythm can sometimes persist during sleep. It can manifest as a voltage increase in spindles in stage 2 of sleep.
裂隙节律，也称为裂隙效应，是一种良性脑电图（EEG）模式，具有高电压，形态通常尖锐且不规则，可能类似于由局灶性颅骨异常引起的癫痫样形态。局灶性颅骨缺损，如开颅术后，可导致α、β和μ节律的振幅增加，从而产生裂隙效应。区分同一区域的裂隙节律和癫痫样活动可能具有挑战性。裂隙节律通常具有尖锐的轮廓和不规则的形态，频率通常为6至11赫兹，但可能与更快或更慢的波活动相关。有时很难将其与同一区域的实际癫痫样活动区分开来，这可能导致癫痫的漏诊或误诊，从而产生重大的临床后果。脑电图是一种用于提供大脑神经生理活动的非侵入性检查。通常通过将电极放置在头皮上来测量皮质神经元的活动。脑电图波形是皮质神经元兴奋性突触后电位（EPSP）和抑制性突触后电位（IPSP）的总和。了解如何区分脑电图的正常/良性变异与病理性变异至关重要。脑电图的良性变异被认为是正常的，但可能与癫痫样活动相混淆。准确识别脑电图中的良性变异对于避免错误诊断癫痫至关重要。裂隙节律通常是一种局灶性、不对称的高电压脑电图活动。它通常具有拱形波形，有时具有尖峰形态。它可表现为不规则节律，有时与尖波活动相关。在中央和颞区记录时，裂隙节律最为明显。当裂隙节律以连续序列出现时很容易识别。单个、尖峰状或轮廓尖锐的波形更有可能被误认为是癫痫样活动。应将这些波形与构成裂隙节律的节律性活动的波形进行比较，以确定这些是不同的波形还是与构成裂隙节律的波形相似。缺乏后续慢波成分且不扩散至其他区域是裂隙节律的特征。如果裂隙节律与多形性δ活动相关，则应怀疑有脑损伤。如果裂隙节律位于中央区，由于存在潜在的正常μ活动，它可因身体运动而被阻断。裂隙节律有时可在睡眠期间持续存在。它可表现为睡眠二期纺锤波电压增加。
