What should the asymmetry of occipital alpha rhythm voltage between two hemispheres not exceed?

The asymmetry of occipital alpha rhythm voltage between two hemispheres should not exceed 50%. In clinical EEG practice, the occipital alpha rhythm is an important feature, typically observed when a patient is relaxed and eyes are closed. A symmetrical alpha rhythm is a sign of normal brain function; however, significant asymmetry can suggest underlying pathologies, such as lesions or other neurological issues.

When evaluating asymmetry, a 50% threshold is clinically relevant because it facilitates the identification of potentially abnormal conditions. Values above this threshold could indicate significant neurological abnormalities, warranting further investigation. Understanding the limits of asymmetry helps in distinguishing normal physiological variations from pathological changes in the brain’s electrical activity. The other thresholds mentioned, such as 25%, 75%, or 10%, do not align with established clinical norms and are not typically used in practice for assessing occipital alpha rhythm asymmetry.