focal slowing
Localized abnormal EEG activity characterized by slower frequency waves in a specific brain region, suggesting underlying pathology.
Full Definition
Focal slowing refers to the presence of theta (4-8 Hz) or delta (1-4 Hz) frequency waves that are localized to a specific region of the brain, as opposed to the normal background rhythm for that area. This finding indicates dysfunction of the underlying cortical tissue and can result from various pathological processes including stroke, tumor, infection, or metabolic disturbances. Focal slowing may be intermittent or continuous and can be further classified as polymorphic (irregular) or monomorphic (regular). The degree, persistence, and morphology of focal slowing provide important diagnostic and prognostic information about the underlying neurological condition.
Usage
Usage note: Specify frequency range, morphology (polymorphic vs monomorphic), and anatomical location.
In Context
- "Continuous polymorphic delta slowing was present over the right frontotemporal region." — EEG report
- "The focal slowing corresponded to the area of recent infarction on MRI." — Stroke evaluation