penumbra
Pronunciation: peh-NUM-bruh
In stroke imaging, brain tissue that is hypoperfused but not yet irreversibly damaged, representing potentially salvageable tissue.
Full Definition
The ischemic penumbra represents a critical concept in acute stroke management, referring to brain tissue that is functionally impaired due to reduced blood flow but remains structurally intact and potentially viable if reperfusion is achieved promptly. Neuroimaging defines penumbra as the mismatch between the perfusion deficit (shown on perfusion-weighted imaging) and the area of irreversible injury (shown on diffusion-weighted imaging). This tissue is electrically silent but metabolically active, making it the primary target for acute stroke interventions. The penumbra evolves over time, with tissue either recovering through reperfusion or progressing to infarction.
Usage
Usage note: Can be used without 'ischemic' modifier in neuroimaging contexts where meaning is clear.
In Context
- "The large penumbra on imaging supported the decision for mechanical thrombectomy despite the extended time window." — Stroke team discussion
- "Penumbra salvage was achieved through successful recanalization of the middle cerebral artery." — Interventional radiology report