penumbra

The penumbra is the area surrounding a central zone of damage, such as in a stroke or a blackout vision field. In medical terms, during a stroke, the penumbra refers to the brain tissue that is at risk but still salvageable if treated quickly. It receives some blood flow but not enough for normal function. Recognizing and protecting the penumbra is crucial because timely medical intervention can save this tissue from irreversible damage, improving the patient’s recovery chances. Essentially, the penumbra is the margin of vulnerable but potentially rescuable tissue around the core of injury.