Brain ischemia is an interruption of the supply of blood to the brain, disrupting the flow of oxygen and nutrients needed to keep brain cells functioning. Depending on the location of the ischemia, the extent, and how long it lasts, the patient could develop impairments and be at risk of death. A number of things can cause brain ischemia, including strokes, trauma to the brain, and blood vessel abnormalities. Neurologists are usually involved in treatment and the patient may need medications, surgery, or other interventions.
The brain needs a lot of blood to function, and the structure of the circulatory system is designed to meet that need. Freshly oxygenated blood travels up the carotid arteries to the head and neck, providing a steady supply of blood to the brain. Even brief interruptions can cause brain ischemia, and potentially result in a situation called an ischemic cascade, where brain cells with inadequate blood supply start dying and releasing toxins that damage neighboring cells, causing them to rupture and release toxins of their own, creating a ripple effect across the brain.
Most commonly, brain ischemia involves not the carotid artery, but one of the smaller blood vessels in the brain. Blood vessels may develop clots, obstructing blood flow and causing a stroke. They can also rupture, or a patient may develop vascular malformations, where the vessels grow abnormally and fail to get blood to locations where it needs to go. Severe head trauma can also result in ischemia by rupturing or crushing vessels to prevent blood from reaching some areas of the brain.
Symptoms of brain ischemia vary, depending on the area of the brain involved. Things like slurred speech, confusion, vision changes and stiffness, as well as trouble controlling the muscles, are common. The onset of symptoms can be very rapid. If prompt treatment is provided, there is a chance of recovery. Other patients may experience brain damage and could need therapy to relearn some skills. In some cases, the damage cannot be addressed with therapy and the patient will have a permanent impairment like a limp.
When brain ischemia involves the areas of the brain responsible for regulating functions like breathing, heart rate, and metabolism, this can lead to coma, persistent vegetative state, or death. The brain stem cannot recover from severe damage. More mild brain stem damage may result in impairments requiring a patient to use a ventilator for respiration.