Cerebral perfusion is the process of supplying blood to the brain to deliver necessary oxygen and nutrients. When this supply is diminished, a condition known as decreased cerebral perfusion, the brain is deprived of these resources. This condition can be likened to a garden hose with low water pressure; the garden receives some water, but not enough to remain healthy.
Causes of Reduced Brain Blood Flow
A reduction in brain blood flow can originate from issues affecting the entire circulatory system. Conditions that cause a severe drop in blood pressure (hypotension) prevent the heart from pumping blood with enough force to adequately reach the brain. Similarly, heart failure or circulatory shock from trauma or severe illness can compromise the body’s ability to maintain the necessary pressure to drive blood into the cranial compartment.
Blockages within blood vessels are another source of diminished cerebral perfusion. Atherosclerosis, the gradual buildup of fatty plaques in arteries, can cause them to narrow over time, restricting blood flow. In more acute scenarios, a piece of this plaque or a blood clot can travel to the brain, causing a sudden blockage and an ischemic stroke.
Pressure inside the skull, or intracranial pressure, also regulates blood flow to the brain. A traumatic brain injury, tumor, or swelling can increase this pressure, compressing blood vessels from the outside. This compression impedes blood from entering and circulating within the brain, and the body’s attempts to compensate by raising blood pressure may not be sufficient.
Recognizing the Signs and Symptoms
The signs of decreased cerebral perfusion depend on whether the reduction in blood flow is sudden or gradual. An abrupt drop can trigger acute symptoms like dizziness, fainting, confusion, or disorientation. Some individuals experience sudden difficulty speaking, vision changes, or weakness affecting one side of the body.
When cerebral perfusion is reduced chronically, symptoms are more gradual and may be mistaken for other conditions. Common signs include persistent cognitive difficulties, such as memory problems and a reduced ability to concentrate. Chronic fatigue, mood disturbances, and personality changes can also manifest over time.
Diagnostic Procedures
Diagnosis begins with a clinical evaluation, including a neurological exam to assess cognitive function, motor skills, and sensory responses. A healthcare provider will also measure vital signs, especially blood pressure, to identify systemic issues like hypotension that could contribute to reduced brain blood flow.
To visualize and measure blood flow directly, physicians use specialized brain imaging. CT and MR perfusion scans can generate detailed maps showing which areas of the brain are receiving adequate blood and which are not. This information helps determine the extent and severity of the perfusion deficit.
If a blockage is suspected, imaging of the blood vessels is necessary. A carotid ultrasound uses sound waves to create images of the carotid arteries in the neck to spot narrowing. For a more detailed view, a cerebral angiogram involves injecting a special dye and taking X-rays to reveal the precise location of blockages within the brain’s vascular network.
Medical and Surgical Interventions
Treatment is tailored to the specific cause. If the issue is low blood pressure, the goal is to restore circulation with intravenous fluids or medications. For an acute ischemic stroke caused by a blood clot, thrombolytic drugs (“clot-busters”) may be administered to dissolve the blockage and restore flow.
For arterial narrowing, surgical or procedural interventions may be required. Carotid angioplasty and stenting uses a balloon to widen a neck artery, followed by placing a stent to keep it open. For severe blockages, a carotid endarterectomy is a surgical procedure to remove plaque buildup. If increased intracranial pressure is the cause, surgery may be needed to relieve it.
Long-term management focuses on preventing future episodes by addressing the chronic conditions that contribute to poor perfusion. This involves lifestyle modifications like a healthier diet, regular exercise, and smoking cessation to manage atherosclerosis. Medications to control high blood pressure, high cholesterol, or heart disease are also prescribed to protect the brain’s blood supply.