Hyperbaric Center

Stroke accounts for 10% of deaths in all industrialized countries. It is the most common cause of disability worldwide. The causes and risk factors for ischemic stroke overlap. Among the different causes of a stroke, 70% are due to an ischemic infarct, of which 9% are due to large-artery occlusion, 5% are due to tandem arterial pathology, 26% are lacunar, 19% are from cardiac source, and 40% are of uncertain cause.

Changes that occur in the brain during a stroke are both histological and biochemical (metabolic). The brain requires 500-600ml oxygen/min (25% of the total body consumption). One liter of blood circulates to the brain each minute. If this flow is interrupted completely, neuron metabolism is disturbed after 6 s, brain activity ceases after 2 min, and brain damage begins in 5 minutes. Two major types of strokes are ischemic (lesions or infarcts) and hemorrhagic.

Some important factors in a stroke patient's recovery is the extent of two separate things: the infarct and the penumbra. The penumbra lies between the zones of infarction and normal brain - containing the so-called dormant or idling neurons. These neurons are nonfunctional but anatomically intact and can be revived. The presence of viable brain tissue in the penumbra explains why the acute clinical presentation of a stroke is a rather poor predictor of the outcome.

Key attributes of HBOT are that it decreases swelling and reawakens the stunned neurons within the penumbra by providing them with oxygen. Activation of these neurons explains why patients can show improvement when HBOT is administered years after stroke occurs - in some cases, up to thirteen years afterward.

Other benefits include: relief of oxygen starvation, improvement of microcirculation, relief of brain swelling, and reduction or relief of spasticity.

Relief of oxygen starvation . Oxygen starvation, also known as hypoxia, occurs during ischemia, when the flow of blood is reduced. Since full blood circulation to an ischemic area cannot be restored immediately, the only way to get oxygen into the ischemic tissues is by increasing the rate at which oxygen diffuses into all of the body's fluids. HBOT increases the amount of oxygen carried to the tissues by forcing oxygen into the plasma (the liquid portion of the blood), the lymph, and the cerebrospinal fluid (the fluid that bathes the brain and spinal cord). If absolutely no blood can reach an area, as in the case in a complete arterial blockage, the oxygen-enriched cerebrospinal fluid will help to nurture the tissues.

Improvement of microcirculation . Microcirculation refers to blood flow through the capillaries, the tiny blood vessels that connect the arteries and veins. The capillaries are where nutrients, including oxygen, leave the bloodstream and enter the tissues. Oxygenated tissues are also able to repair themselves by producing new capillaries with the help of HBOT. This process is called Angiogenesis.

Relief of brain swelling . Following a stroke, there is considerable swelling, also known as edema, of the brain. Drugs can reduce this swelling but often have adverse effects on normal brain tissue. Swelling tends to recur after the patient stops taking drugs. Moreover, although drugs can reduce edema, they cannot supply the brain with the needed oxygen. HBOT safely reduces edema by causing the blood vessels to contract. Once the extra fluid around the brain cells is drained away, the cells can function more effectively. It also allows cell wastes to be more easily removed, which keeps the wastes from building up toxic levels.

Reduction or Relief of spasticity . A stroke patient's muscles often become spastic, or rigid. This spasticity becomes the greatest obstacle to proper physical therapy. HBOT has been proven to be an effective and nontoxic antispasticity measure. It is not clear how HBOT reduces spasticity, but it probably has something to do with the activation of neurons in the penumbra zone of the brain.