A cerebral infarction is a medical condition that occurs when the blood flow to the brain is disrupted due to issues with the arteries that supply it. A lack of sufficient blood supply to brain cells deprives them of oxygen and critical nutrients, potentially leading to the death of brain cells. This condition is also called an ischemic stroke.
What are the causes?
Atherosclerosis, which is the formation of a fatty plaque in the blood vessel, causes the brain’s blood supply to diminish. This deposit can induce a thrombus or blood clot in the artery supplying the brain or elsewhere in the body. A fragment of this clot may break off and migrate to the brain’s blood arteries, which lodges there and causes a cerebral embolism.
Atrial fibrillation that can cause a clot to develop in the heart, can also get dislodged and move to the blood vessels supplying the brain via the bloodstream.
Cerebral infarction is more likely to develop in people who have high blood cholesterol and blood pressure. Diabetes, smoking, excessive alcohol intake, obesity and a family history of heart disease, are all risk factors.
How is cerebral infarction classified?
Based on the severity of the initial symptoms, cerebral infarction is classified into four categories.
The following are the four categories:
- Total anterior circulation infarct (TACI)
- Partial anterior circulation infarct (PACI)
- Lacunar infarct (LACI)
- Posterior circulation infarct (POCI)
The Oxford Community Stroke Project classification (OCSP) classifications can be used to classify the source of the stroke, the extent of damage, the impacted brain locations, and the expected patient outcome.
Another categorization system, TOAST (Trial of Org 10172 in Acute Stroke Treatment), classifies strokes based on clinical symptoms and other tests. The cause of the stroke is then determined to be one of the following:
- Embolism or thrombosis due to atherosclerosis of a large artery
- Embolism originating in the heart
- Occlusion of a small blood vessel
- Other identified cause
- Other undetermined cause
What are the symptoms?
Contralateral hemiparesis is a symptom that occurs when an infarct occurs in the primary motor cortex.
Infarctions also cause weakness and loss of sensation. On physical examination, the following are discovered:
- Sudden confusion
- Sudden trouble in speaking or difficulty in understanding speech
- Sudden weakness, or numbness in the face, arm or leg, specifically on one side of the body
- Sudden trouble in visibility – in one or both eyes.
- Sudden dizziness, loss of balance, trouble walking or lack of coordination.
What is the pathophysiology of cerebral infarction?
Cerebral infarction is produced by a disturbance in blood supply severe enough and lasting long enough to induce tissue death. Many factors can disrupt blood supply, including:
- Thrombosis – A blood clot that forms locally and obstructs a blood vessel.
- Embolism – A blood clot from another part of the body causes blockage.
- Systemic hypoperfusion – Shock, for example, causes a general decrease in blood supply.
- Cerebral venous sinus thrombosis
- Gas embolism from rapid ascents in scuba diving is an unusual cause.
Even if a major blood vessel supplying the brain is completely blocked, there is usually some blood flow to downstream tissue via collateral blood vessels, allowing the tissue to survive for some time.
When blood flow diminishes, oxygen supply is limited, causing the tissue to go through the ischemic cascade. The ischemic cascade causes energy failure in neurons, preventing them from moving enough ions through active transport. It also causes them to stop firing and depolarize, and results in imbalances. These imbalances, in turn, causes fluid inflows and cellular inflammation and finally going through a complex chain of events that can lead to cell death by one or more pathways.
How is cerebral infarction diagnosed?
MRI and CT scans can reveal areas of the brain that are injured. This indicates that the symptoms are not due to subdural hematoma, a tumor, or other brain problem. The blockage can be seen on the angiography as well.
What are the treatment options for cerebral infarction?
- Emergency IV medication: Therapy with medications, which can break up the clot (if given intravenously) should be administered within 4.5 hours from when symptoms first started. The sooner these medicines are administered, the better. Faster treatment not only improves the chances of survival, but may also reduce complications.
Recombinant tissue plasminogen activator (tPA), an IV injection also called alteplase (Activase), is considered the gold standard treatment for ischemic stroke. Usually, an injection of tPA is delivered through the vein in the arm within the first 3 hours. At times, tPA injection can be also be given up to 4.5 hours after the symptoms of stroke started.
This drug helps in restoring the blood flow by dissolving blood clot in the brain causing the stroke. Removing the cause of the stroke quickly may help people recover more fully from it. Your doctor will determine if tPA is appropriate for you based on certain risks, like potential bleeding in the brain.
- Emergency endovascular procedures: Sometimesdoctors treat ischemic strokes directly inside the blocked blood vessel. Endovascular therapy have shown significantly improved results thus reducing long-term disability after an ischemic stroke. These procedures must be done as soon as possible:
- Removing the clot with a stent retriever: Physicians may use a device attached to thin, long tube (catheter) to remove the clot directly from the blocked blood vessel in the brain. This procedure is beneficial particularly for those with large clots that cannot be completely dissolved with a tPA injection. Often, this procedure is performed in combination with injected tPA.
- Medications delivered directly to the brain: Physicians insert a catheter through an artery in the groin and thread it to the brain to directly deliver tPA where the stroke is occuring. The time window for this therapy is somewhat longer compared to the injected tPA, but is still limited.
Due to newer imaging technology, the time window on when these procedures can be considered has been expanding. Doctors specialized in stroke treatment may order perfusion imaging tests, which done using MRI or CT, to help determine how likely a person may benefit from the endovascular therapy.
To reduce the risk of having another stroke/ transient ischemic attack, your treating doctor may suggest a procedure to open up a artery that is narrowed by a plaque. Options may vary depending on the situation, but could include:
- Carotid endarterectomy: Carotid arteries are blood vessels that go along each side of the neck, supplying the brain with blood. Carotid endarterectomy is a surgery that is used to removes the plaque blocking a carotid artery, which may reduce the risk of an ischemic stroke. Carotid endarterectomy may also involves risks, particularly for those with heart disease or other medical issues.
- Angioplasty and stents: In an angioplasty, a physician threads a catheter to the carotid arteries through an artery in the groin. Then, a balloon is inflated in order to expand the narrowed artery. And then, a stent can be inserted to support the opened artery. After emergency treatment, you will be monitored closely for at least one day. After that, stroke management will focus on helping the patient recover as much function as possible and return to an independent living.