Stroke

A stoke is a condition where the flow of blood is disrupted to a region of the brain, causing damage to the brain. There are two categories of stroke -

  • ischemic stroke – obstruction of a blood vessel supplying the brain, causing inadequate perfusion of brain tissue. 
  • hemorrhagic stroke – cerebral blood vessel ruptures and bleeds into the brain tissue (intracerebral hemorrhage) or into the subarachnoid space surrounding the brain (subarachnoid hemorrhage)

Causes
80% of strokes are ischemic – caused by atherosclerosis inside an artery supplying the brain, which can result in occlusion to the flow of blood through it. Another cause of ischemic stroke is due to a blood clot travelling through the cerebral arteries which gets lodged inside a small artery and occludes the flow of blood through it. 

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15% of strokes are intracerebral hemorrhage – caused by a cerebral blood vessel ruptures and bleeds into the brain tissue. 

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 5% of strokes are subarachnoid hemorrhage – this condition shall be discussed separately at the end of the chapter

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Risk factors
Risk factors for ischemic stroke include hypertension, smoking and excessive alcohol consumption, diabetes, high cholesterol, obesity and sedimentary lifestyle.
Risk factors for hemorrhagic stroke include hypertension, smoking and excessive alcohol consumption, trauma and illicit drug use (amphetamines and cocaine).

Signs and Symptoms
The severity of symptoms depends on the extent of damage to the brain. Symptoms may include weakness to the facial muscles and limbs on one side of the body, or even paralysis to the facial muscles and limbs on one side of the body. There may be slurred speech, and difficulty finding the correct words. There may even be an inability to speak. There may be confusion and a decrease of level of consciousness. Extensive strokes can cause coma.

There may sometimes also be headache, nausea and vomiting and seizure, although these symptoms are more common for hemorrhagic than ischemic strokes.

Investigations
The blood glucose must be checked at the patient’s bedside, because hypoglycemia can cause symptoms similar to a stroke.

An accurate history and thorough physical examination is required. The neurological examination must include level of consciousness, limb strength, facial symmetry and pupil size and pupil reactivity.

Routine bloods must be taken, and electrocardiogram (ECG) performed.

Where feasible, a CT scan should be done to diagnose whether the cause is ischemic or hemorrhagic.

Treatment
The specific treatment depends on whether the cause is ischemic or hemorrhagic: 

  • if an ischemic stroke, then medications that thin the blood must be given, such as aspirin (which is an anti-platelet). More advanced treatment involves giving thrombolytic therapy intravenously.
  • if a hemorrhagic stroke, then surgery may be considered, however, this is not always feasible nor appropriate.

If the patient is unconscious then an open airway must be maintained, and oxygen administered as required.

Blood pressure is usually high during an acute stroke, and this must be managed carefully. Blood pressure should only be lowered if excessively high, and only very carefully. If the blood pressure is lowered too quickly then it may result in inadequate perfusion of brain tissue.

Blood glucose must be managed to ensure that it remains inside the correct range. Both hypoglycemia and hyperglycemia are damaging to the brain cells.

The patient must be observed for seizures, and treated appropriately if seizure occurs.

The patient should have their swallowing ability assessed, as stroke can cause impairment of the swallowing mechanism making it easy for the patient to aspirate food, drink and medications. Patients that cough aVer swallowing liquids may need thickened fluids, or may even need a nasogastric tube inserted.

If there is weakness or paralysis in a limb, then this limb should receive regular gentle exercises, otherwise the muscles in the affected limb will become hardened (contractures). It is important not to pull on the affected limb as this can easily cause dislocation. If the patient is unconscious, then they must be assisted with regular positional changes, so as to prevent pressure sores developing. A urinary catheter may be required if the patient has urinary retention.

Long term and daily medication may be required aVer a stroke, such as antihypertensives and statins. Daily aspirin may be required for ischemic stroke. It is important that diseases such as hypertension, diabetes and atrial fibrillation are well managed. Lifestyle modifications may also be required, such as cessation of smoking and eating a low fat diet. 

Subarachnoid Hemorrhage
As previously mentioned, 5% of strokes are from a blood vessel on the surface of the brain rupturing and bleeding into the subarachnoid space. Normally the only fluid in the subarachnoid space is cerebrospinal fluid (CSF). When bleeding occurs into the subarachnoid space, the pressure is greatly increased. 

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Causes – the most common cause of spontaneous subarachnoid hemorrhage is the rupture of an artery on the surface of the brain. Risk factors for subarachnoid hemorrhage include hypertension, smoking and excessive alcohol consumption, trauma and illicit drug use (amphetamines and cocaine).

Signs and symptoms – there is usually a sudden onset of severe headache, which is usually described as the worst headache ever experienced. The pain may radiate to neck or back. Less commonly, there may be a brief loss of consciousness, nausea and vomiting, photophobia and sometimes a seizure at the early stage of the headache. 

If the bleeding into the subarachnoid space continues, then this puts high pressure onto the brain, which can cause coma. If bleeding continues further, then death can occur. Subarachnoid hemorrhage has a high mortality rate.

Investigations – a CT scan of the head enables identification of blood in the subarachnoid space. After the CT scan, if the diagnosis is uncertain, then a lumbar puncture can be performed and the cerebrospinal fluid (CSF) examined for blood.

Treatment – surgery is the treatment for subarachnoid hemorrhage, however this is not always feasible nor appropriate. Actions should be taken to lower the risk of rebleeding, such as bedrest, administration of analgesia, and administration of stool softeners. Severe hypertension should be treated, whilst ensuring that the blood pressure is not decreased too drastically or quickly. Medication to prevent seizure may also be required.