Ischaemic Stroke Vs. Haemorrhagic Stroke

Overview

What is an ischemic stroke?

An ischaemic stroke occurs when an artery (a blood vessel that carries blood to your brain) becomes blocked by a blood clot. This results in your brain not receiving enough oxygenated blood, which is rich in nutrients needed for your brain tissues’ continued survival. Sadly, as a result, your brain cells will begin to die within a timeframe of minutes due to a lack of nutrients being received.¹ 

What is a haemorrhagic stroke?

A haemorrhagic stroke occurs when a weakened blood vessel, providing a blood supply for your brain tissues, ruptures, and this causes bleeding either into the brain tissue or in the areas surrounding your brain.^1,2 

Why is it important to know if a stroke is ischemic or haemorrhagic?

Ischaemic strokes are much more common than haemorrhagic strokes, with ischaemic strokes accounting for 87% of stroke cases, whilst haemorrhagic strokes account for only 13% of stroke cases. The treatment of ischaemic and haemorrhagic strokes also differs, which is why it is important that the correct stroke diagnosis is reached so that the correct treatment can be given. This ensures that the best outcome for the patient is attained.^2,3

Causes and pathophysiology

Ischaemic Stroke

Blockage of a blood vessel

An ischaemic stroke occurs when the arteries carrying oxygen-rich blood to your brain become blocked by a blood clot. The blood clot causes a reduction in the amount of oxygen-rich blood flowing to the brain, and sadly your brain cells start to die due to oxygen deprivation.⁴

Types of ischaemic strokes: thrombotic and embolic

An embolic ischaemic stroke occurs when a blood clot first forms elsewhere in your body rather than in your brain. The original clot can be cardiac (in the heart), arterial, aortic or possibly venous (where it may originate from the lower limbs or pelvis), to name a few. This blood clot then travels to your brain, restricting the amount of oxygen-rich blood reaching your brain, sadly resulting in an ischaemic stroke.⁵ 

Having atrial fibrillation, a condition where your heart beats irregularly and at a faster pace, can increase your risk of having an embolic ischaemic stroke. Approximately 15% of all embolic stroke cases occur in individuals with atrial fibrillation. In contrast, a thrombotic ischaemic stroke occurs when a blood clot develops within one of the arteries supplying oxygen-rich blood to your brain. This type of stroke is more prevalent in older adults, especially those who have atherosclerosis and diabetes.

Thrombotic ischaemic strokes can be preceded by one or multiple transient ischaemic attacks (TIAs), also known as mini-strokes. Mini strokes are a warning sign that a thrombotic ischaemic stroke may be imminent.

Mechanisms of Injury

Both thrombosis and embolisms can inflict injury by resulting in a blood clot that restricts oxygen-rich blood flow to the brain. However, what are the other mechanisms of injury? Are there any other mechanisms that can result in the obstruction of a blood vessel providing oxygen to the brain? The answer is yes, and some of these mechanisms are listed below:

• Arterial dissection: put simply, this is when there is a tear in the lining of an artery, causing a build-up of blood in the damaged artery, which can result in the formation of a blood clot
• Atherosclerosis: a build-up of fatty acids and cholesterol in your arterial walls, causing the artery to become more narrow. A smaller arterial lumen results in a restriction in the amount of oxygen-rich blood flowing to the brain
• Atrial fibrillation
• Small vessel disease: when damage has occurred to the small blood vessels that are within your brain, the blood vessels become narrower, which restricts the amount of oxygen-rich blood flowing to the brain

Haemorrhagic stroke

Rupture of a blood vessel

A haemorrhagic stroke occurs when a weakened blood vessel ruptures, resulting in bleeding into the brain, or in the tissues surrounding the brain.^1,2

Types of haemorrhagic strokes: intracerebral and subarachnoid

An intracerebral haemorrhage (ICH) occurs within the brain parenchymal (the functional part of your brain where your brain cells are located). ICH occurs when blood vessels within the brain rupture, causing blood to leak out of them, which in turn can cause increased pressure in the brain as the blood collects. ICH is the most common type of haemorrhagic stroke, accounting for approximately 66% of cases.⁶

In contrast, a subarachnoid haemorrhagic stroke occurs not within the functional part of your brain, but between the inner and outer layers of the tissues that cover the brain. Typically, this type of stroke occurs when a weak part of a blood vessel on the surface of your brain ruptures, causing blood to collect around your brain, and increasing the pressure on your brain.

Mechanisms of injury

The mechanisms of injury for haemorrhagic stroke include both intracerebral and subarachnoid mechanisms.

Clinical presentation

Ischaemic stroke

Symptoms

The symptoms experienced during a stroke can be alarming and frightening for the individual experiencing them, but it is important to act fast to support prompt initiation of treatment and improved long-term outcomes. The most common symptoms of an ischaemic stroke are listed below:

• Slurring your words
• Experiencing dizziness
• Having problems balancing
• Difficulty speaking or understanding others
• Drooping muscles on only one side of your face
• Loss of feeling or abnormal sensations on one side of your body
• Paralysis or weakness on one side of your body
• Loss of vision or double vision in either one or both eyes
• Feeling confused
• Vomiting
• Memory problems
• Feeling nauseous

Hemorrhagic stroke

Symptoms

Symptoms of a haemorrhagic stroke include the following:

• Feeling lethargic
• Seizures
• Sudden onset of an intense headache
• Having a stiff neck
• Feeling nauseous*
• Vomiting*
• Difficulty speaking or understanding others*
• Confusion*
• Experiencing double vision*
• Memory problems*
• Weakness or paralysis on one side of your face or body*
• Having a loss of feeling on one side of your body*

(Yale Medicine)

Symptoms marked with a * can be symptoms of both haemorrhagic and ischaemic strokes.

Time course for ischaemic and haemorrhagic strokes

Acute phase: the first 48 hours after a stroke are the most crucial, and individuals will benefit from access to high-quality care to improve their outcomes. During this phase, a brain scan is conducted to determine the cause and type of the stroke, the severity of the stroke, and which area of the brain it has occurred in.

If an ischaemic stroke is identified, your treatment plan may include thrombolysis. This is a treatment that aims to break down the blood clot, thereby restoring oxygen-rich blood flow to the brain. In addition, an assessment of your ability to swallow may be conducted within 4 hours of admission to assess the extent of the stroke and ensure patient safety during the stay.

Rehabilitation: this takes place over many months after a stroke, and can include occupational therapy, physiotherapy and speech and language therapy. This may be conducted in either a hospital environment or in a community setting.

Diagnostic of ischaemic and haemorrhagic strokes

The diagnosis of a stroke commonly includes the following:

• Blood pressure measurements
• Assessing your heart rate for an irregular heartbeat
• A blood test, which will allow your blood cholesterol and sugar levels to be quantified
• Brain scans: Computed tomography (CT) scan, which builds a 3D image of your brain. You may also have a special dye injected into a vein in your arm. This allows your blood vessels to be visualised to see if your stroke was caused by a narrowing of the arteries, a blood clot (ischaemic stroke) or a burst blood vessel Brain scans: Magnetic resonance imaging (MRI) scan: scan can allow visualisation of the area of your brain that has been affected by the stroke
• Carotid ultrasound: to see if there is any narrowing or blockages in the arteries leading to your brain, which may be present if you have had an ischaemic stroke

Management and treatment

Ischaemic stroke

Acute management

Thrombolysis

Thrombolytics are a type of medication used to treat intravascular (within blood vessels) blood clots by dissolving them. This treatment helps to restore blood flow to the area of the brain that had been deprived of oxygen-rich blood due to a blood clot (as is the case in ischaemic strokes), and helps to prevent ischaemic damage. The benefit of thrombolytics is most significant if the medication is given within 4.5 hours of stroke onset.⁷

Thrombectomy

Thrombectomy differs from thrombolysis as it does not use medication to dissolve the blood clot, but surgery to remove the blood clot from a blood vessel under image guidance. A catheter is inserted into an artery, and a small clot retrieval device is passed through the catheter and into the artery in the brain where the blood clot is located. The blood clot is then either removed via suction or using the small device. Like with thrombolysis, the aim of a thrombectomy is to restore oxygen-rich blood flow to the brain.⁸ 

Secondary prevention

Antiplatelet therapy

Antiplatelet therapy also forms part of the management plan in the case of an ischaemic stroke or TIA. Common antiplatelets include clopidogrel and ticagrelor.. The right antiplatelet medication, dose, and duration of treatment for you will depend on your medical history and current medications..

Anticoagulation

After an ischaemic stroke or a TIA, an individual may be offered anticoagulant medication to help reduce their risk of developing blood clots in the future. Anticoagulants work by interrupting the chain of events that occur to form a blood clot. Anticoagulation after a stroke can decrease your risk of having another ischaemic stroke in the future by 66%.⁹

Haemorrhagic stroke

Acute management

Control of bleeding

High blood pressure can lead to a haemorrhagic stroke and contribute to further bleeding. Therefore it is important to bring high blood pressure down to control the bleeding.² Blood pressure will be gradually lowered to a rate of 150/90 mmHg using the following medications:

• Beta blockers, e.g. labetalol
• Calcium channel blockers, e.g. nicardipine
• ACE inhibitors, e.g. enalapril

Surgical Interventions²

Craniotomy

A craniotomy involves removing part of the skull to relieve pressure on the brain from a haemorrhage. Access to the brain also allows the surgeon to repair any ruptured blood vessels.

Shunt surgery for excess fluid in the brain

A subarachnoid haemorrhagic stroke can lead to an accumulation of fluid in the tissues surrounding your brain. This accumulation of fluid can be dangerous and possibly result in vomiting and other stroke-related symptoms as a result of the increased pressure. In order to relieve the brain of this surrounding fluid, shunt surgery is used to drain the fluid away.

Secondary prevention

Blood pressure control

Blood pressure can be controlled after a haemorrhagic stroke using antihypertensive medication. If the individual has systolic blood pressure in the range of 150-220 mmHg, it has been demonstrated that it is safe to bring this blood pressure down to 140 mmHg using antihypertensives. Additionally, this reduction in blood pressure has also been shown to improve functional outcomes for the patient, as well as prevent another stroke.¹⁰

Please note that anticoagulants may not be used in the secondary prevention of a haemorrhagic stroke as this may aggravate this type of stroke.

Prognosis and complications

Ischaemic Stroke

Common complications after a stroke

Both ischaemic and haemorrhagic strokes carry a risk of complications, including those listed below:

• Clinical depression
• Seizures
• Urinary tract infections
• Pneumonia
• Edema
• Deep vein thrombosis
• Shoulder pain

Haemorrhagic strokes also carry the possibility of cerebral vasospasms after the stroke. This is when the blood vessels within the brain become narrow enough to restrict blood flow. Early detection of this complication is crucial in improving the outcomes for an individual, and ensuring that irreversible neurological deficits do not occur.¹¹

Prognostic Factors

Poor prognostic factors for a stroke include the following:

• Older age
• Being assigned male at birth
• Hypertension (high blood pressure)
• Having a history of stroke
• Diabetes
• Dyslipidemia (deranged blood cholesterol levels)
• The prolonged time elapsing between a stroke tando and neurorehabilitation^12,13

Summary

• An ischaemic stroke is more common than a haemorrhagic stroke
• An ischaemic stroke occurs when a blood clot limits blood flow to the brain, whereas a haemorrhagic stroke occurs when a blood vessel ruptures either in the brain or surrounding the brain, resulting in bleeding in the brain or around it
• Early detection of a stroke is crucial for improving patient outcomes
• A stroke can be identified via a brain scan, such as a CT or MRI scan
• Treatment for an ischaemic stroke involves thrombolysis and a thrombectomy, whereas a haemorrhagic stroke may require surgical intervention to relieve pressure around the brain
• Rehabilitation for both strokes involves physiotherapy, language and speech therapy and occupational therapy