Ischemic Stroke-

Inadequate blood supply to a part of the brain

KNOW THE SIGNS, PREVENT DEATH AND DISABILITY

Key points: let us reiterate this again and again

Do not ignore symptoms of stroke no matter how minimal or how quickly resolved it was.

Most people will have a second attack which may be devastating.

Stroke is defined as rapidly developing clinical signs of focal or global disturbance of cerebral function, lasting more than 24 hours, or leading to death. There should be no other apparent cause other than a vascular origin. Thus, stroke includes cerebral Ischemia, cerebral Haemorrhage (ICH) and Subarachnoid Haemorrhage (SAH). A stroke is a sudden onset of neurological deficit which could be weakness of an arm, a leg, speech problems, confusion and even acute anxiety in an elderly patient. It could present with difficulty with walking and falls. Stroke could last for only a few minutes and this is sometimes called a transient ischaemic attack (TIA) or it could become persistent and lasting for more than 24 hours.

The interruption of the blood supply to a part of the brain leads to cell damage and if no early reparation, that part of the brain ultimately dies. Loss of cerebral tissue in this way is called infarction. The disruption of critical blood flow to parts of the brain can occur due to vascular occlusion from a thrombus, an embolus, from pathological damage to the vessel wall or via pressure on the vessel.

SYMPTOMS OF STROKE

1. Difficulty Walking
2. Weakness of an arm or a leg
3. Difficulty with speech
4. Sudden loss of vision

SIGNS OF STROKE

1. Any of the above confirmed clinically
2. Loss of conciousness (use GCS to evaluate)
3. Seizures

Brain Attack

"Brain attack!" is a term used to describe the acute presentation of stroke, which emphasises the need for urgent action. The concept of "brain attack" is very important to sensitize physicians and the public to the need for rapid mobilization and treatment of stroke patients.

This approach of treating stroke as an emergency requires educational programs directed at the general public, general practitioners, and primary and emergency department physicians, to teach the recognition of stroke symptoms and the importance of treating stroke with the same urgency as for myocardial infarction (MI) (Fieschi & Falcou, 2001).

"Time is brain"

The longer the delay before active and effective therapy the more brain tissue is lost by the patient. Most basic studies show that to be effective, acute intervention to reperfuse the ischaemic brain must take place within a few hours. Damaged brain and the surrounding at risk brain need to be protected as soon as possible. Doctors have a duty to evaluate a stroke patient rapidly, investigate astutely and prescribe effective medication within 1-3 hours of the event or within the first hour of arrival in hospital.

What causes delays?

• Patients failing to recognize the symptoms of stroke
• Hospital delays for clinical evaluation and investigations.

Modern stroke therapy requires patients to correctly identify stroke symptoms and seek immediate hospital admission. US studies showed that only 57% of the population knew at least one stroke symptom. Knowledge among German populations was also poor with significant information deficits about stroke especially among the elderly people. (Weltermann et al., 2000). If patients reach the hospital in time, the reaction of the staff is then most important.

Early treatment is a critical determinant of successful intervention in acute stroke. There is convincing evidence supporting intravenous thrombolysis using recombinant tissue plasminogen activator in selected patients within 3 hours of stroke onset. Intravenous tissue plasminogen activator improves outcome after ischemic stroke but must be given that early. However, only a small proportion of acute stroke patients are currently eligible for thrombolysis, mainly because of excessive delay to hospital presentation. Only 33% of suspected-stroke patients arrive in Accident & Emergency departments in the UK or in France within 3 hours of onset.

What about stroke in Africa and Asia? How much do people know about the need for immediate medical review of symptoms of transient ischemic attack (TIA)?

Stroke is the third leading cause of death in most industrialised countries, among adults aged 65 years or more. The current incidence of stroke in Europe and the USA is about 200 per 100,000 population per annum. In Portugal, however, it is the leading cause of death. Epidemiological studies indicate that the risk of first ever stroke is strongly related to age. People of African Caribbean descent have higher mortality rates from stroke than other ethnic groups. Eighty percent of strokes are ischaemic and 20% are due to hemorrhage. Intracerebral hemorrhages comprise approximately 10 to 15% of all strokes and subarachnoid haemorrhage the remainder. More women than men are now having strokes?

Hypertension and diabetes are the key risk factors of ischaemic stroke. Alcohol consumption, smoking, hyperlipaemia have also been implicated in the aetiology of stroke.

"Acute strokes are here to stay"

This could be the sad conclusion after decades of stroke research. After the decline in stroke incidence observed by 1970, partly related to better management of vascular risk factors, there has again been an increase in stroke frequency all around the world. Stroke places a huge burden on society in terms of premature death, disability, and costs of care. Having a stroke constitutes a major life event.

Presentation of ischemic stroke

Retinal arteriolar emboli can be found in approximately 1% of adults more than 40 years of age. The frequency of retinal emboli increases with age and are more common in men than in women.

Approximately half the patients with ischaemic stroke have carotid artery stenosis and about one third (10% all stroke victims) have had no warning symptoms such as transient ischaemic attacks

Diagnosis of stroke: Rely heavily on the symptoms. Have a low threshold and work to rule out stroke immediately

Stroke should be medically diagnosed and confirmed radiologically. The history and clinical examination should give sufficient clues to heighten suspicion that the patient is suffering or has suffered a stroke. Stroke can be radiologically confirmed using a wide variety of techniques such as CT, CTA, MRI and MRA. The commonest initial investigation is the CT scan. CT shows the site of the stroke and lead to appreciation of the vessel likely involved. The cerebral vessels supply distinct areas of the brain. This can be complimented by a CT angiography or a CT perfusion scan.

CT Perfusion scan

The purpose of a recent study was to determine the prognostic accuracy of perfusion computed tomography (CT), performed at the time of emergency room admission, in acute stroke patients. Accuracy was determined by comparison of perfusion CT with delayed magnetic resonance (MR) and by monitoring the evolution of each patient's clinical condition. It was concluded that perfusion CT allows the accurate prediction of the final infarct size and the evaluation of clinical prognosis for acute stroke patients at the time of emergency evaluation. It may also provide information about the extent of the penumbra and could therefore be a valuable tool in the early management of acute stroke patients.

MRA

New techniques in MR imaging, particularly diffusion weighted imaging, are transforming the approach to diagnosis of acute stroke. Magnetic resonance angiography (MRA) is a technique for imaging blood vessels that contain flowing blood.

It can be performed on most magnetic resonance scanners installed in hospitals today, and represents an alternative to conventional angiographic techniques using X-rays (digital subtraction angiography (DSA)), or more recent imaging developments, including ultrasound.

Sensitivity and specificity of MRA in detecting high-grade stenosis (> or = 70%) and occlusion of the extracranial internal carotid artery were 97.7 and 94.0%. Therapeutic relevant misinterpretations were mostly based on overestimating the stenoses. The applied Contrast Enhanced-MRA technique with a 1.0 T system is suitable for the assessment of carotid artery stenoses.

Doppler ultrasound

Duplex sonography is an effective tool for evaluating internal carotid artery (ICA) stenosis, and power Doppler imaging has improved its value in this regard. Doppler grading of internal carotid artery (ICA) stenosis using the two parameters of spectral analysis and internal carotid to common carotid artery peak systolic velocity (ICA/CCA PSV) ratio is well established. In particular, PSV greater than 200 cm/s was the most reliable predictor of ICA stenosis greater than 70%.

The improvements in B-Mode ultrasound image quality now make direct ultrasound NASCET-style stenosis measurement possible. The use of good quality B-Mode NASCET style stenosis measurement as the initial ultrasound measurement, with Doppler ultrasound only being performed when the B-mode stenosis measurement is greater than 35% or if the B-mode image is unsatisfactory. This approach would save considerable time enabling better utilization of ultrasound resources. In one series, both duplex-derived PSV as well as MRA provided high sensitivity to detect surgically relevant ICA stenosis. However, to select patients for surgery inclusion of EDV proved to be important due to a high PPV and may spare conventional angiography half of patients with stenosis exceeding 70 %.

Digital subtraction angiography DSA

DSA can also be utilised to confirm occlusion or obstruction of a cerebral vessel. It is however not without risk. Stroke rate following DSA amounted to 2.1 %. DSA can be replaced by less invasive diagnostic modalities such as duplex scanning (DS) and magnetic resonance angiography (MRA) for the detection of angiographically defined internal carotid artery (ICA) stenosis >/= 70 %.

Treatment of stroke

Acute stroke treatment aims to preserve the ischaemic penumbra, protect neurons against further ischaemia and enhance brain plasticity to maximize recovery. Rational treatment requires individual causes of stroke to be identified early and treatment targeted at the mechanism.

There is a strong evidence base supporting the routine use of aspirin within 48 hours, but not heparin, in acute ischaemic stroke. Although neuroprotective drugs have proved disappointing, active neuroprotection in acute stroke should include control of blood pressure within certain limits, antipyretic therapy, maintenance of blood glucose, and early feeding and fluid replacement. Manipulation of blood pressure (BP) in acute stroke may improve outcome.

There is good evidence that the best way to enhance recovery from stroke is to admit the patient to a stroke unit. To enable patients to benefit from the early active approach outlined in the article, the following are needed: the development of acute stroke units; imaging protocols; and education of patients, general practitioners and the ambulance services.

There is also now considerable evidence that careful monitoring and management of general and cerebral functions in a dedicated stroke unit or by a specialized stroke team are superior to management in a neurologic or general ward. Stroke care has become a specialised field, requiring input from stroke physicians, as well as the multidisciplinary rehabilitation team.

Thrombolysis

Early treatment is a critical determinant of successful intervention in acute stroke. There is convincing evidence supporting intravenous thrombolysis using recombinant tissue plasminogen activator in selected patients within 3 hours of stroke onset. Intravenous tissue plasminogen activator improves outcome after ischemic stroke but must be given that early. However, only a small proportion of acute stroke patients are currently eligible for thrombolysis, mainly because of excessive delay to hospital presentation. Surprisingly, as only 33% of suspected-stroke patients arrive in Accident & Emergency departments in the UK or in France within 3 hours of onset. Surgical hemicraniectomy should be considered in patients with malignant cerebral oedema.

Intravenous tissue-type plasminogen activator (tPA) therapy using the National Institute of Neurological Disorders and Stroke criteria has been given with variable safety to less than 5% of the patients who have ischemic strokes. According to the National Institute of Neurological Disorders and Stroke protocol, 0.9 mg/kg of intravenous tissue-type plasminogen activator was administered to suitable patients. Safety and efficacy concerns toward thrombolysis for ischemic stroke prevail among many neurologists because of the risks of hemorrhage and the small proportion of suitable patients.

A prospective study confirmed that thrombolytic therapy can be performed safely and efficaciously in daily clinical routine. More than a minority of acute stroke patients might be eligible for intravenous thrombolysis. Intravenous tPA therapy can be given to up to 15% of the patients with acute ischemic stroke with a low risk of symptomatic intracerebral hemorrhage. Successful experience with intravenous tPA therapy depends on the experience and organization of the treating team and adherence to published guidelines. The performance of a stroke team can be improved over time, subsequently increasing the proportion of eligible patients and thereby the efficiency of the method.

Whether acute stroke patients with major early infarct signs on CT should be treated with intravenous thrombolysis remains controversial. Given the poor prognosis of patients with hemispheric stroke and early CT changes, alternative treatment modalities such as intra-arterial thrombolysis, early hemicraniectomy, and neuroprotective therapy should be vigorously pursued.

Carotid endarterectomy

The European Carotid Surgery Trial (ECST) and North American Symptomatic Carotid Endarterectomy Trial (NASCET) have effectively shown that carotid endarterectomy (CEA) can prevent strokes in symptomatic patients.

Carotid Stenting

The safety and efficacy of carotid endarterectomy (CEA) has been compared with carotid angioplasty and stenting. CEA remains the standard of care and superior to similar data regarding stents. Nevertheless, carotid stenting for extracranial carotid stenosis has demonstrated procedural results approaching those reported with endarterectomy, but with limited cost and long-term data. In contrast, the role of Percutaneous transluminal angioplasty (PTA) and stenting for treatment of symptomatic and asymptomatic atherosclerotic stenosis of carotid bifurcation is still debated.

PTA and stenting seems to be, at present, the treatment of choice for early restenosis after endarterectomy and for atherosclerotic stenoses of supra-aortic trunks near or at the ostium.

Data for 136 endarterectomies and 136 carotid stent procedures at a tertiary-care community hospital were obtained in one study. These nonrandomized groups were similar, but the endarterectomy group had more symptomatic patients (42% versus 31%; P=0.0004), and the stent group had more NASCET-excluded patients (68% versus 35%; P<0.0001). The conclusions were that outcomes with carotid stenting were similar to those with endarterectomy but were achieved in patients with significantly more comorbidities.

Cost and resource utilization with stenting were substantially less than those with endarterectomy. At 2 years, carotid stenting appeared not only durable but also effective in stroke prevention.

Let us see some images related to ischaemic strokes

Essays and important papers

Must read Essays

If you have any information about this in your local area or how the concept has been put across to the public and physicians, please write a short essay and e-mail it to us

Must read Essays

• "Brain attack": The rational for treating stroke as a medical emergency. Neurosurgery, 1994, vol.34, 1, 144-158
• Weltermann BM, Rogalewski A et al. Knowledge about stroke among the German population. Deutsche Medizinische Wochenschrift. 125(14): 416-420, 2000 (Abstract)
• Fieschi C, Falcou A. Keynote address. Neurology. 57(5 suppl 2): S82-86, 2001