Dubai Healthcare City Update



Management of stroke

There are limited treatment options for stroke. Numan Amir, MD outlines the latest stroke management practices in an acute care setting.

Harvard Medical School Dubai Center (HMSDC) Institute for Postgraduate Education and Research recently held a national continuing medical education (CME) Practi-med 2- day course on critical care.

The meeting aimed to inform specialists engaged in critical and emergency patient care on the latest information on diagnosis and treatment of the most common issues seen in emergency and critical care settings. It consisted of sessions comprising sepsis, sedation, trauma, mechanical ventilation, management of strokes in neurological intensive care units and implementation of quality in the intensive care unit (ICU). This article will focus on the management of stroke in the acute care setting.

Acute stroke

Stroke is the clinical term for acute loss of perfusion to vascular territory of the brain, resulting in ischemia and a corresponding loss of neurologic function. It is a complex disorder with distinct subtypes, whose identification is important in order to tailor appropriate treatments according to specific pathophysiological mechanisms.

Stroke is the second leading cause of death and number one cause of chronic disability. Its incidence is expected to increase 25% by 2050. Chronic disability caused by stroke is a major economic burden on healthcare systems with limited current treatment options and poor general awareness of stroke.

Hemorrhagic strokes account for about 20% of all strokes, yet are responsible for more than 30% of all stroke deaths. A hemorrhagic stroke occurs when a blood vessel in the brain breaks leaking blood into the brain. Ischemic stroke, on the other hand, occurs when arteries are blocked by blood clots or by the gradual build-up of plaque and other fatty deposits. Clots are caused by emboli which travel to the brain from the heart. Approximately 80% of strokes are ischemic. The differential diagnosis of hemorrhagic versus ischemic stroke has critical implications for stroke management. The treatment of ischemic stroke involves the use of fibrinolytic and antithrombotic agents, which are contraindicated in hemorrhagic stroke. Diagnostic tests such as CT or MRI are required (see stroke perfusion report page 59) to confidently discriminate between the stroke subtypes.

Among those who survive stroke, only 25% recover completely, and many of the remaining survivors need rehabilitation because of resulting impairments. The severity of stroke and the brain territory it affects determines the type and severity of residual disabilities, which may include speech difficulties, loss of sensory function, bilateral loss of motor control, or hemiparesis.

Acute hemorrhagic stroke

Cerebrovascular damage to small arteries due to chronic hypertension is recognised as the most significant cause of primary spontaneous intracranial hemorrhage (SICH). The main locations of SICH are: putamen, subcortical cerebral lobe, thalamus, cerebellum, brainstem, and caudate nucleus. Almost half of ICH patients die without recovery and more than half of the survivors are permanently disabled.

The general symptoms for ICH include headache, vomiting and a decreased level of consciousness. The focal symptoms, as determined by CT or MRI, depend on location and size of the hematoma. Expansion of hematoma can lead to worsening of symptoms, which can occur anytime from the first 30 minutes up to 24 hours after an initial episode. The treatment of ICH requires limiting the hematoma expansion, controlling associated hypertension, limiting rebleeding from any underlying structural vascular abnormality, and managing any complications that develop around the hematoma.

Limiting hematoma expansion


Hematoma expansion is common early after acute ICH. The ideal hemostatic agent for use in ICH patients would be one that inhibits fibrinolysis and activates coagulation locally, allowing fast and effective hemostasis without causing systemic thromboembolic adverse events. Patients on oral warfarin who present with acute ICH are typically reversed with fresh frozen plasma or prothrombin complex concentrate and vitamin K immediately in an attempt to avoid progressive bleeding. Unfortunately, the effectiveness of this approach is often hampered by the large volumes administered. An alternative to conventional factor replacement for reversing warfarin anticoagulation is Recombinant activated factor VII (rFVIIa; NovoSeven; Novo Nordisk; Bagsvaerd, Denmark) administration.

A phase III trial, Factor Seven for Acute Hemorrhagic Stroke (FAST) study, in 841 patients, to confirm a previous study where rFVIIa reduced growth of the hematoma and improved survival and functional outcomes demonstrated that treatment with rFVIIa, within 4 hours after the onset of stroke, results in significant reduction in growth in volume of the hemorrhage. However, at 72 hours, the percent increase in total lesion volume was similar among the patient groups. Therefore, despite the reduction in bleeding, there was no significant difference among the three groups in the proportion of patients with poor clinical outcomes.

Associated hypertension


Management of arterial hypertension in the period immediately after stroke remains controversial. Severely hypertensive patients probably benefit from modest blood pressure (BP) reductions, but aggressive BP reduction may worsen outcome. In the absence of specific guidelines from randomised controlled trials, the general consensus is to treat hypertension if diastolic BP is >120mmHg or mean arterial BP (MAP) is >125-135 mmHg. Many effective agents exist for the treatment of hypertensive crises such as labetalol, captopril, clonidine and urapidil. Vasodilators e.g. sodium nitroprusside should be avoided due to concerns of increasing intracranial pressure with these drugs.

Underlying abnormality


In patients with ruptured aneurysms, surgical intervention is the method of treatment and includes placing a clip across the aneurysm or embolization if the damaged area is difficult to approach. Patients with ICH may benefit from a surgical evacuation of the hematoma. Surgical intervention is contraindicated in patients who are 75 years old or older, who have significant preexisting disease, or who arrive at the hospital in very poor condition.

Acute ischemic stroke


The initial causes of ischemic stroke can be thrombosis, embolism, or hypoperfusion. Arterial stenosis precipitated by turbulent blood flow, atherosclerosis, and platelet adherence cause blood clots to form, leading to an ischemic stroke. Small vessel disease within the brain causes a further 20% of ischemic strokes.

The fundamental goal of stroke therapy is to restore normal blood flow as soon as possible to improve survival and reduce disability. Intravenous administration of recombinant tissue plasminogen activator (rtPA) is currently the only FDA-approved therapy for treatment of patients with acute ischemic stroke presenting within 3 hours of onset. tPA is a serine protease that converts the zymogen plasminogen to its active form, plasmin, another serine protease that degrades the fibrin network in a clot. It is indicated for a clinical diagnosis of ischemic stroke causing a measurable neurological deficit with a time of symptom onset of less than 3 hours.

After rtPA (0.9 mg/kg) treatment, the patient must be admitted for hemodynamic and neurologic monitoring in order to optimise the stroke patient's outcome. These practices include treatment of conditions that would exacerbate newly infarcted brain tissue such as hypoxia, dehydration, hypertension, hyperglycemia, hyperthermia, poor nutrition and interventions to prevent secondary complications. Other medical complications that have been associated with stroke, include urinary tract infection, pneumonia and sepsis.

In conclusion, type and cause of stroke must be determined in order to provide suitable treatment. Treating conditions that would exacerbate infracted brain tissue or affect outcomes is essential after initial treatment. Careful monitoring and management of stroke patients in a stroke or intensive care unit improves probability of favorable outcomes.

● Numan Amir, MD, is a Senior Consultant, Neurology Division at Sheikh Khalifa Medical City, Abu Dhabi.



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ate of upload: 25th January 2009

                                  
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