This 64 year old man has presented with right sided hemiparesis of acute onset, in association with expressive aphasia. Given his age and history of hypertension, this should be considered a stroke until proven otherwise. However, it should also be noted that several other conditions can present similarly, e.g., hypoglycemia, cerebral infections, epilepsy (Todd’s paresis) and hemiplegic migraine.
The normal capillary blood sugar makes hypoglycemia unlikely. Cerebral infections are clinically less likely given the absence of meningeal signs, and lack of headache, photophobia or fever. Todd’s paresis and hemiplegic migraine are comparatively rare; and the absence of a history of migraines or seizures further lowers their likelihood. Therefore, stroke is indeed the probable diagnosis.
The next steps should be assessment of the current degree of neurological impairment and localization of the lesion. The National Institute of Health Stroke Scale (NIHSS) is a suitable tool for this p
urpose; in parallel, an urgent stroke protocol CT scan should be performed. The latter includes a non-contrast CT brain, as well as a perfusion CT and CT angiography.
He scores a total of 12 on the NIHSS, losing points for right upper limb weakness, sensory loss, hemianopia, right facial droop, right sided inattention and dysphasia. The right sided hemiparesis indicates a lesion of either the left brainstem, internal capsule or cortex. The presence of expressive aphasia (Broca's aphasia), hemianopia, and inattention further localizes this to a cortical lesion in the left middle cerebral artery (MCA) territory.
Stroke can be classified as either ischemic or hemorrhagic in nature; it is impossible to distinguish between these two types via clinical findings alone. Here, non-contrast CT films show the "hyperdense MCA sign," an early indicator of ischemic stroke involving the MCA.; they also show no evidence of hemorrhage. CT angiography confirms a M1 segment left MCA thrombus, while the perfusion CT reveals a large ischemic penumbra.
The American Heart Association/American Stroke Association (AHA/ASA) guidelines for the early management of patients with acute stroke (2018, updated 2019) recommend urgent thrombolytic therapy in all patients who present within 4.5 hours of onset of ischemic stroke, and who have no contraindications to thrombolysis. Furthermore, endovascular clot retrieval (ECR) should be considered in patients with a large vessel occlusion (i.e., occlusion of the internal carotid artery or proximal segments of the MCA) who present within 24 hours of onset of ischemic stroke.
While further neuroimaging with magnetic resonance imaging (MRI) will help demarcate the exact location of infarction, this need not be performed emergently; and thrombolytic therapy should not be delayed pending this. While it is also important to determine whether the stroke was due to thrombosis or embolism, this workup too can be delayed post-thrombolysis. Note also that coronary angiography is not indicated in his current workup.
Adjunct therapy with antiplatelet drugs is contraindicated in the first 24 hours following thrombolytic therapy. Furthermore, the recommended blood pressure during the same period is 180/105 mmHg or less; as his current blood pressure is only 160/90 mmHg, there is no need for immediate lowering. Doing so unnecessarily risks compromising cerebral perfusion.
Stroke is the leading cause of disability in the world, as well as the third leading cause of death in the United States.
Strokes are either ischemic or hemorrhagic in nature; the remainder of this monograph focuses on ischemic strokes alone. These are a result of cerebral infarction secondary to thromboembolism, vasculitis, or rarely, relative hypoperfusion (also known as watershed infarctions).
Men are at a greater risk for ischemic strokes than women, with this risk increasing with age. Other key risk factors include comorbidities such as hypertension, diabetes mellitus, and dyslipidemia; cardiac conditions such as atrial fibrillation, valvular heart disease, or ischemic heart disease with hypokinesia; carotid artery stenosis; previous transient ischemic attacks (TIAs); and the excessive use of alcohol and tobacco.
Ischemic strokes are further classified as those of either the anterior or posterior circulation. Anterior circulation strokes involve the middle and anterior cerebral arteries. Posterior circulation strokes involve the posterior cerebral, vertebrobasilar, or lacunar arteries. While both have characteristic features corresponding to the areas supplied, in practice, the clinical picture can be highly variable from patient to patient. A thorough history and examination is essential to accurately deduce the likely site of the lesion (but should not delay neuroimaging).
A standardized examination can be performed via the National Institutes of Health Stroke Scale (NIHSS). This enables a complete and quick neurological examination, quantifies the impairment, and helps to localize the site of infarction. However, clinical discretion must still be exercised; in particular, the NIHSS score is at a disadvantage in assessing posterior circulation stroke.
Neuroimaging is of utmost importance in the initial evaluation, and influences decision making; hence, it is recommended in all patients prior to specific treatment. Key points of information include the site, size, vascular distribution, and most importantly, presence of bleeding.
Non-contrast computed tomography (CT) is the most commonly used imaging modality. It is fast, widely available, and sensitive (particularly for detection of hemorrhage). Perfusion CT and CT angiography are now also of key importance in guiding acute stroke management. MRI scans are an alternative; however, these require more time to perform and may delay the initiation of treatment.
Routine laboratory tests should be performed to rule out conditions that may mimic stroke; these include a capillary blood sugar, full blood count, renal profile and coagulation profile. A 12 lead ECG is also a must, as the incidence of cardiac disease is higher in stroke patients. Note that aside from exclusion of hypoglycemia, the other tests should not delay thombolysis; and there is no need to await their results before administering thrombolysis to eligible patients.
Intravenous (IV) thrombolysis with recombinant tissue plasminogen activator (rtPA) or alteplase is recommended in eligible patients. There is emerging evidence to support the use of tenecteplase, which can be given as a bolus, as compared to alteplase. The relevant eligibility criteria can be read in the AHA/ASA guidelines. The decision to administer thrombolytics should never be taken lightly, as severe intracranial hemorrhage is a potential complication; angioedema is another adverse effect.
Arguably, the most significant advancement in acute stroke management in recent years is endovascular clot retrieval (ECR). Several landmark studies have shown this to result in significantly lower rates of disability and improved functional outcomes. Data support the use of ECR within 24 hours of symptom onset and suitable imaging criteria. The relevant eligibility criteria can be read in the AHA/ASA guidelines.
Antiplatelet therapy can be administered within 24 to 48 hours of onset, but are not a substitute for thrombolysis in eligible patients. Note also that adjunct therapy with antiplatelets or anticoagulants is contraindicated within the first 24 hours of thrombolysis, and should be preceded by a non-contrast CT brain at 24 hours to look for any intracranial bleeding post-thrombolysis.
An important and controversial aspect of treatment is the management of elevated blood pressure. This is a delicate situation, as both excessively high blood pressure and overly low blood pressure are associated with a poor outcome.
Over 60% of patients with acute stroke are found to have an elevated blood pressure (SBP >160 mmHg); this falls spontaneously without any medical intervention in the majority of cases. However, patients who have not undergone thrombolysis and have very high blood pressure (SBP >220 mmHg or DBP >120 mmHg) may have their blood pressure lowered by not more than 15% during the first 24 hours. Adhering to this target is especially important as rapid lowering may interfere with cerebral autoregulation and lead to neurological worsening. Patients who are eligible for thrombolysis (or other interventions to recanalize the vessel), can be treated to achieve a target SBP of <185 mmHg and a DBP of <110 mmHg. Antihypertensive medications can be restarted after 24 to 48 hours in diagnosed hypertensives.
Cardiac monitoring is recommended in the first 24 hours to detect and screen for serious conditions such as atrial fibrillation and other arrhythmias that may warrant emergency treatment.
General measures should not be forgotten. Unconscious patients may need airway support and caution should be taken to prevent aspiration in patients with bulbar dysfunction. Note that a preserved gag reflex does not indicate safe swallowing; a bedside water swallow test is a more useful guide. Hydration and nutrition should be optimized. Following thrombolysis, patients should be started on pneumatic compression to prevent deep vein thrombosis and pulmonary embolism. In patients who did not receive thrombolysis, prophylactic enoxaparin should be started as well.
Physiotherapy should be initiated as early as the time of diagnosis. A multidisciplinary team approach with active participation of the patient and caregiver improves the outcome. The benefits of a specialized stroke unit are invaluable, and are associated with a better long-term outcome.
Prevention of further ischemic strokes is achieved via lifestyle modification, medical management of risk factors, and continued pharmacological treatment with antithrombotic agents. Patients with risk factors for embolic disease (e.g., cardiac arrhythmias) may require long term anticoagulation.
The prognosis depends on the severity of the ischemic stroke, patient's age, other comorbidities, and presence of complications such as cerebral edema, hemorrhagic transformation, or seizures. In the United States, it is estimated that 20% of patients die within the first year following their first stroke.