What is the most likely diagnosis and recommended acute management for a patient presenting with right‑upper and lower‑limb weakness and leftward deviation of the mouth?

Acute Left Hemisphere Stroke (Left MCA Territory)

This patient has an acute ischemic stroke in the left middle cerebral artery (MCA) territory, and you must activate a stroke code immediately and transfer to the nearest stroke-capable emergency department within minutes. 1, 2, 3

Clinical Localization

The combination of right upper and lower limb weakness with leftward mouth deviation (indicating right facial droop) localizes to the left cerebral hemisphere, specifically the left MCA territory. 1, 2 This is the most common stroke presentation pattern because:

• Right-sided body weakness arises from injury to the left motor cortex or its descending corticospinal tract 2
• Right facial droop reflects a left-sided upper motor neuron lesion producing contralateral lower face weakness 2
• The motor and sensory pathways decussate in the brainstem, so left hemisphere damage produces right-sided deficits 2

Critical Distinguishing Features to Assess

You must immediately evaluate for aphasia (language dysfunction), which is the key distinguishing feature of left hemisphere stroke in right-handed individuals. 1 Also assess for:

• Right-sided sensory loss or paresthesias 1
• Left visual field deficits (left homonymous hemianopsia) 1
• The absence of crossed findings (ipsilateral face + contralateral body weakness) rules out brainstem stroke 2

Immediate Emergency Management (First 60 Minutes)

Time-Critical Actions

Record the exact time of symptom onset or last known normal immediately—this single piece of information determines all treatment eligibility. 2, 3 Every minute of delay results in loss of approximately 1.9 million neurons. 3

Activate EMS with prehospital notification to shorten door-to-CT time and improve treatment rates. 2 Transport directly to a designated stroke center with CT/MRI and capabilities for IV thrombolysis and mechanical thrombectomy. 2

Prehospital Management

• Provide supplemental oxygen only if oxygen saturation is <94% 2
• Do not treat elevated blood pressure in the field unless systolic BP <90 mmHg (hypotension) 2
• Hypertension should be left untreated until hospital arrival to maintain cerebral perfusion 2
• Obtain focused history: time of onset, current medications (especially anticoagulants), recent trauma, substance use 2

Emergency Department Imaging Protocol

Perform non-contrast head CT immediately on arrival to exclude intracranial hemorrhage before any antithrombotic therapy—this can be completed within 25 minutes of ED arrival. 2, 3 This is the minimum required imaging. 3

Complete CT angiography from aortic arch to vertex within 24 hours to identify large vessel occlusion amenable to thrombectomy. 1, 2 Do not delay tPA administration while waiting for CTA if the patient is within the treatment window. 3

Brain MRI with diffusion-weighted imaging (DWI) is the preferred test if available, as it detects acute infarction within minutes with higher sensitivity than CT. 1, 2

Baseline Laboratory Studies

Obtain without delay: 2

• Complete blood count
• Electrolytes, renal function, glucose
• Coagulation profile (PT/INR, aPTT)
• Cardiac troponin
• 12-lead ECG to detect atrial fibrillation or acute coronary syndrome 2

Time-Sensitive Treatment Decisions

Intravenous Thrombolysis (tPA)

Within 4.5 hours of symptom onset, administer IV alteplase (0.9 mg/kg, maximum 90 mg) if CT excludes hemorrhage and no contraindications exist. 4, 2, 3 The dose is:

• 10% as bolus over 1 minute
• Remaining 90% as continuous infusion over 60 minutes 4

Blood pressure must be maintained at <185/110 mmHg before tPA and <180/105 mmHg for 24 hours after tPA. 4 Use short-acting IV agents (labetalol if tachycardic, nicardipine if bradycardic or heart failure). 4

The risk of symptomatic intracerebral hemorrhage is approximately 6% in tPA-treated patients. 3

Delay all antiplatelet agents (aspirin, clopidogrel) until ≥24 hours after thrombolysis to reduce hemorrhagic transformation risk. 2, 3

Mechanical Thrombectomy

Within 24 hours of symptom onset, assess for endovascular thrombectomy when CTA shows proximal occlusion of the left internal carotid artery or left MCA. 1, 2, 3 Thrombectomy may be performed even when IV thrombolysis is contraindicated. 2

Transfer to a comprehensive stroke center immediately if endovascular capabilities are not available locally. 3

Blood Pressure Management Algorithm

Do not aggressively lower blood pressure unless: 4, 2, 3

• Systolic BP >220 mmHg or diastolic BP >120 mmHg (in non-tPA candidates)
• Systolic BP >185 mmHg or diastolic BP >110 mmHg (in tPA candidates)
• Concurrent cardiac ischemia, heart failure, or aortic dissection exists 4

Allow permissive hypertension to maintain perfusion of the ischemic penumbra. 2 In the penumbra, autoregulation is impaired and cerebral blood flow depends on systemic blood pressure. 4

Beyond the Thrombolysis Window

If presenting >4.5 hours but ≤48 hours, initiate dual antiplatelet therapy (aspirin 81 mg + clopidogrel 75 mg daily) for 21-30 days in patients with minor nondisabling stroke, followed by lifelong aspirin monotherapy, provided hemorrhage has been excluded and thrombolysis was not given. 2

Start aspirin within 24-48 hours if not receiving tPA, or after 24 hours if tPA was given. 3 In patients with dysphagia, aspirin may be delivered via enteral tube or rectal suppository (325 mg). 2

Critical Complication: Malignant Cerebral Edema

For extensive left MCA infarctions involving >50% of the MCA territory or >145 mL, monitor closely for life-threatening cerebral swelling within 24-96 hours. 2, 3

Prompt neurosurgical consultation for decompressive hemicraniectomy is recommended in patients <60 years with such large infarctions to improve survival. 2, 3 This is a life-saving intervention that must not be delayed.

Monitor continuously for signs of herniation: 2

• Deteriorating consciousness
• Pupillary changes
• Worsening neurological status

Post-Acute Management

Admit directly to a dedicated stroke unit or neuroscience intensive care unit after emergency department stabilization. 2 Initiate time-sensitive treatments in the ED to avoid prolonged stays that worsen outcomes. 2

Perform dysphagia screening before allowing any oral intake—use the Toronto Bedside Swallowing Screening test or water swallow test. 4 Patients with left hemisphere strokes are at high risk for aspiration. 4

Switch to anticoagulation if cardioembolic source (e.g., atrial fibrillation) is identified. 3

Begin comprehensive multidisciplinary rehabilitation assessment early, addressing motor deficits, aphasia, and activities of daily living. 2, 3 Structured rehabilitation benefits all stroke patients. 2

Common Pitfalls to Avoid

• Do not delay imaging while obtaining detailed history—parallel processing of history and imaging expedites care 2
• Do not administer aspirin or antiplatelet agents before CT has ruled out hemorrhage 2
• Do not dismiss the urgency based on symptom severity—treat with the same urgency as acute myocardial infarction 2, 3
• Do not aggressively lower blood pressure in acute ischemic stroke unless meeting specific criteria above 4, 2
• Do not delay tPA administration while waiting for CTA if the patient is within the treatment window 3