What is the next step in management for a patient with symptoms concerning for acute ischemic stroke, who has a normal cranial computed tomography (CT) scan and is experiencing drowsiness, with a history of hypertension (high blood pressure)?

Management of Acute Ischemic Stroke with Normal CT and Drowsiness

When a patient with suspected acute ischemic stroke presents with drowsiness and a normal cranial CT scan, proceed immediately with MRI including diffusion-weighted imaging (DWI) to detect acute ischemia that CT cannot visualize, while simultaneously addressing the drowsiness through airway assessment, oxygen saturation monitoring, and evaluation for common stroke-related causes of altered consciousness. 1

Why the CT Scan May Be Normal

• Early ischemic stroke is frequently invisible on non-contrast CT (NCCT), particularly within the first few hours after symptom onset 1, 2
• NCCT is primarily performed to exclude hemorrhage before thrombolytic therapy, not to confirm ischemia 3
• DWI-MRI is significantly more sensitive than CT for detecting acute ischemic stroke, especially in the hyperacute phase 1, 4
• In one study, 58% of patients with non-diagnostic CT scans showed recent brain ischemia on DWI, including 52% of those with completely normal CT 4

Why the Patient Is Drowsy

Primary Stroke-Related Causes

Decreased consciousness in acute stroke indicates either:

• Brain stem involvement affecting the reticular activating system 3
• Large hemispheric infarction causing mass effect or bilateral involvement 3
• Hypoxia, which occurs in 63% of hemiparetic stroke patients within 48 hours, and in 100% of those with cardiac or pulmonary disease history 3

Critical Immediate Assessment Required

Evaluate the following systematically:

• Airway patency and protective reflexes - patients with decreased consciousness are at high risk for airway compromise due to impaired oropharyngeal mobility 3
• Oxygen saturation - hypoxia is extremely common and may be caused by partial airway obstruction, hypoventilation, aspiration, atelectasis, or pneumonia 3
• Respiratory pattern - Cheyne-Stokes respirations (central periodic breathing) frequently complicates stroke and causes oxygen desaturation 3
• Blood pressure - both extremes can worsen outcomes, but permissive hypertension is generally recommended unless SBP >220 mmHg or DBP >120 mmHg 5, 6

Immediate Next Steps

1. Advanced Neuroimaging

Obtain MRI with DWI immediately if the patient remains symptomatic and stroke is still suspected despite normal CT 3, 1

• DWI can detect acute ischemia in patients with "puzzling clinical presentations" where CT is negative 1
• This is particularly important when clinical localization is uncertain 1
• Do not delay this imaging - it directly impacts treatment decisions 2

2. Vascular Imaging

Perform noninvasive intracranial vascular imaging (CTA or MRA) to identify large vessel occlusion 3

• This is Class I recommendation if intra-arterial therapy or mechanical thrombectomy is being considered 3
• Should be obtained when knowledge of intracranial steno-occlusive disease will alter management 3
• Can be done immediately following CT without delaying IV tPA if indicated 3

3. Airway and Oxygenation Management

Address hypoxia aggressively:

• Position the patient appropriately: if hypoxic or with significant pulmonary comorbidities, avoid supine position as it lowers oxygen saturation 3
• In nonhypoxic patients, supine position may offer cerebral perfusion advantages 3
• Provide supplemental oxygen to maintain adequate saturation 3
• Consider intubation if airway protective reflexes are compromised 7

4. Neurological Monitoring

Use a standardized stroke severity scale (NIHSS preferred) to quantify deficit and track changes 1

• Formal scoring identifies patients at higher risk for complications including intracerebral hemorrhage 1
• Allows objective measurement of changing clinical status 1
• Facilitates communication between providers 1

Critical Pitfalls to Avoid

Do not assume stroke is ruled out by normal CT - this is a dangerous misconception that can delay appropriate treatment 4

Do not attribute drowsiness solely to "post-ictal state" or other causes without excluding ongoing ischemia, particularly posterior circulation stroke which is notoriously difficult to detect on CT 3

Do not aggressively lower blood pressure unless it exceeds 220/120 mmHg (or 185/110 mmHg if thrombolysis is planned) - permissive hypertension is protective in acute ischemic stroke 5, 6, 8

Do not delay MRI to pursue other diagnostic studies if stroke remains in the differential diagnosis 1

Special Considerations for Drowsy Patients

• Drowsiness with hypertension history suggests possible large vessel occlusion or posterior circulation involvement requiring urgent vascular imaging 3
• Reassess airway, breathing, and circulation constantly - these can deteriorate rapidly in patients with decreased consciousness 3
• Consider glucose level - hypoglycemia can mimic stroke and cause altered consciousness 5
• Monitor for seizure activity - post-ictal states can confound the clinical picture 9