What is the best course of action for a patient with a history of chronic lacunar infarctions in the bilateral lateral capsular ganglionic regions and right insular cortex, who presents with possible acute stroke but has no acute abnormality on CT scan, and also has nonspecific soft tissue opacification in the bilateral external auditory canals?

Management of Suspected Acute Stroke with Normal CT and Chronic Lacunar Infarctions

Immediate MRI Brain is Mandatory

You must obtain an MRI brain with diffusion-weighted imaging (DWI) immediately, as CT is highly insensitive for acute ischemic stroke—detecting only 16% of acute infarcts within 3 hours compared to 77% with DWI-MRI. 1, 2 The normal CT does not exclude acute stroke; it primarily rules out hemorrhage before potential thrombolytic therapy. 3, 1

Why MRI is Critical in This Case

• DWI-MRI has 88-100% sensitivity for acute ischemic stroke versus CT's poor early detection, making it the gold standard when stroke remains clinically suspected despite normal CT. 2, 4
• In TIA patients (symptoms resolved), DWI detected acute infarction in 32.5% of those with normal baseline CT, demonstrating CT's inadequacy for excluding acute ischemia. 4
• MRI should be obtained within 24 hours of symptom onset (or as soon as possible for delayed presentations) when acute stroke or TIA is suspected. 3
• A streamlined MRI protocol (DWI, FLAIR, gradient echo/SWI, MRA) can be completed in approximately 10 minutes, making it time-competitive with CT. 2

Vascular Imaging is Equally Essential

Obtain noninvasive intracranial and cervical vascular imaging (CTA or MRA) during the initial evaluation to identify large vessel occlusion and assess stroke mechanism. 3, 1

• This is a Class I recommendation if intra-arterial therapy or mechanical thrombectomy is being considered. 3, 1
• Vascular imaging should be performed to evaluate stroke mechanism and assess future stroke risk in all acute stroke patients. 3
• Given the history of chronic lacunar infarctions, identifying large vessel disease versus small vessel disease is critical, as management differs substantially. 5, 6

Address the Chronic Lacunar Infarctions

The bilateral lateral capsular ganglionic and right insular chronic lacunar infarcts require specific consideration:

• 23-36% of patients with lacunar-sized infarcts have large vessel atherosclerotic disease or cardiac sources as the actual mechanism, not pure small vessel disease. 5, 6
• Evaluate for carotid atherosclerotic disease with cervical vascular imaging (CTA or MRA), as 23% of lacunar infarct patients have atherosclerotic plaque as a possible embolic source. 6
• Perform cardiac evaluation (ECG at minimum, consider echocardiography) as 18% of lacunar infarct patients are at high risk for cardioembolism. 7, 6
• The presence of multiple chronic lacunar infarcts indicates increased risk for recurrent stroke, cognitive decline, and cardiovascular mortality. 8

Evaluate the External Auditory Canal Findings

The bilateral soft tissue opacification in the external auditory canals requires clinical correlation:

• Perform otoscopic examination to assess for cerumen impaction, otitis externa, or other local pathology.
• This finding is unrelated to the stroke evaluation but should not be ignored, as infection could theoretically contribute to systemic illness.

Algorithmic Approach

Step 1: Immediate Imaging (Do Not Delay)

• MRI brain without contrast (DWI, FLAIR, GRE/SWI sequences) 3, 1, 2
• MRA head and neck (or CTA if MRI unavailable/contraindicated) 3, 1

Step 2: Cardiac Assessment

• 12-lead ECG immediately 7
• Echocardiography (TTE initially) if cryptogenic stroke, young patient, or cardiac source suspected 7

Step 3: Risk Factor Modification

• Aggressive blood pressure control (target <130/80 mmHg for secondary prevention) given chronic lacunar disease 8
• Assess for diabetes, hyperlipidemia, and other modifiable vascular risk factors 8, 6

Step 4: Secondary Prevention Based on Mechanism

• If large vessel disease identified: consider carotid revascularization if appropriate stenosis present 3
• If cardioembolic source: anticoagulation may be indicated 7
• If pure small vessel disease: antiplatelet therapy and intensive risk factor modification 8

Critical Pitfalls to Avoid

• Never assume normal CT excludes acute stroke—this is the most dangerous error in stroke management. 1, 2, 4
• Do not attribute new symptoms solely to chronic lacunar disease without excluding acute pathology with MRI. 1
• Do not assume all lacunar infarcts are due to small vessel disease; 32-36% have alternative mechanisms requiring different treatment. 5, 6
• Do not delay MRI to obtain cardiac imaging first—brain imaging takes priority for acute stroke evaluation. 7