Investigations for Lacunar Strokes
All patients with suspected lacunar stroke require immediate brain imaging (preferably MRI with DWI), vascular imaging of intracranial and cervical arteries, ECG, and echocardiography to exclude alternative causes, as approximately 27% of clinically-diagnosed lacunar strokes have etiologies other than small vessel disease that require different management. 1, 2
Essential Imaging Studies
Brain Imaging (First Priority)
MRI with diffusion-weighted imaging (DWI) is the imaging modality of choice for lacunar stroke evaluation, as it is significantly more sensitive than CT for detecting small deep infarcts (77% vs 16% sensitivity in first 3 hours) 3, 4, 5. Core MRI sequences should include:
- DWI - most sensitive for acute lacunar infarcts
- FLAIR - assesses white matter disease burden
- T1 and T2-weighted sequences - evaluates chronic changes
- Susceptibility-weighted imaging (SWI) or gradient echo (GRE) - detects microbleeds and chronic hemorrhage 5
If MRI is contraindicated or unavailable, non-contrast CT is acceptable but substantially less sensitive for small vessel disease 3, 6. CT should include coronal reformations to better assess deep structures 5.
Vascular Imaging (Mandatory)
Vascular imaging of both intracranial and extracranial arteries must be performed to exclude large artery atherosclerosis and identify alternative stroke mechanisms 3, 1. Options include:
- CTA (CT angiography) - covering head and neck vessels
- MRA (MR angiography) - particularly useful for arteriopathies 4
- Carotid duplex ultrasound - can complement other modalities 7
This is critical because potential sources of cardioembolism and ipsilateral large-artery stenosis must be excluded before confirming a diagnosis of lacunar stroke 8, 9.
Cardiac Evaluation
ECG and Rhythm Monitoring
- 12-lead ECG immediately upon presentation to assess for atrial fibrillation, prior MI, and left ventricular hypertrophy 3
- Prolonged cardiac monitoring up to 30 days if initial ECG is negative but cardioembolic mechanism is suspected 3
Echocardiography
Echocardiography (transthoracic and/or transesophageal) should be performed when cardiac sources are suspected 3, 10. This is particularly important because:
- Cardiac embolic sources are found in a significant proportion of clinically-diagnosed lacunar strokes 2, 11
- Any cardiac source of embolism significantly increases stroke recurrence risk (5-year recurrence rate) 11
- TEE can detect aortic atheroma and other embolic sources not visible on TTE 11
Laboratory Testing
Essential blood work includes 5:
- Complete blood count (CBC)
- Lipid panel
- Hemoglobin A1c (HbA1c)
- Thyroid-stimulating hormone (TSH)
- Vitamin B12
- Electrolytes, creatinine, calcium
- Alanine transaminase (ALT)
Critical Clinical Considerations
Why Extensive Workup Matters
The rationale for comprehensive investigation is compelling: 27.6% of patients with clinical lacunar syndromes have causes other than small vessel disease 2. These patients with alternative etiologies (L-nonSVD) have:
- Significantly worse outcomes (OR 2.87 for death/disability) 2
- Five-fold higher stroke recurrence risk (OR 5.03) 2
- Annual recurrence rate of 20.4% vs 11.3% for true small vessel disease 2
Diagnostic Accuracy Pitfalls
Clinical diagnosis alone is unreliable:
- The positive predictive value of lacunar syndrome is only 65.1% overall 12
- Pure motor syndrome has slightly better accuracy at 75% 12
- Sensorimotor syndromes are particularly inaccurate 12
DWI is mandatory for accurate diagnosis - clinical assessment alone will misclassify a substantial proportion of patients 12.
Assessment of Small Vessel Disease Burden
Beyond acute diagnosis, imaging should assess overall SVD burden using validated scales:
- Fazekas scale for white matter hyperintensities 5
- Document presence and number of lacunes, microbleeds, and perivascular spaces
- Higher SVD burden predicts worse outcomes and may influence secondary prevention strategies 13
Timing Considerations
- Brain imaging must occur within 30 minutes of hospital arrival 10, 6
- Vascular imaging should be performed during initial evaluation, not delayed 3, 7
- Cardiac workup can be completed after acute treatment decisions but should not be deferred indefinitely 3
This comprehensive approach ensures that treatable alternative causes (large artery disease, cardioembolic sources, arteriopathies) are not missed, as these require fundamentally different secondary prevention strategies than true small vessel disease.