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Updated: Jul 20, 2026
Brain Infarct Segmentation and Registration on MRI or CT for Lesion-symptom Mapping
Published on: September 25, 2019
Is 15 mm size criterion for lacunar infarction still valid? A study on strictly subcortical middle cerebral artery
A-Hyun Cho1, Dong-Wha Kang, Sun U Kwon
1Department of Neurology, University of Ulsan College of Medicine, Asan Medical Center, Songpa-gu, Seoul, Korea.
Background And Purpose:
The 'lacunar hypothesis' has been challenged, since small (diameter <15 mm) subcortical infarcts can be produced by middle cerebral artery disease (MCAD) or cardioembolism (CE), while a larger infarct can occur without evidence of MCAD or CE. We sought to assess whether the lacunar hypothesis based on size is still valid.
Methods:
We studied 118 patients who were admitted within 72 h after stroke onset and had acute deep subcortical MCA territory infarcts detected by diffusion-weighted MRI, and who had undergone angiography (mostly MR angiography). Stroke mechanisms were arbitrarily categorized regardless of lesion size: (1) MCAD when there was a corresponding MCA lesion; (2) internal carotid artery disease (ICAD) when there was a significant (>50%) ipsilateral ICAD; (3) CE when there was emboligenic heart disease without MCAD or ICAD, and (4) small vessel disease (SVD) when there was neither CE nor MCAD. SVD was further divided into definite SVD (dSVD, longest diameter <15 mm) or probable SVD (pSVD, longest diameter > or =15 mm).
Results:
Seventy-three patients (62%) had SVD, of which 38 (32%) had pSVD and 35 (30%) dSVD. Thirty-three patients (28%) had MCAD, five (4%) CE, and seven (6%) ICAD. The infarct diameter in MCAD was not larger than in SVD (p = 0.35), and there was no difference in clinical features or risk factors between MCAD and SVD, or between pSVD and dSVD. CE was distinguished from SVD by its larger size and cortical symptoms.
Conclusions:
There are no clinical and lesion-size differences between MCAD and SVD, suggesting that there seems to be no rationale for the 15 mm size criterion for lacunar or small-vessel infarction.
Insights
The 15 mm size criterion for lacunar infarction is not valid. Middle cerebral artery disease (MCAD) and cardioembolism (CE) can cause small infarcts, while large infarcts can occur without these causes.
Area of Science:
- Neurology
- Neuroimaging
- Vascular Neurology
Background:
- The lacunar hypothesis suggests small infarcts (<15 mm) are caused by small vessel disease.
- This hypothesis is challenged as larger infarcts can occur without clear causes like middle cerebral artery disease (MCAD) or cardioembolism (CE).
Purpose of the Study:
- To evaluate the validity of the lacunar hypothesis based on infarct size.
- To compare infarct characteristics across different stroke mechanisms.
Main Methods:
- 118 patients with acute deep subcortical infarcts on MRI were studied.
- Stroke mechanisms categorized as MCAD, internal carotid artery disease (ICAD), cardioembolism (CE), or small vessel disease (SVD).
- SVD further classified into definite (<15 mm) or probable (>=15 mm) based on infarct diameter.
Main Results:
- Small vessel disease (SVD) accounted for 62% of infarcts.
- Middle cerebral artery disease (MCAD) infarcts were not significantly larger than SVD infarcts.
- Cardioembolism (CE) infarcts were larger and presented with cortical symptoms, distinguishing them from SVD.
Conclusions:
- No significant differences in clinical features or lesion size exist between MCAD and SVD.
- The 15 mm size criterion for differentiating lacunar or small-vessel infarction lacks a clear rationale.
- Stroke etiology, not just infarct size, is crucial for classification.
