CASE 18821 Published on 17.01.2025

Moyamoya disease with internal carotid artery hypoplasia

Section

Neuroradiology

Case Type

Clinical Case

Authors

Ankur Chandra, Salil Uppal, Shikhil Uppal, Ashok Uppal, Asharab K. Tadvi

Patient

39 years, male

Categories
Area of Interest CNS ; Imaging Technique Catheter arteriography, CT, CT-Angiography, MR
Clinical History

A 39-year-old male presented with sudden-onset left-sided weakness and mild slurring of speech lasting two days, accompanied by forgetfulness, particularly difficulty in retaining new information. Neurological examination showed left hemiparesis in the left upper and lower extremities, with intact cranial nerve functions.

Imaging Findings

MRI revealed acute watershed infarcts in the right centrum semiovale (Figures 1a, 1b, 1c and 1d). Sulcal hyperintensity in the right temporal region (ivy sign) was noted (Figure 1d).

CT demonstrated a hypoplastic carotid canal on the left (Figure 2).

CT angiography (CTA) showed left internal carotid artery hypoplasia and focal stenosis of bilateral supraclinoid internal carotid arteries (ICAs) (Figure 3). The left middle cerebral artery (MCA) was supplied via the posterior circulation, while the left anterior cerebral artery (ACA) was perfused through the anterior communicating (ACom) artery. The foetal origin of the left posterior cerebral artery (PCA) was identified.

Digital subtraction angiography (DSA) confirmed these findings, showing no “puff of smoke” appearance (Figures 4a and 4b) and indicating an absence of collateral formation.

Discussion

Background

Moyamoya disease (MMD) is a rare cerebrovascular disorder characterised by progressive stenosis and occlusion of arteries at the base of the brain, triggering the formation of abnormal collateral vessels. Unilateral internal carotid artery (ICA) hypoplasia is a congenital condition with underdeveloped ICA, altering cerebral haemodynamics. The coexistence of these conditions exacerbates ischemic risk through compromised cerebral perfusion and dynamic flow alterations [1].

Clinical Perspective

The patient presented with acute neurological symptoms, including weakness and cognitive impairment, indicative of ischemic stroke. Imaging was critical to differentiate this condition from other cerebrovascular disorders. The lack of typical MMD collaterals (“puff of smoke”) added complexity to the diagnostic process. Conveying the haemodynamic instability and risk of recurrent ischemia was essential for therapeutic planning [2].

Imaging Perspective

Key imaging findings included hypoplasia of the left ICA, focal stenosis of bilateral supraclinoid ICAs, and watershed infarcts. Diagnostic procedures like MRI and CTA highlighted the ischemic burden and vascular anomalies, while DSA confirmed the findings and ruled out secondary Moyamoya syndromes. The absence of developed collateral vessels further clarified the disease progression [3]. The “puff of smoke” appearance is absent in Moyamoya disease in its early stages, mild cases, or atypical variants. It may also be missed using non-invasive imaging modalities like MRI and MRA. Approximately 20–30% of cases, particularly secondary Moyamoya syndrome, may lack this finding, emphasising the need for thorough angiographic evaluation and clinical correlation.

Outcome

Management involved medical therapy with antiplatelet agents and neuroprotective drugs to minimise thromboembolic events and optimise cerebral perfusion. Surgical options like direct or indirect bypass were considered based on ischemic severity and individualised risk. Long-term prognosis depends on early intervention and consistent follow-up to monitor disease progression and prevent recurrent strokes [4].

Take Home Message / Teaching Points

  • The coexistence of Moyamoya disease and ICA hypoplasia demands meticulous diagnostic evaluation.
  • Imaging is indispensable in identifying vascular anomalies and ischemic risks.
  • Early intervention, including surgical revascularisation in selected cases, improves patient outcomes.

Written informed patient consent for publication has been obtained.

Differential Diagnosis List
Atherosclerotic ICA stenosis with secondary ischemic events
Primary Moyamoya syndrome with bilateral involvement
Moyamoya disease with ICA hypoplasia
ICA dissection causing ischemia
Vasculitis-induced stenosis of cerebral arteries
Final Diagnosis
Moyamoya disease with ICA hypoplasia
Case information
URL: https://www.eurorad.org/case/18821
DOI: 10.35100/eurorad/case.18821
ISSN: 1563-4086
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