Discussion
Moyamoya disease is a progressive cerebrovascular disorder which is
characterized by stenosis of internal carotid arteries and its
territories, which eventually lead to recurrent stroke episodes (8). In
children, ischemic events are more common compared to adults, where
adults are more prone to hemorrhagic manifestation (2). Ischemic and
hemorrhagic strokes exhibit distinct lesion patterns, with ischemic
strokes predominantly affecting the insula, putamen, operculum, and
superior temporal cortex. In contrast, hemorrhagic strokes tend to
involve more posterior and medial areas (10). Patients typically exhibit
neurological deficits, with severity correlating to the extent of brain
damage (11). Toh et al. (2023) revealed the prevalence of cognitive
impairment in 54.4% of adult patients, including 31.55% with executive
dysfunction. However, cognitive impairment had no association with
stroke history, age or education level (9). In this case, a 20-year-old
patient presented with headache, weakness of upper and lower left limbs,
slurring of speech and facial deviation.
The exact etiopathogenesis of MMD is still uncertain. However,
Diffusion-weighted MRI studies have revealed white matter alterations in
watershed regions of children with MMD, even without overt stroke or
silent infarction, suggesting ongoing injury due to chronic
hypoperfusion (12). In adults, cognitive impairment, particularly in
intelligence and arithmetic functions, is associated with white matter
changes in specific brain regions, such as the uncinate fasciculus and
inferior frontal-occipital fasciculus (13). There is a complex genetic
association underlying MMD. Genetic variants in genes like ALPK1 and
THBS2 have been linked to susceptibility for both coronary artery
disease and ischemic stroke, which may share genetic architecture with
MMD (14).
Neuroimaging plays a crucial role in diagnosing and assessing. MRI
studies reveal white matter alterations in children with MMD,
particularly in watershed regions, even without overt stroke or silent
infarction (12). Computational fluid dynamics simulations based on
phase-contrast MRI data show significant hemodynamic changes in MMD
patients, including higher pressure drop differences between internal
carotid arteries and increased flow in posterior communicating arteries
(15). CT angiography (CTA) findings in MMD reveal significant vascular
changes. In MMD patients, the basilar artery tends to move towards the
midline and upward, with enlarged posterior circulation vessels compared
to healthy controls. The disease progression is characterized by a
longitudinal shift of collateral channels from anterior to posterior
components, potentially increasing the risk of hemorrhagic stroke in
adults (16,17). In our case, MRI angiography and venography were sent
and suggested of frontal, parietal, temporal lobe, basal ganglia and
internal capsule acute/ subacute infarct, mainly proper middle cerebral
artery territory with mass effect. To confirm further, a CT Angiogram
was sent and suggested a narrowing of the bilateral internal carotid
artery (left> suitable) through its course with collateral
vessels around a clinoid segment of the bilateral internal carotid
artery and bilateral middle cerebral artery territory- features
suggestive of MMD.
Treatment modalities for MMD vary depending on the type and patient’s
age. For adult hemorrhagic MMD, bypass surgery significantly reduces
stroke recurrence compared to medical treatment. However, bypass surgery
for adult ischemic MMD shows no significant benefit over medical
treatment (18). Antiplatelets have shown effective results in
controlling the recurrence of infarcts in the cerebral artery,
highlighting the complex role of antiplatelet treatments in
cerebrovascular treatment. This case highlights the importance of
considering MMD in young patients presenting with stroke-like symptoms,
the critical role of imaging in diagnosis, and the potential for
recovery with appropriate treatment.