Moyamoya disease involving anterior and posterior circulation.

A 6-year-old female presented with sudden-onset right-sided hemiparesis with motor aphasia for the past 7 days. Magnetic resonance imaging of the brain [Figure 1a] revealed acute infarct in the left parietooccipital region. Magnetic resonance angiogram (MRA) [Figure 1b] and computed tomography angiogram (CTA) [Figure 2] showed narrowing of bilateral supraclinoid internal carotid arteries (ICAs), nonvisualization of bilateral middle cerebral arteries and distal part of posterior cerebral arteries (PCAs) along with extensive collateralization of vessels, creating a “puff of smoke” appearance, diagnostic of moyamoya disease.

Figure 1

Magnetic resonance imaging of the brain diffusion-weighted image (a) showed diffusion restriction in the left parietooccipital region, which was suggestive of acute infarct. Magnetic resonance angiogram of the intracranial vessels (b) revealed narrowing of bilateral supraclinoid internal carotid arteries, nonvisualization of bilateral middle cerebral arteries and distal part of posterior cerebral arteries along with extensive collateralization of vessels, creating a “puff of smoke” appearance

Figure 2

Computed tomography angiography of the brain revealed extensive collateralization of vessels involving the arteries of anterior and posterior circulation, creating a classical “puff of smoke” appearance, diagnostic of moyamoya disease

Moyamoya disease is characterized by progressive stenosis of the intracranial ICAs and their proximal branches. This results in the limited supply of blood flow in the major vessels of anterior circulation, which consecutively leads to the development of collateral circulation, by the small vessels. The posterior circulation involvement in moyamoya disease has not been well studied.[1] This process may rarely involve posterior circulation also, including the basilar cerebral arteries and PCAs.[2] The PCA if involved mainly affects the distal portion.[3] This is because of posterior circulation behaves as collateral pathway for maintenance of the circulation. The posterior circulation involvement is an adverse prognostic factor for outcome in moyamoya disease.[4] A study from India reported the absence of posterior circulation involvement in case series of 44 patients.[5] The ischemic episodes are rare in the posterior circulation territory till the late phase in moyamoya disease.[6] Development of extensive collateral vasculature results in the angiographic appearance of “puff of smoke” which is considered as a hallmark of the disease. The MRA and CTA images shown here depict the classical “puff of smoke” appearance and thus will serve as an excellent learning resource for medical graduates and postgraduates to understand the basic pathophysiology of the disease.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.