Corticostriatal Hypermetabolism in Moyamoya Disease-Induced Hemichorea: Two Case Reports and a Literature Review

Abstract

Moyamoya disease (MMD) is a rare cause of chorea, and its pathophysiological mechanism remains unclear. We explore the use of cerebral positron emission tomography (PET) to study brain functional connectivity in 2 patients with MMD-induced hemichorea. Abnormal metabolism of brain was analyzed by 18F-fluorodeoxyglucose (18F-FDG) PET images. Dopamine transporters (DAT) PET evaluated the integrity of the cerebral dopamine system. A comprehensive systemic literature search of the PubMed database was also conducted. The 18F-FDG imaging of our patients showed no responsible hypometabolism in affected brain areas, while hypermetabolism in the affected caudate nucleus, putamen and fronto-parietal areas could be seen. DAT PET imaging was normal in patient 1 (a 23-year-old woman), while remarkably reduced DAT binding was seen in the left striatum of patient 2 (a 48-year-old woman). The literature review of 9 publications revealed that 11 patients who underwent single photon emission computed tomography (SPECT) showed cerebral hypoperfusion in the cortex and subcortical area; 18F-FDG PET was performed in 3 cases, which revealed hypermetabolism in the affected striatum in 2 cases. These findings suggest that the striatal and cortical hypermetabolism in the first patient result from underactivity in indirect pathway from basal ganglia-thalamocortical circuits, causing increased activity of excitatory glutamatergic thalamostriatal and thalamocortical projection neurons. The collateral vessels in the basal ganglia might lead to disruption of normal basal ganglia signaling. A dominant left hemisphere with corpus callosal connections to the right basal ganglia resulting into left hemichorea is the most probable explanation for the second patient. We have identified abnormal functional connectivity in basal ganglia-thalamocortical circuits in patients with MMD-induced chorea highlighting the corticostriatal pathway plays an important role in the pathogenesis of MMD-induced chorea.

Case report: Steroid-responsive acute chorea as first presentation of the coexistence of Moyamoya and Graves' disease

“…Its pathophysiological mechanism is still poorly understood; some have suggested that the choreoathetosis in MMD is a result of active ischemic changes affecting the excitatory–inhibitory circuits between the basal ganglia and the neocortex ( 6 ). A small literature review published in Frontiers in Neurology ( 16 ) revealed that hypermetabolism noticed in the pathway of basal ganglia-thalamocortical circuits using an 18F-FDG PET may explain the MMD-induced chorea, rather than the striatal hypoperfusion previously detected by SPECT ( 16 ).…”

The Impact of Revascularization in a Patient with Atypical Manifestations of Hypoperfusion

“…In this disease, there is reduced activation of the indirect pathway of the corticobasal ganglia—thalamocortical—loop leading to a hypermetabolic state of the striatum and cortex that eventually leads to increased activation of the excitatory neurons [ 5 ]. Cortical and subcortical hypoperfusion in frontoparietal and temporal occipital regions also may be causes of atypical manifestations of hypoperfusion [ 6 ].…”