Paradoxical Association of Symptomatic Local Vasogenic Edema with Global Cerebral Hypoperfusion after Direct Revascularization Surgery for Adult Moyamoya Disease

Background: Superficial temporal artery–middle cerebral artery (STA–MCA) anastomosis is the standard treatment for Moyamoya disease (MMD). Cerebral hyperperfusion syndrome is a potential complication of this procedure and can cause local vasogenic edema and/or delayed intracerebral hemorrhage. Cerebral hypoperfusion is a contradictory postoperative pathophysiological condition implicated in MMD, but its association with symptomatic local vasogenic edema has not been reported. Case Report: A 31-year-old woman with MMD underwent left STA–MCA anastomosis 3 months after a minor completed stroke in bilateral hemispheres. Eight hours after the operation, the patient developed neurological deterioration of dysarthria and mono-paresis in her right hand. Magnetic resonance (MR) angiography showed apparently patent STA–MCA bypass, whereas MR imaging of fluid-attenuated inversion recovery demonstrated a local high–signal-intensity lesion at the vascular territory supplied by the bypass. The apparent diffusion coefficient value was significantly increased in this lesion, suggesting local vasogenic edema formation. N-isopropyl-p-[¹²³I] iodoamphetamine single-photon emission computed tomography revealed global hypoperfusion in the left hemisphere. The administration of a free-radical scavenger and antiepileptic agent gradually relieved her symptoms, and MR imaging 1 month after surgery confirmed the complete disappearance of local vasogenic edema. Conclusions: Vasogenic edema may be associated not only with cerebral hyperperfusion but also with hypoperfusion after STA–MCA anastomosis for MMD. Although the exact mechanism of this rare association is unknown, the intrinsic vulnerability of intracranial vascular wall structures and the increased vascular permeability in MMD may partly explain the paradoxical association of hypoperfusion and local vasogenic edema.