Abstract TP438: De Novo Ivy Sign Indicates Postoperative Hyperperfusion in Moyamoya Disease

Abstract

Background and Purpose: The ivy sign on fluid-attenuated inversion recovery (FLAIR) magnetic resonance imaging (MRI) is a specific finding in moyamoya disease (MMD). This sign indicates decreased cerebral perfusion, dilated pial vasculature, and slow leptomeningeal collateral flow. This study aimed to clarify the characteristics of perioperative changes in the ivy sign in relation to cerebral hyperperfusion (HP), which frequently occurs in MMD of unknown etiology. Methods: This prospective study included patients with MMD who underwent superior temporal artery-middle cerebral artery single bypass. FLAIR MRI was performed to evaluate the appearance of the ivy sign in the ipsilateral hemisphere preoperatively and on postoperative days 2 and 30. The ivy sign was assessed in combination with perioperative symptoms and cerebral hemodynamics using single-photon emission computed tomography (SPECT). Results: Of 42 consecutive patients (55 sides) who underwent bypass surgery, 32 (58.2%) showed an increase in the ivy sign (de novo ivy sign) on postoperative day 2; this had disappeared by day 30. Interestingly, these 32 patients had a significantly higher incidence of HP on SPECT and HP syndrome, and there was no correlation between the de novo ivy sign and a preoperative ivy sign or the preoperative cerebral hemodynamics. In multivariate analysis, a de novo ivy sign was significantly correlated with postoperative HP. Conclusions: In MMD, a de novo ivy sign could indicate postoperative HP after bypass, which is not always correlated with preoperative hemodynamic impairment. Additional factors other than preoperative cerebral hemodynamics might be involved in postoperative HP in MMD.