Abstract TP132: The Clinical Role of Microembolic Signals in Adult Moyamoya Disease

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Background: Both hemodynamic compromise and artery-to-artery embolism have been thought to be implicated in moyamoya disease (MMD) with ischemic symptoms. The relationship between microembolic signals (MESs) and ischemic stroke remains to be clarified. We aimed to identify associated risk factors of MESs and to explore clinical significance of MESs in adult MMD with ischemic stroke.

Methods: A total of 48 patients (89 hemispheres) newly diagnosed with adult MMD were enrolled and angiographically classified according to the Suzuki staging system. For detection of MESs, transcranial doppler (TCD) monitoring was performed within 2 days after first admission. Recent ischemic events, including transient ischemic attack (TIA), which occurred within 3 months of diagnosis, were also recorded. Mean flow velocities in middle cerebral artery using TCD were also evaluated.

Results: Eleven hemispheres were found to have MESs, and 78 had no MESs. Among clinical types of MMD in 89 hemispheres, ischemic-type MMD (n = 42, 47%) was most common. Antiplatelet agents were prescribed for 22 patients (43 hemispheres) before evaluation for MES. The incidence of recent ischemic event was associated with the MES status (P = 0.024). Recent ischemic event was found to be predictive of MESs in adult MMD (hazard ratio: 6.294; 95% CI 1.345-29.46). Detection of MESs was significantly higher in the high mean flow velocity of the middle cerebral artery (P = 0.019). After controlling for age, sex, recent ischemic event, and antiplatelets, ‘early stage’ MMD (Suzuki stage I and II) was the independent predictor of MESs at baseline (hazard ratio: 6.172; 95% CI 1.235-31.25).

Conclusions: MESs, known to be indicative of artery-to-artery embolism in steno-occlusive cerebrovascular diseases, were observed in ‘early stage’ MMD, particularly with high MFVs and clinically associated with recent ischemic stroke. This necessitates the need for the efficacy of antiplatelets in the treatment of adult MMD with ischemic stroke in a prospective controlled study in the future.

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