BACKGROUND: Transcranial Doppler (TCD) is widely accepted to monitor cerebral vasospasm after subarachnoid hemorrhage (SAH); however, its predictive value remains controversial. OBJECTIVE: To investigate the predictive reliability of an increase in the mean blood flow velocity (mBFV) ratio of the ipsilateral to contralateral middle cerebral arteries (I/C mBFV) compared with the conventional absolute flow velocity. METHODS: We retrospectively investigated the clinical and radiologic data of consecutive patients with SAH admitted from July 2003 to August 2009 who underwent TCD ultrasonography. The highest mBFV value in bilateral middle cerebral arteries was recorded, while delayed cerebral ischemia (DCI) was defined as neurological deficits or computed tomographic evidence of cerebral infarction caused by vasospasm. The ipsilateral side was defined as the side with higher mBFV value when evaluating the I/C mBFV. We thus elucidated the reliability of this rate in comparison with the conventional method for predicting DCI with receiver operating characteristic (ROC) analysis. RESULTS: One hundred and forty-two patients were retrospectively analyzed with specific data from 1262 TCD studies. The ROC curve showed that the overall predictive value for DCI had an area under the curve of 0.86 (95% confidence interval: 0.76-0.96) when the I/C mBFV was used vs 0.80 (0.71-0.88) when the absolute flow velocity was used. The threshold value that best discriminated between patients with and without DCI was I/C mBFV of 1.5. CONCLUSION: In patients with SAH, the I/C mBFV demonstrated a more significant correlation to vasospasm than the absolute mean flow velocity.
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