Value of transcranial Doppler, perfusion-CT and neurological evaluation to forecast secondary ischemia after aneurysmal SAH.

INTRODUCTION: This study was conducted to prospectively evaluate the diagnostic value of detailed neurological evaluation, transcranial Doppler sonography (TCD) and Perfusion-CT (PCT) to predict delayed vasospasm (DV) and delayed cerebral infarction (DCI) within the following 3 days in patients with aneurysmal subarachnoid hemorrhage (SAH).

METHODS: A total of 61 patients with aneurysmal SAH were included in the study. All patients were amenable for neurological evaluation throughout the critical phase to develop secondary ischemia after SAH. The neurological status was assessed three times a day according to a detailed examination protocol. Mean flow velocities (MFV) in intracranial vessel trunks were measured daily by TCD. Native CT and PCT were routinely acquired at 3-day intervals and, in addition, whenever it was thought to be of diagnostic relevance. The predictive values of abnormal PCT and accelerations in TCD (MFV > 140 cm/s) to detect angiographic DV and DCI within the following 2 days were calculated and compared to the predictive value of delayed ischemic neurological deficits (DIND).

RESULTS: The accuracy of TCD and PCT to predict DV or DCI was 0.65 and 0.63, respectively. In comparison, DIND predicted DV or DCI with an accuracy of 0.96. Pathological PCT findings had a higher sensitivity (0.93) and negative predictive value (0.98) than TCD (0.81 and 0.96).

CONCLUSION: Neurological assessment at close intervals is the most accurate parameter to detect DV and DCI in the following 3 days. However, DIND may not be reversible. The routine acquisition of PCT in addition to daily TCD examinations seems reasonable, particularly in patients who are not amenable to a detailed neurological examination since it has a higher sensitivity and negative predictive value than TCD and leaves a lower number of undetected cases of vasospasm and infarction.