Vasospasm diagnosis: theoretical sensitivity of transcranial Doppler evaluated using 135 angiograms demonstrating vasospasm. Practical consequences.

The authors inspected 135 angiograms (A zero) demonstrating vasospasm (VS) after aneurysm (An) rupture. There were 54 anterior communicating artery (ACoA), 38 internal carotid artery (ICA) and 43 middle cerebral artery (MCA) ruptured aneurysms. VS was searched for on each A zero in distal branches of MCA (M2) proximal MCA (M1), ICA, anterior cerebral artery (A1) and pericallosal artery (A2). In each An group (ACoA - ICA - MCA) the theoretical sensitivity of transcranial doppler (TCD) was calculated postulating that when present (M1) or (M1 + ICA) or (M1 + ICA + A1) angiographic VS would be constantly and reliably recorded by TCD. If only M1 is insonated TCD sensitivity would be 54% after ACoA, 82% after ICA and 88% after MCA An rupture. If M1 and ICA are insonated TCD sensitivity would be 61% after ACoA, 95% after ICA and 88% after MCA An rupture. TCD sensitivity would be almost perfect with a reliable and constant A1 insonation but that hypothesis is today purely speculative. An additional A zero appears to be necessary to establish VS diagnosis, mainly after ACoA An rupture when a discrepancy is observed between normal TCD data and delayed clinical worsening.