Elevated Flow Velocity in Transcranial Doppler: Discrepancies Between Actual Vasospasm Locations and Flow...

Area of Science:

• Neurology
• Medical Imaging
• Vascular Surgery

Background:

• Transcranial Doppler (TCD) is a key tool for detecting cerebral vasospasm post-subarachnoid hemorrhage.
• Current TCD interpretation relies on Mean Flow Velocity (MFV) but its accuracy in pinpointing specific arteries is debated.
• The influence of adjacent arterial vasospasm on MFV readings requires further investigation.

Purpose of the Study:

• To investigate the correlation between elevated MFV and the precise location of vasospasm.
• To assess how vasospasm in adjacent arteries affects MFV readings in specific cerebral vessels.
• To evaluate the reliability of TCD in identifying specific arteries affected by vasospasm.

Main Methods:

• Retrospective observational study of subarachnoid hemorrhage patients undergoing TCD and angiography (March 2017 - December 2020).
• MFV measurements in the middle cerebral artery (MCA), anterior cerebral artery (ACA), and intracranial internal carotid artery (ICA) were analyzed.
• Statistical analysis included Kruskal-Wallis test and logistic regression to compare MFV distributions and assess associations with vasospasm.

Main Results:

• Vasospasm was identified in 16% of 367 hemispheres, with 8% involving multiple arteries.
• MFV elevations were observed in both affected and adjacent arteries (P<0.001).
• ACA vasospasm correlated significantly with MCA MFV (OR, 1.040; P<0.001), not ACA MFV (P=0.142).

Conclusions:

• MFV elevations in TCD may reflect a generalized cerebral arterial response to vasospasm, not solely localized to the affected artery.
• The findings challenge the assumption of artery-specific MFV interpretation for vasospasm detection.
• Clinical interpretation of TCD should consider potential MFV changes in adjacent vessels and a broader indication of vasospasm.