Effect of Percutaneous Inferior Sympathetic Ganglion Block on Medium-Sized Intracranial Artery Diameters on Cerebral Angiography

Background: Some data suggest a vasodilatory effect of sympathetic blockade in patients with aneurysmal subarachnoid hemorrhage, but the effect on medium-sized intracranial arteries remains unclear. We report the results of serial cerebral angiography to study the cerebral vasodilatory effects of percutaneous inferior sympathetic ganglion block in 2 patients. Methods: Serial ipsilateral intracranial angiograms were obtained before and after percutaneous inferior sympathetic ganglion block and were imported to a DICOM reader, Horos Open-Source Medical Image Viewer (version 3.3.6). The percent change of arterial diameter was calculated in the intracranial internal carotid artery (ICA), middle carotid artery (MCA), and anterior cerebral artery (ACA). We assessed the interobserver reliability using the Bland-Altman method. Results: In Patient 1, there was an average increase in diameter of intracranial ICA and MCA at 1 minute, 5 minutes, and 10 minutes, with a relative decrease in the diameter of the ACA. In Patient 2, there was an average relative increase in diameter of intracranial ICA and MCA at 1 minute, 5 minutes, 10 minutes, 20 minutes, and 30 minutes, with a relative increase in diameter at 5 minutes, 10 minutes, and 30 minutes in the ACA. The Bland-Altman coefficient of variation was −5.35 (range −0.44 to 0.28) with all the data points within the 98% upper and lower limits of acceptance. Conclusions: We observed vasodilation in medium-sized intracranial arteries ipsilateral to the percutaneous inferior sympathetic ganglion block as early as 1 minute post treatment and persisting for at least until 30 minutes post blockade.