Assessment of the CO2 response by means of non diffusible contrast media and angio-CT in patients with cluster headache

We analyzed the possibility of assessing functional vasomotor changes by means of Arm-Brain Circulation Time (rABCT) and Vascular volume images (Vv) obtained with Angio-CT, in basal condition and following CO2 inhalation, in a sample of 48 patients with cluster headache. CO2 inhalation resulted in the appearance of local changes, which were detected in 28 regions. Analysis by indicator images of Vv-dependent rABCT distribution showed two main patterns: abnormal rABCT mostly evident at the smallest Vv pixels and abnormal rABCT dependent on abnormal Vv distribution. The former pattern was linked to abnormality at the circle of Willis; the latter to abnormal local vasomotor responses. Patients with cluster headache showed both patterns, which prompted us to conclude for the presence of low-degree stenosis in carotid arteries and vasomotor instability in peripheral brain vessels.