The effect of internal carotid artery elongation on intracranial blood flow

Redundant length of the cervical part of the internal carotid artery (ICA) is a clear angiographic entity although the clinical significance is uncertain. Transcranial Doppler sonography (TCD) examinations were performed on 15 patients with 23 elongated ICAs. The recordings were obtained with the use of flat 2 MHz probe from the middle cerebral artery (MCA) and the intracranial part of ICA at rest and in eight possible extreme positions of head and neck rotation. The mean blood flow velocity in the intracranial part of the ICA obtained in the neutral position was 50.1 +/- 8.3 cm s-1 and after head and neck rotations was 49.8 +/- 9.5 cm s-1. The mean blood flow velocity in the MCA was 55.8 +/- 6.7 cm s-1 and did not change significantly after head and neck movements (54.9 +/- 7.6 cm s-1). Analysis of 368 one minute recordings from all possible head positions showed no significant changes of blood flow velocity. Rotation of the head and neck has no significant influence on intracranial blood flow velocity in the presence of carotid artery elongation.