Transoral carotid ultrasonography.

Abstract

We attempted ultrasonographic evaluation of the distal extracranial internal carotid artery (ICA) using the transoral method (transoral carotid ultrasonography [TOCU]). The subjects consisted of five healthy volunteers and seven stroke patients. Examinations were performed with a color Doppler flow imaging system equipped with convex array transducers (7 or 9.5 MHz), originally designed for transrectal use. After local anesthesia of the pharynx, we inserted a probe covered with thin gum transorally, touching the tip to the pharyngeal posterolateral wall. We then attempted to detect the ICA and measure flow velocity of the distal extracranial ICA using principal images obtained by TOCU. TOCU was successfully performed in all subjects without any difficulty. In the healthy volunteers, the ICA was identified at a depth of 2.2+/-0.6 cm and visualized as a vertical linear vessel 2.9+/-0.3 cm in length and bent slightly backward. The diameter and mean flow velocity of the distal extracranial ICA were 4.7+/-0.2 mm and 50+/-7 cm/s, respectively. In the stroke patients, some remarkable findings were obtained, including a narrow ICA with low flow velocity in a patient with possible ICA dissection, a lucent echo without flow signal in a patient with acute cardioembolic ICA occlusion, and decreased ICA flow velocity in a patient with ipsilateral MCA stenosis. These preliminary data demonstrate the potential applicability of TOCU to the evaluation of flow in the far distal extracranial ICA. TOCU definitely warrants further investigation in patients with carotid artery disease.