Selection of the approach to the distal internal carotid artery from the second cervical vertebra to the base of the skull.

Although several approaches for exposure of distal internal carotid artery lesions have been reported, the precise anatomic levels for which each of these maneuvers are most appropriate have not been well described. Since these techniques may require preoperative preparation, it is useful to determine in advance how much exposure will be needed and to select the most suitable and effective technique. We used anatomic dissection in 12 human cadaver specimens (24 carotid bifurcations) to define the limits of distal internal carotid artery exposure by several commonly advocated methods. The standard anterior approach along the sternocleidomastoid muscle allowed exposure of the internal carotid artery to the level of the upper one third of the second cervical vertebra. The upper limit of this exposure was extended to the middle of the first cervical vertebra by division of the posterior belly of the digastric muscle. Anterior subluxation of the mandible increased the distal exposure of the internal carotid artery to the superior border of the first cervical vertebra. Styloidectomy in combination with the preceding maneuvers extended the exposure an additional 0.5 cm cephalad. Lateral mandibulotomy did not significantly extend exposure beyond that obtained with mandibular subluxation and styloidectomy. Exposure of the internal carotid artery in the 1 cm immediately below the base of the skull required a posterior approach with mastoidectomy.