The Nuchal Lines as Anatomic Landmarks to Dissect the Muscles in the Far Lateral Approach.

BACKGROUND: A critical step in the far lateral approach (FLA) is exposure of the V3 segment of the vertebral artery, located deep in the suboccipital triangle (SOT). Safe exposure of the SOT is achieved by means of a plane-by-plane dissection, which carries the risk of devascularization. A suitable alternative is to lift a cutaneous muscle flap including the 3 first muscle planes and leave the deepest plane (SOT) attached to the skull base. To achieve this, it is necessary to have superficial anatomic landmarks to help identify the cleavage site. We describe the use of the nuchal lines as a safe, effective, and reproducible method to dissect the muscles to expose the SOT and vertebral artery.

METHODS: Eight adult cadaveric heads, fixed with formaldehyde and injected, were studied. On both sides, FLA was simulated by using the nuchal lines as anatomic landmarks to expose the SOT. This technique was later applied on 10 patients requiring FLA.

RESULTS: Anatomic dissections confirmed identification, by means of the nuchal lines, of a cleavage site, which made it possible to separate the deepest muscle plane from the rest of the flap. This technique was successfully applied in 10 patients undergoing FLA.

CONCLUSIONS: The nuchal lines allow dissection of muscles in 2 groups, one superficial and the other deep (SOT), which remains attached to the skull base. The V3 segment of the vertebral artery is easily exposed.