Unilateral aberrant anatomy of the hypoglossal nerve.

Purpose: Neck dissection is often performed in patients with oral cancer to both treat and reduce the risk of subsequent neck metastases. Injury to the hypoglossal nerve may result in dysarthria, dysphagia, and profound difficulty with upper airway control. Although surgical landmarks facilitate intra-operative identification of vital structures to be preserved, they should not be an absolute measure, due to anatomical variants.