Anterior Cervical Decompression for Cervical Myelopathy Caused by Ossification of the Posterior Longitudinal Ligament

Abstract

As ossifi cation and hypertrophy of the posterior longitudinal ligament (OPLL) develop, the spinal cord is compressed from the anterior direction, resulting in myelopathy. Anterior decompression for OPLL, a rational operative choice, directly relieves the cervical spinal cord that has been invaded by OPLL and enlarges the narrowed spinal canal while at the same time restoring the spinal cord to its original place and shape. In fact, locally protruding OPLL, resembling a beak, and a highly narrowed canal with a canal narrowing ratio (CNR) of more than 60% do not always achieve the expected improvement after laminoplasty. Yamaura et al. initially reported the direct removal method of OPLL [1], but they modifi ed the procedure to anterior fl otation of the OPLL based on the rationale that this was what was necessary to obtain a suffi cient aperture in the vertebral canal [2]. The method minimizes surgical invasion and the risk of hemorrhage from the anterior internal vertebral vein plexus while avoiding too close an approach to the spinal cord with its risk of damage. It is also characteristic in that it lessens the risk of localized acute dural swelling and leakage of cerebrospinal fl uid (CSF). Long-term followup showed that the residual ossifi cation stopped growing after anterior fl otation. The purpose of this chapter is to demonstrate the anterior fl oating method and to report the excellent long-term results of the procedure. Anterior Floating Method