胸髄前方病変に対する胸椎後方進入前方除圧法の経験—その利点，適応，安全な術操作，支持性の獲得について

Anterior Decompression of the Thoracic Spine through the Posterior Approach:Its usefulness, indications, technique, and the preservation of postoperative spinal stability

I．はじめに

　胸椎脊椎管前方病変に対する後方進入前方除圧法^3,6）は，胸椎後方より進入することにより，従来の前方進入法にはない利点を有する．一方，本法は術中に脊髄を圧迫する危険性，あるいは術後の脊柱不安定性の出現などといった問題をかかえており，その適応は熟慮されるべきである．われわれは胸椎脊椎管前方病変によりmyelopathyをきたした3症例に対し本法を行い良好な結果を得た．本稿ではこの3症例の経験をもとに，安全な術中操作，術後の脊椎安定性の問題および本法の適応について検討した．

Three patients with thoracic myelopathy were oper-ated on using a modified surgical approach, anterior de-compression of the thoracic cord through the posterior approach. The usefulness of and indication for this approach were discussed.

Operative technique is as follows. In the prone posi-tion, laminae are removed widely enough to include the medial half of the facets and pedicles. This creates cavi-ties lateral to the dural sac as deep as the diameter of the spinal canal. Through these cavities the anterior wall of the spinal canal and the posterior portion of the intervertebral disc are drilled out to make a space into which lesions are pulled away from the dural sac. The lesions can be removed under direct vision with mini-mum retraction to the dural sac. Our technique pre-serves the integrity of the spinous prosesses and supra/ inter spinal ligaments, which do not restrict access to the cord and have the potential to be one of the sup-ports of the spine. Postoperative course was uneventful in all of the patients.

This approach has several advantages. It can be ap-plied to any levels of the thoracic spine and can be used for decompression all around the thoracic cord. The procedure is minimumly invasive. The indications for this operation are considered to be 1) lesions at the level of T3, 2) anterior lesions associated with OYL at the same or adjacent level, 3) multilevel lesions which need staged operations, 4) laterally protruded discs and 5) lesions in elderly or high risk patients.