環椎外側塊単独骨折—1症例の報告

Isolated Fracture of the Lateral Mass of the Atlas: A case report

I．はじめに

　環椎骨折は頻度が少なく，頸椎骨折の2-13％，全脊椎骨折の1.3％とされている^12）．神経学的にも，他覚的所見に乏しく，非特異的な自覚症状のみであることが多い．診断についても，頸椎単純撮影のみでは困難な場合が少なくない．今回著者らは環椎骨折の中でも極めて稀な外側塊単独骨折の1例を経験し，その診断から治癒過程に到るまでをCTにて観察しえたので，CTの有用性を強調するとともに，本症例の紹介および若干の文献的考察を試みた．

Isolated fracture of the lateral mass of the atlas is ex-tremely rare. The authors report such a case because of its rarity and to emphasize the usefulness of computed tomography (CT) for its diagnosis.

The case was that of a 63-year-old male, who had been hit on his left parietal region by a board falling from behind, and which forced him to hyperflex his neck. He complained of neck pain on arrival at our hos-pital without any resulting neurological deficits. Routine plain cervical spine films were normal, but CT scan revealed a vertical fracture of the lateral mass of the atlas.