[Original Short Communication] Eighty-four cases of the crowned dens syndrome

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[要旨]頚椎環軸関節偽痛風Crowned Dens Syndrome（CDS）は，頚椎環軸関節の靭帯等にピロリン酸カルシウム結晶（CPPD）が沈着し何らかの誘因で炎症を生じる急性疾患で偽痛風の一型といわれている。1985年Bouvetらが初めて報告した後，稀な疾患と考えられてきた。近年多くの研究が報告されてきているが，未だ全体像は明らかではなく，症例の蓄積が必要である。CDSの84例を経験したので病態を検討し，本疾患の知見を蓄積することが本研究の目的である。2014年1 月より，2019年6 月までの5 年6 か月間に神崎クリニックで経験した84症例を後ろ向き的に検討した。84症例中，偽痛風又はCDSで入院歴のある15症例を，重症例と仮定し抽出して比較をした。CT画像で横靭帯に薄い沈着が認められるものをタイプA，横靭帯に濃い沈着が認められるものをタイプB，横靭帯及び歯状突起を濃く取り巻いて沈着が認められるものをタイプCと3 群に分類して病歴・炎症所見・頚椎・腰椎及び膝のレントゲン所見を比較検討した。CT上，CPPDの沈着を認めても，鑑別診断上他の疾患は除外をした。タイプAは33例，初診時年齢45～96歳，平均年齢74.5歳，タイプBは18例， 63～93歳平均80.2歳，タイプCは33例，61～91歳平均83.8歳であった。男女比は1 : 1.8であった。40歳代50歳代はタイプAのみで，高齢者はタイプB・Cが多かった。レントゲン上脊椎は全例で高度な変形を生じていた。しかし，膝関節では，全例にCPPD沈着を認めていても，変形性変化が高度なグループと，軽度なグループがあることが分かった。入院歴のある15例でも膝関節レントゲンで変形が軽度な例を認めた。また，本検討以後の症例だが，40歳男性でCPPDが治療後消失した例を経験した。治療には，非ステロイド性抗炎症薬とプレドニゾロンの併用が最も効果的であった。臨床症状，男女比，治療は従来の報告とほぼ同一であった。結論として，CDSは若年者でも発症し，治療によりCPPDの自然吸収がありうるが，その後経時的にA・B・Cの順で蓄積が進行して行く事が考えられた。レントゲン所見上，脊椎は高度な変形性変化を呈するが，膝においては変形が軽度なグループがあることが分かった。診療に際しては適切な生活指導が必要である。

[ABSTRACT]Crowned Dens Syndrome (CDS) is an acute inflammatory disease which is caused by deposition of calcium pyrophosphate dehydrate (CPPD) crystal around the odontoid process, being considered to be a type of pseudogout. After the first report by Bouvet et al. in 1985, it had been thought to be a rare disease. Although many cases have been reported recently, the exact etiology is not yet elucidated. Eighty-four cases experienced from January, 2014 through June, 2019 were retrospectively evaluated. Of the 84, 15 were hospitalized cases of CDS or pseudogout. We classified the deposition pattern into three types based on the computed tomographic findings. Type A: thin deposition in the transverse ligament. Type B: thick deposition in the transverse ligament. Type C: circumferential deposition around the odontoid process. Among the three types, clinical and radiographic findings (the cervical spine, lumbar spine, and the knee joints) were compared. There were 33 cases of Type A (mean age: 74.5 years, range 45 to 96 years); 18 of Type B (mean age: 80.2 years, range 63 to 93 years); and 33 of Type C (mean age: 83.8 years, range 61 to 91 years). Male and female ratio was 1 : 1.8. The cases of the 5th and 6th decade were all classified into type A. Types B and C were generally seen in elder subjects. The radiographs of the cervical spine and the lumbar spine showed high-grade degenerative changes, though those of the knee joints showed both high-grade (76％) and lowgrade osteoarthritic changes (24％) in spite of CPPD deposition in all cases. Of 15 hospitalized cases, there were 5 of Type A (mean age: 81.2 years), 2 of Type B (mean age: 89.0 years), and 8 of Type C (mean age: 81.4 years). Male and female ratio was 1 : 6.5. The findings were almost the same as those of hole cases. Although not included in this series, we have seen a 40 year-old man whose CPPD deposition was spontaneously absorbed. For the treatment, combined administration of nonsteroidal anti-inflammatory drugs and prednisolone seemed to be most effective. The current study may have some limitations due to the retrospective nature. However, we believe some informative data were presented for CDS. CDS was considered to be started in young generation and the CPPD deposition could be absorbed. But with age, CPPD deposition was progressed in size and density. The course of progression was considered mainly from type A to C. Although most radiographs of the spine and knee joints show severe osteoarthritic changes, there are some cases whose radiographs of the knee joints show less osteoarthritic changes. In clinical settings, instruction to the patient is important.