頸椎黄靱帯石灰化症による頸髄症—2例報告と文献的考察

RADICULOMYELOPATHY DUE TO THE CALCIFICATION OF THE CERVICAL LIGAMENTA FLAVA:A REPORT OF 2 CASES AND REVIEW OF LITERATURES

　抄録　頸椎に限局した黄靱帯の石灰化巣による頸髄症の報告は非常にまれである。今回，我々はこの2症例を経験したので報告する。第1例は60歳女性。両手知覚異常，右下肢痙性麻痺を主訴として入院。C_3-4，C_4-5，C_5-6，C_6-7間後部脊椎管に小豆大の石灰化像を認め，手術的に切除した。術後，症状改善し独歩退院した。第2例は，66歳女性。脳血栓後遺症による左片麻痺に加えて，右手のradidulopathy，左半身のしびれ感の増強，歩行障害にて入院。C_5-6，C_6-7間後部脊椎管に症例1と同様の石灰化像を認めた。手術的に切除された石灰化巣はX線回折法にてリン酸カルシウムと同定された。これら2症例を諸家の報告例と共に比較検討したところ，興味ある共通点が見出された。すなわち，1）全例が50歳以上である。2）圧倒的に女性に多い。3）他の脊椎靱帯に合併骨を認めない。4）石灰化巣は小豆大，卵円形で下部頸椎の傍正中部に存在する。以上の共通点は黄靱帯石灰化症の病態を理解する上に重要であると考えられ，a）石灰化に関する全身的因子，b）黄靱帯の組織解剖学的特徴の2点より考察を加えた。

Calcification of ligamenta flava in the cervical spine is rarely seen. Only few cases in the literature have been available. Recently we have had experience with two cases on that lesion who had progressive radiculomyelopathy. The purpose of this report is not only case presenta-tion but also an analysis of 11 cases from the literature in clinical, radiological and histological aspects.

Case 1 was a 60-year-old woman who had numbness in both hands, mild weakness of the right foot on walking and clumsiness of the right hand. Ten years before she had suffered tbcmeningitis, but no history of neck injury. Neuro-logical examination revealed spastic paresis in right extremities, muscle atrophy in both forearms, hypesthesia and hypalgesia in both hands and feet. Vibration sense was disturbed below the knee joint and both feet. Sphincter function was normal. Radiological examination of cervical spine revealed oval calcified nodules in the pos-terior spinal canal at the level of C₃₄, C₄₅, C₅₆ and C₆₇. These were all situated in the parame-dian protion and symmetrically situated at C₅₆. Air myelogram demonstrated that the spinal cord was displaced forward and choked by the poste-rioly situated calcification.

Cervical laminectomy was carried out from C₂ through Th₁ and calcified nodules in the hyper-trophied ligamenta flava were successfully removed.

Case 2 was also 66-year-old woman who had been suffering from cerebral thrombosis with left hemiparesis. In addition with left hemiparesis she started to complain with paresthesia in right hand, deteriorated numbness in left extremities and gait disturbance developed a year later. Neurological examination revealed left spastic hemiparesis, clumsiness of the right hand. Deep tendon reflexes were increased in left extremeties. Pathological reflexes such as Hoffmann and Babinski were noted in left side. She also had left hemihy-palgesia, hemihypesthesia, and paresthesia of right hand and foot. Her gait was spastic and wide-based. Deep sensation and sphincter function were normal. Radiological examination of cervical spine observed similar nodular calification as Case 1 in C₅₆ and C₆₇ of ligamenta flava. Metri-zamide cervical myelogram revieled posterior indentation of dye column induced with the calcification of ligamenta flava. CT scan was very helpful because calcified nodules were clearly visible projecting posteriorly from the lamina through C₅ and C₆. Cervical laminectomy was carried out from C₃ through C₇ and calcified nodules in the ligamenta flava were removed. Xray diffraction analysis of the calcification from the surgical specimen revealed to calcium Hy-droxide Orthophosphate (Ca₅(PO₄)₃(OH)).

A review of the literature we yielded 11 cases of the calcification of cervical ligamenta flava and found interestingly similar findings with our cases. That is 1) all the patients were over 50 years old, 2 ) most cases were female, 3 ) no concomitant ossification in any other spinal liga-mints (e. g. ossification of the posterior longitu-dinal ligament), and 4 ) radiologically calcification is oval nodule and located symmetrically in the paramedian lower cervical regions. These charac-teristic similarities in both clinical and radiological features seems very important to consider the etiology of the calcification of cervical ligamenta flava. An analysis of calcified nodules by Xray diffraction study had shown either calcium py-rophosphate dihydrate (CPPD: Ca₂P₂O₇-2H₂0) or Calicum Hydroxide Orthophosphate (Ca₅(PO₄)₃ (OH)).

In addition to the systemic factors for deve-loping of the calcification, histo-anatomical charac-teristics of ligumenta flava and hormonal participa-tion were discussed.