OSSIFICATION AND CALCIFICATION OF THE YELLOW LIGAMENTS: 19 PATIENTS

Abstract

Purpose: Ossification (YLO) and calcification (YLC) of the yellow ligaments constitute an exceptional pathological situation described almost exclusively in Japan. We report a retrospective series of 19 patients from the French West Indies followed between 1996 and 2003.

Material and methods: The series included six men and thirteen women, mean age 67.8 years (31–79). A neurological examination was performed in all patients. Positive diagnosis was based on computed tomography results. MRI was performed in fifteen patients. Twelve patients underwent surgery (eight for laminectomy and four for laminoplasty). Operative specimens were analysed. The Rankin score was used to assess treatment efficacy.

Results: The patients generally consulted for progressive aggravation of gait disorders. Physical examination disclosed spastic tetra- or paraparesia associated with a pyramidal reflex syndrome and sphincter disorders. Computed tomography provided the positive and differential diagnosis. YLO was seen as a linear hyperdensity underlining the laminae, generally at the lower thoracic level (T9–T12 in six of ten patients). YLC was found at the lower cervical level in nine of the nine patients and appeared as round bilateral hyperdensities independent of the laminae. MRI revealed cord involvement seen as a high intensity signal on T2 sequences. The fifteen operated patients improved 1 to 3 points on the Rankin scale. Prognosis was better for YLC. Pathology examination revealed cartilaginous metaplasia of the yellow ligament leading to laminar bone for the YLO and microcrystal deposits (calcium pyrophosphate and/or hydroxyapatite) for he YLC.

Discussion: YLO and YLC are exceptional pathologies. More than 90% of the cases have been described in Japan and only one case in a black patient has been reported. YLO generally affects men in the fifth decade, YLC more often women after the age of 65 years. Positive and differential diagnosis are provided by CT scan. MRI visualises cord involvement. Treatment is based on posterior decompression. Prudence is particularly important for YLO due to dural adherences and the risk of dural breaches.

Conclusion: The frequency of YLO and YLC appears to be underestimated in the black population. These conditions can lead to severe myelopathy. Treatment is based on posterior decompression, best performed before appearance of a high intensity signal on the MRI.