[Vitamin-resistant hypophosphatemic rickets and spinal cord compression. Apropos of 2 cases]

Adults with X-linked vitamin-resistant hypophosphatemic rickets can develop spinal cord compression as a result of spinal canal stenosis due to involvement of the spine with the increased periosteal and ligamentary calcification which is typical of the disease. Two cases are reported. In both patients, spinal cord compression manifested as rapidly progressive spastic paraplegia due to compression at T9 and T5, respectively. Decompressive laminectomy ensured full recovery in one case but was ineffective in the other. In both cases, paraplegia developed approximately one year after initiation of therapy combining a metabolite of vitamin D and phosphorus in high doses. Current imaging techniques (CT scan, magnetic resonance imaging) provide highly accurate information on the anatomic mechanism of the stenosis, its often multiple locations, and its course. Three factors are involved in the stenosis, in variable degrees: thickening of the laminae, hypertrophy of the facet joints, thickening and calcification of the yellow ligament. Magnetic resonance imaging is the investigation of choice in these patients. A deleterious effect vitamin D-phosphorus treatment cannot be outruled. The appropriateness of initiating this treatment should be prudently discussed and treated patients should be closely monitored.