Cauda equina syndrome with pagetic vertebral fusion. Clinical recovery under calcium-vitamin D supplementation plus clodronate after apparent failure of pamidronate and acquired resistance to etidronate.

A patient with an osteolytic L2-L3 pagetic block and pagetic lesions of L1 and the sacrum seen only as increased radionuclide activity became resistant to etidronate after the fifth course (5 mg/kg/d six months per year) and developed severe cauda equina syndrome (reduction in walking distance to 30 m and sphincter dysfunction) due primarily to vertebral hypertrophy. Five months after a ten-day course of intravenous pamidronate (22.5 mg/d), the clinical symptoms were unchanged, although the alkaline phosphatase level was down 50%. Oral clodronate (1,600 mg/day for six months per year) in combination with calcium and vitamin D supplementation dramatically improved the walking distance and sphincter disorders. Resolution of the neurological manifestations was complete after the second clodronate course. At last follow-up nine months after the fourth clodronate course, there was no evidence of a relapse and the alkaline phosphatase level was normal. The time course of events in this patient does not allow to affirm that pamidronate was ineffective and suggests that calcium and vitamin D supplementation improved mineralization of the pagetic block and enhanced the effect of bisphosphonate therapy.