ESPE Abstracts

Background: Rett Syndrome (RS) is a disabling condition due to mutations in MECP2. Girls affected with RS are at risk of developing osteoporosis and fractures at a young age because of their lack of mobility and though a direct effect of MECP2 on bone mineralization. In these girls, bone fragility inflicts pain and may seriously impair the quality of life.

Objective: To retrospectively assess the effect of pamidronate on fractures, bone mineral density (BMD) and bone markers in RS girls with bone fragility.

Methods: Once diagnosed with bone fragility, RS girls received 1.5 mg/kg of pamidronate IV every 3 months cycle for 2 years. Values are median (min; max).

Results: 13 patients were studied (age: 9.5 years (6; 42)). All were not ambulatory. 24 fractures for 13 patients were observed in the 6-months interval preceding the start of therapy, whereas 0 fracture occurred during or after pamidronate (length of follow-up: 32 months). The DXA BMD Z-score improved from −3.7 (−5; −2) to −1.3 (−0.7; −3.8), P<0.01. Most parents reported a decrease in chronic pain; two patients started to walk around the end of the 2-years therapy. The urinary calcium excretion, which reflects bone resorption, decreased significantly from 0.6 (0.2; 1.5) to 0.3 (0.0; 0.5) mmol/mmol of creatinine. Except for moderate hypocalcemia and fever, pamidronate was well tolerated in all girls.

Conclusion: Our result are in accordance with the beneficial effect of bisphosphonates in children with cerebral palsy. Impaired bone mineralization in RS girls should be screened and prevented through measures including vitamin D supplements, nutritional support and careful mechanical loading. In girls experiencing fractures, IV bisphosphonates may be an adjuvant treatment to diminish the risk of fracture and restore the bone density.