Progressive bone deficit in epilepsy

Objective: Chronic treatment with antiepileptic medication is associated with reduced bone mineral density (BMD), which may underlie the two- to sixfold increase in fracture rates observed in patients with epilepsy. The objective was to determine the timing of the BMD deficit in ambulatory children with epilepsy. Methods: A cross-sectional evaluation was conducted in 82 ambulatory children aged 6 to 18 years (12.4 +/- 3.3 years) with epilepsy for < 1 year (n = 18), 1 to 5 years (n = 37), and 6 or more years (n = 27). Controls were 32 healthy children aged 12.8 +/- 2.6 years. Age- and sex-corrected total body BMD Z-score was measured. Results: Total BMD Z-score was lower in children with epilepsy (0.10 +/- 0.96; CI = -0.08, 0.34) compared to controls (0.57 +/- 0.74; CI = 0.3, 0.84; p = 0.03). Increasing duration of epilepsy was associated with a progressive reduction in BMD compared to controls (Spearman r = -0.197; p = 0.03). Compared to controls, those with epilepsy for 1 to 5 years had a mean BMD Z-score of 0.13 +/- 0.78 (CI = -0.13, 0.39; p = 0.04) and in those treated for 6 or more years BMD was 0.06 +/- 1.11 (CI = -0.38, 0.5; p = 0.04). For those with epilepsy for < 1 year BMD was 0.23 +/- 1.1 (CI = -0.31, 0.77; p = 0.21). Conclusions: Children treated for epilepsy sustain significant bone mineral density (BMD) deficit compared to controls during the initial 1 to 5 years of treatment which progressively worsens thereafter. This progressive BMD deficit may be a contributing factor to the increased fracture risk observed in patients with epilepsy and may accelerate aging-related osteoporosis.