High prevalence of vertebral fractures in seizure patients with normal bone density receiving chronic anti-epileptic drugs.

Abstract

Chronic use of antiepileptic drugs (AEDs), both enzyme-inducing (phenytoin, phenobarbital, carbamazepine, and primidone) and non-enzyme-inducing (i.e., valproate), is recognized as acauseof secondary osteoporosis. Vertebral compression fractures (VF) are the most common type of osteoporotic fractures and may confer an increased risk of future hip, wrist, and vertebral fractures. Vertebral compression fractures in the general population are frequently asymptomatic, and under-diagnosed. The purpose of this study is to describe the prevalence of VF in a cohort of male veterans with epilepsy on chronic AEDs. The cohort for this study consisted of 146 male veterans who carried a diagnosis of epilepsy and were chronic users of AEDs known to cause osteoporosis (phenobarbital, phenytoin, carbamazepine, primidone, and valproate). Chronic AED use wasdefined as receiving an AED for at least 2 years. Subjects were previously seen in the osteoporosis clinic and had been evaluated by a dual-energy X-Ray absormetry (DXA) instrument including morphometric studies following a standard vertebral fracture assessment (VFA) protocol during the same DXA imaging acquisition session. The mean age was 63 years. Low bone mineral density defined as osteoporosis or osteopenia was observed in 29% and 43% respectively. We observed at least one VF in 41 % of the subjects who had normal BMD, 54% in the osteopenic range, and 75% in the osteoporotic range. By performing a VFA in addition to standard bone densitometric studies, we disclosed a large prevalence of compression fractures in individuals with epilepsy chronically treated with AEDs who had BMDs in the normal and osteopenic ranges. The addition of VFA or other imaging methods to evaluate VF should be included in the evaluation of bone health in individuals with epilepsy receiving AEDs since it may modify treatment recommendations to prevent future osteoporotic fractures.