Background Osteoporosis is the most common type of bone disease. There is recent mounting evidence indicating that patients with multiple sclerosis (MS) and epilepsy (EP) have decreasing bone mineral density (BMD) in femoral neck and lumbar spine and consequently carry a higher risk of osteoporosis.
Objectives The aim of the study is to analyze the BMD in patients with MS and EP, and to determine the risk factors of osteoporosis in the two groups.
Methods A prospective, consecutive cohort of 46 patients with epilepsy and 46 patients diagnosed with MS, matched for age, race, and smoking status were included in the study. Postmenopausal women were excluded from the study. BMD was measured by dual energy X-ray absorptiometry (DXA) at lumbar spine and femoral neck. All statistical analysis were performed using the Windows SPSS 19 package.
Results In each group there were 23 male and 23 female. The mean age was 34.86 + 9.58 years in EP group and 35.17 + 8.14 years in MS group. There were no significant differences between the two groups in age, height, weight, body mass index. The mean disease duration was 8.54 + 4.7 years in MS group and 18.31 + 9.1 years in EP group. Of these 46 epileptic subjects, 50% (n=23) had abnormal DXA results (osteopenia n=17, osteoporosis n=6) and 50% were normal. Similarly, evaluation of MS patients revealed reduced BMD in 74% of patients (52.2% with osteopenia and 22.8% with osteoporosis). Despite a longer disease course in EP group, the lumbar and femur BMD values of patients with MS were significantly lower than those of the EP group (p<0.01).
In the EP group, the average length of antiepileptic drugs (AED) exposure was 14.5 + 7 years. Inducing AED was used by 64.5% of the EP population and noninducing AED by 63%. Fifty percent of EP group received two or more AEDs concurrently. In the MS group, the average Expanded Disability Status Scale (EDSS) score was 4.25 (min=1, max=8.5), all patients had been administered pulse steroids at least once during the duration of the disease. The average dose of pulse steroids was 48 ± 15 g for the duration of the disease.
Our study shows that osteoporosis in EP group is associated with AED (p<0.001). However, in MS group, osteoporosis is associated with immobilization and higher doses of steroids. (p<0.05)
Conclusions Patients taking AEDs are at increased risk for low bone mineral density. The mechanisms of AEDs-induced bone loss appear to be multiple, and all types of antiepileptic drugs are potentially implicated. Enzyme-inducing AEDs alter vitamin D concentrations and may predispose to reduced bone mass, although nonenzyme-inducing AEDs may also affect bone density by possibly altering osteoblastic function.(1) Polytherapy and duration of AED therapy are also correlated with low BMD. In people with MS, a major disease causing disability in young adults, BMD is affected by several factors such as immobilization, steroid and/or immunosuppressant drug use and cytokines involved in the pathogenesis of the disease. (2)
Understanding the risk factors associated with decreased BMD in EP and SM patients allows neurologists to conduct timely prevention of osteoporosis in these groups of patients.
Fitzpatrick LA. Pathophysiology of bone loss in patients receiving anticonvulsant therapy. Epilepsy Behav. 2004 Feb;5 Suppl 2:S3-15.
Chrissa Sioka. Multiple sclerosis, osteoporosis, and vitamin D. Journal of the Neurological Sciences 287 (2009) 1–6
Disclosure of Interest None Declared