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

People with epilepsy who take certain medications are at risk for developing osteoporosis and fractures of the vertebrae that commonly go undiagnosed. By using technology available in a bone density scan, we observed at least one fracture in many subjects with bone density in the normal and osteopenic range.

PURPOSE/INTRODUCTION

Chronic use of antiepileptic drugs (AEDs), both enzyme-inducing (phenytoin, phenobarbital, carbamazepine, and primidone) and non-enzyme-inducing (i.e., valproate), is recognized as a cause of 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.

METHODS

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 was defined 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.

RESULTS

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.

CONCLUSIONS

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.

Clinical factors associated with C-reactive protein in chronic spinal cord injury

STUDY DESIGN

Cross-sectional study.

OBJECTIVES

Determine clinical factors associated with plasma C-reactive protein (CRP) in persons with chronic spinal cord injury (SCI).

SETTING

Veterans Affairs Medical Center in Boston, MA, USA.

METHODS

Participants provided a blood sample, completed a respiratory health questionnaire and underwent dual X-ray absorptiometry (DXA) to assess total and regional body fat. Linear regression models were used to assess cross-sectional associations with plasma CRP.

RESULTS

In multivariable models, factors associated with a higher CRP included a greater BMI, urinary catheter use, a respiratory illness in the past week and non-white race. Mean CRP also increased with decreasing mobility (motorized wheelchair >hand-propelled wheelchair >walk with an assistive device >walk independently). Results were similar when adjusting for percentage android, gynoid, trunk or total fat mass in place of BMI. Level and completeness of SCI was not associated with CRP in multivariable models.

CONCLUSIONS

Clinical characteristics common in chronic SCI are associated with plasma CRP. These factors are more important than the level and completeness of SCI and some are potentially modifiable.

Adiponectin is associated with bone strength and fracture history in paralyzed men with spinal cord injury

We explored the association between adiponectin levels and bone strength in paralyzed men with spinal cord injury. We found that bone strength was inversely associated with circulating adiponectin levels. Thus, strength estimates and adiponectin levels may improve fracture risk prediction and detection of response to osteogenic therapies following spinal cord injury.

PURPOSE

Previous research has demonstrated an inverse relationship between circulating adiponectin and bone mineral density, suggesting that adiponectin may be used as a biomarker for bone health. However, this relationship may reflect indirect effects on bone metabolism via adipose-mediated mechanical pathways rather than the direct effects of adipokines on bone metabolism. Thus, we explored the association between circulating adiponectin levels and bone strength in 27 men with spinal cord injury.

METHODS

Plasma adiponectin levels were quantified by ELISA assay. Axial stiffness and maximal load to fracture of the distal femur were quantified via finite element analysis using reconstructed 3D models of volumetric CT scans. We also collected information on timing, location, and cause of previous fractures.

RESULTS

Axial stiffness and maximal load were inversely associated with circulating adiponectin levels (R (2) = 0.44, p = 0.01; R (2) = 0.58, p = 0.05) after adjusting for injury duration and lower extremity lean mass. In individuals with post-SCI osteoporotic fractures, distal femur stiffness (p = 0.01) and maximal load (p = 0.005) were lower, and adiponectin was higher (p = 0.04) than those with no fracture history.

CONCLUSIONS

Based on these findings, strength estimates may improve fracture risk prediction and detection of response to osteogenic therapies following spinal cord injury. Furthermore, our findings suggest that circulating adiponectin may indeed be a feasible biomarker for bone health and osteoporotic fracture risk in paralyzed individuals with spinal cord injury.

Sclerostin: a candidate biomarker of SCI-induced osteoporosis

We assessed several circulating proteins as candidate biomarkers of bone status in men with chronic spinal cord injury. We report that sclerostin is significantly associated with bone mineral content and bone density at all skeletal sites tested. We found no association between bone and any other tested biomarker.

INTRODUCTION

Spinal cord injury results in severe osteoporosis. To date, no circulating biomarker of spinal cord injury (SCI)-induced osteoporosis has been identified. We recently reported that circulating sclerostin is associated with bone density in chronic SCI. In this study, we assessed several circulating proteins as candidate biomarkers of bone in men with chronic SCI.

METHODS

We assessed the relationship between bone mineral content or bone density and the following circulating bone-related proteins: sclerostin, DKK-1, soluble receptor activator of nuclear factor kappa B ligand, osteoprotegerin, osteocalcin, and c-telopeptide in 39 men with chronic SCI and 10 men with no SCI.

RESULTS

After adjusting for age, lower sclerostin levels were significantly associated with lower bone mineral content and bone density at all skeletal sites tested (p = 0.0002-0.03). No other circulating protein was associated with bone mineral content or bone mineral density (p = 0.18-0.99).

CONCLUSION

These findings suggest that circulating sclerostin reflects the severity of bone loss and is a candidate biomarker of osteoporosis severity in chronic SCI.

Osteoporotic fractures and hospitalization risk in chronic spinal cord injury

Osteoporosis is a well acknowledged complication of spinal cord injury. We report that motor complete spinal cord injury and post-injury alcohol consumption are risk factors for hospitalization for fracture treatment. The clinical assessment did not include osteoporosis diagnosis and treatment considerations, indicating a need for improved clinical protocols.

INTRODUCTION

Treatment of osteoporotic long bone fractures often results in lengthy hospitalizations for individuals with spinal cord injury. Clinical features and factors that contribute to hospitalization risk have not previously been described.

METHODS

Three hundred and fifteen veterans > or = 1 year after spinal cord injury completed a health questionnaire and underwent clinical exam at study entry. Multivariate Cox regression accounting for repeated events was used to assess longitudinal predictors of fracture-related hospitalizations in Veterans Affairs Medical Centers 1996-2003.

RESULTS

One thousand four hundred and eighty-seven hospital admissions occurred among 315 participants, and 39 hospitalizations (2.6%) were for fracture treatment. Median length of stay was 35 days. Fracture-related complications occurred in 53%. Independent risk factors for admission were motor complete versus motor incomplete spinal cord injury (hazard ratio = 3.73, 95% CI = 1.46-10.50). There was a significant linear trend in risk with greater alcohol consumption after injury. Record review indicated that evaluation for osteoporosis was not obtained during these admissions.

CONCLUSIONS

Assessed prospectively, hospitalization in Veterans Affairs Medical Centers for low-impact fractures is more common in motor complete spinal cord injury and is associated with greater alcohol use after injury. Osteoporosis diagnosis and treatment considerations were not part of a clinical assessment, indicating the need for improved protocols that might prevent low-impact fractures and related admissions.

Antibodies to collagen in experimental antigen induced arthritis of the rabbit

Fifteen rabbits with antigen (bovine serum albumin) induced arthritis had antibodies to collagens type I, II and III detected weekly by passive hemagglutination. Antitype I collagen antibodies were detected in 80% of the animals in the 3rd week of arthritis; antitypes II and III were found less frequently. No anticollagen antibody was detected after the 6th week of arthritis. Although the appearance of these antibodies was clearly related to the induction of arthritis, results indicate that humoral immunity to collagen is unable to initiate or contribute to the perpetuation of synovitis in this experimental model. Antibodies to collagen are probably an epiphenomenon of articular damage in the antigen induced arthritis of the rabbit.

Experimental arthritis in a nonhuman primate. I. Induction by bovine type II collagen

Six squirrel monkeys immunized with native fetal bovine type II collagen (CII) in complete Freund's adjuvant developed arthritis 3 to 6 weeks later. None of three cebus monkeys given CII plus complete Freund's adjuvant or three control squirrel monkeys immunized with complete Freund's adjuvant alone developed arthritis. In four of the squirrel monkeys, arthritis was symmetrical and involved mainly the interphalangeal and metacarpal phalangeal joints. Two other monkeys had pauciarticular disease. Although three monkeys became cachetic and died, the others regained weight and their arthritis spontaneously remitted with minor residual deformities in digits and larger joints. Each squirrel monkey with arthritis had high titers of CII antibodies whereas the arthritis-resistant cebus monkeys had lower titers of CII antibodies whereas the arthritis-resistant cebus monkeys had lower titers of CII antibodies. As an animal model, experimentally induced arthritis in primates appears to resemble an acute arthropathy in man rather than chronic rheumatoid arthritis.