Young Male Epilepsy Patients With Normal Bone Density Scores at Risk of Vertebral Compression Fractures

Wednesday, May 02, 2007

BOSTON — Young men with epilepsy who have normal bone density measurements are at risk of developing seizure-related vertebral fractures, according to a new study by Mayo Clinic. The results were presented May 2 at the annual meeting of the American Academy of Neurology.

A neurology team from Mayo Clinic's Scottsdale and Phoenix, Ariz., campuses reported that the testing that generally predicts bone weakening and osteoporosis did not predict the risk of compression fractures in young men. The patients' T-scores — the bone mineral density measurements — were within normal ranges. Yet all felt acute back pain after well-documented seizures, and X-rays confirmed the presence of vertebrae fractured from the mechanical stress of seizures.

The vertebral compression fractures appear to result from bone demineralization caused by anticonvulsants prescribed to control seizures. "Some drugs induce certain enzymes which may result in bone demineralization — and our study shows that this bone weakening is not accurately predicted by traditional bone density measurements," explains Katherine Noe, M.D., Ph.D., the lead Mayo Clinic neurologist on the study. "If further studies validate our finding, we need to find a way to accurately predict this risk, to make patients aware of it and to help them prevent fractures."

Significance of the Mayo Clinic Study

The Mayo Clinic team is the first to identify a new potential negative side effect of some seizure medications by noting that traditional bone density measurements do not adequately predict the risk of compression fractures.

About the Study

Records of 400 hundred male patients who had been evaluated for epilepsy surgery at Mayo Clinic in Arizona over the past two years were reviewed by the Mayo Clinic team. The physicians looked specifically for evidence of vertebral fractures discovered during their Mayo evaluation.

Results

Results of the medical record review showed that:

— Four men, ages 32-41 years, had a long-standing seizure disorder and each presented with acute severe back pain following well-documented seizures.

— Each had taken hepatic enzyme-inducing anticonvulsants for 20-28 years.

— All had multiple thoracic vertebrae compression fractures that were confirmed by X-ray. All required medical therapy for pain, and one required inpatient admission for pain control.

"These fractures were unexpected based on the current surveillance methods for bone weakening," says Joseph Drazkowski, M.D., another neurologist on the research team. "What our study tells us is that we can serve our patients better by helping improve prediction methods for who is at risk for compression fractures, and doing whatever we can to prevent the fractures."

Collaboration and Support

The Mayo Clinic Arizona team also included Joseph Sirven, M.D., and Sara Schrader, M.D., in Scottsdale. Their work was supported by Mayo Foundation for Medical Education and Research.

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