Study of serum factors potentially involved in the pathogenesis of heterotopic bone formation after severe brain injury.

ABSTRACT

OBJECTIVE: To look for serum factors detectable early after head injury and predictive of heterotopic bone formation. PATIENTS AND METHODS: In this prospective study of a homogeneous population of 31 men with severe brain injury, blood samples were obtained 3 months after the accident, and levels of serum factors influenced by bone metabolism were compared between patients with and without heterotopic bone formation. As extensive fractures can influence serum factors, the patients without heterotopic bone formation were divided into two groups based on whether they had major fractures. Radionuclide bone scanning was used to validate patient classification. RESULTS: The group with heterotopic bone formation had significantly higher serum alkaline phosphatase levels (P < 0.01) and significantly lower serum leptin levels (P < 0.01), as compared to the other two groups. Body mass index and serum creatinine were comparable in the three groups. CONCLUSION: Leptin may be associated with the development of heterotopic bone formation. The antiosteogenic effect of leptin mediated by hypothalamic neurons may be impaired by hypothalamic damage related to severe brain injury.