Concentration of brain free magnesium following severe brain injury correlates with neurologic motor outcome

Recent studies have shown that brain intracellular free magnesium concentra tion significantly declines following mild to severe, focal and diffuse tra umatic brain injury. However, little is known about how this decline or its attenuation by magnesium salts relates to neurologic outcome. This study u ses phosphorus magnetic resonance spectroscopy and rotarod tests to charact erise the relationship between brain free magnesium concentration and neuro logic motor scores following severe, diffuse traumatic brain injury in rats . An intravenous bolus of MgSO4 or MgCl2 (100 mu moles/kg) at 30 min follow ing brain injury significantly attenuated the postinjury brain free magnesi um decline. This improved magnesium homeostasis was sustained for the entir e postinjury monitoring period (1 week). There was an associated significan t improvement in neurologic motor function in magnesium treated rats. Moreo ver, the brain free magnesium concentration over the one week period was li nearly correlated with the neurologic motor function (r=0.70; P < 0.001) as assessed on a daily basis. We propose that brain free magnesium concentrat ion may be used as a prognostic indicator of neurologic motor function afte r traumatic brain injury. (C) 1999 Harcourt Publishers Ltd.