OBJECT: To determine the extent and duration of change in extracellular glutamate levels after human traumatic brain injury (TBI), 17 severely brain injured adults underwent implantation of a cerebral microdialysis probe and systematic sampling was conducted for 1 to 9 days postinjury. METHODS: A total of 772 hourly microdialysis samples were obtained in 17 patients (median Glasgow Coma Scale score 5+/-2.5, mean age 39.4+/-20.4 years). The mean (+/-standard deviation) glutamate levels in the dialysate were evaluated for 9 days, during which the mean peak concentration reached 25.4+/-13.7 microM on postinjury Day 3. In each patient transient elevations in glutamate were seen each day. However, these elevations were most commonly seen on Day 3. In all patients there was a mean of 4.5+/-2.5 transient elevations in glutamate lasting a mean duration of 4.4+/-4.9 hours. These increases were seen in conjunction with seizure activity. However, in many seizure-free patients the increase in extracellular glutamate occurred when cerebral perfusion pressure was less than 70 mm Hg (p < 0.001). Given the potential injury-induced uncoupling of cerebral blood flow and metabolism after TBI, these increases in extracellular glutamate may reflect a degree of enhanced cellular crisis, which in severe head injury in humans appears to last up to 9 days. CONCLUSIONS: Extracellular neurochemical measurements of excitatory amino acids may provide a marker for secondary insults that can compound human TBI.
OBJECT: To determine the extent and duration of change in extracellular glutamate levels after humantraumatic brain injury (TBI), 17 severely brain injured adults underwent implantation of a cerebral microdialysis probe and systematic sampling was conducted for 1 to 9 days postinjury. METHODS: A total of 772 hourly microdialysis samples were obtained in 17 patients (median Glasgow Coma Scale score 5+/-2.5, mean age 39.4+/-20.4 years). The mean (+/-standard deviation) glutamate levels in the dialysate were evaluated for 9 days, during which the mean peak concentration reached 25.4+/-13.7 microM on postinjury Day 3. In each patient transient elevations in glutamate were seen each day. However, these elevations were most commonly seen on Day 3. In all patients there was a mean of 4.5+/-2.5 transient elevations in glutamate lasting a mean duration of 4.4+/-4.9 hours. These increases were seen in conjunction with seizure activity. However, in many seizure-free patients the increase in extracellular glutamate occurred when cerebral perfusion pressure was less than 70 mm Hg (p < 0.001). Given the potential injury-induced uncoupling of cerebral blood flow and metabolism after TBI, these increases in extracellular glutamate may reflect a degree of enhanced cellular crisis, which in severe head injury in humans appears to last up to 9 days. CONCLUSIONS: Extracellular neurochemical measurements of excitatory amino acids may provide a marker for secondary insults that can compound human TBI.
Authors: Jon C Rittenberger; Alexandra Popescu; Richard P Brenner; Francis X Guyette; Clifton W Callaway Journal: Neurocrit Care Date: 2012-02 Impact factor: 3.210
Authors: Jan Claassen; David Albers; J Michael Schmidt; Gian Marco De Marchis; Deborah Pugin; Christina Maria Falo; Stephan A Mayer; Serge Cremers; Sachin Agarwal; Mitchell S V Elkind; E Sander Connolly; Vanja Dukic; George Hripcsak; Neeraj Badjatia Journal: Ann Neurol Date: 2014-05-16 Impact factor: 10.422
Authors: Matthew Ferguson; Matt T Bianchi; Raoul Sutter; Eric S Rosenthal; Sydney S Cash; Peter W Kaplan; M Brandon Westover Journal: Neurocrit Care Date: 2013-04 Impact factor: 3.210
Authors: Charles Gasparovic; Ronald Yeo; Maggie Mannell; Josef Ling; Robert Elgie; John Phillips; David Doezema; Andrew R Mayer Journal: J Neurotrauma Date: 2009-10 Impact factor: 5.269