Microdialysis enables the chemistry of the extracellular interstitial space to be monitored. Use of this technique in patients with acute brain injury has increased our understanding of the pathophysiology of several acute neurological disorders. In 2004, a consensus document on the clinical application of cerebral microdialysis was published. Since then, there have been significant advances in the clinical use of microdialysis in neurocritical care. The objective of this review is to report on the International Microdialysis Forum held in Cambridge, UK, in April 2014 and to produce a revised and updated consensus statement about its clinical use including technique, data interpretation, relationship with outcome, role in guiding therapy in neurocritical care and research applications.Electronic supplementary materialThe online version of this article (doi:10.1007/s00134-015-3930-y) contains supplementary material, which is available to authorized users.

Seizures occur commonly after ICH and may be nonconvulsive. Seizures are independently associated with increased midline shift after intraparenchymal hemorrhage.

Disturbed glucose brain metabolism after brain trauma is reflected by changes in extracellular glucose levels. The authors hypothesized that posttraumatic reductions in extracellular glucose levels are not due to ischemia and are associated with poor outcome. Intracerebral microdialysis, electroencephalography, and measurements of brain tissue oxygen levels and jugular venous oxygen saturation were performed in 30 patients with traumatic brain injury. Levels of glucose, lactate, pyruvate, glutamate, and urea were analyzed hourly. The 6-month Glasgow Outcome Scale extended (GOSe6) score was assessed for each patient. In regions of increased glucose utilization defined by positron emission tomography, the extracellular glucose concentration was less than 0.2 mmol/l. Extracellular glucose values were less than 0.2 mmol during postinjury days 0 to 7 in 19% to 30% of hourly samples on each day. Transient decreases in glucose levels occurred with electrographic seizures and nonischemic reductions in cerebral perfusion pressure and jugular venous oxygen saturation. Glutamate levels were elevated in the majority of low-glucose samples, but the lactate/pyruvate ratio did not indicate focal ischemia. Terminal herniation resulted in reductions in glucose with increases in the lactate/pyruvate ratio but not in lactate concentration alone. GOSe6 scores correlated with persistently low glucose levels, combined early low glucose levels and low lactate/glucose ratio, and with the overall lactate/glucose ratio. These results suggest that the level of extracellular glucose is typically reduced after traumatic brain injury and associated with poor outcome, but is not associated with ischemia.

ContributionsMagdy Selim --organized the trial hypotheses, designed the trial, provided guidance about the data analysis and interpretation and presentation of the data, and drafted most of the sections of the manuscript. Lydia Foster --involved in the statistical analysis and data interpretation, and Contributed to the development and revisions to the manuscript. Claudia Moy --involved in the oversight of the trial conduct and progress Guohua Xi --organized the trial hypotheses, and provided critical revisions to the manuscript. MH, MJ, VS, and WC contributed to recruitment and randomization of trial participants, and provided critical revisions to the manuscript. LM and SG were involved in the design of the trial and provided critical revisions to the manuscript. Casey Norton --provided volumetric measurements of imaging data. Yuko Palesch --involved in the design of the study, statistical analysis and data interpretation, and provided critical revisions to the manuscript. Sharon yeatts --involved in the design of the study, statistical analysis and data interpretation, and contributed to the development and revisions to the manuscript. The idef investigators (see appendix) --contributed to the identification and, when eligible, randomization of trial participants. DECLARATION OF INTERESTSThis was an investigator-initiated study, funded by the NINDS (U01 NS074425). Deferoxamine Mesylate is a generic drug, and there was no commercial or industrial support for the trial. None of the authors has any competing interests related to the submitted work. MS reports grants from the NIH/NINDS (i-DEF) and the American Heart Association (outside the submitted work), and personal fees for serving on the advisory board of CSL Behring (outside the submitted work) during the conduct of the trial. SDY reports grant support from the NINDS, personal fees from Genentech and other fees from CR Bard Inc. (outside the submitted work) during the conduct of the study. SG, LDF, YP, and GX report grants from the NIH/NINDS. MDH reports personal fees from Merck, nonfinancial support from Hoffmann-La Roche Canada Ltd, grants from Covidien (Medtronic), grants from Boehringer-Ingleheim, grants from Stryker Inc., grants from Medtronic LLC, grants from NoNO Inc., (outside the submitted work); In addition, MDH has a patent Systems and Methods for Assisting in Decision-Making and Triaging for Acute Stroke Patients pending to US Patent office Number: 62/086,077 and owns stock in Calgary Scientific Incorporated, a company that focuses on medical imaging software, is a director of the Canadian Federation of Neurological Sciences, a not-for-profit group and has received grant support from Alberta Innovates Health Solutions, CIHR, Heart & Stroke Foundation of Canada, and NINDS. LM, VS, WC, MJ, CM, and CN have nothing to disclose.

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Frameless stereotactic aspiration and thrombolysis (FAST) of deep spontaneous intracerebral hemorrhage is a safe therapy that is associated with reduction in ICH volume, early improvement in NIHSS and potentially could be used to improve outcome.

There was no benefit to IIT in this small critically ill neurologic population. This is the first glycemic control study to specifically examine both critically ill stroke and traumatic brain injury (TBI) patients and functional outcome. Given these results, IIT cannot be recommended over conventional control.

We unexpectedly found alcohol and methamphetamine use to be associated with decreased mortality. Neurotoxic and possible neuroprotective mechanisms of these substances are discussed as well as possible interactions between cannabis and methamphetamine. The potential influence of psycho-social factors are also considered. Prospective studies are needed to further investigate the effects of drug and alcohol use on outcome after severe TBI.