Ross Bullock

The heterogeneity of traumatic brain injury (TBI) is considered one of the most significant barriers to finding effective therapeutic interventions. In October, 2007, the National Institute of Neurological Disorders and Stroke, with support from the Brain Injury Association of America, the Defense and Veterans Brain Injury Center, and the National Institute of Disability and Rehabilitation Research, convened a workshop to outline the steps needed to develop a reliable, efficient and valid classification system for TBI that could be used to link specific patterns of brain and neurovascular injury with appropriate therapeutic interventions. Currently, the Glasgow Coma Scale (GCS) is the primary selection criterion for inclusion in most TBI clinical trials. While the GCS is extremely useful in the clinical management and prognosis of TBI, it does not provide specific information about the pathophysiologic mechanisms which are responsible for neurological deficits and targeted by interventions. On the premise that brain injuries with similar pathoanatomic features are likely to share common pathophysiologic mechanisms, participants proposed that a new, multidimensional classification system should be developed for TBI clinical trials. It was agreed that preclinical models were vital in establishing pathophysiologic mechanisms relevant to specific pathoanatomic types of TBI and verifying that a given therapeutic approach improves outcome in these targeted TBI types. In a clinical trial, patients with the targeted pathoanatomic injury type would be selected using an initial diagnostic entry criterion, including their severity of injury. Coexisting brain injury types would be identified and multivariate prognostic modeling used for refinement of inclusion/exclusion criteria and patient stratification. Outcome assessment would utilize endpoints relevant to the targeted injury type. Advantages and disadvantages of currently available diagnostic, monitoring, and assessment tools were discussed. Recommendations were made for enhancing the utility of available or emerging tools in order to facilitate implementation of a pathoanatomic classification approach for clinical trials.

Spreading depolarizations are waves of mass neuronal and glial depolarization that propagate across the injured human cortex. They can occur with depression of neuronal activity as spreading depressions or isoelectric spreading depolarizations on a background of absent or minimal electroencephalogram activity. Spreading depolarizations are characterized by the loss of neuronal ion homeostasis and are believed to damage functional neurons, leading to neuronal necrosis or neurological degeneration and poor outcome. Analgesics and sedatives influence activity-dependent neuronal ion homeostasis and therefore represent potential modulators of spreading depolarizations. In this exploratory retrospective international multicentre analysis, we investigated the influence of midazolam, propofol, fentanyl, sufentanil, ketamine and morphine on the occurrence of spreading depolarizations in 115 brain-injured patients. A surface electrode strip was placed on the cortex, and continuous electrocorticographical recordings were obtained. We used multivariable binary logistic regression to quantify associations between the investigated drugs and the hours of electrocorticographical recordings with and without spreading depolarizations or clusters of spreading depolarizations. We found that administration of ketamine was associated with a reduction of spreading depolarizations and spreading depolarization clusters (P < 0.05). Midazolam anaesthesia, in contrast, was associated with an increased number of spreading depolarization clusters (P < 0.05). By using a univariate odds ratio analysis, we also found a significant association between ketamine administration and reduced occurrence of isoelectric spreading depolarizations in patients suffering from traumatic brain injury, subarachnoid haemorrhage and malignant hemispheric stroke (P < 0.05). Our findings suggest that ketamine-or another N-methyl-d-aspartate receptor antagonist-may represent a viable treatment for patients at risk for spreading depolarizations. This hypothesis will be tested in a prospective study.

OBJECTIVE: Animal models and clinical studies suggest that intraventricular thrombolysis improves clot resolution and clinical outcomes among patients with intraventricular hemorrhage. However, this intervention may increase the rates of rebleeding and infection. To assess the safety and efficacy of intraventricular thrombolysis, we conducted a pilot, randomized, double-blind, controlled, multicenter study. METHODS: Patients with intraventricular hemorrhage requiring ventriculostomy were randomized to receive intraventricular injections of normal saline solution or urokinase (25000 international units) at 12-hour intervals. Injections continued until ventricular drainage was discontinued according to prespecified clinical criteria. Head computed tomographic scans were obtained daily, for quantitative determinations of intraventricular hemorrhage volumes. The rate of clot resolution was estimated for each group. RESULTS: Twelve subjects were enrolled (urokinase, seven patients; placebo, five patients). Commercial withdrawal of urokinase precluded additional enrollment. The urokinase and placebo groups were similar with respect to age (49.6 versus 55.2 yr, P = 0.43) and presenting Glasgow Coma Scale scores (7.14 versus 8.00, P = 0.72). Randomization to the urokinase treatment arm (P = 0.02) and female sex (P = 0.008) favorably affected the clot resolution rate. The sex-adjusted clot half-life for the urokinase-treated group was reduced 44.6%, compared with the value for the placebo group (4.69 versus 8.48 d). CONCLUSION: Intraventricular thrombolysis with urokinase speeds the resolution of intraventricular blood clots, compared with treatment with ventricular drainage alone.