Pharmacological targeting of secondary brain damage following ischemic or hemorrhagic stroke, traumatic brain injury, and bacterial meningitis - a systematic review and meta-analysis

Thomas Beez, Hans-Jakob Steiger, Nima Etminan

The effectiveness of pharmacological strategies exclusively targeting secondary brain damage (SBD) following ischemic stroke, aneurysmal subarachnoid hemorrhage, aSAH, intracerebral hemorrhage (ICH), traumatic brain injury (TBI) and bacterial meningitis is unclear. This meta-analysis studied the effect of SBD targeted treatment on clinical outcome across the pathological entities. Randomized, controlled, double-blinded trials on aforementioned entities with 'death' as endpoint were identified. Effect sizes were analyzed and expressed as pooled risk ratio (RR) estimates with 95% confidence intervals (CI). 123 studies fulfilled the criteria, with data on 66,561 patients. In the pooled analysis, there was a minor reduction of mortality for aSAH [RR 0.93 (95% CI:0.85-1.02)], ICH [RR 0.92 (95% CI:0.82-1.03)] and bacterial meningitis [RR 0.86 (95% CI:0.68-1.09)]. No reduction of mortality was found for ischemic stroke [RR 1.05 (95% CI:1.00-1.11)] and TBI [RR 1.03 (95% CI:0.93-1.15)]. Additional analysis of "poor outcome" as endpoint gave similar results. Subgroup analysis with respect to effector mechanisms showed a tendency towards a reduced mortality for the effector mechanism category "oxidative metabolism/stress" for aSAH with a risk ratio of 0.86 [95% CI: 0.73-1.00]. Regarding specific medications, a statistically significant reduction of mortality and poor outcome was confirmed only for nimodipine for aSAH and dexamethasone for bacterial meningitis. Our results show that only a few selected SBD directed medications are likely to reduce the rate of death and poor outcome following aSAH, and bacterial meningitis, while no convincing evidence could be found for the usefulness of SBD directed medications in ischemic stroke, ICH and TBI. However, a subtle effect on good or excellent outcome might remain undetected. These results should lead to a new perspective of secondary reactions following cerebral injury. These processes should not be seen as suicide mechanisms that need to be fought. They should be rather seen as well orchestrated clean-up mechanisms, which may today be somewhat too active in a few very specific constellations, such as meningitis under antibiotic treatment and aSAH after surgical or endovascular exclusion of the aneurysm.