Editorial: Why monitor the injured brain?

Abstract

Pediatric traumatic brain injury (TBI) and indeed all forms of acute brain injury account for significant mortality and disability in children of all communities. In managing these patients, we aim to limit the progression of the primary injury and avoid secondary insults. This is important because secondary injury plays a major and yet probably underestimated role in determining prognosis, so in theory, there exists an opportunity to intervene and improve functional outcome. However, the brain is the most complex organ of the body, and the multitude of physiological and biochemical derangements that occur after injury often overwhelms the treating clinician. Compounding this is the fact that the tools that we have had to monitor and treat brain injury traditionally have been few in number and blunt in efficacy. We wait for clinical deterioration to occur before intervening, knowing that such intervention may then be too late. We rely on structural assessment of brain injury with conventional imaging, even though these provide no information about dynamic physiological changes or brain function and provide information only on events that have already happened, and we often rely on intracranial pressure (ICP) monitoring alone, a relatively blunt measure of the underlying brain disturbance. When ICP is increased, we respond in a uniform stepwise manner regardless of the several factors that may cause increased ICP. Furthermore, all our treatments for increased ICP may have adverse effects on the brain that contribute to worse outcome (such as hyperventilation), but we are often unaware of these when they occur. For all of these reasons and more, it seems logical that we need better tools to diagnose mechanisms of injury, markers to select and titrate appropriate therapy, and more sensitive measures to predict outcome. In response to this need, the last decade has witnessed a proliferation of publications on newer monitors of brain physiology, biochemistry and function that have the potential to change the way we manage brain injury. However, none of these tools have achieved widespread acceptance yet, in part because no randomized trials have been conducted to definitively demonstrate their impact on patient care and outcome. Even for ICP monitoring, which has long been a cornerstone of care in TBI, no randomized trials have been conducted as yet. Furthermore, as is evident from our experience with ICP monitoring, it is not the presence of the monitor that benefits (or harms) the patient but the interpretation of the monitor’s data and the clinician’s response to it. Misinterpretation of the monitor or incorrect intervention has the potential to undo any potential benefit of monitoring. This may in part explain studies where monitoring did not appear to benefit patients [4, 6]. Several newer methods of monitoring brain metabolism, markers of inflammation, cerebral hemodynamics, brain oxygenation, and serum markers of brain injury are now available, all of which await validation in large studies. There is some evidence that the use of individual monitors, especially along with protocol-driven and guideline-based care in a specialized neurocritical care unit, does improve outcome [1, 3, 7]. However, whether this can be replicated in a general neurosurgical practice and whether the additional cost or effort justifies the benefit still need to A. A. Figaji Division of Neurosurgery, School of Child and Adolescent Health, University of Cape Town, Cape Town, South Africa