Severe brain injuries in children

The Glasgow Outcome Scale - 40 years of application and refinement

The Glasgow Outcome Scale (GOS) was first published in 1975 by Bryan Jennett and Michael Bond. With over 4,000 citations to the original paper, it is the most highly cited outcome measure in studies of brain injury and the second most-cited paper in clinical neurosurgery. The original GOS and the subsequently developed extended GOS (GOSE) are recommended by several national bodies as the outcome measure for major trauma and for head injury. The enduring appeal of the GOS is linked to its simplicity, short administration time, reliability and validity, stability, flexibility of administration (face-to-face, over the telephone and by post), cost-free availability and ease of access. These benefits apply to other derivatives of the scale, including the Glasgow Outcome at Discharge Scale (GODS) and the GOS paediatric revision. The GOS was devised to provide an overview of outcome and to focus on social recovery. Since the initial development of the GOS, there has been an increasing focus on the multidimensional nature of outcome after head injury. This Review charts the development of the GOS, its refinement and usage over the past 40 years, and considers its current and future roles in developing an understanding of brain injury.

Increased intracranial pressure is associated with the development of acute lung injury following severe traumatic brain injury

OBJECTIVE

This study investigated the relationship among intracranial pressure (ICP), the development of acute lung injury (ALI) and systemic inflammatory response syndrome (SIRS) following a severe traumatic brain injury (TBI).

METHODS

Post-traumatic ICP was continuously monitored for the first week following injury in a series of consecutive patients with isolated severe TBI. The initial ICP and the duration of intracranial hypertension (ICH) were calculated. The risk factors associated with the development of ALI and SIRS were evaluated.

RESULTS

Of the 86 patients enrolled, 22 patients developed ALI and 52 patients developed SIRS during the observation period. The patients with ALI presented with a significantly higher initial ICP (31.3±7.8 mmHg vs. 23.0±8.8 mmHg, p<0.001) and a longer duration of ICH (16.8±6.5 h vs. 11.9±6.0 h, p=0.002) than those without ALI. The incidence of both ALI and SIRS increased with increasing initial ICP, and the presence of SIRS was associated with a fourfold increase in the risk of developing ALI (odds ratio [OR], 4.0; 95% confidence interval [CI], 1.2-13.0).

CONCLUSIONS

Increased ICP is associated with increased risks of developing ALI and SIRS following severe TBI. Future studies designed to verify the causative relationship between increased ICP and the systemic responses are warranted.

Midline brain injury in the immature rat induces sustained cognitive deficits, bihemispheric axonal injury and neurodegeneration

Infants and children less than 4 years old suffer chronic cognitive deficits following mild, moderate or severe diffuse traumatic brain injury (TBI). It has been suggested that the underlying neuropathologic basis for behavioral deficits following severe TBI is acute brain swelling, subarachnoid hemorrhage and axonal injury. To better understand mechanisms of cognitive dysfunction in mild-moderate TBI, a closed head injury model of midline TBI in the immature rat was developed. Following an impact over the midline suture of the intact skull, 17-day-old rats exhibited short apnea times (3-15 s), did not require ventilatory support and suffered no mortality, suggestive of mild TBI. Compared to un-injured rats, brain-injured rats exhibited significant learning deficits over the first week post-injury (p<0.0005), and, significant learning (p<0.005) and memory deficits (p<0.05) in the third post-injury week. Between 6 and 72 h, blood-brain barrier breakdown, extensive traumatic axonal injury in the subcortical white matter and thalamus, and focal areas of neurodegeneration in the cortex and hippocampus were observed in both hemispheres of the injured brain. At 8 to 18 days post-injury, reactive astrocytosis in the cortex, axonal degeneration in the subcortical white matter tracts, and degeneration of neuronal cell bodies and processes in the thalamus of both hemispheres were observed; however, cortical volumes were not different between un-injured and injured rat brains. These data suggest that diffuse TBI in the immature rat can lead to ongoing degeneration of both cell soma and axonal compartments of neurons, which may contribute, in part, to the observed sustained cognitive deficits.

ICP and CPP: excellent predictors of long term outcome in severely brain injured children

OBJECTIVE

To determine the predictive powers of intracranial pressure (ICP) and cerebral perfusion pressure (CPP) amongst severely brain injured children.

MATERIALS AND METHODS

ICP and CPP were recorded from thirty-five severely brain injured children who were prospectively recruited after admission to paediatric intensive care. Twenty-five suffered traumatic brain injury (TBI) and ten suffered non-TBI. Peak ICP and minimum CPP recorded for each patient during their admission were related to 5 year Glasgow Outcome Scale outcome. Receiver operator characteristic curves determined that the optimum threshold for unfavourable outcome prediction was >or=40 mmHg for ICP and <or=49 mmHg for CPP. At these thresholds the sensitivity/specificity pairs for the prediction of unfavourable outcome were 33.3/100% and 55.6/100% for ICP and CPP, respectively, amongst patients suffering TBI and were 46.2/100% and 66.2/100% for ICP and CPP, respectively, amongst all patients.

CONCLUSION

ICP and CPP are accurate predictors of unfavourable outcome.

Diffuse brain injury in the immature rat: evidence for an age-at-injury effect on cognitive function and histopathologic damage

Diffuse axonal injury is a significant component of the pathology of moderate-severe pediatric traumatic brain injury in children less than 4 years of age, and is associated with poor cognitive outcome. However, cognitive deficits or gross histopathologic abnormalities are typically not observed following moderate-severe diffuse brain injury in the immature (17-day-old) rat. In order to test whether the age of the immature animal may influence post-traumatic outcome, non-contusive brain trauma was induced in post-natal day (PND) 11 or 17 rats. Brain injury in the PND11 rat, but not in the PND17 rat, was associated with a significant acquisition deficit at 28 days post-injury (p<0.0005 compared with age-matched sham rats, and with brain-injured PND17 rats). All brain-injured animals exhibited a retention deficit in the probe trial (p<0.001), but also demonstrated a significant visual deficit in the visible platform trial (p<0.05 compared to sham animals). Although significantly longer times of apnea and loss of righting reflex were observed in brain-injured PND17 rats compared to PND11 rats (p<0.05), overt cytoarchitectural alterations and reactive gliosis were not observed in the older age group. No focal pathology was observed in the cortex below the impact site in the PND11 rat but by 28 days, the brain-injured PND11 rat exhibited atrophy in multiple brain regions and an enlarged lateral ventricle in the impact hemisphere. Quantitative analysis revealed a time-dependent increase in tissue loss in the injured hemisphere (7-10%) in the younger animals, and a modest extent of tissue loss in the older animals (3-4%). Traumatic axonal injury was observed to similar extents in the white matter and thalamus below the impact site in both brain-injured PND11 and 17 rats. These data demonstrate that non-contusive (diffuse) brain injury of moderate severity in the immature rat is associated with chronic cognitive deficits and long-term histopathologic alterations and suggest that the age-at-injury is an important parameter of behavioral and pathologic outcome following closed head injury in the immature age group.