Non-accidental head injury: a consequence of deprivation?

BACKGROUND: Non-accidental head injury (NAHI) is a significant personal and public health problem, with considerable mortality and morbidity. The evidence base for risk factors specific for NAHI is limited due to difficulties with case definition and study design. The risk factors associated with NAHI in infants was evaluated in this study, and the extent to which indices of deprivation influence this health problem was addressed. METHODS: A 10-year prospective study was conducted in Scotland involving all paediatric hospitals and other general hospital departments admitting children. Subjects were children ≤2 years of age, with a diagnosis of "suspected NAHI". Socioeconomic characteristics of the index cases were compared to the general population, using the Scottish Index of Multiple Deprivation (SIMD) 2006. RESULTS: There were highly significant differences (p<0.001) between the SIMD rank scores of the NAHI cases and scores for the whole Scottish population. For the cohort, SIMD ranks ranged from 34 to 6253 (median 1210; mean 1577) compared to the population range of 1-6505 (median and mean=3253). Similar differences were found for each of the component domains of income, employment, health, education, crime and housing (p<0.001). In contrast, the scores for "geographic access" (to essential service) were higher than for the whole population (p<0.001), indicating that the deprivation was not due to lack of local services. CONCLUSION: In Scotland, children who present with suspected NAHI originate predominantly from the most deprived areas of the community. Public health and intervention strategies should be focused in these areas.

Modulating effect of apolipoprotein E polymorphisms on secondary brain insult and outcome after childhood brain trauma.

OBJECTIVE: The aim of this study was to determine the relationship between apolipoprotein E (APO E) alleles, the amount of cerebral perfusion pressure (CPP) insult and outcome in children after brain trauma. MATERIALS AND METHODS: In a prospective two-centre case-control study, the APO E genotypes of 65 critically ill children admitted after brain trauma were correlated with age-related CPP insult quantification, conscious state at the time of discharge from intensive care and global outcome at 6 months post-injury. One hundred sixty healthy age- and sex-matched children were genotyped as controls. RESULTS: The CPP insult level among the e4 carriers with poor outcome was significantly less than the non-e4 carriers (p=0.03). Homozygotic e3 patients with good recovery did so despite having suffered nearly 26 times more CPP insult than those who were not e3 homzygous (p=0.02). CONCLUSION: Different APO E alleles may potentially affect cerebral ischaemic tolerance differently in children after brain trauma.

Low frequency pressure waves of possible autonomic origin in severely head-injured children.

BACKGROUND: Useful information (both clinical and pathophysiological) which may be extracted from intracranial pressure (ICP) recordings include: (1) the mean level of ICP (and CPP), (2) cerebrovascular autoregulation status, (3) the intracranial pulse pressure (the pulse wave index, ICPpp/ICPm) or the pressure-volume compensatory reserve index (RAP) and (4) the presence of any abnormal ICP waveform. This paper describes a slow frequency ICP waveform in children with TBI and postulates the pathophysiological basis and whether it contains clinically useful detail. METHODS: Children admitted to the Regional Head Injury Service in Edinburgh with TBI have continuously monitored ICP, MAP, CPP, and other physiological data (stored at a 1-min resolution). Slow frequency waveforms were noted, prompting a review of the stored monitoring from all cases over a 10 year period. FINDINGS: Episodic slow pressure waves were detected in 11 of 122 severely head-injured (HI) children. The waveforms were detected in children of all ages (1.6-15 years) in the ICP signal, which were in phase with similar fluctuations in the MAP, CPP, and HR signals. Their mean periodicity was 1 per 7 min (range 1 per 5-10 min), with a mean ICP pulse wave amplitude of 5.45 mmHg (range 4-7.5), and mean MAP pulse wave amplitude (pulse pressure) of 10.4 mmHg (range 4-15 mmHg). The duration was variable (range approx 2 h to 4.5 days). They were detected in the preterminal phase after serious HI, as well as in those children who made an independent recovery (GOS 4/5). The waves were not related to the mean levels of ICP, CPP, MAP, temperature or the state of cerebrovascular autoregulation. CONCLUSIONS: We postulate that these previously unreported slow waveforms may reflect the very low frequency (VLF) and ultra low frequency (ULF; < or = 1 per 5 min) components of heart rate and arterial blood pressure variability.

Are head injury guidelines changing the outcome of head injured children? A regional investigation.

BACKGROUND: Secondary pathophysiological CPP insult is related to outcome after head injury, and improved management would be expected to reduce secondary brain insult. Paediatric head injury management guidelines have been published in recent years, by SIGN (2000), RCPCH (2001), NICE (June 2003), and jointly by Critical/Intensive Care Societies (C/ICS July 2003). We investigated whether outcome of children's head injury (and total burden of secondary CPP insult) has changed (1) annually; (2) before and after the introduction of any HI guidelines, and (3) following other service changes. METHODS: Seventy-six children (aged 1-14 years with severe HI) were admitted to the Edinburgh Regional Head Injury Service between 1989 and 2006, and dichotomised at various time points and compared in terms of: demographic factors, intracranial pressure (ICP), cerebral perfusion pressure (CPP) insults [e.g. age-banded pressure-time index (PTI)], and Glasgow Outcome Scale (GOS) score (assessed at 6 months post injury). FINDINGS: When dichotomised around the SIGN guidelines, there were no statistically significant differences between the two group's demography or in primary brain injury, but the outcomes were different (p = 0.03), with 6 vs 4 GOS1 (died), 2 vs 4 GOS3 (severely disabled), 5 vs 16 GOS4 (moderately disabled) and 23 vs 14 GOS5 (good recovery), when comparing before and after year 2000. GOS4 was significantly different (chi-square = 7.99, p < 0.007). There was a (non-significant) trend for the later years to have longer insult durations of ICP, hypertension, CPP, hypoxia, pyrexia, tachycardia and bradycardia, greater PTI for both CPP and ICP, and more CPP insults (p = 0.003). There was, however, significantly less CPP insult (p = 0.030) after the introduction of the more management-oriented C/ICS guidelines. CONCLUSIONS: The most recent paediatric HI guidelines appear to have reduced the burden of secondary insult, but more time is required to determine if this will be reflected in improved outcomes.

Critical thresholds of intracranial pressure and cerebral perfusion pressure related to age in paediatric head injury.

BACKGROUND: The principal strategy for managing head injury is to reduce the frequency and severity of secondary brain insults from intracranial pressure (ICP) and cerebral perfusion pressure (CPP), and hence improve outcome. Precise critical threshold levels have not been determined in head injured children. OBJECTIVE: To create a novel pressure-time index (PTI) measuring both duration and amplitude of insult, and then employ it to determine critical insult thresholds of ICP and CPP in children. METHODS: Prospective, observational, physiologically based study from Edinburgh and Newcastle, using patient monitored blood pressure, ICP, and CPP time series data. The PTI for ICP and CPP for 81 children, using theoretical values derived from physiological norms, was varied systematically to derive critical insult thresholds which delineate Glasgow outcome scale categories. RESULTS: The PTI for CPP had a very high predictive value for outcome (receiver operating characteristic analyses: area under curve = 0.957 and 0.890 for mortality and favourable outcome, respectively) and was more predictive than for ICP. Initial physiological values most accurately predicted favourable outcome. The CPP critical threshold values determined for children aged 2-6, 7-10, and 11-15 years were 48, 54, and 58 mm Hg. respectively. CONCLUSIONS: The PTI is the first substantive paediatric index of total ICP and CPP following head injury. The insult thresholds generated are identical to age related physiological values. Management guidelines for paediatric head injuries should take account of these CPP thresholds to titrate appropriate pressor therapy.

Which paediatric head injured patients might benefit from decompression? Thresholds of ICP and CPP in the first six hours.

Severe head injury in childhood continues to be associated with considerable mortality and morbidity. Early surgical decompression may be beneficial and the objective of this study was to examine the relationship between age-related thresholds of mean intracranial pressure (ICP) and cerebral perfusion pressure (CPP) over the first 6 hours and age outcome in paediatric head injury patients. A total of 209 head injured children admitted to five UK hospitals were studied. Patients aged 2 to 16 years were included if they had a minimum of six hours of invasive pressure monitoring. Mean values of ICP and CPP over this period were calculated and compared to those with independent (good recovery and moderate disability) and poor outcome (severe disability, and death) for different age groups. There were 148 children with independent outcome (92 good recovery, 56 moderately disabled), and 61 with poor outcome (30 severely disabled, 31 deaths). There was a significant difference between those with independent compared to poor outcome in relation to ICP (p < 0.001) and CPP (p < 0.001). Patients were divided into three groups according to age. The sensitivity of ICP and CPP in predicting outcome was similar for all groups but the specificity differed between groups. At a CPP of 50 mmHg the specificity varied between the age groups (2 to 6 years: 0.47, 7 to 10 years: 0.28 and 11 to 16 years: 0.10) and similarly for an ICP of 25 mmHg (2 to 6 years: 0.53, 7 to 10 years: 0.44 and 11 to 16 years: 0.38). Younger children may be able to tolerate lower perfusion pressures and still have an independent outcome. Our threshold values for young children are likely to be important in the identification of patients who might benefit from new treatments such as surgical decompression.

Quantification of secondary CPP insult severity in paediatric head injured patients using a pressure-time index.

This paper describes and validates a new Cumulative Pressure-Time Index (CPT) which takes into account both duration and degree of cerebral perfusion pressure (CPP) derangement and determines critical thresholds for CPP, in a paediatric head injury dataset. Sixty-six head-injured children, with invasive minute-to-minute intracranial pressure (ICP) and blood pressure monitoring, had their pre-set CPP derangement episodes (outside the normal range) identified in three childhood age-bands (2-6, 7-10, and 11-16 years) and global outcome assessed at six months post injury. The new cumulative pressure-time index more accurately predicted outcome than previously used summary measures and by varying the threshold CPP values, it was found that these physiological threshold values (< or = 48, < or = 52 and < or = 56 mmHg for 2-6, 7-10, and 11-16 years respectively) best predicted brain insult in terms of subsequent mortality and morbidity.

Inner calvarial erosion from traumatic subdural haematoma in infancy.

CASE REPORT: This is a report of a case of a subdural haematoma in infancy of possible non-accidental aetiology with raised pericerebral pressure, which we postulate has eroded the inner table of the cranial bones and resulted in leakage of marrow precursor cells into the extradural space. RESULT: Subdural tapping via the fontanelle has created a channel allowing subsequent ingress of nucleated red cell precursors into the subdural space. This addition to the subdural collection has prolonged its course necessitating subduro-peritoneal shunting.

Age-related differences in intracranial pressure and cerebral perfusion pressure in the first 6 hours of monitoring after children's head injury: association with outcome.

OBJECTIVES: Severe head injury in childhood is associated with considerable mortality and morbidity. In this study we determined age-related differences in the relationship between outcome and intracranial pressure (ICP) and cerebral perfusion pressure (CPP) in the first 6 h of monitoring in a large cohort of head-injured children. METHODS: Two hundred and thirty-five head-injured children (admitted to five UK hospitals over a 15-year period) in whom intracranial pressure monitoring was clinically indicated were studied. RESULTS: Patients were divided into three age groups (2-6, 7-10 and 11-16 years). The sensitivity of ICP and CPP were similar. Differences were found in the specificity of ICP and CPP for each group and these were more marked for CPP. For a specificity of 50% the pressures were 53, 63 and 66 mmHg for the three age groups. CONCLUSIONS: There are age-related differences in the specificity of intracranial pressure and cerebral perfusion pressure in relation to outcome. These differences may be important in the clinical management of head-injured children. Thus cerebral perfusion pressures of 53, 63 and 66 mmHg should be the minimum to strive for in these three age groups respectively.

Traumatic brain injury in childhood: intensive care time series data and outcome.

Age-specific norms are necessary to determine potential secondary brain insult after head injury in children. We describe and quantify the secondary physiological derangement recorded in children of different ages following traumatic brain injury, and relate it to outcome at 12 months post-injury. Prospective time-series data (including intracranial pressure, arterial blood pressure, cerebral perfusion pressure, oxygen saturation, temperature and heart rate) downloaded from ICU monitors, were examined to identify abnormal (i.e. outside normal age-specific limits) recordings lasting more than 5 min. Cumulated total duration of derangement was calculated for each parameter and as a percentage of the time that the ICP monitor was in situ. Univariate and multivariate logistic regression modelling was used to evaluate predictors of outcome. Age-specificity allows realistic comparisons of physiological data among children. Duration of age-specific derangement of CPP was found to predict outcome (dead v. alive: p = 0.003 and Glasgow Outcome Score 1-3 v. 4-5, i.e. poor v. independent outcome p = 0.004).

Cerebral atrophy following shaken impact syndrome and other non-accidental head injury (NAHI).

PURPOSE OF THE STUDY: To determine the frequency of cerebral atrophy and microcephaly in a group of children with sequential MRI brain scans after surviving a non-accidental head injury (n = 16). METHODS: Serial head circumference measurements (OFC) were extracted and plotted on standard growth charts for each child retrospectively to determine the frequency of secondary microcephaly. Cerebral atrophy was diagnosed and quantified by measurement of the ventricular/cortical ratio on coronal images of the sequential scans. RESULTS: Acquired microcephaly was found in 15 children (93.8%) over a median follow-up period of 67.93 weeks. There was a significant reduction in the median Z-score for the OFC at the most recent follow-up when compared with that at presentation (p < 0.001, Wilcoxon Signed Rank Test). Cerebral atrophy was found to be the cause of the microcephaly in eight of the 15 children and was evident as early as 9 days after presentation. CONCLUSION: A large proportion of the cohort (93.8%) develops acquired microcephaly after an inflicted head injury and cerebral atrophy is responsible in half of these cases.

Graphical display of variability and inter-relationships of pressure signals in children with traumatic brain injury.

A prospective observational study was undertaken to examine time series ICU data of pressure variables (mean arterial pressure (MAP), intracranial pressure (ICP) and cerebral perfusion pressure (CPP)) and relate their variability (SD) to outcome, together with simple graphical displays which could be useful at the ICU bedspace. Forty-three children (aged < 1-15 years) were admitted to the intensive care unit for Regional Neurosurgical Service, Edinburgh, following traumatic brain injury (TBI). The standard deviations from 221,291 validated pressure data measurements (representing three variables) were calculated for the duration of ICP monitoring (and in 48 h epochs from the time of injury). Data were displayed on polygraphs, and several well-defined 'patterns' were described. The standard deviations of MAP, ICP and CPP for the total duration of monitoring were found to be significantly related to survival (p = 0.003, <0.001 and 0.005, respectively), while the SD of ICP alone was strongly related to global recovery (p = 0.008) in the first 48 h post-injury. Patterns in 104 epochs (each of 48 h) were identified. Ninety-two were of the type I (MAP > CPP > ICP) pattern and 12 were of the non-type I pattern. Glasgow Outcome Scale scores at 12 months were significantly related to the dichotomized pattern type (Fisher's exact test p < 0.001 for both alive versus dead and independent versus dependent outcomes). Only one patient with type I pattern died in this series. While variability of ICP during the first 48 h post-injury is predictive of the outcome, the pattern behaviour of three pressure signals gives useful outcome prediction information throughout monitoring. These displays may help interpret some of the plethora of data produced at the bedside.

Long-term risks and benefits of a separate CSF access device with ventriculoperitoneal shunting in childhood hydrocephalus.

To determine the long-term risks and benefits of a separate CSF reservoir in the management of 52 children (23 males, 29 females) with shunted hydrocephalus, a retrospective study was performed comparing the use and complications after separate reservoir insertion, with a prereservoir control period. Median age at first shunt insertion was 1 month and median age at reservoir insertion was 2 years 6 months. Median follow-up for shunt with the additional reservoir was 19 years 1 month. There was no mortality due to shunt failure nor CNS infection, and there were significantly fewer episodes of ventriculitis (p < 0.01) and shunt blockage (p < 0.0001) compared with the prereservoir period. There was no hemiplegia, epilepsy, visual, nor cognitive loss from the additional reservoir. The reservoir was used for access in 344 attendances (mean 6.62 attendances per patient) for diagnosis or treatment of raised pressure or CNS infection. It was concluded that a separate CSF reservoir is useful in the long-term management of patients with shunted hydrocephalus and is without mortality or significant increased morbidity.

Pressure compensation in shunt-dependent hydrocephalus with CSF shunt malfunction.

This study is a retrospective analysis of intracranial pressure (ICP) and cerebral perfusion pressure (CPP) data from 56 children with active hydrocephalus and cerebrospinal fluid (CSF) shunt malfunction. The pressures were measured from a separately sited CSF access device placed in the frontal horn of the lateral ventricle. Of the patients, 79% had an elevated ICP (mean 20+/-12 mmHg). A subgroup of patients demonstrated ten different forms of CSF-filled swelling. This group had significantly lower ICP recordings (P=0.000075) with a mean ICP of 8.5 mmHg compared with the remainder (22.9 mmHg). This pressure 'compensation' was because of additional nonphysiological accommodation of CSF volume. Overall the CPP was normal in 35% of cases despite normal ICP occurring in only 11% of cases. The CPPs were not significantly different in those with and without compensation. Measurement of ICP may not always be a reliable indicator of shunt malfunction in shunt-dependent children who present with compensatory CSF-filled spaces.

Annual incidence of shaken impact syndrome in young children.

We looked at the incidence and demography of nonaccidental head injury in children in a prospective population-based study of paediatric units in Scotland during 1998-99. Shaken impact syndrome occurs with an annual incidence of 24.6 per 100000 children younger than 1 year (95% CI 14.9-38.5). Cases are more common in urban regions, and during autumn and winter months. The risk of a child suffering non-accidental head injury by age 1 year is one in 4065. These brain injuries occur almost exclusively in young infants (median age 2.2 months).

Early posttraumatic seizures in non-accidental head injury: relation to outcome.

To document the characteristics of early posttraumatic seizures (EPTS) in non-accidental head injury (NAHI), and examine their relation with outcome, a retrospective study was carried out. All children with NAHI admitted to the Royal Hospital for Sick Children, Edinburgh, since 1981 were identified. The characteristics of EPTS, EEG, and outcome were noted. Forty-four cases were identified. The average age of children at presentation was 5.9 months. Thirty-two of these children had EPTS. The median length of follow-up was 3 years. The mortality rate was six in 44 (14%). The neurodevelopmental outcome correlated significantly with the presence and severity of EPTS (Tau=0.317,p=0.017). Of survivors, 22% developed late posttraumatic epilepsy; the outcome in those with epilepsy was significantly worse than those without (p<0.0001). It was concluded that the severity of the primary brain injury dictates the severity of the EPTS and neurodevelopmental status at follow-up.

Magnetic resonance imaging in acute non-accidental head injury.

Making the diagnosis of non-accidental head injury, particularly in the acute illness, can be difficult. The aim of this retrospective study was to evaluate the use of magnetic resonance imaging in the acute presentation of non-accidental head injury. Twelve cases admitted to the Royal Hospital for Sick Children, Edinburgh with a diagnosis of non-accidental head injury, and who had magnetic resonance imaging in the acute illness, were identified. The average age was 5.7 mo (range 1 to 34 mo). The mechanism of the primary injury was whiplash-shaking injury syndrome with impact in four cases and without evidence of impact in seven; in one case there was a compression injury. The magnetic resonance imaging findings reflected the pathological consequences of rotational acceleration-deceleration injury and did not differ between those cases with evidence of impact and those without. Subdural haematomas were identified in all cases; the commonest location for subdural blood was the subtemporal region. It is surprising and important that the most frequent location of subdural blood was in the subtemporal area. This is an area difficult to assess by computerized tomography. Evidence of repeated injuries was found in two cases. These findings confirm the value of magnetic resonance imaging in the acute phase of non-accidental head injury.

The relation between intracranial pressure and outcome in non-accidental head injury.

The aim of this retrospective study was to ascertain whether physiological derangement and potential secondary brain insult from raised intracranial pressure (ICP) or reduced cerebral perfusion pressure (CPP) in non-accidental head injury (NAHI) influences outcome. Any child who had a diagnosis of NAHI and had ICP monitoring or measurements during the acute illness was entered in the study. Seventeen children with an average age 5.1 months (range 1 to 20 months) were identified. Details of the acute encephalopathy, lowest mean arterial blood pressure (MAP), mean of maximum ICP measured, lowest CPP, and neurodevelopmental outcome at follow up were obtained from the hospital case notes. Seshia's (1994) outcome classification scale was used. The lowest CPP was very significantly related to outcome (P=0.0047, tau=-0.544). Mean of maximum ICP did not correlate with outcome. The lowest MAP was significantly related to outcome (P=0.039). It was concluded that the degree of secondary brain insult from reduced CPP influences outcome.