Anatomical and Physiological Differences between Children and Adults Relevant to Traumatic Brain Injury and the Implications for Clinical Assessment and Care

General and central nervous system anatomy and physiology in children is different to that of adults and this is relevant to traumatic brain injury (TBI) and spinal cord injury. The controversies and uncertainties in adult neurotrauma are magnified by these differences, the lack of normative data for children, the scarcity of pediatric studies, and inappropriate generalization from adult studies. Cerebral metabolism develops rapidly in the early years, driven by cortical development, synaptogenesis, and rapid myelination, followed by equally dramatic changes in baseline and stimulated cerebral blood flow. Therefore, adult values for cerebral hemodynamics do not apply to children, and children cannot be easily approached as a homogenous group, especially given the marked changes between birth and age 8. Their cranial and spinal anatomy undergoes many changes, from the presence and disappearance of the fontanels, the presence and closure of cranial sutures, the thickness and pliability of the cranium, anatomy of the vertebra, and the maturity of the cervical ligaments and muscles. Moreover, their systemic anatomy changes over time. The head is relatively large in young children, the airway is easily compromised, the chest is poorly protected, the abdominal organs are large. Physiology changes—blood volume is small by comparison, hypothermia develops easily, intracranial pressure (ICP) is lower, and blood pressure normograms are considerably different at different ages, with potentially important implications for cerebral perfusion pressure (CPP) thresholds. Mechanisms and pathologies also differ—diffuse injuries are common in accidental injury, and growing fractures, non-accidental injury and spinal cord injury without radiographic abnormality are unique to the pediatric population. Despite these clear differences and the vulnerability of children, the amount of pediatric-specific data in TBI is surprisingly weak. There are no robust guidelines for even basics aspects of care in children, such as ICP and CPP management. This is particularly alarming given that TBI is a leading cause of death in children. To address this, there is an urgent need for pediatric-specific clinical research. If this goal is to be achieved, any clinician or researcher interested in pediatric neurotrauma must be familiar with its unique pathophysiological characteristics.

The pathogenesis of tuberculous meningitis

Tuberculosis (TB) remains a leading cause of death globally. Dissemination of TB to the brain results in the most severe form of extrapulmonary TB, tuberculous meningitis (TBM), which represents a medical emergency associated with high rates of mortality and disability. Via various mechanisms the Mycobacterium tuberculosis (M.tb) bacillus disseminates from the primary site of infection and overcomes protective barriers to enter the CNS. There it induces an inflammatory response involving both the peripheral and resident immune cells, which initiates a cascade of pathologic mechanisms that may either contain the disease or result in significant brain injury. Here we review the steps from primary infection to cerebral disease, factors that contribute to the virulence of the organism and the vulnerability of the host and discuss the immune response and the clinical manifestations arising. Priorities for future research directions are suggested.

Early decompressive craniotomy in children with severe traumatic brain injury

INTRODUCTION

Decompressive craniectomy remains a controversial procedure in the treatment of raised intracranial pressure (ICP) associated with post-traumatic brain swelling. Although there are a number of studies in adults published in the literature on this topic, most commonly as a salvage procedure in the treatment of refractory raised ICP, there are few that investigate it primarily in children with head injuries.

AIM

Our aim was to report the experience with decompressive craniotomy in children with severe traumatic brain injury (TBI) at the Red Cross Children's' hospital.

METHODS

This study reports five patients in whom decompressive craniectomy or craniotomy with duraplasty was used as an early, aggressive treatment of raised ICP causing secondary acute neurological deterioration after head injury. The rationale was to save the patient from acute cerebral herniation and to prevent exposure to a prolonged course of intracranial hypertension.

RESULTS

All patients benefited from the procedure, demonstrating control of ICP, radiological improvement and neurological recovery. Long-term follow-up was available, with outcome assessed at a minimum of 14 months after injury.

DISCUSSION

The early approach to the use of decompressive craniotomy in the treatment of severe traumatic brain injury (TBI) with secondary deterioration due to raised ICP is emphasised. A favourable outcome was achieved in all of the cases presented. The potential benefit of decompressive craniectomy/craniotomy in the management of children with severe TBI is discussed.

Transcranial Doppler pulsatility index is not a reliable indicator of intracranial pressure in children with severe traumatic brain injury

BACKGROUND

The TCD-derived PI has been associated with ICP in adult studies but has not been well investigated in children. We examined the relationship between PI and ICP and CPP in children with severe TBI.

METHODS

Data were prospectively collected from consecutive TCD studies in children with severe TBI undergoing ICP monitoring. Ipsilateral ICP and CPP values were examined with Spearman correlation coefficient (mean values and raw observations), with a GEE, and as binary values (1 and 20 mm Hg, respectively).

RESULTS

Thirty-four children underwent 275 TCD studies. There was a weak relationship between mean values of ICP and PI (P = .04, r = 0.36), but not when raw observations (P = .54) or GEE (P = .23) were used. Pulsatility index was 0.76 when ICP was lower than 20 mm Hg and 0.86 when ICP was 20 mm Hg or higher. When PI was 1 or higher, ICP was lower than 20 mm Hg in 62.5% (25 of 40 studies), and when ICP was 20 mm Hg or higher, PI was lower than 1 in 75% (46 of 61 studies). The sensitivity and specificity of a PI threshold of 1 for examining the ICP threshold of 20 mm Hg were 25% and 88%, respectively. The relationship between CPP and PI was stronger (P = .001, r = -0.41), but there were too few observations below 50 mm Hg to examine PI at this threshold.

CONCLUSION

The absolute value of the PI is not a reliable noninvasive indicator of ICP in children with severe TBI. Further study is required to examine the relationship between PI and a CPP threshold of 50 mm Hg.

Biomarkers of Cerebral Injury and Inflammation in Pediatric Tuberculous Meningitis

Background

Tuberculous meningitis (TBM) leads to death or disability in half the affected individuals. Tools to assess severity and predict outcome are lacking. Neurospecific biomarkers could serve as markers of the severity and evolution of brain injury, but have not been widely explored in TBM. We examined biomarkers of neurological injury (neuromarkers) and inflammation in pediatric TBM and their association with outcome.

Methods

Blood and cerebrospinal fluid (CSF) of children with TBM and hydrocephalus taken on admission and over 3 weeks were analyzed for the neuromarkers S100B, neuron-specific enolase (NSE), and glial fibrillary acidic protein (GFAP), in addition to multiple inflammatory markers. Results were compared with 2 control groups: patients with (1) a fatty filum (abnormal filum terminale of the spinal cord); and (2) pulmonary tuberculosis (PTB). Imaging was conducted on admission and at 3 weeks. Outcome was assessed at 6 months.

Results

Data were collected from 44 patients with TBM (cases; median age, 3.3 [min-max 0.3-13.1] years), 11 fatty filum controls (median age, 2.8 [min-max 0.8-8] years) and 9 PTB controls (median age, 3.7 [min-max 1.3-11.8] years). Seven cases (16%) died and 16 (36%) had disabilities. Neuromarkers and inflammatory markers were elevated in CSF on admission and for up to 3 weeks, but not in serum. Initial and highest concentrations in week 1 of S100B and NSE were associated with poor outcome, as were highest concentration overall and an increasing profile over time in S100B, NSE, and GFAP. Combined neuromarker concentrations increased over time in patients who died, whereas inflammatory markers decreased. Cerebral infarcts were associated with highest overall neuromarker concentrations and an increasing profile over time. Tuberculomas were associated with elevated interleukin (IL) 12p40, interferon-inducible protein 10, and monocyte chemoattractant protein 1 concentrations, whereas infarcts were associated with elevated tumor necrosis factor α, macrophage inflammatory protein 1α, IL-6, and IL-8.

Conclusions

CSF neuromarkers are promising biomarkers of injury severity and are predictive of mortality. An increasing trend suggested ongoing brain injury, even though markers of inflammation declined with treatment. These findings could offer novel insight into the pathophysiology of TBM.

Pressure autoregulation, intracranial pressure, and brain tissue oxygenation in children with severe traumatic brain injury

OBJECT

Cerebral pressure autoregulation is an important neuroprotective mechanism that stabilizes cerebral blood flow when blood pressure (BP) changes. In this study the authors examined the association between autoregulation and clinical factors, BP, intracranial pressure (ICP), brain tissue oxygen tension (PbtO(2)), and outcome after pediatric severe traumatic brain injury (TBI). In particular we examined how the status of autoregulation influenced the effect of BP changes on ICP and PbtO(2).

METHODS

In this prospective observational study, 52 autoregulation tests were performed in 24 patients with severe TBI. The patients had a mean age of 6.3 +/- 3.2 years, and a postresuscitation Glasgow Coma Scale score of 6 (range 3-8). All patients underwent continuous ICP and PbtO(2) monitoring, and transcranial Doppler ultrasonography was used to examine the autoregulatory index (ARI) based on blood flow velocity of the middle cerebral artery after increasing mean arterial pressure by 20% of the baseline value. Impaired autoregulation was defined as an ARI < 0.4 and intact autoregulation as an ARI >or= 0.4. The relationships between autoregulation (measured as both a continuous and dichotomous variable), outcome, and clinical and physiological variables were examined using multiple logistic regression analysis.

RESULTS

Autoregulation was impaired (ARI < 0.4) in 29% of patients (7 patients). The initial Glasgow Coma Scale score was significantly associated with the ARI (p = 0.02, r = 0.32) but no other clinical factors were associated with autoregulation status. Baseline values at the time of testing for ICP, PbtO(2), the ratio of PbtO(2)/PaO(2), mean arterial pressure, and middle cerebral artery blood flow velocity were similar in the patients with impaired or intact autoregulation. There was an inverse relationship between ARI (continuous and dichotomous) with a change in ICP (continuous ARI, p = 0.005; dichotomous ARI, p = 0.02); that is, ICP increased with the BP increase when ARI was low (weak autoregulation). The ARI (continuous and dichotomous) was also inversely associated with a change in PbtO(2) (continuous ARI, p = 0.002; dichotomous ARI, p = 0.02). The PbtO(2) increased when BP was increased in most patients, even when the ARI was relatively high (stronger autoregulation), but the magnitude of this response was still associated with the ARI. There was no relationship between the ARI and outcome.

CONCLUSIONS

These data demonstrate the influence of the strength of autoregulation on the response of ICP and PbtO(2) to BP changes and the variability of this response between individuals. The findings suggest that autoregulation testing may assist clinical decision-making in pediatric severe TBI and help better define optimal BP or cerebral perfusion pressure targets for individual patients.

Intracranial pressure monitoring for traumatic brain injury in the modern era

INTRODUCTION

Intracranial pressure (ICP) has become a cornerstone of care in adult and pediatric patients with traumatic brain injury (TBI).

DISCUSSION

Despite the fact that continuous monitoring of ICP in TBI was described almost 60 years ago, there are no randomized trials confirming the benefit of ICP monitoring and treatment in TBI. There is, however, a large body of clinical evidence showing that ICP monitoring influences treatment and leads to better outcomes if part of protocol-driven therapy. However, treatment of ICP has adverse effects, and there are several questions about ICP management that have yet to be definitively answered, particularly in pediatric TBI. This review examines the history and evolution of ICP monitoring, pathophysiological concepts that influence ICP interpretation, ongoing controversies, and the place of ICP monitoring in modern neurocritical care.

Does adherence to treatment targets in children with severe traumatic brain injury avoid brain hypoxia? A brain tissue oxygenation study

OBJECTIVE

Most physicians rely on conventional treatment targets for intracranial pressure, cerebral perfusion pressure, systemic oxygenation, and hemoglobin to direct management of traumatic brain injury (TBI) in children. In this study, we used brain tissue oxygen tension (PbtO2) monitoring to examine the association between PbtO2 values and outcome in pediatric severe TBI and to determine the incidence of compromised PbtO2 in patients for whom acceptable treatment targets had been achieved.

METHODS

In this prospective observational study, 26 children with severe TBI and a median postresuscitation Glasgow Coma Scale score of 5 were managed with continuous PbtO2 monitoring. The relationships between outcome and the 6-hour period of lowest PbtO2 values and the length of time that PbtO2 was less than 20, 15, 10, and 5 mmHg were examined. The incidence of reduced PbtO2 for each threshold was evaluated where the following targets were met: intracranial pressure less than 20 mmHg, cerebral perfusion pressure greater than 50 mmHg, arterial oxygen tension greater than 60 mmHg (and peripheral oxygen saturation > 90%), and hemoglobin greater than 8 g/dl.

RESULTS

There was a significant association between poor outcome and the 6-hour period of lowest PbtO2 and length of time that PbtO2 was less than 15 and 10 mmHg. Multiple logistic regression analysis showed that low PbtO2 had an independent association with poor outcome. Despite achieving the management targets described above, 80% of patients experienced one or more episodes of compromised PbtO2 (< 20 mmHg), and almost one-third experienced episodes of brain hypoxia (PbtO2 < 10 mmHg).

CONCLUSION

Reduced PbtO2 is associated with poor outcome in pediatric severe TBI. In addition, many patients experience episodes of compromised PbtO2 despite achieving acceptable treatment targets.

The neurosurgical and acute care management of tuberculous meningitis: evidence and current practice

Tuberculous meningitis (TBM) is the most lethal form of tuberculosis; mortality is high and survivors are often left neurologically disabled. Several factors contribute to this poor outcome, including cerebrovascular involvement with ensuing brain ischemia, hydrocephalus and raised intracranial pressure, direct parenchymal injury, hyponatremia, and seizures. However, there is little standardisation of management with respect to these aspects of care across different centers, largely because the evidence base for much of the supportive treatment of patients with TBM is poor, leading to substantial differences in management protocols. This review emphasizes some of the uncertainties and controversies pertinent to the surgical treatment of hydrocephalus in TBM and the medical supportive management of the patient during the acute phase of the illness, with the aims of raising awareness and stimulating debate. The focus is on the management of hyponatremia, cerebral hemodynamics and intracranial pressure, medical and surgical treatment for hydrocephalus, and the intensive care management of patients in the acute severe stage of the illness. Very little data are available to address these issues with good evidence and so institutional preferences are common; this is perhaps most notable for the management of hydrocephalus, and so in this the review highlights our personal practice. The brain needs protection while the source of the illness is addressed. Without attention to these aspects of management there will always be a limit to the effectiveness of antimicrobial therapy in TBM, so there is a strong imperative for the controversies to be resolved and the limitations of our current care to be addressed. Existing protocols should be rigorously examined and novel strategies to protect the brain should be explored. To this end, a prospective, multi-disciplinary and multi-centered approach may yield answers to the questions raised in this review.

Methods of monitoring brain oxygenation

INTRODUCTION

Posttraumatic brain ischemia or hypoxia is a major potential cause of secondary injury that may lead to poor outcome. Avoidance, or amelioration, of this secondary injury depends on early diagnosis and intervention before permanent injury occurs. However, tools to monitor brain oxygenation continuously in the neuro-intensive care unit have been lacking.

DISCUSSION

In recent times, methods of monitoring aspects of brain oxygenation continuously by the bedside have been evaluated in several experimental and clinical series and are potentially changing the way we manage head-injured patients. These monitors have the potential to alert the clinician to possible secondary injury and enable intervention, help interpret pathophysiological changes (e.g., hyperemia causing raised intracranial pressure), monitor interventions (e.g., hyperventilation for increased intracranial pressure), and prognosticate. This review focuses on jugular venous saturation, brain tissue oxygen tension, and near-infrared spectroscopy as practical methods that may have an important role in managing patients with brain injury, with a particular focus on the available evidence in children. However, to use these monitors effectively and to understand the studies in which these monitors are employed, it is important for the clinician to appreciate the technical characteristics of each monitor, as well as respective strengths and limitations of each. It is equally important that the clinician understands relevant aspects of brain oxygen physiology and head trauma pathophysiology to enable correct interpretation of the monitored data and therefore to direct an appropriate therapeutic response that is likely to benefit, not harm, the patient.

Brain tissue oxygen tension monitoring in pediatric severe traumatic brain injury. Part 2: Relationship with clinical, physiological, and treatment factors

INTRODUCTION

Brain tissue oxygen tension (PbtO(2)) monitoring is used increasingly in adult severe traumatic brain injury (TBI) management. Several factors are known to influence PbtO(2) in adults, but the variables that affect PbtO(2) in pediatric TBI are not well described. This study examines the relationships between PbtO(2) and (1) physiological markers of potential secondary insults commonly used in pediatric TBI, in particular intracranial pressure (ICP), cerebral perfusion pressure (CPP), and systemic hypoxia, and (2) other clinical factors and treatment received that may influence PbtO(2).

MATERIALS AND METHODS

In this prospective observational study, 52 children (mean age, 6.5 +/- 3.4 years; range, 9 months to 14 years old) with severe TBI and a median post-resuscitation Glasgow Coma Score (GCS) of 5 were managed with continuous PbtO(2) monitoring. The relationships between PbtO(2) parameters (Pbt)(2)(low), PbtO(2) < 5, PbtO(2) < 10, and mPbtAO(2)(24)) and clinical, physiological, and treatment factors were explored using time-linked data and Spearman's correlation coefficients.

RESULTS

No clinical, physiological, or treatment variable was significantly associated with all PbtO(2) parameters, but individual associations were found with initial GCS (PbtO(2) < 5, p = 0.0113), admission Pediatric Trauma Score (PbtO(2) < 10, 0.0175), mICP > 20 (mPbtO(2)(24), p = 0.0377), CPP(low) (PbtO(2)(low), p = 0.0065), CPP < 40 (PbtO(2)(low), p = 0.0269; PbtO(2) < 5, p = 0.0212), P(a)O(2) < 60 (mPbtO(2)(24), p = 0.0037), S(a)O(2) < 90 (PbtO(2)(low), p = 0.0438), and use of inotropes during ICU care (PbtO(2)(low), p = 0.0276; PbtO(2) < 10, p = 0.0277; p = mPbtO(2)(24)).

CONCLUSION

Delivery of oxygen to the brain is important to limit secondary neuronal injury after severe TBI. Our data show that PbtO(2) is poorly predicted by clinical and physiological factors commonly measured in the pediatric ICU. Multimodality monitoring may be needed to detect all secondary cerebral insults in pediatric TBI.

Clinical characteristics and neurodevelopmental outcomes of children with tuberculous meningitis and hydrocephalus

AIM

Tuberculous meningitis (TBM) is a lethal and commonly occurring form of extra-pulmonary tuberculosis in children, often complicated by hydrocephalus which worsens outcome. Despite high mortality and morbidity, little data on the impact on neurodevelopment exists. We examined the clinical characteristics, and clinical and neurodevelopmental outcomes of TBM and hydrocephalus.

METHOD

Demographic and clinical data (laboratory and radiological findings) were prospectively collected on children treated for probable and definite TBM with hydrocephalus. At 6 months, clinical outcome was assessed using the Paediatric Cerebral Performance Category Scale and neurodevelopmental outcome was assessed with the Griffiths Mental Development Scale - Extended Version.

RESULTS

Forty-four patients (median age 3y 3mo, range 3mo-13y 1mo, [SD 3y 5mo]) were enrolled. The mortality rate was 16%, three patients (6.8%) were in a persistent vegetative state, two were severely disabled (4.5%), and 11 (25%) suffered mild-moderate disability. All cases demonstrated neurodevelopmental deficits relative to controls. Multiple or large infarcts were prognostic of poor outcome.

INTERPRETATION

Neurological and neurodevelopmental deficits are common after paediatric TBM with hydrocephalus, and appear to be related to ongoing cerebral ischaemia and consequent infarction. The impact of TBM on these children is multidimensional and presents short- and long-term challenges.

The relationship between intracranial pressure and brain oxygenation in children with severe traumatic brain injury

BACKGROUND

Intracranial pressure (ICP) monitoring is a cornerstone of care for severe traumatic brain injury (TBI). Management of ICP can help ensure adequate cerebral blood flow and oxygenation. However, studies indicate that brain hypoxia may occur despite normal ICP and the relationship between ICP and brain oxygenation is poorly defined. This is particularly important for children in whom less is known about intracranial dynamics.

OBJECTIVE

To examine the relationship between ICP and partial pressure of brain tissue oxygen (PbtO2) in children with severe TBI (Glasgow Coma Scale score ≤ 8) admitted to Red Cross War Memorial Children's Hospital, Cape Town.

METHODS

The relationship between time-linked hourly and high-frequency ICP and PbtO2 data was examined using correlation, regression, and generalized estimating equations. Thresholds for ICP were examined against reduced PbtO2 using age bands and receiver-operating characteristic curves.

RESULTS

Analysis using more than 8300 hourly (n = 75) and 1 million high-frequency data points (n = 30) demonstrated a weak relationship between ICP and PbtO2 (r = 0.05 and r = 0.04, respectively). No critical ICP threshold for low PbtO2 was identified. Individual patients revealed a strong relationship between ICP and PbtO2 at specific times, but different relationships were evident over longer periods.

CONCLUSION

The relationship between ICP and PbtO2 appears complex, and several factors likely influence both variables separately and in combination. Although very high ICP is associated with reduced PbtO2, in general, absolute ICP has a poor relationship with PbtO2. Because reduced PbtO2 is independently associated with poor outcome, a better understanding of ICP and PbtO2 management in pediatric TBI seems to be needed.

Endoscopic third ventriculostomy in tuberculous meningitis

INTRODUCTION

We report our preliminary experience with two cases of tuberculous meningitis (TBM) in which endoscopic third ventriculostomy (ETV) was performed to treat non-communicating hydrocephalus. For many years, the insertion of ventriculoperitoneal shunts has been the standard treatment for hydrocephalus in patients with TBM, although the indications for and timing of surgery are not uniformly accepted. Shunt insertion is associated with a high incidence of complications, particularly with long-term follow-up. An alternative treatment for hydrocephalus in this group of patients would clearly be of great benefit. The indications for ETV have increased in the last decade, and there are reports of some effectiveness of the procedure in patients with hydrocephalus due to bacterial meningitis. To our knowledge, ETV has not been described in the management of TBM.

METHODS

We report the early results of our preliminary experience with ETV in two patients who presented with neurological compromise due to hydrocephalus and raised intracranial pressure. The clinical context and pre-operative investigation of these patients are presented. The emphasis is placed on the distinction between communicating and non-communicating pathologies as a guide to management options. We detail our surgical findings and the peculiar endoscopic challenges that the condition presented to us. Follow-up in these patients included clinical and investigational data suggesting early effectiveness of the procedure in converting non-communicating hydrocephalus into a communicating one, which can then be treated medically.

DISCUSSION

Endoscopic third ventriculostomy is presented as a new application of a procedure accepted for other indications in the treatment of non-communicating hydrocephalus. There are particular aspects of the use of this procedure related to the unique pathology of TBM that are significantly different. We explain our rationale for endoscopy in these patients, and suggest a protocol in which endoscopy may play a role in the management of patients with raised intracranial pressure due to tuberculous hydrocephalus.

Incidence of spinal abnormalities in patients with spastic diplegia 17 to 26 years after selective dorsal rhizotomy

INTRODUCTION

The aim of this study was to evaluate the mechanical status of the spine in patients with spastic diplegia 17-26 years after selective dorsal rhizotomy (SDR).

METHODS

We compared original radiographic reports from our earlier short-term follow-up study with current X-rays. In addition, we obtained magnetic resonance images (MRI) of the spine and additional information regarding back pain and clinical assessments.

RESULTS

Thirty patients (17 males and 13 females; median age 26.8 years) participated in the current study, with median follow-up times of 4.0 and 21.4 years. Comparison of the X-ray results showed respectively: scoliosis 0% and 57%; kyphosis 0% and 7%; lordosis 21% and 40%; spondylolysis 18% and 37%; and spondylolisthesis grade I occurred in one patient. The only statistically significant difference was found for scoliosis (p < 0.01). The majority had Cobb angles <30 degrees with only two patients with curves of 35 degrees. MRI scans showed spinal stenosis in 27%, black discs in 10%, and disc protrusion in 3%. Daily back pain was reported in 17%, while 23% reported "moderate disability" as a result of back and leg pain. No patient to date has required any surgical intervention on the spine.

CONCLUSIONS

Except for spondylolisthesis, spinal deformities did appear to progress with time. However, this increase was not marked, and the development of relatively mild scoliosis was the only statistically significant increase. This group of patients requires continued follow-up. Further studies are required to ascertain the natural history of spinal deformity in adults with spastic diplegia who have not had SDR.

Endoscopy for tuberculous hydrocephalus

INTRODUCTION

The role of endoscopy in hydrocephalus due to infectious aetiology is unclear. Tuberculous hydrocephalus is a useful model to study because it presents particular challenges and the pathophysiology of the cerebrospinal fluid disturbance is well known.

MATERIALS AND METHODS

We present the results of 24 endoscopic operations in tuberculous meningitis.

RESULT

Endoscopic third ventriculostomy (ETV) was attempted in 17 patients: seven were successful, five failed, and five were not completed due to abnormal anatomy. There were five fenestration procedures, three of which were successful. Endoscopic biopsy of two tuberculomas failed to yield a bacteriological result. These operations were more difficult to perform than for hydrocephalus due to other aetiologies.

CONCLUSION

Although ETV is technically possible in this situation, it is imperative that the patients are adequately selected for the procedure to ensure optimal treatment and that the surgeon has experience with difficult cases.

Imaging Features of the Brain, Cerebral Vessels and Spine in Pediatric Tuberculous Meningitis With Associated Hydrocephalus

BACKGROUND

Pediatric tuberculous meningitis (TBM) leads to high rates of mortality and morbidity. Prompt diagnosis and initiation of treatment are challenging; imaging findings play a key role in establishing the presumptive diagnosis. General brain imaging findings are well reported; however, specific data on cerebral vascular and spinal involvement in children are sparse.

METHODS

This prospective cohort study examined admission and followed up computed tomography brain scans and magnetic resonance imaging scans of the brain, cerebral vessels (magnetic resonance angiogram) and spine at 3 weeks in children treated for TBM with hydrocephalus (HCP; inclusion criteria). Exclusion criteria were no HCP on admission, treatment of HCP or commencement of antituberculosis treatment before study enrollment. Imaging findings were examined in association with outcome at 6 months.

RESULTS

Forty-four patients (median age 3.3 [0.3-13.1] years) with definite (54%) or probable TBM were enrolled. Good clinical outcome was reported in 72%; the mortality rate was 16%. Infarcts were reported in 66% of patients and were predictive of poor outcome. Magnetic resonance angiogram abnormalities were reported in 55% of patients. Delayed tuberculomas developed in 11% of patients (after starting treatment). Spinal pathology was more common than expected, occurring in 76% of patients. Exudate in the spinal canal increased the difficulty of lumbar puncture and correlated with high cerebrospinal fluid protein content.

CONCLUSION

TBM involves extensive pathology in the central nervous system. Severe infarction was predictive of poor outcome although this was not the case for angiographic abnormalities. Spinal disease occurs commonly and has important implications for diagnosis and treatment. Comprehensive imaging of the brain, spine and cerebral vessels adds insight into disease pathophysiology.

The relationship between basal cisterns on CT and time-linked intracranial pressure in paediatric head injury

PURPOSE

Although intracranial pressure (ICP) monitoring is a cornerstone of care for severe traumatic brain injury (TBI), the indications for ICP monitoring in children are unclear. Often, decisions are based on head computed tomography (CT) scan characteristics. Arguably, the patency of the basal cisterns is the most commonly used of these signs. Although raised ICP is more likely with obliterated basal cisterns, the implications of open cisterns are less clear. We examined the association between the status of perimesencephalic cisterns and time-linked ICP values in paediatric severe TBI.

METHODS

ICP data linked to individual head CT scans were reviewed. Basal cisterns were classified as open or closed by blinded reviewers. For the initial CT scan, we examined ICP values for the first 6 h after monitor insertion. For follow-up scans, we examined ICP values 3 h before and after scanning. Mean ICP and any episode of ICP ≥ 20 mmHg during this period were recorded.

RESULTS

Data from 104 patients were examined. Basal cisterns were patent in 51.72% of scans, effaced in 34.48% and obliterated in 13.79%. Even when cisterns were open, more than 40% of scans had at least one episode of ICP ≥ 20 mmHg, and 14% of scans had a mean ICP ≥ 20 mmHg. The specificity of open cisterns in predicting ICP < 20 mmHg was poor (57.9%). Age-related data were worse.

CONCLUSION

Children with severe TBI frequently may have open basal cisterns on head CT despite increased ICP. Open cisterns should not discourage ICP monitoring.

Biomarkers of Brain Injury in Cerebral Infections

BACKGROUND

Central nervous system (CNS) infections present a major burden of disease worldwide and are associated with high rates of mortality and morbidity. Swift diagnosis and initiation of appropriate treatment are vital to minimize the risk of poor outcome; however, tools are lacking to accurately diagnose infection, assess injury severity, and predict outcome. Biomarkers of structural neurological injury could provide valuable information in addressing some of these challenges.

CONTENT

In this review, we summarize experimental and clinical research on biomarkers of neurological injury in a range of CNS infectious diseases. Data suggest that in both adults and children, the biomarkers S100B and neuron-specific enlose (NSE), among others, can provide insight into the pathophysiology of CNS infection and injury severity, evolution, and response to treatment. Research into the added utility of combining a panel of biomarkers and in assessing biomarker association with clinical and radiological outcomes warrants further work. Various factors, including age, the establishment of normative values, and comparison of biomarker concentrations across different testing platforms still present challenges in biomarker application.

SUMMARY

Research regarding the value of biomarkers in CNS infections is still in its infancy. However, early evidence supports their utility in diagnosis and prognosis, and potentially as effective surrogate end points in the assessment of novel interventions.

Air encephalography for hydrocephalus in the era of neuroendoscopy

INTRODUCTION

There is often uncertainty regarding the site of the cerebrospinal fluid (CSF) block in individual patients with hydrocephalus, leading to a significant failure rate for endoscopic third ventriculostomy (ETV) when performed for unconventional pathologies such as postmeningitic and posthaemorrhagic hydrocephalus. We describe the use of lumbar air encephalography (AEG) to refine the indications for ETV in such circumstances.

METHODS

Data from AEG studies used to guide indications for ETV were collected prospectively. The technique and protocol for AEG have been modified from the historical description of the procedure in the interest of safety and to minimise discomfort. In a separate evaluation, the level of the CSF block was determined by one of the authors, who was blinded to the results of the AEG, based on conventional computerised tomographic criteria. These results are compared with those obtained from the AEG.

RESULTS

Forty-five studies were performed over a 2-year period. Thirty-seven were preinterventional, the majority of which demonstrated communicating hydrocephalus. ETV performed in five cases of non-communicating hydrocephalus was successful in each. The prediction of the level of block based on CT criteria was poor.

CONCLUSION

It is often difficult to determine whether hydrocephalus is communicating or not with conventional imaging in the absence of a clearly demonstrable lesional obstruction to the CSF pathways. We have found AEG helpful in excluding patients with communicating hydrocephalus from an inappropriate ETV. On the basis of our experience, we consider the modified procedure safe as long as a strict protocol is followed.

Acute clinical grading in pediatric severe traumatic brain injury and its association with subsequent intracranial pressure, cerebral perfusion pressure, and brain oxygenation

Object

The goal of this paper was to examine the relationship between methods of acute clinical assessment and measures of secondary cerebral insults in severe traumatic brain injury in children.

Methods

Patients who underwent intracranial pressure (ICP), cerebral perfusion pressure (CPP), and brain oxygenation (PbtO2) monitoring and who had an initial Glasgow Coma Scale score, Pediatric Trauma Score, Pediatric Index of Mortality 2 score, and CT classification were evaluated. The relationship between these acute clinical scores and secondary cerebral insult measures, including ICP, CPP, PbtO2, and systemic hypoxia were evaluated using univariate and multivariate analysis.

Results

The authors found significant associations between individual acute clinical scores and select physiological markers of secondary injury. However, there was a large amount of variability in these results, and none of the scores evaluated predicted each and every insult. Furthermore, a number of physiological measures were not predicted by any of the scores.

Conclusions

Although they may guide initial treatment, grading systems used to classify initial injury severity appear to have a limited value in predicting who is at risk for secondary cerebral insults.

Low brain oxygenation and differences in neuropsychological outcomes following severe pediatric TBI

PURPOSE

Traumatic brain injury (TBI) is a leading cause of morbidity and mortality in children. Preventing secondary injury by controlling physiological parameters (e.g. intracranial pressure [ICP], cerebral perfusion pressure [CPP] and brain tissue oxygen [PbtO2]) has a potential to improve outcome. Low PbtO2 is independently associated with poor clinical outcomes in both adults and children. However, no studies have investigated associations between low PbtO2 and neuropsychological and behavioural outcomes following severe pediatric TBI (pTBI).

METHODS

We used a quasi-experimental case-control design to investigate these relationships. A sample of 11 TBI patients with a Glasgow Coma Scale score ≤8 who had PbtO2 and ICP monitoring at the Red Cross War Memorial Children's Hospital underwent neuropsychological evaluation ≥1 year post-injury. Their performance was compared to that of 11 demographically matched healthy controls. We then assigned each TBI participant into one of two subgroups, (1) children who had experienced at least one episode of PbtO2 ≤ 10 mmHg or (2) children for whom PbtO2 > 10 mmHg throughout the monitoring period, and compared their results on neuropsychological evaluation.

RESULTS

TBI participants performed significantly more poorly than controls in several cognitive domains (IQ, attention, visual memory, executive functions and expressive language) and behavioural (e.g. externalizing behaviour) domains. The PbtO2 ≤ 10 mmHg group performed significantly worse than the PbtO2 > 10 mmHg group in several cognitive domains (IQ, attention, verbal memory, executive functions and expressive language), but not on behavioural measures.

CONCLUSION

Results demonstrate that low PbtO2 may be prognostic of not only mortality but also neuropsychological outcomes.

Intracranial pressure and cerebral oxygenation changes after decompressive craniectomy in a child with traumatic brain swelling

CASE REPORT

The authors present the case of a 5-year-old child with severe traumatic brain injury in whom decompressive hemicraniectomy was performed for progressive increased intracranial pressure (ICP) unresponsive to medical treatment. Data from ICP and cerebral tissue oxygenation monitoring in the contralateral hemisphere were recorded, which demonstrated the immediate and delayed mechanical and physiological changes occurring after bony and dural decompression.

DISCUSSION

The role of the procedure and that of the monitoring approach are discussed.