Cerebrospinal fluid dynamics in pediatric pseudotumor cerebri syndrome.

PURPOSE: There is a growing body of evidence highlighting the importance of comprehensive intracranial pressure (ICP) values in pseudotumor cerebri syndrome (PTCS). Due to the highly dynamic nature of ICP, several methods of ICP monitoring have been established, including the CSF infusion study. We have performed a retrospective review of the CSF dynamics measurements for all pediatric patients investigated for PTCS in our center and examined their diagnostic value compared with clinical classification. METHODS: We retrospectively recruited 31 patients under 16 years of age investigated for PTCS by CSF infusion test. We used the clinically provided Friedman classification 13/31 patients with definite PTCS (group A), 13/31 with probable PTCS (group B), and 5/31 not PTCS (group C), to compare CSF dynamics in the 3 groups. RESULTS: CSF pressure (CSFp) was significantly increased in group A (29.18 ± 7.72 mmHg) compared with B (15.31 ± 3.47 mmHg; p = 1.644e-05) and C (17.51 ± 5.87; p = 0.01368). The amplitude (AMP) was higher in the definite (2.18 ± 2.06 mmHg) than in group B (0.68 ± 0.37; p = 0.01382). There was no in either CSFp or AMP between groups B and C. No lower breakpoint of the AMP-P line was observed in group A but was present in 2/13 and 2/5 patients in groups B and C. In group A, sagittal sinus pressure (SSp) and elasticity were the only parameters above threshold (p = 4.2e-06 and p = 0.001953, respectively), In group B, only the elasticity was significantly higher than the threshold (p = 004257). Group C did not have any of the parameters raised. The AUC of CSFp, elasticity, and SSp for the 3 groups was 93.8% (84.8-100% CI). CONCLUSIONS: Monitoring of CSFp and its dynamics, besides providing a more precise methodology for measuring CSFp, could yield information on the dynamic parameters of CSFp that cannot be derived from CSFp as a number, accurately differentiating between the clinically and radiologically derived entities of PTCS.

Shunt infusion studies: impact on patient outcome, including health economics.

OBJECTIVES: The diagnosis of shunt malfunction is often not straightforward. We have explored, in symptomatic shunted patients with hydrocephalus or pseudotumour cerebri syndrome (PTCS), the accuracy of CSF infusion tests in differentiating a functioning shunt from one with possible problems, and the health economic consequences. METHODS: Participants: hydrocephalus/PTCS patients with infusion tests performed from January 2013 until December 2015. We followed patients up after 6 and 12 months from the test to determine whether they had improved, had persisting symptoms or had required urgent revision. We calculated the total cost savings of revision versus infusion tests and standard protocol of revision and ICP monitoring versus infusion tests. RESULTS: Three hundred sixty-five shunt infusion tests had been performed where a shunt prechamber/reservoir was present. For hydrocephalus patients, more than half of the tests (~ 55%, 155 out of 280) showed no shunt malfunction versus 125 with possible malfunction (ages 4 months to 90 years old). For PTCS patients aged 10 to 77 years old, 47 had possible problems and 38 no indication for shunt malfunction. Overall, > 290 unnecessary revisions were avoided over 3 years' time. Two hundred fifty-eight (> 85%) of those non-surgically managed, remained well, did not deteriorate and did not require surgery. No infections were associated with infusion studies. For Cambridge, the overall savings from avoiding revisions was £945,415 annually. CONCLUSIONS: Our results provide evidence of the importance of shunt testing in vivo to confirm shunt malfunction. Avoiding unnecessary shunt revisions carries a strong health benefit for patients that also translates to a significant financial benefit for the National Health Service and potentially for other healthcare systems worldwide.

Correction: Modelling outcomes after paediatric brain injury with admission laboratory values: a machine-learning approach.

A correction to this paper has been published and can be accessed via a link at the top of the paper.

Modelling outcomes after paediatric brain injury with admission laboratory values: a machine-learning approach.

BACKGROUND: Severe traumatic brain injury (TBI) is a leading cause of mortality in children, but the accurate prediction of outcomes at the point of admission remains very challenging. Admission laboratory results are a promising potential source of prognostic data, but have not been widely explored in paediatric cohorts. Herein, we use machine-learning methods to analyse 14 different serum parameters together and develop a prognostic model to predict 6-month outcomes in children with severe TBI. METHODS: A retrospective review of patients admitted to Cambridge University Hospital's Paediatric Intensive Care Unit between 2009 and 2013 with a TBI. The data for 14 admission serum parameters were recorded. Logistic regression and a support vector machine (SVM) were trained with these data against dichotimised outcomes from the recorded 6-month Glasgow Outcome Scale. RESULTS: Ninety-four patients were identified. Admission levels of lactate, H+, and glucose were identified as being the most informative of 6-month outcomes. Four different models were produced. The SVM using just the three most informative parameters was the best able to predict favourable outcomes at 6 months (sensitivity = 80%, specificity = 99%). CONCLUSIONS: Our results demonstrate the potential for highly accurate outcome prediction after severe paediatric TBI using admission laboratory data.

Pre-hospital Predictors of Impaired ICP Trends in Continuous Monitoring of Paediatric Traumatic Brain Injury Patients.

OBJECTIVE: Although secondary insults such as raised intracranial pressure (ICP) or cardiovascular compromise strongly contribute to morbidity, a growing interest can be noticed in how the pre-hospital management can affect outcomes after traumatic brain injury (TBI). The objective of this study was to determine whether pre-hospital co-morbidity has influence on patterns of continuously measured waveforms of intracranial physiology after paediatric TBI. MATERIALS AND METHODS: Thirty-nine patients (mean age, 10 years; range, 0.5-15) admitted between 2002 and 2015 were used for the current analysis. Pre-hospital motor score, pupil reactivity, pre-hospital hypoxia (SpO2 < 90%) and hypotension (mean arterial pressure < 70 mmHg) were documented. ICP and arterial blood pressure (ABP) were monitored continuously with an intraparenchymal microtransducer and an indwelling arterial line. Pressure monitors were connected to bedside computers running ICM+ software. Pressure reactivity was determined as the moving correlation between 30 10-s averages of ABP and ICP (PRx). The mean ICP and PRx were calculated for the whole monitoring period for each patient. RESULTS: Those with pre-hospital hypotension were susceptible to higher ICP [20 (IQR 8) vs 13 (IQR 6) mmHg; p = 0.01] and more frequent ICP plateau waves [median = 0 (IQR 1), median = 4 (IQR 9); p = 0.001], despite having similar MAP, CPP and PRx during monitoring. Those with unreactive pupils tended to have higher ICP than those with reactive pupils (18 vs 14 mmHg, p = 0.08). Pre-hospital hypoxia, motor score and pupillary reactivity were not related to subsequent monitored intracranial or systemic physiology. CONCLUSION: In paediatric TBI, pre-hospital hypotension is associated with increased ICP in the intensive care unit.

Computed Tomography Indicators of Deranged Intracranial Physiology in Paediatric Traumatic Brain Injury.

OBJECTIVE: Computed tomography (CT) of the brain can allow rapid assessment of intracranial pathology after traumatic brain injury (TBI). Frequently in paediatric TBI, CT imaging can fail to display the classical features of severe brain injury with raised intracranial pressure. The objective of this study was to determine early CT brain features that influence intracranial or systemic physiological trends following paediatric TBI. MATERIALS AND METHODS: Thirty-three patients (mean age, 10 years; range, 0.5-16) admitted between 2002 and 2015 were used for the current analysis. Presence of petechial haemorrhages, basal cistern compression, subarachnoid blood, midline shift and extra-axial masses on the initial trauma CT head were assessed. ICP and arterial blood pressure (ABP) were then monitored continuously with an intraparenchymal microtransducer and an indwelling arterial line. Pressure monitors were connected to bedside computers running ICM+ software. Pressure reactivity was determined as the moving correlation between 30, 10-s averages of ABP and ICP (PRx). The mean ICP, ABP, cerebral perfusion pressure (CPP; ABP minus ICP) and PRx were calculated for the whole monitoring period for each patient. RESULTS: The presence of subarachnoid blood was related to higher ICP, higher ABP and a trend toward higher PRx. Smaller basal cisterns were related to increased ICP (R = -0.42, p = 0.02), impaired PRx (R = -0.5, p = 0.003). The presence of an extra-axial mass was associated with deranged PRx (-0.02 vs. 0.41, p = 0.003) and a trend toward higher ICP (14 vs. 40, p = 0.07). Interestingly the degree of midline shift was not related to ICP or PRx. CONCLUSIONS: The size of the basal cisterns, the presence of subarachnoid blood or an extra-axial mass are all related to disturbed ICP and pressure reactivity in this paediatric TBI cohort. Patients with these features are ideal candidates for invasive multimodal monitoring.

Isolated oculomotor nerve palsy in patients with mild head injury.

Isolated oculomotor nerve palsy following head injury is uncommon. It can only be diagnosed with confidence if it is known to have developed immediately following trauma and if adequate investigations exclude secondary causes. The recovery is only partial and this has repercussion on patients' quality of life.

Cerebral Critical Closing Pressure During Infusion Tests.

We studied possible correlations between cerebral hemodynamic indices based on critical closing pressure (CrCP) and cerebrospinal fluid (CSF) compensatory dynamics, as assessed during lumbar infusion tests. Our data consisted of 34 patients with normal-pressure hydrocephalus who undertook an infusion test, in conjunction with simultaneous transcranial Doppler ultrasonography (TCD) monitoring of blood flow velocity (FV). CrCP was calculated from the monitored signals of ICP, arterial blood pressure (ABP), and FV, whereas vascular wall tension (WT) was estimated as CrCP - ICP. The closing margin (CM) expresses the difference between ABP and CrCP. ICP increased during infusion from 6.67 ± 4.61 to 24.98 ± 10.49 mmHg (mean ± SD; p < 0.001), resulting in CrCP rising by 22.93 % (p < 0.001), with WT decreasing by 11.33 % (p = 0.005) owing to vasodilatation. CM showed a tendency to decrease, albeit not significantly (p = 0.070), because of rising ABP (9.12 %; p = 0.005), and was significantly different from zero for the whole duration of the tests (52.78 ± 22.82 mmHg; p < 0.001). CM at baseline correlated inversely with brain elasticity (R = -0.358; p = 0.038). Neither CrCP nor WT correlated with CSF compensatory parameters. Overall, CrCP increases and WT decreases during infusion tests, whereas CM at baseline pressure may act as a characterizing indicator of the cerebrospinal compensatory reserve.

Student-selected components in neurosurgery.

Student-selected components (SSCs) are protected periods of time in the undergraduate medical curriculum which allow students to explore an area of medicine they are interested in. They are particularly valuable in exposing students to smaller specialties like neurosurgery, which are often sparsely covered in the rest of the undergraduate curriculum. Moreover, they provide opportunities for students interested in pursuing a career in neurosurgery to increase their likelihood of being successful in specialty training applications. In this article, we summarise our department's experience of hosting SSCs. Furthermore, we have set out to establish a series of achievable objectives over the course of a typical SSC in neurosurgery. This includes the possibility of participation in research and audit, which, if well planned, can be rewarding for both the student and the host unit. SSCs are an effective means of exposing medical students to neurosurgery and provide a multitude of opportunities for enhancing clinical competencies and career development.

Phase-shift between arterial flow and ICP pulse during infusion test.

BACKGROUND: The dynamic relationship between pulse waveform of intracranial pressure (ICP) and transcranial Doppler (TCD) cerebral blood flow velocity (CBFV) may contain information about cerebrospinal compliance. This study investigated the possibility by focusing on the phase shift between fundamental harmonics of CBFV and ICP. METHODS: Thirty-seven normal pressure hydrocephalus patients (20 men, mean age 58) underwent the cerebrospinal fluid (CSF) infusion tests. The infusion was performed via pre-implanted Ommaya reservoir. The TCD FV was recorded in the middle cerebral artery. Resulting continuous ICP and pressure-volume (PV) signals were analyzed by ICM+ software. RESULTS: In initial stage of the CSF infusion, the phase shift was negative (median value = -11°, range = +60 to -117). There was significant inverse association of phase shift with brain elasticity (R = -0.51; p = 0.0009). In all tests, phase shift consistently decreased during gradual elevation of ICP (p = 0.00001). Magnitude of decrease in phase shift was inversely related to the peak-to-peak amplitude of ICP pulse waveform at a baseline (R = -0.51; p = 0.001). CONCLUSIONS: Phase shift between fundamental harmonics of ICP and TCD waveforms decreases during elevation of ICP. This is caused by an increase of time delay between systolic peak of flow velocity wave and ICP pulse.

Giant intracranial hemangioma in a neonate.

In this report we detail the case of an infant presenting with a giant intracranial congenital hemangioma and describe the clinical features and surgical management. Congenital hemangiomas are benign vascular tumors that typically present as skin lesions in neonates and infants. On rare occasions they present as intracranial tumors. The possibility that these tumors may undergo spontaneous regression poses a treatment dilemma.

Diffuse cerebral vasospasm following resection of a hypoglossal schwannoma in a child.

Diffuse cerebral vasospasm is a rare complication following tumour resection. This phenomenon seems to be even rarer in the paediatric population and more so following resections of posterior fossa tumours. Here we report diffuse cerebral vasospasm in a child with hypoglossal nerve Schwannoma eight days following resection of the tumour.

Neuro-critical care: a valuable placement during foundation and early neurosurgical training.

INTRODUCTION: Neurosciences critical care units (NCCUs) present a unique opportunity to junior trainees in neurosurgery as well as foundation trainees looking to gain experience in the management of critically ill patients with neurological conditions. Placements in NCCUs are undertaken in the early years of neurosurgical training or during neurosciences themed foundation programmes. We sought to quantify the educational benefits of such placements from the trainee perspective. METHODS: Thirty-two trainees who had undertaken placements at Foundation Year 2 (FY2) to Specialty Trainee Year 3 (ST3) level between August 2009 and April 2013 were invited to take part in an online questionnaire survey. Competence in individual skills was self-rated on a ranked scale from one (never observed) to five (performed unsupervised) both before and after the placement. Trainees were also asked a series of questions pertaining to their ability to manage common neurosurgical conditions, as well as the perceived educational rigour of their placement. RESULTS: Twenty-three responses were received. Eighteen responses were from FY2s and seven were from ST1-3 level trainees. Following their placements, 100% of respondents felt better equipped to deal with neurosurgical and neurological emergencies and cranial trauma. Most felt better equipped to manage hydrocephalus (95.7%), polytrauma patients (95.7%), spontaneous intracranial haemorrhage (91.3%) and spinal trauma (82.6%). Significant increases were seen in experience in all practical skills assessed. These included central venous catheterisation (p < 0.001), intracranial pressure (ICP) bolt insertion (p < 0.001), ICP bolt removal (p < 0.001), external ventricular drain (EVD) insertion (p = 0.001) and tapping of EVD for cerebrospinal fluid sample (p < 0.001). CONCLUSION: Our results clearly demonstrate the educational benefits of NCCU placements in the early stages of a neurosurgical training programme as well as in the Foundation Programme. This supports the incorporation of a four- to six-month NCCU rotation in early years training as educationally valuable.

A map of transcriptional heterogeneity and regulatory variation in human microglia.

Microglia, the tissue-resident macrophages of the central nervous system (CNS), play critical roles in immune defense, development and homeostasis. However, isolating microglia from humans in large numbers is challenging. Here, we profiled gene expression variation in primary human microglia isolated from 141 patients undergoing neurosurgery. Using single-cell and bulk RNA sequencing, we identify how age, sex and clinical pathology influence microglia gene expression and which genetic variants have microglia-specific functions using expression quantitative trait loci (eQTL) mapping. We follow up one of our findings using a human induced pluripotent stem cell-based macrophage model to fine-map a candidate causal variant for Alzheimer's disease at the BIN1 locus. Our study provides a population-scale transcriptional map of a critically important cell for human CNS development and disease.

Radiological Correlates of Raised Intracranial Pressure in Children: A Review.

Radiological assessment of the head is a routine part of the management of traumatic brain injury. This assessment can help to determine the requirement for invasive intracranial pressure (ICP) monitoring. The radiological correlates of elevated ICP have been widely studied in adults but far fewer specific pediatric studies have been conducted. There is, however, growing evidence that there are important differences in the radiological presentations of elevated ICP between children and adults; a reflection of the anatomical and physiological differences, as well as a difference in the pathophysiology of brain injury in children. Here in, we review the radiological parameters that correspond with increased ICP in children that have been described in the literature. We then describe the future directions of this work and our recommendations in order to develop non-invasive and radiological markers of raised ICP in children.

Cerebral localization of Rosai-Dorfman disease in a child. Case report.

Rosai-Dorfman disease (RDD) is a rare idiopathic histiocytic disorder that only occasionally involves the central nervous system (CNS). Previous cases of RDD involving the CNS were generally seen in adults. Pediatric cases of RDD are rare, and the disease in these cases typically has an indolent clinical course. In this report, the authors describe a pediatric case of intracranial RDD with rapid clinical and radiological progression. A previously healthy 13-year-old girl presented with a 15-day history of progressive left-sided headaches, vomiting, and fever. On examination she was pyrexial but otherwise normal. Neuroimaging results demonstrated an extraaxial left frontal lesion with peripheral enhancement. A bur hole was drilled over the lesion to obtain a tissue sample and de-bulk the lesion. The initial histological results showed a nonspecific inflammatory lesion. Postoperatively, the patient was asymptomatic, and neuroimaging results confirmed a significant reduction in the size of the lesion. Repeated neuroimaging 3 months later, however, revealed a large recurrence of the lesion, which was removed macroscopically by a craniotomy. Histological analysis of the tissue confirmed the RDD diagnosis. At the latest follow-up (12 months) the patient had remained asymptomatic with no evidence of recurrence on neuroimaging. This is the first reported case of intracranial RDD with an aggressive clinical course.

Thalamic tumors in children: a reappraisal.

OBJECT: Two to five percent of pediatric brain tumors are located in the thalamus. The optimal management for these tumors remains unclear. The aim of this study was to determine whether clinical and neuroimaging features could guide treatment, and to what extent these features, together with histological diagnosis and treatment modalities, influenced survival. METHODS: The records of 69 children who presented with a thalamic tumor between 1989 and 2003 were retrospectively reviewed. Three groups of tumors were analyzed separately: 1) unilateral thalamic tumors (54 lesions); 2) thalamopeduncular tumors (six); and 3) bilateral thalamic tumors (nine). In the patients in whom a unilateral thalamic tumor was diagnosed, 33 had an astrocytic tumor. Of the 54 patients, 32 had a low-grade and 22 had a high-grade tumor. The survival rate was significantly better for patients with the following characteristics: symptom duration longer than 2 months (p < 0.001), lesions with low-grade histological features (p = 0.003), and tumor excision greater than 90% at surgery (p = 0.04). The perioperative morbidity and mortality rates were 37 and 4%, respectively. Fifty-four percent of the patients in this group had a long-term and independent survival. The thalamopeduncular tumors were mostly pilocytic astrocytomas, which had a good prognosis following surgery. The bilateral thalamic tumors in this series were mainly low-grade astrocytic lesions, and more than half of the children attained long-term survival (mean follow-up duration 4.5 years). CONCLUSIONS: The majority of tumors arising in the thalamus are astrocytic, of which less than half are high-grade lesions. Histological evaluations should be performed in all patients in whom resection is being considered for discrete lesions. Long-term survival is possible in patients with these tumors.

Stereotactic biopsy of diffuse pontine lesions in children.

OBJECT: Empirical radiotherapy is the current treatment for children with diffuse pontine lesions that have imaging characteristics of an infiltrative malignant astrocytoma. The use of chemotherapeutic agents is, however, currently under investigation in the treatment of these tumors. To be included into a trial, patients need a definitive histological diagnosis. The authors present their prospective study of the stereotactic biopsy of these lesions during a 4-year period. METHODS: A suboccipital, transcerebellar approach was used to obtain biopsy samples in 24 children. RESULTS: Two patients suffered deficits. Both had a transient (< 2 months) new cranial nerve palsy; one of these patients also experienced an exacerbation of a preoperative hemiparesis. No patient died during the perioperative period. A histological diagnosis was made in all 24 patients as follows: 22 had a malignant infiltrative astrocytoma, one had a low-grade astrocytoma, and one had a pilocytic astrocytoma. The diagnosis of the latter two patients affected the initial treatment after the biopsy. CONCLUSIONS: The findings of this study imply that stereotactic biopsy sampling of a diffuse pontine tumor is a safe procedure, is associated with minimal morbidity, and has a high diagnostic yield. A nonmalignant tumor was identified in two of the 24 patients in whom the imaging findings were characteristic of a malignant infiltrative astrocytoma. With the advent of new treatment protocols, stereotactic biopsy sampling, which would allow specific tumor characterization of diffuse pontine lesions, may become standard.

Pediatric infratentorial gangliogliomas: a retrospective series.

OBJECT: The aim of this study was to retrospectively review the clinical presentation, the roles of surgery and adjuvant therapy, and the treatment-related morbidity in children with a ganglioglioma in the posterior fossa and to try and determine the prognostic factors. METHODS: Between 1991 and 2006, 10 children were treated for a posterior fossa ganglioglioma at the authors' institution. The mean age of the children, the duration of symptoms prior to diagnosis, and the follow-up were 8.2, 2.4, and 3.9 years, respectively. Nine of the children presented with symptoms of raised intracranial pressure. Preoperative imaging showed enhancement in all patients; in eight it was in a patchy distribution. The operations consisted of radical resection (> 75%) in seven children, biopsy in two, and a total macroscopic excision in one. RESULTS: The surgical procedure did not cause deterioration in the neurological condition in any of the children. There was no recurrence in the child who underwent total macroscopic excision of the tumor, and there has been no tumor progression in three children, two of whom have had no evidence of enhancement of the postoperative residual tumor. The tumor has progressed in six children, requiring further surgery in three, chemotherapy in four, and radiotherapy and second-line chemotherapy in one child to control the tumor. CONCLUSIONS: The imaging of gangliogliomas in the posterior fossa showed patchy enhancement. The patients in whom it was possible to achieve a radical resection, aimed at removing at least the enhancing portion of the tumor, have not required further treatment. A second excision, for progressive tumors, is an effective adjuvant therapy.