Exploration of the relationship between partial pressure of brain tissue oxygen and intracranial pressure.

Introduction: Partial pressure of brain tissue oxygen (PbtO2) has been shown to be a safe an effective monitoring modality to compliment intracranial pressure (ICP) monitoring. It is related to metabolic activity, disease severity and mortality. Research question: Understanding the complex relationship between PbtO2 and ICP for patients with traumatic brain injury will enable better clinical decision making beyond simple threshold treatment strategies. Material and methods: Patients with PbtO2 monitoring were identified from the BrainIT database, a multi-centre dataset, containing minute by minute PbtO2 and ICP readings. Missing data was imputed and a multi-level log-normal regression model with a compound symmetry correlation structure was built. This accounted for any increased correlation due to the repeated measurements. The model was adjusted for mean arterial pressure and the partial pressure of carbon dioxide. Non-linearity was assessed using analysis of deviance and trends using expected marginal means. Results: 11 subjects with over 82,000 readings were included. They had a median age of 38 (IQR: 37-47), 73% were male, a median length of stay of 11.8 (IQR: 6.6-19.7) days and a median extended Glasgow outcome scale of 7.00 (IQR: 5-8).There is a statistically significant (p < 0.001) non-linear effect of ICP on PbtO2. With an overall increase in PbtO2 of 5.2% (95% CI 4%-6.4%, p < 0.001) for a 10 mmHg increase in ICP below 22 mmHg and a decrease of 5.5% (95% CI 2.7%-8.3%, p=<0.001) in PbtO2 for a 10 mmHg increase in ICP above 22 mmHg. As well as a decrease of 40.9% (95% CI 2.3%-64.3%, p = 0.040) in PbtO2 per day in the intensive care unit. Discussion and conclusion: This model demonstrates that there is a significant non-linear relationship between ICP and PbtO2, however, this is a small heterogeneous cohort and further validation will be required.

Presentation and outcomes of paediatric craniopharyngioma in the west of Scotland: a 25 year experience.

PURPOSE: Craniopharyngiomas can be aggressive leading to significant complications and morbidity. It is not clear whether there are any predictive factors for incidence or outcomes. Our aim was therefore to record the incidence, presentation, characteristics and progression of paediatric craniopharyngiomas in the West of Scotland. METHOD: Retrospective case note review for children diagnosed with paediatric craniopharyngiomas at the Royal Hospital for Children Glasgow, from 1995 to 2021 was conducted. All analyses were conducted using GraphPad Prism 9.4.0. RESULTS: Of 21 patients diagnosed with craniopharyngiomas, the most common presenting symptoms were headaches (17/21, 81%); visual impairment (13/21, 62%); vomiting (9/21, 43%) and growth failure (7/21, 33%). Seventeen (81%) patients underwent hydrocephalus and/or resection surgery within 3 months of diagnosis, usually within the first 2 weeks (13/21, 62%). Subtotal resection surgeries were performed in 71% of patients, and median time between subsequent resection surgeries for tumour recurrence was 4 years (0,11). BMI SDS increased at 5 year follow-up (p = 0.021) with 43% being obese (BMI > + 2SD). More patients acquired hypopituitarism post-operatively (14/16, 88%) compared to pre-operatively (4/15, 27%). A greater incidence of craniopharyngiomas were reported in more affluent areas (10/21, 48%) (SIMD score 8-10) compared to more deprived areas (6/10, 29%) (SIMD score 1-3). Five patients (24%) died with a median time between diagnosis and death of 9 years (6,13). CONCLUSION: Over 25 years the management of craniopharyngioma has changed substantially. Co-morbidities such as obesity are difficult to manage post-operatively and mortality risk can be up to 25% according to our cohort.

Role of a medical student neuro-society organized neurosurgical conference: The Glasgow neuro experience.

Background: Entering neurosurgical training in the United Kingdom demands extensive prior commitment and achievement, despite little to no exposure to the specialty in medical school. Conferences run by student "neuro-societies" offer a means to bridge this gap. This paper describes one student-led neuro-society's experience of curating a 1-day national neurosurgical conference supported by our neurosurgical department. Methods: A pre-and post-conference survey was distributed to attendees to ascertain baseline opinions and conference impact using a five-point Likert Scale, and free text questions explored medical students' opinions of neurosurgery and neurosurgical training. The conference offered four lectures and three workshops; the latter provided practical skills and networking opportunities. There were also 11 posters displayed throughout the day. Results: 47 medical students participated in our study. Post-conference, participants were more likely to understand what a neurosurgical career involves and how to secure training. They also reported increased knowledge about neurosurgery research, electives, audits, and project opportunities. Respondents enjoyed the workshops provided and suggested the inclusion of more female speakers in future. Conclusion: Neurosurgical conferences organized by student neuro-societies successfully address the gap between a lack of neurosurgery exposure and a competitive training selection. These events give medical students an initial understanding of a neurosurgical career through lectures and practical workshops; attendees also gain insight into attaining relevant achievements and have an opportunity to present research. Student neuro-society-organized conferences have the potential to be adopted internationally and used as a tool to educate on a global level and greatly aid medical students who are aspiring neurosurgeons.

Use of Direct Intracranial Pressure and Brain Tissue Oxygen Monitoring in Perioperative Management of Patients with Moyamoya Disease.

Intracranial pressure monitoring and brain tissue oxygen monitoring are commonly used in head injury for goal-directed therapies, but there may be more indications for its use. Moyamoya disease involves progressive stenosis of the arterial circulation and formation of collateral vessels that are at risk of hemorrhage. The risk of ischemic events during revascularization surgery and postoperatively is high. Impaired cerebral autoregulation may be one of the factors that are implicated. We present our experience with monitoring of cerebral oxygenation and autoregulation in the pathological hemisphere during the perioperative period in four patients with moyamoya disease.

Evaluation of Software for Automated Measurement of Adherence to ICP-Monitoring Threshold Guideline.

Challenges inherent in clinical guideline development include a long time lag between the key results and incorporation into best practice and the qualitative nature of adherence measurement, meaning it will have no directly measurable impact. To address these issues, a framework has been developed to automatically measure adherence by clinicians in neurological intensive care units to the Brain Trauma Foundation's intracranial pressure (ICP)-monitoring guidelines for severe traumatic brain injury (TBI).The framework processes physiological and treatment data taken from the bedside, standardises the data as a set of process models, then compares these models against similar process models constructed from published guidelines. A similarity metric (i.e. adherence measure) between the two models is calculated, composed of duration and scale of non-adherence.In a pilot clinical validation test, the framework was applied to physiological/treatment data from three TBI patients exhibiting ICP secondary insults at a local neuro-centre where clinical experts coded key clinical interventions/decisions about patient management.The framework identified non-adherence with respect to drug administration in one patient, with a spike in non-adherence due to an inappropriately high dosage; a second patient showed a high severity of guideline non-adherence; and a third patient showed non-adherence due to a low number of associated events and treatment annotations.

Time Series Analysis and Prediction of Intracranial Pressure Using Time-Varying Dynamic Linear Models.

Intracranial pressure (ICP) monitoring is a key clinical tool in the assessment and treatment of patients in a neuro-intensive care unit (neuro-ICU). As such, a deeper understanding of how an individual patient's ICP can be influenced by therapeutic interventions could improve clinical decision-making. A pilot application of a time-varying dynamic linear model was conducted using the BrainIT dataset, a multi-centre European dataset containing temporaneous treatment and vital-sign recordings. The study included 106 patients with a minimum of 27 h of ICP monitoring. The model was trained on the first 24 h of each patient's ICU stay, and then the next 2 h of ICP was forecast. The algorithm enabled switching between three interventional states: analgesia, osmotic therapy and paralysis, with the inclusion of arterial blood pressure, age and gender as exogenous regressors. The overall median absolute error was 2.98 (2.41-5.24) mmHg calculated using all 106 2-h forecasts. This is a novel technique which shows some promise for forecasting ICP with an adequate accuracy of approximately 3 mmHg. Further optimisation is required for the algorithm to become a usable clinical tool.

Telemetric Intracranial Pressure: A Snapshot Does not Give the Full Story.

Telemetric intracranial pressure (ICP) monitors are useful tools in the management of complex hydrocephalus and idiopathic intracranial hypertension (IIH). Clinicians may use them as a "snapshot" screening tool to assess shunt function or ICP. We compared "snapshot" telemetric ICP recordings with extended, in-patient periods of monitoring to determine whether this practice is safe and useful for clinical decision making.

The Management of Hypertension in Pre-Aneurysmal Treatment Subarachnoid Hemorrhage Patients.

BACKGROUND: Management of hypertension in subarachnoid hemorrhage patients within the preaneurysmal treatment period remains ambiguous, in part due to the lack of high-level, evidence-based guidelines. Despite this, current recommendations offer guidance regarding certain parameters (e.g., mean arterial pressure, systolic blood pressure). However, managing hypertension within this critical period is difficult because a fine balance must be achieved between lowering blood pressure enough to minimize the risk of rebleeding and preventing reduced cerebral perfusion and subsequent ischemic damage. Furthermore, the different causes of hypertension within the preaneurysmal treatment period are polyfactorial and include pathophysiologic responses, sympathetic nervous system activation, and iatrogenic from hyperdynamic therapy and vasopressors, which requires consideration for these patients to receive optimal management. Other factors including loss of autoregulation and concomitant conditions must also be considered when deciding whether to start antihypertensive therapy. METHODS: We review the literature and provide a comprehensive update on management of hypertension within the preaneurysmal treatment period, which we hope stresses the need for better evidence-based guidelines that will in turn help manage this cohort. RESULTS: Thorough review revealed no high-grade, evidence-based guidelines to manage these patients, which results in variation in clinical practice among different clinicians and institutions. Despite this, current recommendations seem reasonable until such guidelines are established. CONCLUSIONS: It is clear that further, larger studies are warranted in order to clarify the effect of antihypertensive therapy on patient outcome and what the BP thresholds are, along with establishing the best treatment, for commencing antihypertensive therapy.

The Extracranial Consequences of Subarachnoid Hemorrhage.

BACKGROUND: Subarachnoid hemorrhage (SAH) is managed across the full spectrum of healthcare, from clinical diagnosis to management of the hemorrhage and associated complications. Knowledge of the pathogenesis and pathophysiology of SAH is widely known; however, a full understanding of the underlying molecular, cellular, and circulatory dynamics has still to be achieved. Intracranial complications including delayed ischemic neurologic deficit (vasospasm), rebleed, and hydrocephalus form the targets for initial management. However, the extracranial consequences including hypertension, hyponatremia, and cardiopulmonary abnormalities can frequently arise during the management phase and have shown to directly affect clinical outcome. This review will provide an update on the pathophysiology of SAH, including the intra- and extracranial consequences, with a particular focus on the extracranial consequences of SAH. METHODS: We review the literature and provide a comprehensive update on the extracranial consequences of SAH that we hope will help the management of these cohort of patients. RESULTS: In addition to the pathophysiology of SAH, the following complications were examined and discussed: vasospasm, seizures, rebleed, hydrocephalus, fever, anemia, hypertension, hypotension, hyperglycemia, hyponatremia, hypernatremia, cardiac abnormalities, pulmonary edema, venous thromboembolism, gastric ulceration, nosocomial infection, bloodstream infection/sepsis, and iatrogenic complications. CONCLUSIONS: Although the intracranial complications of SAH can take priority in the initial management, the extracranial complications should be monitored for and recognized as early as possible because these complications can develop at varying times throughout the course of the condition. Therefore, a variety of investigations, as described by this article, should be undertaken on admission to maximize early recognition of any of the extracranial consequences. Furthermore, because the extracranial complications have a direct effect on clinical outcome and can lead to and exacerbate the intracranial complications, monitoring, recognizing, and managing these complications in parallel with the intracranial complications is important and would allow optimization of the patient's management and thus help improve their overall outcome.

The best marker for guiding the clinical management of patients with raised intracranial pressure-the RAP index or the mean pulse amplitude?

Raised intracranial pressure is a common problem in a variety of neurosurgical conditions including traumatic brain injury, hydrocephalus and intracranial haemorrhage. The clinical management of these patients is guided by a variety of haemodynamic, biochemical and clinical factors. However to date there is no single parameter that is used to guide clinical management of patients with raised intracranial pressure (ICP). However, the role of ICP indices, specifically the mean pulse amplitude (AMP) and RAP index [correlation coefficient (R) between AMP amplitude (A) and mean ICP pressure (P); index of compensatory reserve], as an indicator of true ICP has been investigated. Whilst the RAP index has been used both as a descriptor of neurological deterioration in TBI patients and as a way of characterising the compensatory reserve in hydrocephalus, more recent studies have highlighted the limitation of the RAP index due to the influence that baseline effect errors have on the mean ICP, which is used in the calculation of the RAP index. These studies have suggested that the ICP mean pulse amplitude may be a more accurate marker of true intracranial pressure due to the fact that it is uninfluenced by the mean ICP and, therefore, the AMP may be a more reliable marker than the RAP index for guiding the clinical management of patients with raised ICP. Although further investigation needs to be undertaken in order to fully assess the role of ICP indices in guiding the clinical management of patients with raised ICP, the studies undertaken to date provide an insight into the potential role of ICP indices to treat raised ICP proactively rather than reactively and therefore help prevent or minimise secondary brain injury.

Telemetric Intracranial Pressure Monitoring in Syndromic Craniosynostosis.

Syndromic and nonsyndromic craniosynostosis can be associated with raised intracranial pressure (ICP). After corrective surgery, raised ICP persists or reoccurs in a subgroup of patients. The standard procedure for monitoring ICP is insertion of a percutaneous intraparenchymal probe for a limited time, usually 24 to 48 hours. However, in selected patients repeated ICP measurements might be useful in the clinical setting, and a noninvasive method for achieving this would be desirable. The authors present the use of a telemetric ICP monitoring system implanted during cranial vault expansion in a child with syndromic craniosynostosis. This system, once implanted, allows for noninvasive transdermal ICP readings and might represent a promising alternative to conventional ICP monitoring devices in selected patients with craniofacial conditions.

Comparison of survival between the UK and US after surgery for most common pediatric CNS tumors.

BACKGROUND: We report a population-based study examining long-term outcomes for common pediatric CNS tumors comparing results from the UK with the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) data set and with the literature. No such international study has previously been reported. METHODS: Data between 1996 and 2005 from the UK National Registry of Childhood Tumours (NRCT) and the SEER registry were analyzed. We calculated actuarial survival at each time point from histological diagnosis, with death from any cause as the endpoint. Kaplan-Meier estimation and log-rank testing (Cox proportional hazards regression analysis) were used to calculate survival differences among tumor subtypes, adjusting for age at diagnosis. RESULTS: Population-based outcomes for each tumor type are presented. Overall age-adjusted survival, stratifying for histology (combining pilocytic astrocytoma, anaplastic astrocytoma, glioblastoma, primitive neuroectodermal tumor, medulloblastoma, and ependymoma), is significantly lower for NRCT than SEER (hazard ratio 0.71, P < .001) and at 1, 5, and 10 years. Both NRCT and SEER outcomes are worse than those reported from trials. CONCLUSION: Analyzing data from comprehensive registries minimizes bias associated with trials and institutional studies. The reasons for the poorer outcomes in children treated in the UK are unclear. Likewise, the differences in outcomes between patients in trials and those not in trials need further investigation. We recommend that all children with CNS tumors be recruited into studies-even if these are observational studies. We also suggest that registries be suitably funded to publish independent outcome data (including morbidity) at both a national and an institutional level.

United Kingdom 30-day mortality rates after surgery for pediatric central nervous system tumors.

OBJECT: In an increasing culture of medical accountability, 30-day operative mortality rates remain one of the most objective measurements reported for the surgical field. The authors report population-based 30-day postoperative mortality rates among children who had undergone CNS tumor surgery in the United Kingdom. METHODS: To determine overall 30-day operative mortality rates, the authors analyzed the National Registry of Childhood Tumors for CNS tumors for the period 2004-2007. The operative mortality rate for each tumor category was derived. In addition, comparison was made with the 30-day operative mortality rates after CNS tumor surgery reported in the contemporary literature. Finally, by use of a funnel plot, institutional performance for 30-day operative mortality was compared for all units across the United Kingdom. RESULTS: The overall 30-day operative mortality rate for children undergoing CNS tumor surgery in the United Kingdom during the study period was 2.7%. When only malignant CNS tumors were analyzed, the rate increased to 3.5%. One third of the deaths occurred after discharge from the hospital in which the surgery had been performed. The highest 30-day operative mortality rate (19%) was for patients with choroid plexus carcinomas. A total of 20 institutions performed CNS tumor surgery during the study period. Rates for all institutions fell within 2 SDs. No trend associating operative mortality rates and institutional volume was found. In comparison, review of the contemporary literature suggests that the postoperative mortality rate should be approximately 1%. CONCLUSIONS: The authors believe this to be the first report of national 30-day surgical mortality rates specifically for children with CNS tumors. The study raises questions about the 30-day mortality rate among children undergoing surgery for CNS tumors. International consensus should be reached on a minimum data set for outcomes and should include 30-day operative mortality rates.

Neurologist vs the neurosurgeons: who is the NICEst? The medical management of the neurosurgical patient with seizures.

Seizures and epilepsy are a relatively common occurrence in the neurosurgical patient. Neurosurgeons are often involved in the medical management utilising anti-epileptic drugs (AEDs). There is a distinct lack of contemporary literature in relation to management of seizures/epilepsy in the neurosurgical patient, in particular, for the newer AEDs. In the UK, clinical practice guidelines have been issued from both the National Institute for Health and Clinical Excellence (NICE) and Scottish Intercollegiate Guidelines Network (SIGN) in relation to epilepsy in primary and secondary care. We sought to determine current management practice for neurosurgical patients with epilepsy/seizures. The relevance of the issued guidelines was examined within the neurosurgical setting. An audit by telephone survey was conducted in Neurosurgical and Neurology units in the UK. Respondents were asked about the management of patients in two clinical scenarios. We received 25 responses from the neurosurgical and 22 responses from the neurology communities. Management of the patient scenarios is described and is further considered in relation to the published guidelines. There was considerable disparity between the guidelines and the management strategies pursued by both groups. We conclude that the standard of treatment is sub-optimal in many cases. The guidelines have not had a significant influence and are not felt to be strictly relevant within the neurosurgical setting. The development of guidelines relevant to the neurosurgical setting is proposed. Further research within this field and investment in education for neurosurgeons relating to AED therapy is advocated. The neurologists responses were more closely aligned to the guidelines and so they were deemed the 'NICEst'.

Multiple cranial neuropathy as the initial presentation of metastatic prostate adenocarcinoma: case report and review of literature.

The skull base is an atypical metastatic site for prostate carcinoma. It is usually encountered late in the disease process in patients with known advanced disease. However, skull base involvement causing cranial nerve palsies may rarely be the presenting sign of prostate carcinoma. Such patients may present to a number of specialties including neurosurgery and can pose a diagnostic challenge in the absence of lower urinary tract symptoms. Here, we describe an unusual case of prostate adenocarcinoma presenting as a central skull base tumour with multiple cranial neuropathy.