Feasibility of Telemetric Intracranial Pressure Monitoring in the Neuro Intensive Care Unit.

Intracranial pressure (ICP) monitoring is crucial in the management of acute neurosurgical conditions such as traumatic brain injury (TBI). However, pathological ICP may persist beyond the admission to the neuro intensive care unit (NICU). We investigated the feasibility of telemetric ICP monitoring in the NICU, as this technology provides the possibility of long-term ICP assessment beyond NICU discharge. In this prospective investigation, we implanted telemetric ICP sensors (Raumedic Neurovent-P-tel) instead of conventional, cabled ICP sensors in patients undergoing decompressive craniectomy. We recorded ICP curves, duration of ICP monitoring, signal quality, and complications. Seventeen patients were included (median age 55 years) and diagnoses were: severe TBI (8), malignant middle cerebral artery infarction (8), and spontaneous intracerebral hemorrhage (1). In total, 3015 h of ICP monitoring were performed, and the median duration of ICP monitoring was 188 h (interquartile range [IQR] 54-259). The ICP signal was lost 613 times (displacement of the reader unit on the skin) for a median of 1.5 min, corresponding to 0.8% of the total monitoring period. When the signal was lost, it could always be restored by realignment of the reader unit on the skin above the telemetric sensor. Sixteen of 17 patients survived the NICU admission, and ICP gradually decreased from 10.7 mm Hg (IQR 7.5-13.6) during the first postoperative day to 6.3 mm Hg (IQR 4.0-8.3) after 1 week in the NICU. All 17 implanted telemetric sensors functioned throughout the NICU admission, and no wound infections were observed. Therefore, telemetric ICP monitoring in an acute neurosurgical setting is feasible. Signal quality and stability are sufficient for clinical decision making based on mean ICP. The low sampling frequency (5 Hz) does not permit analysis of intracranial pulse wave morphology, but resolution is sufficient for calculation of derived indices such as the pressure reactivity index (PRx).

Evaluation of Intracranial Pressure in Different Body Postures and Disease Entities.

We currently do not have sufficient knowledge regarding appropriate boundaries between "normal" and "abnormal" intracranial pressure (ICP) in humans. Our objective in this study was to quantify the effects of postural changes on ICP in normal and ill subjects. As a model for normal patients, we included adult patients scheduled for complete removal of a solitary, clearly demarcated, small brain tumor and performed long-term ICP monitoring using a telemetric device. The ill subjects included required invasive ICP monitoring as part of their diagnostic workup or monitoring of the effect of shunt treatment at our department. All patients were included prospectively for a session of monitored changes in body posture. In our preliminary results from 19 patients, we were able to statistically distinguish between patient groups and assumed body postures, highlighting the need for the further characterization of the effects of postural changes on ICP to inform diagnostic and therapeutic decisions.

Valved or valveless ventriculoperitoneal shunting in the treatment of post-haemorrhagic hydrocephalus: a population-based consecutive cohort study.

BACKGROUND: Implant infection and obstruction are major complications for ventriculoperitoneal shunts in patients with post-haemorrhagic hydrocephalus. In an effort to (1) reduce the incidence of these complications, (2) reduce the rate of shunt failure and (3) shorten the duration of neurosurgical hospitalisation, we have implemented valveless ventriculoperitoneal shunts at our department for adult patients with post-haemorrhagic hydrocephalus and haemorrhagic cerebrospinal fluid at the time of shunt insertion. METHODS: All adult patients (>18 years old) treated for post-haemorrhagic hydrocephalus with ventriculoperitoneal shunting at our institution from 1 January 2008 to 31 December 2014 were included in this retrospective population-based consecutive cohort study. Data were collected by retrospectively reviewing medical records. We compared two different shunt modalities (valveless vs valve-regulated), analysing frequencies of complications, shunt survival and duration of neurosurgical hospitalisation. RESULTS: A total of 214 patients aged 22-86 (mean age, 60.5 ± 11.5 years) were included, comprising 137 valveless and 77 valve-regulated shunts. We found no difference in the rate of surgical shunt revision (p = 0.65) or differences in time interval from insertion to first surgical revision (p = 0.31) between the two shunt modalities. The duration of neurosurgical hospitalisation was shorter for patients receiving a valveless shunt (p = 0.004). Patients with valveless shunts had a lower rate of shunt infection (5.1 % vs 14.3 %, p = 0.02), but a higher rate of overdrainage (10.3 % vs 2.6 %, p = 0.04). CONCLUSION: The use of a valveless shunting for patients with post-haemorrhagic hydrocephalus results in shorter duration of neurosurgical hospitalisation and lower rate of shunt infection, although these advantages should be held up against the risk of overdrainage. We propose valveless shunting to be used as first-line shunting strategy in this patient category, with careful follow-up ensuring that these are substituted by a valve-bearing system if necessary.

Effect of postural changes on ICP in healthy and ill subjects.

BACKGROUND: Reference values and physiological measurements of intracranial pressure (ICP) are primarily reported in the supine position, while reports of ICP in the vertical position are surprisingly rare considering that humans maintain the vertical position for the majority of the day. In order to distinguish normal human physiology from disease entities such as idiopathic intracranial hypertension and normal pressure hydrocephalus, we investigated ICP in different body postures in both normal and ill subjects. METHODS: Thirty-one patients were included: four normal patients following complete removal of a solitary clearly demarcated small brain tumour and fitted with a telemetric ICP monitoring device for long-term ICP monitoring; 27 patients requiring invasive ICP monitoring as a part of their diagnostic work-up or monitoring of shunt treatment effect. ICP was recorded in the following body positions: upright standing, sitting in a chair, supine and right lateral lumbar puncture position. RESULTS: Linear regression of median ICP based on patient posture, group, and purpose of monitoring presented a significant model (p < 0.001), but could not distinguish between patient groups (p = 0.88). Regression of differences in median ICP between body postures and supine ICP as the baseline, presented a highly significant model (p < 0.001) and adjusted R (2) = 0.86. Both body posture (p < 0.001) and patient group (p < 0.001) were highly significant factors. CONCLUSIONS: Differences in ICP between body postures enabled us to distinguish the normal group from patient groups. Normal patients appear able to more tightly regulate ICP when switching body postures.

Intracranial pressure following complete removal of a small demarcated brain tumor: a model for normal intracranial pressure in humans.

OBJECTIVES: Current published normal values for intracranial pressure (ICP) are extrapolated from lumbar CSF pressure measurements and ICP measurements in patients treated for CSF pressure disorders. There is an emerging agreement that true normal ICP values are needed for diagnostic and therapeutic purposes. This study documents normal ICP in humans. METHODS: In this study the authors included adult patients scheduled for complete removal of a solitary, clearly demarcated, small brain tumor. The mean age of these patients was 67 years old (range 58-85 years old). Exclusion criteria were intended to create a study population with as normal brains as possible. A new telemetric ICP monitoring device was implanted at the end of surgery and monitoring was conducted 2 and 4 weeks postoperatively. RESULTS: In the supine position, mean ICP was 0.5 ± 4.0 mm Hg at 4 weeks postoperatively. Postural change to the standing position resulted in a decrease in mean ICP to -3.7 ± 3.8 mm Hg. These results show ICP to be considerably lower than previously estimated. CONCLUSIONS: This study provides a preliminary reference range for normal ICP in humans. It is the first study to show that ICP in the healthy human brain decreases to negative values when assuming the upright position. If these results are later confirmed in a larger series, they might provide reference values for diagnosis and treatment in patients with CSF-related disorders. New normal values also have implications for future shunt design and the ICP target range in hydrocephalus treatment.

Intracranial hemorrhage due to intracranial hypertension caused by the superior vena cava syndrome.

We report a patient with intracranial hemorrhage secondary to venous hypertension as a result of a giant aortic pseudoaneurysm that compressed the superior vena cava and caused obstruction of the venous return from the brain. To our knowledge, this is the first patient reported to have an intracranial hemorrhage secondary to a superior vena cava syndrome. The condition appears to be caused by a reversible transient rise in intracranial pressure, as a result of compression of the venous return from the brain. Treatment consisted of surgery for the aortic pseudoaneurysm, which led to normalization of the intracranial pressure and resorption of the intracranial hemorrhage.

Vascular endothelial growth factor A protein level and gene expression in intracranial meningiomas with brain edema.

Meningiomas are the second most common primary intracranial tumors in adults. Although meningiomas are mostly benign, more than 50% of patients with meningioma develop peritumoral brain edema (PTBE), which may be fatal because of increased intracranial pressure. Vascular endothelial growth factor (VEGF) is an endothelial cell-specific mitogen and angiogen. VEGF-A protein, which is identical to vascular permeability factor, is a regulator of angiogenesis. In this study, 101 patients with meningiomas, and possible co-factors to PTBE, such as meningioma subtypes and tumor location, were examined. Forty-three patients had primary, solitary, supratentorial meningiomas with PTBE. In these, correlations in PTBE, edema index, VEGF-A protein, VEGF gene expression, capillary length, and tumor water content were investigated. DNA-branched hybridization was used for measuring VEGF gene expression in tissue homogenates prepared from frozen tissue samples. The method for VEGF-A analysis resembled an ELISA assay, but was based on chemiluminescence. The edema index was positively correlated to VEGF-A protein (p = 0.014) and VEGF gene expression (p < 0.05). The capillary length in the meningiomas was positively correlated to the PTBE (p = 0.038). If VEGF is responsible for the formation of PTBE, the edema may be treated with the anti-VEGF drug Bevacizumab (Avastin), which has been shown to reduce PTBE in patients with glioblastoma multiforme.