Feasibility of telemetric ICP-guided valve adjustments for complex shunt therapy

The Impact of Intracranial Pressure Telesensors: An Observational Propensity-Matched Control Analysis of Service Demand and Costs

BACKGROUND AND OBJECTIVES

Implantable telemetric intracranial pressure (ICP) sensors (telesensors) enable routine, noninvasive ICP feedback, aiding clinical decision-making and attribution of pressure-related symptoms in patients with cerebrospinal fluid shunt systems. Here, we aim to explore the impact of these devices on service demand and costs in patients with adult hydrocephalus.

METHODS

We performed an observational propensity-matched control study, comparing patients who had an MScio/Sensor Reservoir (Christoph Miethke, GmbH & Co) against those with a nontelemetric reservoir inserted between March 2016 and March 2018. Patients were matched on demographics, diagnosis, shunt-type, and revision status. Service usage was recorded with frequencies of neurosurgical admissions, outpatient clinics, scans, and further surgical procedures in the 2 years before and after shunt insertion.

RESULTS

In total, 136 patients, 73 telesensors, and 63 controls were included in this study (48 matched pairs). Telesensor use led to a significant decrease in neurosurgical inpatient admissions, radiographic encounters, and procedures including ICP monitoring. After multivariate adjustment, the mean cumulative saving after 2 years was £5236 ($6338) in telesensor patients (£5498 on matched pair analysis). On break-even analysis, cost-savings were likely to be achieved within 8 months of clinical use, postimplantation. Telesensor patients also experienced a significant reduction in imaging-associated radiation (4 mSv) over 2 years.

CONCLUSION

The findings of this exploratory study reveal that telesensor implantation is associated with reduced service demand and provides net financial savings from an institutional perspective. Moreover, telesensor patients required fewer appointments, invasive procedures, and had less radiation exposure, indicating an improvement in both their experience and safety.

Evaluation of Miethke M.scio Device Implantation for Intracranial Pressure Monitoring in Patients with Cerebrospinal Fluid Disorders

BACKGROUND

Patients with complex shunt-related problems and varying diagnoses of cerebrospinal fluid (CSF) disturbance can present with headache and clinical symptoms that may be difficult to relate to underdrainage or overdrainage. Telemetric intracranial pressure (ICP) monitoring may assist in evaluating individual patients and assessing shunt function and adjustment. We report a case series of patients receiving a Miethke M.scio sensor.

METHODS

Between June 2016 and August 2021, 14 patients older than 18 years with different diagnoses underwent ventriculoperitoneal shunt surgery and received a Miethke M.scio sensor.

RESULTS

Patients had idiopathic intracranial hypertension (n = 3), obstructive hydrocephalus caused by tumors (n = 4), and malformations (n = 5). Headaches (71%) and visual impairment (50%) were the most common symptoms before surgery and 65% of the symptoms were improved after surgery. In total, 25 measurements were made and 11 of these led to changes in the shunt settings. Postoperative measurements were taken in 8 patients and the most common indication of ICP measurement was headache and/or control of the shunt settings.

CONCLUSIONS

The Miethke M.scio is a safe and valuable device to use in shunt-treated patients, in particular those expected to need assessment of ICP monitoring postoperatively. Repeated ICP measurements can also assist in personalized adjustment of the shunt setting to optimize CSF flow in this diverse patient group. Future studies should include a standardized protocol with ICP measurements correlated to the symptoms and cause of CSF disturbances to provide better understanding of the dynamics of the ICP in each patient.

Maneuver protocol for outpatient telemetric intracranial pressure monitoring in hydrocephalus patients

INTRODUCTION

Telemetric intracranial pressure measurement (tICPM) offers new opportunities to acquire objective information in shunted and non-shunted patients. The sensor reservoir (SR) provides tICPM modality at a decent sampling rate as an integrated component of the CSF shunt system. The aim of this study is to perform tICPM during a defined protocol of maneuvers in an outpatient setting as feasibility study including either shunt-dependent patients or candidates for possible shunt therapy.

METHODS

A total of 17 patients received a SR and were investigated within a protocol of maneuver measurements involving different body postures (90°, 10°, 0°, and - 10°), breathing patterns (hypo- and hyperventilation), and mild venous congestion (Valsalva, Jugular vein compression), while the latter two were performed in lying postures (10° and 0°). The cohort included 11 shunted and 6 non-shunted (stand-alone-SR) patients. All measurements were evaluated using an ICP-analysis software (ICPicture, Miethke, Germany) looking at ICP changes and amplitude (AMP) characteristics.

RESULTS

The shunted patient group consisted of 11 patients (median age: 15.8 years; range: 4-35.2 years) with either a primary shunt (n=9) and 2 patients received a shunt after stand-alone-SR tICPM. Six patients were enrolled with a stand-alone SR (median age 11.9 years, range 3.6-17.7 years). In the stand-alone SR group, maneuver related ICP and AMP changes were more sensitive compared to shunted patients. Postural maneuvers caused significant ICP changes in all body positions in both groups. The highest ICP values were seen during Valsalva maneuver, provoked by the patients themselves. In the stand-alone group, significant higher ICP values during hyperventilation were observed compared to shunted individuals. In shunted patients, a significant correlation between ICP and AMP was observed only during hyperventilation maneuver, while this correlation was additionally seen in Valsalva and jugular vein compression in stand-alone patients.

CONCLUSION

SR-related tICPM is helpful to objectify diagnostic evaluation in patients with CSF dynamic disturbances. The defined protocol did result in a wide range of ICP changes with promising potential for effective outpatient tICPM investigation. Since the correlation of ICP and AMP was observed during mild venous congestion maneuvers it appears to be specifically helpful for the evaluation of intracranial compliance. Further investigations of maneuver-related tICPM in a larger population, including variable pathologies, are needed to further establish the protocol in the clinical practice.

An updated model of hydrocephalus in sheep to evaluate the performance of a device for ambulatory wireless monitoring of cerebral pressure through shunts

BACKGROUND

Cerebrospinal fluid (CSF) diversion by shunts is the most common surgical treatment for hydrocephalus. Though effective, shunts are associated with risk of dysfunction leading to multiple surgical revisions, affecting patient quality-of-life and incurring high healthcare costs. There is a need for ambulatory monitoring systems for life-long assessment of shunt status. The present study aimed to develop a preclinical model assessing the feasibility of our wireless device for continuous monitoring of cerebral pressure in shunts.

METHODS

We first adapted a previous hydrocephalus model in sheep, which used an intracisternal kaolin injection. Seven animals were used to establish the model, and 1 sheep with naturally dilated ventricles was used as control. Hydrocephalus was confirmed by clinical examination and brain imaging before inserting the ventriculoperitoneal shunts and the monitoring device allowing continuous measurement of the pressure through the shunt for a few days in 3 sheep. An external ventricular drain was used as gold-standard.

RESULTS

Our results showed that a reduction in kaolin dose associated to postoperative management was crucial to reduce morbidity and mortality rates in the model. Ventriculomegaly was confirmed by imaging 4 days after injection of 75 mg kaolin into the cisterna magna. For the implanted sheep, recordings revealed high sensitivity of our sensor in detecting fluctuations in cerebral pressure compared to conventional measurements.

CONCLUSIONS

This proof-of-concept study highlights the potential of this preclinical model for testing new shunt devices.

Long-term telemetric intracranial pressure monitoring for diagnosis and therapy optimisation of idiopathic intracranial hypertension

Background

Idiopathic intracranial hypertension (IIH) is a disease which is difficult to diagnose and moreover difficult to treat. We developed a strategy for long-term telemonitoring of intracranial pressure (ICP), by incorporation of the NEUROVENT®-P-tel System, with the goal of improved diagnosis and consequent therapy of this disease. We highlight the results obtained through this approach.

Methods

Twenty patients with suspected IIH who were treated in our hospital from August 2014 to October 2020 (16 females, 4 males, median age 36,6 years), were assigned to one of two ICP monitoring settings, “Home-Telemonitoring” (n = 12) and “Home-Monitoring” (n = 8). The ICP data were analysed and used conjointly with the accompanying clinical picture for establishment of IIH diagnosis, and telemonitoring was resumed for therapy optimisation of confirmed cases.

Results

The diagnosis of IIH was confirmed in 18 of the 20 patients. Various surgical/interventional treatments were applied to the confirmed cases, including ventriculoperitoneal (VP) shunting (n = 15), stenting of the transvers venous sinus (n = 1), endoscopic third ventriculostomy (ETV) (n = 1), and ETV in combination with endoscopic laser-based coagulation of the choroid Plexus (n = 1). Optimal adjustment of the implanted shunt valves was achieved with an average valve opening pressure of 6,3 ± 2,17 cm H₂O for differential valves, and of 29,8 ± 3,94 cm H₂O for gravitational valves. The Home-Telemonitoring setting reduced consequent outpatient visits, compared to the Home-Monitoring setting, with an average of 3,1 visits and 4,3 visits, respectively. No complications were associated with the surgical implantation of the P-tel catheter.

Conclusion

This study offers insight into the use of long-term ICP monitoring for management of IIH patients in combination with dual-valve VP shunts. The use of NEUROVENT® P-tel system and potentially other similar fully implantable ICP-monitoring devices, albeit invasive, may be justified in this complex disease. The data suggest recommending an initial adjustment of dual-valve VP-shunts of 30 and 6 cm H₂O, for gravitational and differential valves, respectively. Further research is warranted to explore potential integration of this concept in IIH management guidelines.

Shunt Overdrainage: Reappraisal of the Syndrome and Proposal for an Integrative Model

Although shunt overdrainage is a well-known complication in hydrocephalus management, the problem has been underestimated. Current literature suggests that the topic requires more examination. An insight into this condition is limited by a lack of universally agreed-upon diagnostic criteria, heterogeneity of published series, the multitude of different management options and misunderstanding of relationships among pathophysiological mechanisms involved. We carried out a review of the literature on clinical, radiological, intracranial pressure (ICP), pathophysiological and treatment concepts to finally propose an integrative model. Active prophylaxis and management are proposed according to this model based on determination of pathophysiological mechanisms and predisposing factors behind each individual case. As pathophysiology is progressively multifactorial, prevention of siphoning with gravitational valves or antisiphon devices is mandatory to avoid or minimize further complications. Shunt optimization or transferal and neuroendoscopy may be recommended when ventricular collapse and cerebrospinal fluid isolation appear. Cranial expansion may be useful in congenital or acquired craniocerebral disproportion and shunting the subarachnoid space in communicating venous hydrocephalus and idiopathic intracranial hypertension.

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 Sensor Reservoir-does it change management?

BACKGROUND

The Miethke Sensor Reservoir sits within a ventriculoperitoneal shunt system to give a reading of the pressure within the shunt. This information can guide the management of hydrocephalus patients who present frequently with headaches.

METHODS

We reviewed a cohort of 12 patients who underwent implantation of a Sensor Reservoir to assess how the management of their symptoms changed over a 4-year period.

RESULTS

When comparing the group before the Sensor Reservoir and after the Sensor Reservoir insertion, there was a 75% reduction in number of CT head scans (P<0.05), 100% reduction in episodes of ICP monitoring (P<0.05), 55% reduction in number of X-ray shunt series, and a 50% reduction in acute presentation to hospital with shunt-related symptoms. The number of clinic attendances increased by 44%. In addition, cost analysis showed a saving of £6952 per patients over the 2-year period following Sensor Reservoir insertion as a result of reduced admissions and investigations. Complications were seen in 3 patients-two patients developed shunt-related infections, and 1 patient underwent shunt revision due to a proximal shunt obstruction. Seventy-five percent of patients showed an improvement in their symptoms at the end of the 4-year period.

CONCLUSION

Implantation of a Sensor Reservoir in shunt patients with chronic headaches can reduce the number of investigations and hospital admissions and guide management resulting in a clinical improvement.

Telemetric intracranial pressure monitoring: our experience with 22 patients investigated for intracranial hypertension

INTRODUCTION

We present the application of the Raumedic^® P-tel telemetric device that monitors Intracranial Pressure (ICP) over long periods, in 22 patients, with suspected intracranial hypertension.

METHODS

A telemetric device (Raumedic^®, Neurovent^® P-tel) was surgically implanted in 22 patients aged between 21 and 65 years. Among the patients, the inconclusive diagnosis of benign intracranial hypertension was set in 10, the possible diagnosis of postoperative hydrocephalus in 3, and the possible diagnosis of aqueduct stenosis in 2. Additionally, shunt malfunction and Normal Pressure Hydrocephalus (NPH) were investigated in 1 and 3 patients, respectively. Finally, 3 patients presented ventricular dilatation of unknown origin. All the individuals underwent a 3-day ICP recording within the nursing unit. Three more recordings were obtained over a period of 2-6 months at the outpatient base.

RESULTS

Analysis of the data excluded the diagnosis of intracranial hypertension in 12 patients. Elevated ICP values were confirmed in 10 patients. Subsequently, 7 of them underwent shunts' implantation, while 2 refused further neurosurgical treatment and 1 was treated with acetazolamide. Additionally, 1 patient who demonstrated normal ICP values, thus confirmed with NPH, underwent VP shunt implantation, while another 2 with similar characteristics refused further surgery. In our series the overall clinical complication rate after P-tel implantation was insignificant.

CONCLUSIONS

The telemetric device is safely implanted via a rather simple procedure. In selected patients, it could provide long-term ICP recordings, which are necessary to confirm diagnosis and guide to the appropriate treatment.

Intracranial pressure before and after cranioplasty: insights into intracranial physiology

OBJECTIVE

Decompressive craniectomy (DC) is an emergency neurosurgical procedure used in cases of severe intracranial hypertension or impending intracranial herniation. The procedure is often lifesaving, but it exposes the brain to atmospheric pressure in the subsequent rehabilitation period, which changes intracranial physiology and probably leads to complications such as hydrocephalus, hygromas, and "syndrome of the trephined." The objective of the study was to study the effect of cranioplasty on intracranial pressure (ICP), postural ICP changes, and intracranial pulse wave amplitude (PWA).

METHODS

The authors performed a prospective observational study including patients who underwent DC during a 12-month period. Telemetric ICP sensors were implanted in all patients at the time of DC. ICP was evaluated before and after cranioplasty during weekly measurement sessions including a standardized postural change program.

RESULTS

Twelve of the 17 patients enrolled in the study had cranioplasty performed and were included in the present investigation. Their mean ICP in the supine position increased from -0.5 ± 4.8 mm Hg the week before cranioplasty to 6.3 ± 2.5 mm Hg the week after cranioplasty (p < 0.0001), whereas the mean ICP in the sitting position was unchanged (-1.2 ± 4.8 vs -1.1 ± 3.6 mm Hg, p = 0.90). The difference in ICP between the supine and sitting positions was minimal before cranioplasty (1.1 ± 1.8 mm Hg) and increased to 7.4 ± 3.6 mm Hg in the week following cranioplasty (p < 0.0001). During the succeeding 2 weeks of the follow-up period, the mean ICP in the supine and sitting positions decreased in parallel to, respectively, 4.6 ± 3.0 mm Hg (p = 0.0003) and -3.9 ± 2.7 mm Hg (p = 0.040), meaning that the postural ICP difference remained constant at around 8 mm Hg. The mean intracranial PWA increased from 0.7 ± 0.7 mm Hg to 2.9 ± 0.8 mm Hg after cranioplasty (p < 0.0001) and remained around 3 mm Hg throughout the following weeks.

CONCLUSIONS

Cranioplasty restores normal intracranial physiology regarding postural ICP changes and intracranial PWA. These findings complement those of previous investigations on cerebral blood flow and cerebral metabolism in patients after decompressive craniectomy.

Comparative investigation of different telemetric methods for measuring intracranial pressure: a prospective pilot study

OBJECTIVES

Measurement of intracranial pressure (ICP) plays an important role in long-term monitoring and neuro-intensive treatment of patients with a cerebral shunt. Currently, only two complete telemetric implants with different technical features are available worldwide. This prospective pilot study aims to examine patients who had both probes implanted at overlapping times for clinical reasons and represents the first in vivo comparison of both measurement methods.

MATERIALS AND METHODS

Patients with a primary subarachnoid hemorrhage or a spontaneous intracerebral hemorrhage with ventricular hemorrhage who had received a telemetric ICP probe (Raumedic® NEUROVENT®-P-tel) were included in the study. Conventional external ventricular drainages (EVD) and ventriculoperitoneal shunts with a telemetric ICP probe (Miethke Sensor Reservoir) were implanted in patients with hydrocephalus who required CSF (cerebrospinal fluid) drainage. Absolute ICP values from all systems were obtained. Due to the overlapping implantation time, parallel ICP measurements were performed via two devices simultaneously. ICP measurements via the sensor reservoir were repeated after 3 and 9 months. Differences between the absolute ICP values measured via the NEUROVENT®-P-tel probe, the Miethke sensor reservoir®, and the EVD were analyzed.

RESULTS

Seventeen patients were included in the present study between 2016 and 2018. 63% of all patients were male. In 11 patients the ICP measurements were followed up with both devices for 3 months. ICP measurements of the sensor reservoir showed corresponding trends in 9 cases compared to ICP measurement via the telemetry probe or EVD. Difference in absolute ICP values ranged between 14.5 mmHg and 0.0 mmHg. The average difference of the absolute ICP values in 8 cases was ≤ 3.5 mmHg.

CONCLUSION

ICP measurements with both systems continuously showed synchronous absolute ICP values, however absolute values of ICP measurement with the different systems did not match.

Single center experiences with telemetric intracranial pressure measurements in patients with CSF circulation disturbances

BACKGROUND

Hydrocephalus may present with heterogeneous signs and symptoms. The indication for its treatment and the optimal drainage in complex cases may be challenging. Telemetric intracranial pressure measurements (TICPM) may open new perspectives for those circumstances. We report our experiences using the Neurovent-P-tel and the Sensor Reservoir in a retrospective study.

METHODS

A series of 21 patients (age range 10-39.5 years) treated in our Pediatric Neurosurgical Unit receiving a TICPM was analyzed. In 8 patients, a Neurovent-P-Tel was implanted; 13 patients received a Sensor Reservoir, 6 of which as a stand-alone implant, while 7 were already shunted. TICPM were performed on an outpatient basis. Possible complications, follow-up surgeries, and TICPM were analyzed.

RESULTS

Concerning the complications, one infection was seen in each group and one postoperative seizure was observed in the P-tel group. TICPM-assisted shunt adjustments lead to clinical improvements in six patients in the P-tel group and six patients in the Sensor Reservoir group. In four out of six non-shunted patients, TICPM contributed to the indication toward shunt implantation.

CONCLUSIONS

TICPM seems to be a promising tool to improve clinical management of shunted patients with complex hydrocephalus. The two available systems will need further technical improvements, concerning implantation time, measurements, and data analysis in order to optimize handling and interpretation of the data.

Long-Term Effect of Decompressive Craniectomy on Intracranial Pressure and Possible Implications for Intracranial Fluid Movements

BACKGROUND

Decompressive craniectomy (DC) is used in cases of severe intracranial hypertension or impending intracranial herniation. DC effectively lowers intracranial pressure (ICP) but carries a risk of severe complications related to abnormal ICP and/or cerebrospinal fluid (CSF) circulation, eg, hygroma formation, hydrocephalus, and "syndrome of the trephined."

OBJECTIVE

To study the long-term effect of DC on ICP, postural ICP regulation, and intracranial pulse wave amplitude (PWA).

METHODS

Prospective observational study including patients undergoing DC during a 12-mo period. Telemetric ICP sensors (Neurovent-P-tel; Raumedic, Helmbrechts, Germany) were implanted in all patients. Following discharge from the neuro intensive care unit (NICU), scheduled weekly ICP monitoring sessions were performed during the rehabilitation phase.

RESULTS

A total of 16 patients (traumatic brain injury: 7, stroke: 9) were included (median age: 55 yr, range: 19-71 yr). Median time from NICU discharge to cranioplasty was 48 d (range: 16-98 d) and during this period, mean ICP gradually decreased from 7.8 ± 2.0 mm Hg to -1.8 ± 3.3 mm Hg (P = .02). The most pronounced decrease occurred during the first month. Normal postural ICP change was abolished after DC for the entire follow-up period, ie, there was no difference between ICP in supine and sitting position (P = .67). PWA was markedly reduced and decreased from initially 1.2 ± 0.7 mm Hg to 0.4 ± 0.3 mm Hg (P = .05).

CONCLUSION

Following NICU discharge, ICP decreases to negative values within 4 wk, normal postural ICP regulation is lost and intracranial PWA is diminished significantly. These abnormalities might have implications for intracranial fluid movements (eg, CSF and/or glymphatic flow) following DC and warrants further investigations.

Telemetric Intracranial Pressure Monitoring: A Systematic Review

Telemetric intracranial pressure (ICP) monitoring is a new method of measuring ICP which eliminates some of the shortcomings of previous methods. However, there are limited data on specific characteristics, including the advantages and disadvantages of this method. The main aim of this study was to demonstrate the indications, benefits, and complications of telemetric ICP monitoring. PubMed, MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials were searched for relevant studies without language or date restriction in May 2019. Human studies in which telemetric ICP monitoring was the main subject of the study were included. Our initial search resulted in 1650 articles from which 50 studies were included. There were no randomized controlled trials. The majority of the studies were case reports or case series (68%). The most common aim of studies was testing of the device (52%), and monitoring the disease progression or recovery (46%). The most common indications for telemetric ICP monitoring in these studies were testing cerebrospinal fluid shunt function (46%), ICP control after the procedure (36%), and diagnosing intracranial hypertension (22%) and hydrocephalus (12%). In total, 1423 brain disease patients had been monitored in studies. The possibility of long-term ICP monitoring as the main benefit was reported in 38 (76%) studies. The associated complication rate was 7.1%. Despite the increasing application of telemetric monitoring devices, studies to evaluate specific characteristics of this method have been infrequent and inadequate. Future research using a higher level of scientific methods is needed to evaluate advantage and disadvantages.

Telemetric intracranial pressure monitoring in children

PURPOSE

Repeated intracranial pressure (ICP) measurements are essential in treatment of patients with complex cerebrospinal fluid (CSF) disorders. These patients often have a long surgical history with numerous invasive lumbar or intracranial pressure monitoring sessions and/or ventriculoperitoneal (VP) shunt revisions. Telemetric ICP monitoring might be an advantageous tool in treatment of these patients. In this paper, we evaluate our experience with this technology in paediatric patients.

METHODS

During a 4-year period, we implanted telemetric ICP sensors (Raumedic NEUROVENT-P-tel) in 20 paediatric patients to minimise the number of future invasive procedures. Patients were diagnosed with hydrocephalus, idiopathic intracranial hypertension (IIH) or an arachnoid cyst. Most patients (85%) had a VP shunt at the time of sensor implantation.

RESULTS

In total, 32 sensors were inserted in the 20 patients; the cause of re-implantation was technical malfunction of the implant. One sensor was explanted due to wound infection and one due to skin erosion. We experienced no complications directly related to the implantation/explantation procedures. A total of 149 recording sessions were conducted, including 68 home monitoring sessions. The median implantation period was 523 days with a median duration of clinical use at 202 days. The most likely consequence of a recording session was non-surgical treatment alteration (shunt valve adjustment or acetazolamide dose adjustment).

CONCLUSION

Telemetric ICP monitoring in children is safe and potentially decreases the number of invasive procedures. We find that telemetric ICP monitoring aids the clinical management of patients with complex CSF disorders and improves everyday life for both patient and parents. It allows continuous ICP measurement in the patient's home and thereby potentially reducing hospitalisations, leading to significant cost savings.

Home telemonitoring of intracranial pressure

BACKGROUND

As technical progress advances, telemonitoring has become an important part of patient care in many areas of medical treatment. However, distanced surveillance of intracranial pressure (ICP) could not be established so far. With the recent introduction of a telemetric ICP measurement probe, new possibilities arise. Here, we report on a new home setup enabling home telemonitoring of intracranial pressure.

METHODS

Twenty patients suffering from disturbances of cerebrospinal fluid circulation, who underwent insertion of a telemetric ICP measurement probe, were provided with medical equipment to read ICP at home and save the data on an internet-enabled computer. Training in handling the equipment was performed during in-patient stay; recorded and uploaded ICP data was then analyzed online. Therefore, the treating medical team was able to access the ICP data via a secure internet connection while telephone conferencing with the patient.

RESULTS

Almost 7400 h of ICP data were recorded at home and evaluated via an internet connection according to the telemonitoring setup. This corresponds to an average record time of about 370 h per patient. ICP profiles were observed following endoscopic treatment, shunting procedures, or valve adjustments. The mean distance between the patients' residence and the consulting hospital was 172 km (range, 16-649 km).

CONCLUSIONS

ICP measurements have become accessible for telemonitoring purposes. This new management of hydrocephalus reflects an alternative method in patient care, especially for those who live far away from specialized centers.

Conservative and operative management of iatrogenic craniocerebral disproportion-a case-based review

INTRODUCTION

Craniocerebral disproportion (CCD) can occur as a sequela after shunting in early infancy. It can be understood as a disorder closely related to slit ventricle syndrome and chronic overdrainage syndrome. Here, we present two exemplary cases and summarize the pathophysiological, diagnostic, and therapeutic approaches to CCD.

CLINICAL PRESENTATION

Two premature babies underwent shunting for posthemorrhagic hydrocephalus and presented in later childhood with recurrent episodes of symptomatic raised intracranial pressure (ICP) at 2 and 8 years of age, respectively.

DIAGNOSIS AND MANAGEMENT

Both patients had unchanged ventricular size on cranial imaging and fulfilled the clinical diagnostic criteria of CCD. After confirming shunt patency, ICP monitoring was performed to diagnose intermittent intracranial hypertension. Different treatment pathways were pursued: While readjustment of a programmable shunt valve was sufficient to alleviate the raised ICP in the first case, a cranial expansion surgery was necessary in the second case.

OUTCOME AND CONCLUSIONS

Both children were treated successfully after thorough assessment and careful choice of treatment approaches. This review provides detailed insight into CCD and highlights the importance of individual and critical decision-making in these complex patients.

The applicability of fixed and adjustable gravitational shunt valves in two different clinical settings

BACKGROUND

Gravitational shunt valves and most recently the adjustable proSA® gravitational valve have been designed to counteract overdrainage and thereby improving clinical outcome. So far, the applicability in a broader mix of hydrocephalus patients is unrevealed. The aim of this study was to evaluate the utility of gravitational valves in two different clinical settings.

METHODS

This retrospective double-center cohort study was enabled by two different shunt management policies. At Rigshospitalet, patients with a complicated shunt history receiving a proGAV® and proSA® shunt system during surgical revision were included, and clinical outcome in the follow-up periods before and after was compared. At Aarhus University Hospital, a combination of a proGAV® and a fixed (SA®) or adjustable (proSA®) gravitational valve was used in all shunt procedures. Clinical outcome in a 2-year follow-up period was compared to a cohort receiving non-gravitational valves in the period before the transition to gravitational valves.

RESULTS

Twenty-two patients were included at Rigshospitalet. Mean follow-up time before and after proGAV® and proSA® implantation was 2.3 and 1.5 years, respectively. In each patient, roughly two surgical revisions (p 0.031) and two hospitalizations (p 0.009) were avoided each year after proGAV® and proSA® implantation. At Aarhus University Hospital, 90 patients with non-gravitational valves and 98 patients with gravitational valves were included. Changes in clinical outcome parameters and shunt survivals were either stable or statistically insignificant.

CONCLUSIONS

Gravitational valves are safe and useful in clinical practice and represent an equivalent alternative as a first-line shunt valve in a broad mix of patients, while proSA® valves should be considered for complex shunt patients.

Intracranial Pressure Monitoring-Review and Avenues for Development

Intracranial pressure (ICP) monitoring is a staple of neurocritical care. The most commonly used current methods of monitoring in the acute setting include fluid-based systems, implantable transducers and Doppler ultrasonography. It is well established that management of elevated ICP is critical for clinical outcomes. However, numerous studies show that current methods of ICP monitoring cannot reliably define the limit of the brain's intrinsic compensatory capacity to manage increases in pressure, which would allow for proactive ICP management. Current work in the field hopes to address this gap by harnessing live-streaming ICP pressure-wave data and a multimodal integration with other physiologic measures. Additionally, there is continued development of non-invasive ICP monitoring methods for use in specific clinical scenarios.

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.

In vitro performance of the fixed and adjustable gravity-assisted unit with and without motion-evidence of motion-induced flow

BACKGROUND

Anti-siphon devices and gravitational-assisted valves have been introduced to counteract the effects of overdrainage after implantation of a shunt system. The study examined the flow performance of two gravitational-assisted valves (shunt assistant - SA and programmable shunt assistant - proSA, Miethke & Co. KG, Potsdam, Germany) in an in vitro shunt laboratory with and without motion.

METHODS

An in vitro laboratory setup was used to model the cerebrospinal fluid (CSF) drainage conditions similar to a ventriculo-peritoneal shunt and to test the SA (resistance of +20 cmH2O in 90°) and proSA (adjustable resistance of 0 to +40 cmH2O in 90°). The differential pressure (DP) through the simulated shunt and tested valve was adjusted between 0 and 60 cmH2O by combinations of different inflow pressures (40, 30, 20, 10, and 0 cmH2O) and the hydrostatic negative outflow pressure (0, -20, and -40 cmH2O) in several differing device positions (0°, 30°, 60°, and 90°). In addition, the two devices were tested under vertical motion with movement frequencies of 2, 3, and 4 Hz.

RESULTS

Both gravity-assisted units effectively counteract the hydrostatic effect in relation to the chosen differential pressure. The setting the proSA resulted in flow reductions in the 90° position according to the chosen resistance of the device. Angulation-related flow changes were similar in the two devices in 30-90° position, however, in the 0-30° position, a higher flow is seen in the proSA. Repeated vertical movement significantly increased flow through both devices. While with the proSA a 2-Hz motion was not able to induce additional flow (0.006 ± 0.05 ml/min), 3- and 4-Hz motion significantly induced higher flow values (3 Hz: +0.56 ± 0.12 ml/min, 4 Hz: +0.54 ± 0.04 ml/min). The flow through the SA was not induced by vertical movements at a low DP of 10 cmH2O at all frequencies, but at DPs of 30 cmH2O and higher, all frequencies significantly induced higher flow values (2 Hz: +0.36 ± 0.14 ml/min, 3 Hz: +0.32 ± 0.08 ml/min, 4 Hz: +0.28 ± 0.09 ml/min).

CONCLUSIONS

In a static setup, both tested valves effectively counteracted the hydrostatic effect according to their adjusted or predefined resistance in vertical position. Motion-induced increased flow was demonstrated for both devices with different patterns of flow depending on applied DP and setting of the respective valve. The documented increased drainage should be considered when selecting appropriate valves and settings in very active patients.