Revision surgery following CSF shunt insertion: how often could it be avoided?

BACKGROUND: Cerebrospinal fluid (CSF) shunt revision surgery represents a huge social and economic burden. Few studies, however, have evaluated shunt revision surgeries in the context of their avoidability, and existing data are from paediatric populations. Using ratings from an expert panel, we classified avoidable and unavoidable shunt revisions in a mixed cohort of CSF-shunt patients. METHODS: In a retrospective review of a prospectively maintained, single-centre database, we identified all shunt systems implanted for the first time over a 10-year period (2007-2016) and all subsequent revision surgeries with a follow-up of at least 1 year. A panel of five expert shunt surgeons classified each revision surgery as avoidable or unavoidable. Rates of each were calculated and correlated with clinical data. RESULTS: Of 210 revision surgeries (314 patients, mean age, 49.9 years; mean follow-up, 4.2 years), the panel judged 114 as unavoidable (54.3%) and 96 (45.7%) as avoidable. Level of surgeon education correlated with these rates, but even in the most experienced hands, 12.5% of revisions were classified as avoidable. Avoidable revisions occurred significantly earlier than unavoidable interventions (mean; 112 and 448 days, respectively) after the index surgery. CONCLUSION: Rates of avoidable shunt revision surgery are alarmingly high, even in experienced hands. Avoidable revisions occur significantly earlier, predominantly within the first 3 months after the index surgery.

Cerebral vasospasm after endoscopic fenestration of a temporal arachnoid cyst in a child-a case report and review of the literature.

INTRODUCTION: Intracranial arachnoid cysts (ACs) represent rare extra-axial CSF-containing lesions. Surgical management mainly depends on the cyst location and its size. Nevertheless, pure endoscopic fenestration represents a relatively straightforward and safe technique, and-in most cases-the treatment of choice for symptomatic intracranial ACs. The postoperative complication rate of the procedure is low including subdural hematomas, hygromas, and intraparenchymal hemorrhages. Symptomatic cerebral vasospasm after endoscopic treatment of ACs is a very uncommon event. CASE REPORT/RESULTS: To the authors' knowledge, this adverse event in children has not yet been reported in the literature yet. The authors present a case of a 9-year-old child developing an early symptomatic cerebral vasospasm with an insignificant secondary ischemia following endoscopic fenestration of a large temporal arachnoid cyst. DISCUSSION: The clinical approach, possible pathogenesis, and the therapeutic strategy is discussed particularly with regard to the literature.

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.

Intra-catheter endoscopy for various shunting procedures-a retrospective analysis on surgical practicability, catheter placement, and failure rates.

BACKGROUND: The long-term function of a cerebral shunt is directly influenced by the placement of the ventricle catheter. In this work, an intra-luminal endoscope for best possible catheter positioning was used. Practicability, postoperative imaging, and shunt failure rates were retrospectively evaluated. METHODS: Between January 2012 and June 2016, an intra-catheter endoscope was applied in 71 procedures. Endoscopic technique was used for catheter placement in first-time shunting or cerebrospinal fluid reservoir insertion (n = 38), revision surgery in proximal shunt failure (n = 13), and various intraventricular stenting procedures (n = 20). Catheter positioning was graded on postoperative imaging using a four-point scale. All patients were regularly followed up (mean, 31.6 months) to recognize shunt failures. RESULTS: Endoscopic application could be completed as intended in 68 of 71 procedures. Postoperative imaging could exclude complete misplacement of all catheters, but optimal positioning was only achieved in 64.7% (44/68 cases). Four catheters had to be revised due to malfunction (failure rate, 5.8%). Another five catheters had to be removed due to infectious complications or wound-healing disorders. Direct correlations between catheter complications and suboptimal catheter positioning were not seen. Slit or distorted ventricles also did not prove to be a risk factor for the observed complications. CONCLUSIONS: Versatile application possibilities of the intra-catheter endoscope reflect the advantages of the technique. Independent of the performed procedure, unintended positionings or even complete catheter misplacements could be avoided. However, in more than one-third of all cases, suboptimal catheter placements became obvious. Interestingly, negative influences on later shunt failures were not seen.

Aqueductal stenting with an intra-catheter endoscope--a technical note.

INTRODUCTION: Aqueductoplasty as well as aqueductal stenting is an accepted therapy option in short-segment aqueductal stenosis and isolated fourth ventricle. Over the years, different techniques with only slight modifications by using a conventional neuroendoscope with a working sheath to introduce different instruments have been presented. In summary, the use of Fogarty balloon catheters or flexible endoscopes to pass the narrowed aqueduct is recommended. METHODS: This technical report describes a substantially new technique for this purpose. Six patients underwent aqueductal stenting with a new intracatheter endoscope. RESULTS: Aqueductal stenting was possible in 4 out of 6 cases. No complications occurred. Handling of this new technique was good and easy without a prolonged learning curve. All four stents did work appropriately, and the procedure was considered to be successful. Of the two failures, the technique was abandoned and endoscopic third ventriculostomy (ETV) was performed in one. In the other case, suboccipital shunting was done. CONCLUSION: This technical report describes a substantially new technique for aqueductal stenting. The combination of an intracatheter miniature endoscope and a prepared ventricular catheter enables careful and elegant aqueductal stenting. Large or flexible endoscopes, balloons, or special instruments to place a stent have become completely obsolete in selected cases.

An operative technique combining endoscopic third ventriculostomy and long-term ICP monitoring.

Neuroendoscopy has been well established in the treatment of many neurological and neurosurgical diseases. Especially its application in occlusive hydrocephalus to restore a physiological cerebrospinal fluid circulation has been extensively examined in the past. Although such procedures are believed to be safe and effective, complication as well as failure rates up to 20% have been described pointing to the importance of long-term postoperative care. Therefore, different and partly invasive procedures as ventricular drain insertions or complex cranial imaging methods have been proposed; however, associated pitfalls and restrictions often limited their prognostic value and long-term benefit. An operative technique combining endoscopic third ventriculostomy and telemetric increased intracranial pressure monitoring has now been developed to optimize the postoperative care management. The main intention is to provide sufficient brain pressure data for long-term observation and early recognition of endoscopy failures and complications. The new operative technique was applied in a series with 24 patients suffering from occlusive hydrocephalus. Surgical technique and future perspectives are presented.

Overcoming CSF overdrainage with the adjustable gravitational valve proSA.

BACKGROUND: Despite progress in shunt valve technology, CSF overdrainage is still one of the most frequent complications in shunt-treated hydrocephalus. Particularly with regard to young and adolescent patients, treatment of manifest overdrainage is complicated by several hardly influenceable factors such as increasing height and mobility. Therefore, the aim of this study was to evaluate the therapeutic efficiency of the new adjustable gravitational valve, proSA. METHODS: Sixty-four shunt-treated young hydrocephalus patients aged 1.8-41.4 years (15.5 ± 10.5 years) suffering from clinical and/or radiological overdrainage underwent shunt revision surgery with the implantation of the new proSA valve. Clinical outcome after a 1-year follow-up period, pumping function of the valve chambers as well as the number of necessary postoperative valve adjustments were examined. RESULTS: Fifty-five patients completed the study as planned. All reported a significant improvement of their clinical condition; 91 % described a complete resolution in symptoms related to overdrainage. Preoperatively, more than 85 % of the valve chambers showed no or very slow refilling with CSF. After a year of proSA treatment, more than 90 % exhibited a normal valve chamber function. During the follow-up period, a total of 136 valve adjustments were necessary. None of the proSA valves had to be surgically revised. CONCLUSIONS: The postoperative adjustability of the opening pressure level is the advantage of the new gravitational valve. The good clinical outcome is attributed to the new valve technology. The proSA appears to be a promising shunt valve to overcome overdrainage in adolescent and adult hydrocephalus patients.

Clinical and radiological findings in long-term intracranial pressure monitoring.

BACKGROUND: Advantages of telemetric devices for long-term intracranial pressure (ICP) measurement have been mentioned several times in the literature. However, descriptions of associated complications are lacking. Therefore, the presented observational study focused on clinical and radiological findings after insertion of an intraparenchymal telemetric ICP monitor. METHODS: Between April 2010 and February 2013, 185 telemetric ICP catheters were implanted for diagnostic purposes. All patients were clinically followed. Radiological, microbiological and clinical data were analysed. RESULTS: One brain abscess (0.5 %) and two cutaneous infections (1.1 %) occurred in 185 patients. Staphylococcus spp. could be detected in all cases. Six patients (3.2 %) suffered from single new-onset seizures and one patient (0.5 %) from a temporary hemiparesis. Intracerebral haemorrhages occurred in 15.6 %, most of the time as small punctate bleedings. Perifocal oedematous reactions surrounding inserted telemetric catheters could be observed in 46.9 %. Multiple imaging studies revealed a tendency of complete oedema resolution over time. CONCLUSIONS: Infectious as well as haemorrhagic complication rates are well comparable with the common literature. The long-term implantation of an ICP probe does not seem to increase the risk of wound infections or brain abscess formation. Surprisingly, very high numbers of oedematous reactions after insertion of the intraparenchymal ICP monitor were seen. Reasons therefore could only be speculated upon.

Association of Chiari malformation and vitamin B12 deficit in a family.

PURPOSE: A clear etiology of Chiari malformation is still lacking. Some associations between this disorder and genetical variations have been reported. Documented cases of familial Chiari malformation in three consecutive generations are rare. Furthermore, an association of Chiari disorder and vitamin B12 deficit has rarely been described in literature. METHODS: In this study, three generations of a family suffering from Chiari 1 or Chiari 0 malformation have been examined with MRI, clinically and laboratory (hemograms). RESULTS: Chiari malformation could be confirmed in all presented patients: While the F2 generation (children: 1 × â™€, 1 × â™‚) and the female F1 generation (mother and sister of mother) suffered from Chiari type 1, the male F0 generation showed Chiari 0 malformation. F0 and F1 generation further presented with syringomyelia (F0: C4-D1; F1: C4-D2). All patients except the grandfather (F0) underwent surgical posterior fossa decompression to relive successfully cerebellar and hydrocephalus associated progressing clinical symptoms. The hemograms of generation 1 and 2 revealed familial vitamin B12 deficit. CONCLUSIONS: A hereditary component is discussed in Chiari malformation, yet proved etiology is still lacking. As folic acid plays an important role in the development of the neural tube, vitamin B12 deficit might have some impact on the development of Chiari malformations.

The frontal and temporal horn ratio to assess dimension of paediatric hydrocephalus: a comparative volumetric study.

Magnetic resonance imaging and cranial -ultrasound are the most frequently implemented imaging methods for investigating the infantile hydrocephalic brain. A general and reliable measurement index that can be equally applied in both imaging methods to assess dimension of ventricular dilatation is currently not available. For this purpose, a new parameter called the frontal and temporal horn ratio - determinable in coronal slices of the brain - was developed and evaluated in a comparative volumetric retrospective study: Statistical analyses of 118 MRIs of 46 different shunt-treated pediatric patients revealed a good linear correlation between the new index and the actual ventricular volume.

Augmented Reality-Supported Rod Bending in Multilevel Spinal Fusion Using the ADVISE Software.

BACKGROUND: One of the most common reasons for poor patient outcomes and revision surgery in spinal fusion is hardware failure. Screw loosening or pullout occurs in up to one-quarter of all cases. It is known that even small screw-rod misalignments can cause significant mechanical overloads during rod fixation, which can result in hardware failure. To address this crucial surgical step, a novel augmented reality-assisted software was developed to generate custom rod templates that are precisely adapted to the individual patient. METHODS: The novel software, which runs on a tablet, is used in spinal fusion surgery and is based on the use of a specific pedicle screw system, in which the polyaxial screw heads are connected to detachable guides. These guides can be recognized by the tablet camera and a light detection and ranging scanner. This image information is processed to determine the spatial positions of the screw heads and to calculate an ideally fitting rod template. RESULTS: The calculated rod template is displayed in a 1-to-1 scale on the tablet screen. This template is used to cut and bend the rods of the pedicle screw system. Finally, the custom bent rod can be inserted into the screw heads without tension. CONCLUSIONS: The augmented reality-assisted software is intended to give surgeons access to patient-specific intraoperative real-time data, helping them in bending rods that are more precisely adapted to the individual patient compared with the freehand technique.

Subdural or intraparenchymal placement of long-term telemetric intracranial pressure measurement devices?

We established a CE-certified telemetric device to measure intracranial pressure (ICP) noninvasively. To evaluate whether subdural or intraparenchymal insertion of such devices should be preferred, we implanted these telemetric ICP measurement devices (Raumedic, Rautel) in both locations. The study was performed in nine minipigs. The telemetric data were validated every 3 months using conventional intraparenchymal ICP measurement probes.The intraparenchymal telemetric device failed in one animal 12 months after insertion. Computed tomography (CT) revealed first hints for failure: Despite the implantation in adult animals, the skull dimensions seemingly increased after implantation, and the sensor tip was dislocated on the tabula interna level. This finding could also be verified by histopathological examination which would explain the reason for mismeasurement. The subdural catheter failed after 9 months. CT and histopathological examination revealed a bony encapsulation of a large catheter part, which had been located correctly initially. We propose that chronic pulsatile stress on the device was the underlying reason for this phenomenon, comparable to that in meningeal arteries.In some of the other animals, failure of subdural catheters could be detected. Histopathological examinations in these cases are still pending. Nevertheless, we assume similar underlying reasons for failure in these subdural probes.In conclusion, we favour intraparenchymal placement of telemetric ICP measurement devices.

Pathophysiology of brainstem lesions due to overdrainage.

Overdrainage in hydrocephalus therapy is a common shunt complication responsible for many different side effects. Especially an association with an impairment of upper brainstem structures causing symptoms of a dorsal midbrain syndrome (DMS) has already been described. Yet apart from these known mesencephalic lesions, we found several more brainstem signs and symptoms resulting from overdrainage. Parinaud's syndrome was diagnosed in all six patients examined; moreover, parkinsonism, memory disturbances, fluctuations in the level of consciousness, and hypothalamic dysfunctions could be detected in five of six patients. In addition hypersalivation combined with peripheral facial nerve palsy and blepharospasm occurred in two patients each, respectively. We postulate an upward herniation of the midbrain into the tentorial notch causing a secondary aqueductal stenosis as causal. An obstructed Sylvian aqueduct and the occurrence of shunt failure can lead to a bulging or enlargement of the third ventricle resulting in diencephalic lesions. If combined with fourth ventricle outlet occlusion, secondary aqueductal stenosis aggravates the situation with a fourth ventricle entrapment. Symptomatology and proposed pathophysiology are presented.

Intraventricular cooling during CSF infusion studies.

We implemented ventricular infusion studies on 33 patients suspected of idiopathic normal pressure hydrocephalus (iNPH), benign intracranial hypertension (BIH) or occlusive hydrocephalus (HOC) in order to confirm shunt indications. The initial scope was to study O(2) supply during infusion tests to exclude further violation of already vulnerable brains during ICP elevation. Intraventricular infusion was performed via ventricle catheters with the ICP tip sensor, while brain tissue oxygenation was measured with intraparenchymal Raumedic PTO probes. In 15 out of 23 (65%; 8 NPH, 2BIH, 5 HOC), pO(2) increased constantly (average 140%), while brain temperature decreased (range: 0.2-4.5°C) during the infusion studies. In another six patients, O(2) values remained largely stable during the infusion studies (4NPH, 1BIH, 1HOC). Cerebral deoxygenation during infusion tests occurred only in two patients (1NPH, 1HOC).Overall cerebral oxygenation and temperature inversely correlated well with some temporary delay regarding oxygenation state as a consequence of cerebral temperature. Probably, this effect is a consequence of reduced cerebral metabolism caused by local cooling. We hypothesise that such cooling is mediated via the large basal arteries and suggest that such a pathophysiology, ICP-controlled local cooling, might offer a new option for brain protection (e.g. in an ICP crisis).

Dynamics of cerebrospinal fluid flow in slit ventricle syndrome.

INTRODUCTION: Although slit ventricle syndrome (SVS) is identified as a serious complication in shunt-treated hydrocephalus, cerebral spinal fluid (CSF) flow via external ventricular drainage (EVD) or shunts in SVS have not been studied up to now. MATERIAL AND METHODS: A new apparatus (LiquoGuard(®); Möller-Medical, Fulda, Germany) was used for EVD in a child with SVS. The LiquoGuard actively controls CSF drainage, based on intracranial pressure (ICP). RESULTS: To achieve well-tolerated clinical conditions, an ICP level of 4 mmHg was necessary; realizable by drainage rates between 0 and 35 mL/h. Drainage rate variations typically occurred with repetitive time intervals of 2 h causing a "saw tooth" shaped CSF flow pattern throughout 24 h. DISCUSSION: SVS seems to be characterized largely by quickly varying CSF drainage demands. Whether this is a general phenomenon or just true for this case has still to be studied and needs further clarification.

Telemetric ICP measurement with the first CE-approved device: data from animal experiments and initial clinical experiences.

The objective was to evaluate the qualification of the new telemetric intracranial pressure (ICP) measurement (t-ICP) device Raumedic(®) NEUROVENT P-Tel and S-Tel. The proof of concept was examined in a pilot animal study measuring intraperitoneal pressure with a telemetric and a conventional ICP measurement probe at five rates for 1 h each. Moderate external pressure load allowed measuring values between 0 and 40 mmHg. To estimate long-term performance 18 t-ICP devices were implanted subdurally or intraparenchymally into minipigs. Reference measurements were performed regularly using conventional ICP probes. From the short-term as well as from the long-term perspective t-ICP proved to have excellent dynamic ICP signal components perception (e.g. pulse amplitude). Some zero drift of static ICP was found, ranging between 5 and 8 mmHg. While all telemetric, intraparenchymal probes kept their functionality throughout the follow-up, 33% of the subdurals failed for reasons detailed in another paper. Raumedic's NEUROVENT(®) P-Tel/S-Tel proved to provide reliable data over periods of up to 18 months. Minor zero drift can be well tolerated as the dynamic ICP signal is measured with excellent stability. Clinicians should focus more on such ICP dynamic signal information than on static ICP when using the device over longer follow-up periods.

Frontal and temporal horn ratio: a valid and reliable index to determine ventricular size in paediatric hydrocephalus patients?

Because there is currently no sufficient and prevalent parameter for estimating ventricular size in paediatric hydrocephalus patients by using cranial ultrasound, a new measurement index, called the "frontal and temporal horn ratio", is presented in this study. The advantage of the new quotient is that it can be detected in easily obtainable coronal ultrasound planes. A retrospective analysis of 149 MRIs of young hydrocephalus patients proved the new index to be a promising parameter of ventricular size assessment. Statistical comparison between the "frontal and temporal horn ratio" and the already validated "frontal and occipital horn ratio" revealed a strong and linear correlation between the two quotients. Current research is now evaluating the reliability of the new index in the context of an ultrasound study; first results indicate similar positive findings.

Microstructural alterations of silicone catheters in an animal experiment: histopathology and SEM findings.

INTRODUCTION: Biocompatibility of implants in humans has been classified as "inert," "tolerated," and "bioactive." In shunt-treated patients, catheter-induced complications account for up to 70% of all hardware failures. Our objective was to study whether foreign body reactions to silicone shunt catheters in subcutaneous tissue and at their distal, intraperitoneal ends leading to occlusion can be reproduced in an animal model. MATERIALS AND METHODS: Twelve different silicone catheters were implanted in 6-week-old Wistar rats: (a) purely in the subcutaneous tissue and (b) through the subcutaneous tissue into the peritoneal cavity. One of the catheters was of our own design with a silicated surface. After 1 year, all catheters were explanted and were examined by histopathology and scanning electron microscopy (SEM). RESULTS: Histopathological analysis revealed the development of collagenous membranes and chronic immune reactions around the catheters. Completely organized intraluminal obliteration was seen in six intraperitoneally inserted catheters. SEM demonstrated calcifications and signs of biodegradation. Silicated catheters showed the most extensive calcifications. DISCUSSION: Hydrocephalus shunt catheters cannot be termed "inert" or "biotolerated." Rather, they must be regarded as "bio-active" implants. The extensive reaction on silicated catheters can act as reference to estimate the biocompatibility of surface modifications. The model proved appropriate for further studies.

Real-Time Evaluation of Optic Nerve Sheath Diameter (ONSD) in Awake, Spontaneously Breathing Patients.

(1) Background: Reliable ultrasonographic measurements of optic nerve sheath diameter (ONSD) to detect increased intracerebral pressure (ICP) has not been established in awake patients with continuous invasive ICP monitoring. Therefore, in this study, we included fully awake patients with and without raised ICP and correlated ONSD with continuously measured ICP values. (2) Methods: In a prospective study, intracranial pressure (ICP) was continuously measured in 25 patients with an intraparenchymatic P-tel probe. Ultrasonic measurements were carried out three times for each optic nerve in vertical and horizontal directions. ONSD measurements and ICP were correlated. Patients with ICP of 2.0-10.0 mmHg were compared with patients suffering from an ICP of 10.1-24.2 mmHg. (3) Results: In all patients, the ONSD vertical and horizontal measurement for both eyes correlated well with the ICP (Pearson R = 0.68-0.80). Both measurements yielded similar results (Bland-Altman: vertical bias: -0.09 mm, accuracy: ±0.66 mm; horizontal bias: -0.06 mm, accuracy: ±0.48 mm). For patients with an ICP of 2.0-10.0 mmHg compared to an ICP of 10.1-24.2, ROC (receiver operating characteristic) analyses showed that ONSD measurement accurately predicts elevated ICP (optimal cut-off value 5.05 mm, AUC of 0.91, sensitivity 92% and specificity 90%, p < 0.001). (4) Conclusions: Ultrasonographic measurement of ONSD in awake, spontaneously breathing patients provides a valuable method to evaluate patients with suspected increased ICP. Additionally, it provides a potential tool for rapid assessment of ICP at the bedside and to identify patients at risk for a poor neurological outcome.

Intracranial Pressure-Guided Shunt Valve Adjustments with the Miethke Sensor Reservoir.

BACKGROUND: Telemetric intracranial pressure (ICP) monitoring seems to be a promising therapy-supporting option in shunt-treated patients. Benefits become obvious when headaches are unspecific and clinical symptoms cannot be related to possible overdrainage or underdrainage. In this study, we evaluated a new telemetric device to individually adjust shunt valves according to ICP measurements. METHODS: Between December 2015 and November 2016, 25 patients with suspected suboptimal shunt valve settings underwent insertion of a telemetric ICP sensor (Sensor Reservoir; Christoph Miethke, Potsdam, Germany). Over a 1-year period, a total of 183 telemetric ICP measurements and 85 shunt valve adjustments were carried out. Retrospective statistic analyses focused on valve adjustments, ICP values, and clinical outcomes. RESULTS: ICP-guided valve adjustments positively changed the clinical state in 18 out of 25 patients. Clinical improvement over time was associated with significant changes of the valve settings and ICP values. Interestingly, a therapeutically normalized ICP profile was not automatically associated with clinical improvement. CONCLUSIONS: The Sensor Reservoir is an important and valuable tool for shunt-treated patients suffering from drainage-related problems. The possibility to simultaneously recognize and solve shunt problems represents the decisive advantage. Nevertheless, measurements with the Sensor Reservoir did not allow for the determination of default valve settings or universal target ICP values.