Hans-Georg Schlosser

The adjustable proGAV shunt: a prospective safety and reliability multicenter study.

OBJECTIVETo evaluate the reliability of the gravitation-assisted adjustable proGAV shunt system with a prospective multicenter study conducted in 10 German hospitals. METHODSEnrollment for this observational study began in April 2005 and concluded in February 2006. The protocol required re-examinations 3 and 6 months postoperatively and fixed the endpoint of follow-up at 12 months after implantation. Patients with different types of adult, juvenile, and pediatric hydrocephalus were included and 165 patients were enrolled; 9 died and 12 had incomplete follow-up. RESULTSOf the assessable 144 patients, 130 completed the protocol after 12 months, whereas 14 failed because of the need to explant the device, mainly because of infection. In 12 patients, components of the shunt, not the valve, were revised. In 65 of the 144 patients, there were 102 readjustments of the valve in 67 incidences because of underdrainage and in 35 because of overdrainage. In 1 case, readjustment was not possible. Determination of pressure level with the verification instrument was safe and corresponded to the required x-ray controls after adjustments. No unintended readjustments were noted. CONCLUSIONThe proGAV is a safe and reliable device.

Interleukin-6 serum level assessment using a new qualitative point-of-care test in sepsis: A comparison with ELISA measurements.

OBJECTIVES Interleukin-6 (IL-6) is involved in inflammatory diseases, provides prognostical information, and allows the early identification and monitoring of septic patients. We investigated whether IL-6 can be assessed using a new densitometric point-of-care (POC) bedside assay. DESIGN AND METHODS 392 samples were prospectively collected from 57 intensive care unit patients (38 male, age: 45.2 +/- 16.9years, APACHE II score: 25.4 +/- 4.8). Blinded IL-6 measurements were performed using conventional semiautomatic enzyme-linked immunosorbent assays (ELISA) and the POC test. RESULTS Mean IL-6 levels were 102.9 +/- 388.6pg/mL (ELISA) and 97.0 +/- 535.5 (POC). A significant correlation was found (p < 0.0001, r = 0.92). The sensitivity/specificity for sepsis was 82.6%/86.5% (ELISA, AUC: 0.881), and 76.4%/95.0% (POC, AUC: 0.868). CONCLUSIONS Here we demonstrate significant correlations of IL-6 levels determined using a POC test and semiautomatic ELISA. ROC analyses revealed no significant differences between the two tests. With a turn-around time of 20min, the bedside IL-6 test is a new tool that may help to initiate early goal-directed therapy.

Using video-oculography for galvanic evoked vestibulo-ocular monitoring in comatose patients

Binocular eye movement responses to galvanic vestibular stimulation were measured in comatose patients. Healthy persons have been demonstrated to show a consistent and reproducible relationship between eye movement and galvanic vestibular stimulation. Any pathology of the vestibular integrating structures (brainstem and to some degree the cerebellum and cortex) is assumed to influence this response pathognomonically. A monitoring facility was designed to record eye movements during galvanic labyrinth polarization (GaLa) in order to examine the vestibular response in comatose patients. GaLa was applied by means of two pairs of electrodes attached between the mastoid and interscapular region. A custom-built, battery-driven current-source stimulator served to generate sinusoidal stimuli that could be applied either unilaterally or simultaneously and independently to the left and right labyrinths. The resultant binocular eye movements were recorded using a Chronos Eye Tracker and the digital image sequences stored for subsequent analysis. Repeated testing was performed in five comatose patients with a Glasgow Coma Score of 3, who were intubated and ventilated (subarachnoid hemorrhage (n = 3), traumatic injury (n = 2)). The observed ocular movements varied. In four cases ocular movements in response to GaLa were observed, while one patient showed neither spontaneous nor galvanic-induced eye movements. The latter was diagnosed as brain-dead 2 days after testing. In contrast, the patients who showed ocular movements synchronous with galvanic stimulation left the intensive care unit (ICU) for rehabilitation. These data indicate that it is possible to assess brain function in comatose patients by evaluating the vestibulo-ocular response to galvanic stimulation. The designed monitoring facility can be used on the ICU ward without disconnection of other monitoring equipment.

Tuning in caudal fastigial nucleus units during natural and galvanic labyrinth stimulation.

Neurons of the caudal fastigial nucleus were investigated by means of single unit recordings. Natural vestibular stimuli were applied as well as galvanic labyrinth polarization. One-third of the neurons showed a convergence of vertical and horizontal canals. More than 80% of the neurons responded to polarization of both the ipsilateral and contralateral canals (binaural responders). Most neurons had a limited response range. Two classes of neurons could be distinguished: up to 1 Hz responders and up to 10 Hz responders. In addition a group of fastigial cells showed a tuning within a small range of frequencies (sharp-tuning responders).

Reduction of shunt obstructions by using a peel-away sheath technique? A multicenter prospective randomized trial

OBJECTIVE Shunt obstructions may partly be caused by brain debris, which intrude into the ventricular catheter during ventricle puncture. Avoiding contact between the catheter and brain tissue, by using a peel-away sheath, should reduce the number of shunt failures caused by obstruction. To test this hypothesis, we conducted a randomized, prospective multicenter study. METHODS 201 patients from 6 different neurosurgical centers in Germany receiving a ventriculo-peritoneal shunt were included in this study. Of these, 177 patients completed a 1-year follow-up period. Surgery was randomized in a 1 to 1 fashion, such that out of 177 procedures, 91 were performed using a peel-away sheath and 86 were performed without. The rate of surgical re-interventions and shunt obstructions within a 12-month period was recorded. RESULTS Within 1 year post-surgery, 17 shunt obstructions (9.6%) leading to shunt revisions were recorded. However, no difference was found between surgeries performed using a peel-away sheath (9.9%) or not (9.3%). The overall shunt infection rate was 2.8% and the shunt revision rate for overdrainage was 3.9%. CONCLUSIONS The theoretical advantages attributed to the use of a peel-away sheath to introduce a ventricular catheter could not be confirmed in this randomized study, suggesting that the proposed role of brain debris in shunt obstructions may be overestimated.

Transcranial Doppler ultrasound during galvanic labyrinth polarization depicts central vestibular processing, demonstrating bilateral vestibular projection.

The combination of galvanic labyrinth polarization and transcranial Doppler ultrasound was employed to depict the neurovascular coupling in the cerebral vestibular areas. For galvanic stimulation, surface electrodes were attached to the right and left mastoid and two further electrodes were fixed near to each shoulder blade. Thus, each pair of electrodes (mastoid to shoulder) facilitated unilateral stimulation of the ipsilateral vestibular labyrinth. Blood flow in the middle cerebral artery and the internal carotid artery in both hemispheres was measured by means of Doppler ultrasound. The transcranial Doppler ultrasound system was head‐fixed and allowed continuous monitoring of the blood flow throughout the trials. Using a series of different stimulation modes (bilateral, unilateral left, unilateral right and sham), the changes in mean blood flow velocity were evaluated by comparing baseline blood flow under resting conditions to blood flow during stimulation. A total of 18 trials were performed with each of seven volunteer subjects. Galvanic labyrinth polarization elicited a clear sensation of pendular body movement in all subjects. Significant blood flow increase (P < 0.05) in both hemispheres was observed during bilateral stimulation. Of more interest is that unilateral stimulation also elicited a significant increase in flow in both the ipsilateral and the contralateral hemispheres, demonstrating the existence of bilateral projections from each vestibular labyrinth. The combination of galvanic labyrinth polarization with transcranial Doppler ultrasound blood flow measurement provides a novel approach to the functional assessment of the vestibular system (deep cerebral structures and cortical areas). This novel technique provides a useful tool for clinical examinations.

An improved reservoir for the flushing test to diagnose shunt insufficiency.

OBJECTIVE Reservoirs integrated into hydrocephalus shunts are commonly used for the removal of CSF and for intra-ventricular pressure measurement. Pumping with the reservoir to diagnose shunt sufficiency is still a matter of controversy. The authors describe an improved flushing device and its characteristic features in vitro and in vivo. METHODS The flushing reservoir is constructed with a sapphire ball in a cage as a nonresistance valve to also enable the detection of distal occlusions. The most important reservoir parameters were investigated in vitro, simulating total and partial proximal and distal shunt occlusions. Then the expected advantages were assessed in vivo by evaluating the pump test data of 360 implanted reservoirs. The results were compared with those found in the literature. RESULTS The optimization of the technical parameters of the device, such as the high stroke volume in combination with moderate suction force, are obvious advantages compared with other flushing devices. Total occlusion of the ventricular catheter and the valve could be assessed with high certainty. The detection of a total obstruction of the peritoneal catheter or any partial obstruction is also possible, depending on its exact grade and location. CONCLUSIONS Shunt obstructions can be assessed using the pumping test. The reservoir construction presented here provides a clear enhancement of that diagnostic test.

Confocal Neurolasermicroscopy - Modern Perspectives for Glioma Resection on a Cellular Level

Confocal neurolasermicroscopy (NLM)(Schlosser et al., 2009 (Epub)) is the current front end of the innovative process in neurosurgery for optimizing the operative results. Hence NLM is the continuance of a protracted development. Microscopic imaging technologies in neurosurgery invented 50 years ago revealed new strategies and possibilities for surgeons. These techniques were first used with magnifying lenses in research for introducing blood into the subarachnoid space in the region of circle of Willis in dog (Lougheed and Tom, 1961). It was further used in cerebrovascular diseases (Jacobson et al., 1962) (Chou, 1963), graft interposition (Woringer and Kunlin, 1963) (Lougheed et al., 1971) and aneurysm surgery (Pool and Colton, 1966) (Rand and Jannetta, 1967). From studies assessing radical surgery in the excision of fluorescence labelled tumours (Stummer et al., 2006) (Stummer et al., 1998) the necessity for a high-resolution imaging technique was clearly evident. Intravital fluorescence microscopy was used in animal studies to investigate tumorangiogenesis and microcirculation (Read et al., 2001) (Vajkoczy et al., 2000). In the following section our pilot study using NLM in the neurosurgical operating condition is introduced (Schlosser et al., 2009 (Epub)). We aimed to demonstrate a technique with the potential to be adapted intraoperatively to define cellular and subcellular structures during ongoing neurosurgery. Here we show our results of miniaturized confocal lasermicroscopy in normal brain and brain tumor tissue which we termed NLM. Our pilot study was initiated to test the feasibility of this new technique and to open the door for high resolution imaging during ongoing neurosurgery.

O.105 Survival rate and reliability of the ProGAV adjustable CSF shunt: Results of the German prospective multicenter observational study

Introduction: Surgical treatment of chronic hydrocephalus in an adult requires use of a shunt system that combines low-pressure opening with the absence of overdrainage phenomena. We present the preliminary results of a prospective multicentre study involving 13 hospitals in Spain of treatment of normal pressure hydrocephalus (NPH) with a gravity assisted shunt (GAV; Aesculap), the main purpose of which was to evaluate its efficacy and safety, as well as analyse possible factors influencing patient evolution. Material and Method Design: This prospective, multicentre study of clinical practice with a common protocol for treatment of adult idiopathic hydrocephalus included 136 patients (59% men; age: 73.4±6.4). Of these, six-month follow-up data are available for 62 patients and twelve months for 33. Data were recorded on epidemiological details, symptoms, evolution time, neuroradiological findings, vascular risk factors, and rout/ICP records. The main outcome variables were symptoms associated with hydrocephalus, measured with the NPH scale (gait, sphincter control and cognitive function). Secondary outcome variables included evolution according to radiological parameters and post-surgical complications. Statistics: ANOVA tests. Results: A significant improvement was noted in all the parameters of the NPH scale (gait: 3.2±1.0 vs 2.5±1.1 vs 2.2±1.1; cognitive function: 2.1±0.9 vs 1.8±0.9 vs 1.7±0.9; sphincter control: 2.9±1.2 vs 2.5±1.3 vs 2.4±1.3; p<0.05) highly evident in the third month and slightly less so in the sixth month, with a tendency to stabilise after 12 months. No association was found between improvement and demographic data, evolution time, vascular risk factors, rout value or radiological findings. The complications were less than 5%. Conclusion: The GAV shunt system proves highly efficient for the treatment of hydrocephalus, with a low rate of complications. Most patients showed improvement within six months.

A new technology for adjustability and MR-resistance of shunt-valves - experience after implantation of 54 proGAVs

Bifida Meeting abstracts - A single PDF containing all abstracts in this supplement is available here .