Sven R. Kantelhardt

Risk Management in the Treatment of Malignant Gliomas with BCNU Wafer Implants

Implantation of BCNU wafers (Gliadel®) into the resection cavity has demonstrated a survival benefit for patients with newly diagnosed malignant gliomas. The follow-up of two phase III trails has further shown that the number of long-term survivors was significantly increased by BCNU wafer treatment. BCNU wafer implantation may be integrated into current multimodal first line strategies. In the setting of recurrent disease BCNU wafer implantation has also shown a survival benefit and now extends the treatment options in a patient population that typically has undergone extensive pretreatment. An analysis of the literature has helped to clearly identify the risks associated with topic BCNU treatment. Here we summarize the incidence and time course of adverse events associated with local chemotherapy and propose solutions. The growing body of experience with BCNU wafer implantation may serve as a basis to develop adequate risk management strategies with regard to patient selection, surgical techniques, and follow-up schedules.

Evaluation of a Completely Robotized Neurosurgical Operating Microscope

BACKGROUNDnOperating microscopes are essential for most neurosurgical procedures. Modern robot-assisted controls offer new possibilities, combining the advantages of conventional and automated systems.nnnOBJECTIVEnWe evaluated the prototype of a completely robotized operating microscope with an integrated optical coherence tomography module.nnnMETHODSnA standard operating microscope was fitted with motors and control instruments, with the manual control mode and balance preserved. In the robot mode, the microscope was steered by a remote control that could be fixed to a surgical instrument. External encoders and accelerometers tracked microscope movements. The microscope was additionally fitted with an optical coherence tomography-scanning module.nnnRESULTSnThe robotized microscope was tested on model systems. It could be freely positioned, without forcing the surgeon to take the hands from the instruments or avert the eyes from the oculars. Positioning error was about 1 mm, and vibration faded in 1 second. Tracking of microscope movements, combined with an autofocus function, allowed determination of the focus position within the 3-dimensional space. This constituted a second loop of navigation independent from conventional infrared reflector-based techniques. In the robot mode, automated optical coherence tomography scanning of large surface areas was feasible.nnnCONCLUSIONnThe prototype of a robotized optical coherence tomography-integrated operating microscope combines the advantages of a conventional manually controlled operating microscope with a remote-controlled positioning aid and a self-navigating microscope system that performs automated positioning tasks such as surface scans. This demonstrates that, in the future, operating microscopes may be used to acquire intraoperative spatial data, volume changes, and structural data of brain or brain tumor tissue.

Automatic scanning of large tissue areas in neurosurgery using optical coherence tomography

With its high spatial and temporal resolution, optical coherence tomography (OCT) is an ideal modality for intra‐operative imaging. One possible application is to detect tumour invaded tissue in neurosurgery, e.g. during complete resection of glioblastoma. Ideally, the whole resection cavity is scanned. However, OCT is limited to a small field of view (FOV) and scanning perpendicular to the tissue surface.

In vivo multiphoton tomography and fluorescence lifetime imaging of human brain tumor tissue

High resolution multiphoton tomography and fluorescence lifetime imaging differentiates glioma from adjacent brain in native tissue samples ex vivo. Presently, multiphoton tomography is applied in clinical dermatology and experimentally. We here present the first application of multiphoton and fluorescence lifetime imaging for in vivo imaging on humans during a neurosurgical procedure. We used a MPTflex™ Multiphoton Laser Tomograph (JenLab, Germany). We examined cultured glioma cells in an orthotopic mouse tumor model and native human tissue samples. Finally the multiphoton tomograph was applied to provide optical biopsies during resection of a clinical case of glioblastoma. All tissues imaged by multiphoton tomography were sampled and processed for conventional histopathology. The multiphoton tomograph allowed fluorescence intensity- and fluorescence lifetime imaging with submicron spatial resolution and 200 picosecond temporal resolution. Morphological fluorescence intensity imaging and fluorescence lifetime imaging of tumor-bearing mouse brains and native human tissue samples clearly differentiated tumor and adjacent brain tissue. Intraoperative imaging was found to be technically feasible. Intraoperative image quality was comparable to ex vivo examinations. To our knowledge we here present the first intraoperative application of high resolution multiphoton tomography and fluorescence lifetime imaging of human brain tumors in situ. It allowed in vivo identification and determination of cell density of tumor tissue on a cellular and subcellular level within seconds. The technology shows the potential of rapid intraoperative identification of native glioma tissue without need for tissue processing or staining.

Management of C2 fractures using Iso-C 3D guidance: a single institution's experience

BackgroundAbout 20xa0% of cervical fractures involve the C2 vertebra. Many surgical techniques have been proposed according to the type of fracture. However, morbidity and mortality of these procedures is often high, which can be attributed to the old age and significant co-morbidities of the affected population and the complex anatomy of C2. To target the latter, several authors have applied iso-C3D guidance for most of the common techniques. We here present our experience using a fixed protocol and iso-C3D guidance in all cases of traumatic C2 fractures.MethodsSixteen patients were operated upon between April 2011 and April 2012 using Iso-C3D guidance, following a fixed routine protocol. The screw position was verified by CT-scanning. Intraoperative and clinical parameters were evaluated.ResultsSix patients received anterior lag-screw fixation of odontoid fractures. Two underwent isolated posterior lag-screw fixation of hangman’s fracture. C1 and/or C3 lateral mass, and/or C2 isthmic screws were placed in eight patients. No screw had to be revised, 3 minor breachings of the cortical bone of <2xa0mm were observed.The same standard protocol for draping, registration of the navigation and Iso-C3D guided drilling could be applied for anterior and posterior procedures, leaving only two variables. This led to rapid acceptance of the technique among OR-staff and surgeons, who felt comfortable with iso-C3D guidance after only five cases.ConclusionsIso-C3D guidance is a safe and straightforward technique for anterior and posterior screw placement in the upper cervical spine.

Implementation of a Critical Incident Reporting System in a Neurosurgical Department

BACKGROUNDnCritical incident monitoring is an important tool for quality improvement and the maintenance of high safety standards. It was developed for aviation safety and is now widely accepted as a useful tool to reduce medical care-related morbidity and mortality. Despite this widespread acceptance, the literature has no reports on any neurosurgical applications of critical incident monitoring. We describe the introduction of a mono-institutional critical incident reporting system in a neurosurgical department. Furthermore, we have developed a formula to assess possible counterstrategies.nnnMETHODSnAll staff members of a neurosurgical department were advised to report critical incidents. The anonymous reporting form contained a box for the description of the incident, several multiple-choice questions on specific risk factors, place and reason for occurrence of the incident, severity of the consequences and suggested counterstrategies. The incident data was entered into an online documentation system (ADKA DokuPik) and evaluated by an external specialist. For data analysis we applied a modified assessment scheme initially designed for flight safety.nnnRESULTSnData collection was started in September 2008. The average number of reported incidents was 18 per month (currently 216 in total). Most incidents occurred on the neurosurgical ward (64%). Human error was involved in 86% of the reported incidents. The largest group of incidents consisted of medication-related problems. Accordingly, counterstrategies were developed, resulting in a decrease in the relative number of reported medication-related incidents from 42% (March 09) to 30% (September 09).nnnCONCLUSIONSnImplementation of the critical incident reporting system presented no technical problems. The reporting rate was high compared to that reported in the current literature. The formulation, evaluation and introduction of specific counterstrategies to guard against selected groups of incidents may improve patient safety in neurosurgical departments.

Evaluation of surgical strategy of conventional vs. percutaneous robot-assisted spinal trans-pedicular instrumentation in spondylodiscitis.

Robot-assisted percutaneous insertion of pedicle screws is a recent technique demonstrating high accuracy. The optimal treatment for spondylodiscitis is still a matter of debate. We performed a retrospective cohort study on surgical patients treated with pedicle screw/rod placement alone without the application of intervertebral cages. In this collective, we compare conventional open to a further minimalized percutaneous robot-assisted spinal instrumentation, avoiding a direct contact of implants and infectious focus. 90 records and CT scans of patients treated by dorsal transpedicular instrumentation of the infected segments with and without decompression and antibiotic therapy were analysed for clinical and radiological outcome parameters. 24 patients were treated by free-hand fluoroscopy-guided surgery (121 screws), and 66 patients were treated by percutaneous robot-assisted spinal instrumentation (341 screws). Accurate screw placement was confirmed in 90xa0% of robot-assisted and 73.5xa0% of free-hand placed screws. Implant revision due to misplacement was necessary in 4.95xa0% of the free-hand group compared to 0.58xa0% in the robot-assisted group. The average intraoperative X-ray exposure per case was 0.94xa0±xa01.04xa0min in the free-hand group vs. 0.4xa0±xa00.16xa0min in the percutaneous group (pxa0=xa00.000). Intraoperative adverse events were observed in 12.5xa0% of free-hand placed pedicle screws and 6.1xa0% of robot robot-assisted screws. The mean postoperative hospital stay in the free-hand group was 18.1xa0±xa012.9xa0days, and in percutaneous group, 13.8xa0±xa05.6xa0days (pxa0=xa00.012). This study demonstrates that the robot-guided insertion of pedicle screws is a safe and effective procedure in lumbar and thoracic spondylodiscitis with higher accuracy of implant placement, lower radiation dose, and decreased complication rates. Percutaneous spinal dorsal instrumentation seems to be sufficient to treat lumbar and thoracic spondylodiscitis.

Minimally invasive instrumentation of uncomplicated cervical fractures

PurposeMany authors favor conservative treatment options in oligo-symptomatic non-dislocated cervical fractures. This is mainly because of adverse events, anesthesia times and blood loss associated with surgical treatment of these injuries. We, therefore, sought to minimize the invasiveness of the surgical treatment of simple cervical fractures using image-guidance and a percutaneous approach.MethodsIso-C3D-based image guidance was used to place unilateral lag screws and conventional screws in pedicles, isthmi and lateral masses C1–C6. The navigation reference marker array was attached to the Mayfield clamp avoiding any additional skin incisions. Drilling of the screws trajectories was performed using a high speed drill with diamond tip, minimizing the risk of dislocations of cervical vertebrae and/or bone fragments relative to the iso-C3D scan to which the navigation system was registered.ResultsImage-guided percutaneous placement of cervical pedicle, isthmic and lateral mass screws resulted in correct screw placement in all six cases (three hangman fractures, three odontoid fracture Anderson 2 in elderly patients and one C6 posttraumatic pedicular pseudoarthrosis). Average blood loss was 194xa0ml, total average operating time 106xa0min and average X-ray time 3.8xa0min (395xa0cGy/cm2) including iso-C3D imaging.ConclusionThe technique presented here was found to be a feasible minimally invasive treatment option for uncomplicated cervical fractures. Besides to our best knowledge, we here present the first percutaneous implantation of lateral mass screws.

Video-Assisted Navigation for Adjustment of Image-Guidance Accuracy to Slight Brain Shift

BACKGROUND: Information supplied by an image-guidance system can be superimposed on the operating microscope oculars or on a screen, generating augmented reality. Recently, the outline of a patients head and skull, injected in the oculars of a standard operating microscope, has been used to check the registration accuracy of image guidance. OBJECTIVE: To propose the use of the brain surface relief and superficial vessels for real-time intraoperative visualization and image-guidance accuracy and for intraoperative adjustment for brain shift. METHODS: A commercially available image-guidance system and a standard operating microscope were used. Segmentation of the brain surface and cortical blood vessel relief was performed manually on preoperative computed tomography and magnetic resonance images. The overlay of segmented digital and real operating-microscope images was used to monitor image-guidance accuracy. Adjustment for brain shift was performed by manually matching digital images on real structures. RESULTS: Experimental manipulation on a phantom proved that the brain surface relief could be used to restore accuracy if the primary registration shifted. Afterward, the technique was used to assist during surgery of 5 consecutive patients with 7 deep-seated brain tumors. The brain surface relief could be successfully used to monitor registration accuracy after craniotomy and during the whole procedure. If a certain degree of brain shift occurred after craniotomy, the accuracy could be restored in all cases, and corticotomies were correctly centered in all cases. CONCLUSION: The proposed method was easy to perform and augmented image-guidance accuracy when operating on small deep-seated lesions.

Image-guided implantation of pre-calibrated catheters in the ICU: a feasibility study

BackgroundImage-guided implantation of intracranial catheters is a routine procedure. Although time for surgery is short, transport from the intensive care unit (ICU) to the operation room (OR) is time-consuming and endangers patients in vulnerable intracranial pressure phases. Unfortunately, technical aspects of image guidance have so far required surgery to be performed in the operation room. In this observational study we investigated the feasibility of image-guided catheter placement in the ICU using a pre-calibrated stylet for implantation of intracranial catheters for a variety of indications and compare the results of procedures performed in the OR.MethodsTwenty-three patients received implantation of 31 image-guided intracranial catheters or external ventricular drains using a pre-calibrated stylet in the ICU or in the OR. The times required for navigation planning, transport and surgery were assessed. Pre-operative trajectory planning, intra-operative screenshots of the navigation system and postoperative computed tomography (CT) scans were compared.ResultsEleven external ventricular drains and nine intracranial catheters for fibrinolytic therapy of intracerebral haemorrhage were implanted in the OR, whereas ten external ventricular drains and one catheter for fibrinolytic therapy were implanted in the ICU. All catheters implanted on the ICU, 81.8xa0% of external ventricular drains and 88.8xa0% of lysis catheters placed in the OR had an optimal position to function.ConclusionA pre-calibrated stylet in combination with the flexible headband equipped with reference arrays allows the application of image guidance in the ICU. It reduced time expended for patients and employees, and avoided the risks of ICU transport to the OR.