0000000000042897
AUTHOR
Axel Neulen
showing 9 related works from this author
Image-guided transcranial Doppler sonography for monitoring of vasospasm after subarachnoid hemorrhage.
2016
Transcranial Doppler ultrasound (TCD) is a standard method for bedside vasospasm monitoring after subarachnoid hemorrhage (SAH). Image guidance has previously been shown to reduce intra- and interobserver variability of this method. The aim of the present study was to compare image-guided and conventional TCD in vasospasm monitoring after SAH.418 TCD exams of 24 consecutive SAH patients registered in a database were evaluated. Of these, 130 image-guided exams were identified which had been performed on the same day as conventional Doppler exams. These matched pairs were taken for statistical analysis. Data were tested statistically using the sign test applied at patient level to aggregated …
A Volumetric Method for Quantification of Cerebral Vasospasm in a Murine Model of Subarachnoid Hemorrhage
2018
Subarachnoid hemorrhage (SAH) is a subtype of hemorrhagic stroke. Cerebral vasospasm that occurs in the aftermath of the bleeding is an important factor determining patient outcome and is therefore frequently taken as a study endpoint. However, in small animal studies on SAH, quantification of cerebral vasospasm is a major challenge. Here, an ex vivo method is presented that allows quantification of volumes of entire vessel segments, which can be used as an objective measure to quantify cerebral vasospasm. In a first step, endovascular casting of the cerebral vasculature is performed using a radiopaque casting agent. Then, cross-sectional imaging data are acquired by micro computed tomograp…
Microsurgical fenestration of perineural cysts to the thecal sac at the level of the distal dural sleeve
2011
Background Surgery for symptomatic sacral perineural cysts remains an issue of discussion. Assuming micro-communications between the cyst and thecal sac resulting in a valve mechanism and trapping of CSF as a pathomechanism, microsurgical fenestration from the cyst to the thecal sac was performed to achieve free CSF communication. Methods In 13 consecutive patients (10 female, 3 male), MRI revealed sacral perineural cysts and excluded other pathologies. Micro-communication between the thecal sac and the cysts was shown by delayed contrast filling of the cysts on postmyelographic CT. Surgical fenestration achieved free CSF communication between the thecal sac and cysts in all patients. The p…
Image guidance to improve reliability and data integrity of transcranial Doppler sonography.
2012
Abstract Background Principles and accuracy of image-guided transcranial Doppler (IG TCD) sonography have been published recently. However, it remains open whether combination of image guidance and TCD offers an additional clinical advantage. This study scores the accuracy of conventional TCD examinations and investigates the potential improvement of TCD data integrity and reliability regarding the additional use of IG. Methods Conventional TCD was performed by a group of experienced investigators, who were blinded to images of a navigation system tracking the Doppler probe, whereas an independent observer documented the TCD findings, acquired by the investigators, due to saving spatial dat…
Image-Guided Transcranial Doppler Ultrasound for Monitoring Posthemorrhagic Vasospasms of Infratentorial Arteries: A Feasibility Study
2019
Background A considerable number of patients with subarachnoid hemorrhage (SAH) develop vasospasms of the infratentorial arteries. Transcranial Doppler sonography (TCD) is used to screen for vasospasm. In this study, we used a technical modification that combines TCD with an image guidance device that the operator can use to navigate to the ultrasonic window and to predefined intracranial vascular targets. Our aim was to analyze the feasibility, spatial precision, and spatial reproducibility of serial image-guided TCD of infratentorial and—for comparison—supratentorial arteries in the clinical setting of monitoring for vasospasm after SAH. Methods The study included 10 SAH patients, who eac…
Analysis of Cerebral Vasospasm in a Murine Model of Subarachnoid Hemorrhage with High Frequency Transcranial Duplex Ultrasound
2021
Cerebral vasospasm that occurs in the weeks after subarachnoid hemorrhage, a type of hemorrhagic stroke, contributes to delayed cerebral ischemia. A problem encountered in experimental studies using murine models of SAH is that methods for in vivo monitoring of cerebral vasospasm in mice are lacking. Here, we demonstrate the application of high frequency ultrasound to perform transcranial Duplex sonography examinations on mice. Using the method, the internal carotid arteries (ICA) could be identified. The blood flow velocities in the intracranial ICAs were accelerated significantly after induction of SAH, while blood flow velocities in the extracranial ICAs remained low, indicating cerebral…
Video-Assisted Navigation for Adjustment of Image-Guidance Accuracy to Slight Brain Shift
2015
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 patient's 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 bloo…
Multicolor 3D Printing of Complex Intracranial Tumors in Neurosurgery.
2020
Three-dimensional (3D) printing technologies offer the possibility of visualizing patient-specific pathologies in a physical model of correct dimensions. The model can be used for planning and simulating critical steps of a surgical approach. Therefore, it is important that anatomical structures such as blood vessels inside a tumor can be printed to be colored not only on their surface, but throughout their whole volume. During simulation this allows for the removal of certain parts (e.g., with a high-speed drill) and revealing internally located structures of a different color. Thus, diagnostic information from various imaging modalities (e.g., CT, MRI) can be combined in a single compact …
Evaluation of efficacy and biocompatibility of a novel semisynthetic collagen matrix as a dural onlay graft in a large animal model
2011
Background Semisynthetic collagen matrices are promising duraplasty grafts with low risk of cerebrospinal fluid (CSF) fistulas, good tissue integration and minor foreign body reaction. The present study investigates the efficacy and biocompatibility of a novel semisynthetic bilayered collagen matrix (BCM, B. Braun Aesculap) as dural onlay graft for duraplasty. Methods Thirty-four pigs underwent osteoclastic trepanation, excision of the dura, and placement of a cortical defect, followed by duraplasty using BCM, Suturable DuraGen™ (Integra Neuroscience), or periosteum. CSF tightness and intraoperative handling of the grafts were evaluated. Pigs were sacrificed after 1 and 6 months for histolo…