A timeline of cognitive functioning in glioma patients who undergo awake brain tumor surgery.

BACKGROUND: The purpose of awake brain tumor surgery is to maximize the resection of the tumor and to minimize the risk of neurological and cognitive impairments. The aim of this study is to gain understanding of the development of possible postoperative cognitive deficits after awake brain tumor surgery in patients with suspected gliomas, by comparing preoperative, early postoperative, and late postoperative functioning. A more detailed timeline will be helpful in informing candidates for surgery about what to expect regarding their cognitive functioning. METHODS: Thirty-seven patients were included in this study. Cognitive functioning was measured by means of a broad cognitive screener preoperatively, days after surgery and months after surgery in patients who underwent awake brain tumor surgery with cognitive monitoring. The cognitive screener included tests for object naming, reading, attention span, working memory, inhibition, inhibition/switching, and visuoperception. We performed a Friedman ANOVA to analyze on group level. RESULTS: Overall, no significant differences were found between preoperative cognitive functioning, early postoperative cognitive functioning, and late postoperative cognitive functioning, except for performances on the inhibition task. Directly after surgery, patients were significantly slower on this task. However, in the following months after surgery, they returned to their preoperative level. CONCLUSION: The timeline of cognitive functioning after awake tumor surgery appeared overall stable in the early and late postoperative phase, except for inhibition, which is more difficult in the first days after awake brain tumor surgery. This more detailed timeline of cognitive functioning, in combination with future research, can possibly be contributing in informing patients and caregivers what to expect after awake brain tumor surgery.

Color-Mapping of 4D-CTA for the Detection of Cranial Arteriovenous Shunts.

BACKGROUND AND PURPOSE: 4D CT angiography is increasingly used in clinical practice for the assessment of different neurovascular disorders. Optimized processing of 4D-CTA is crucial for diagnostic interpretation because of the large amount of data that is generated. A color-mapping method for 4D-CTA is presented for improved and enhanced visualization of the cerebral vasculature hemodynamics. This method was applied to detect cranial AVFs. MATERIALS AND METHODS: All patients who underwent both 4D-CTA and DSA in our hospital from 2011 to 2018 for the clinical suspicion of a cranial AVF or carotid cavernous fistula were retrospectively collected. Temporal information in the cerebral vasculature was visualized using a patient-specific color scale. All color-maps were evaluated by 3 observers for the presence or absence of an AVF or carotid cavernous fistula. The presence or absence of cortical venous reflux was evaluated as a secondary outcome measure. RESULTS: In total, 31 patients were included, 21 patients with and 10 without an AVF. Arterialization of venous structures in AVFs was accurately visualized using color-mapping. There was high sensitivity (86%-100%) and moderate-to-high specificity (70%-100%) for the detection of AVFs on color-mapping 4D-CTA, even without the availability of dynamic subtraction rendering. The diagnostic performance of the 3 observers in the detection of cortical venous reflux was variable (sensitivity, 43%-88%; specificity, 60%-80%). CONCLUSIONS: Arterialization of venous structures can be visualized using color-mapping of 4D-CTA and proves to be accurate for the detection of cranial AVFs. This finding makes color-mapping a promising visualization technique for assessing temporal hemodynamics in 4D-CTA.

Evaluation of the yield of post-clipping angiography and nationwide current practice.

BACKGROUND: Surgical treatment of intracranial saccular aneurysms aims to prevent (re)hemorrhage by complete occlusion of the aneurysmal lumen. It is unclear whether routine postoperative imaging, to assess aneurysmal occlusion, is necessary since intraoperative assessment by the neurosurgeon may be sufficient. We assessed routine clinical protocols for post-clipping imaging in the Netherlands and determined whether intraoperative assessment of aneurysm clippings sufficiently predicts aneurysm residuals. METHODS: A survey was conducted to assess postoperative imaging protocols in centers performing clipping of intracranial aneurysms in the Netherlands (n = 9). Furthermore, a retrospective single-center cohort study was performed to determine the predictive value of intraoperative assessment of aneurysm occlusion in relation to postoperative digital subtraction angiography (DSA) findings, between 2009 and 2017. RESULTS: No center performed intraoperative DSA in a hybrid OR, routinely. Respectively, four (44.4%), seven (77.8%), and three (33.3%) centers did not routinely perform early postoperative imaging, late follow-up imaging, or any routine imaging at all. Regarding our retrospective study, 106 patients with 132 clipped aneurysms were included. There were 23 residuals ≥ 1 mm (17.4%), of which 10 (43.5%) were unexpected. For the presence of these residuals, intraoperative assessment showed a sensitivity of 56.5%, a specificity of 86.2%, a positive predictive value of 46.4%, and a negative predictive value of 90.4%. CONCLUSIONS: There is lack of consensus regarding the post-clipping imaging strategy in the Netherlands. Since intraoperative assessment is shown to be insufficient to predict postoperative aneurysm residuals, we advocate routine postoperative imaging after aneurysm clipping unless this is not warranted on the basis of patient age, clinical condition, and/or comorbidity.

Management considerations in ruptured isolated radiculopial artery aneurysms. A report of two cases and literature review.

Little is known on the natural history of ruptured isolated aneurysms of the posterior spinal artery (PSA). To date, only a few of such cases have been described in the literature. This paper aims to assess the most appropriate management strategy, based on the available literature and two new cases. In one of these, treatment was postponed until day 33, when angiography showed slight growth of the aneurysm. In the other, conservative treatment, requested by the patient, was successful. From these data, we conclude that treatment strategies for ruptured PSA aneurysms may vary. Aside from the recommendation by others to perform prompt surgical treatment, we suggest an alternative clinical paradigm allowing for the evaluation of the early clinical course. This may preclude the unnecessary treatment of spontaneously regressing lesions and still allows for appropriate treatment for persistent lesions.

Optimization of the reconstruction interval in neurovascular 4D-CTA imaging. A technical note.

Time resolved whole brain CT angiography (4D-CTA) is a novel imaging technology providing information regarding blood flow. One of the factors that influence the diagnostic value of this examination is the temporal resolution, which is affected by the gantry rotation speed during acquisition and the reconstruction interval during post-processing. Post-processing determines the time spacing between two reconstructed volumes and, unlike rotation speed, does not affect radiation burden. The data sets of six patients who underwent a cranial 4D-CTA were used for this study. Raw data was acquired using a 320-slice scanner with a rotation speed of 2 Hz. The arterial to venous passage of an intravenous contrast bolus was captured during a 15 s continuous scan. The raw data was reconstructed using four different reconstruction-intervals: 0.2, 0.3, 0.5 and 1.0 s. The results were rated by two observers using a standardized score sheet. The appearance of each lesion was rated correctly in all readings. Scoring for quality of temporal resolution revealed a stepwise improvement from the 1.0 s interval to the 0.3 s interval, while no discernable improvement was noted between the 0.3 s and 0.2 s interval. An increase in temporal resolution may improve the diagnostic quality of cranial 4D-CTA. Using a rotation speed of 0.5 s, the optimal reconstruction interval appears to be 0.3 s, beyond which, changes can no longer be discerned.

Detection and classification of cranial dural arteriovenous fistulas using 4D-CT angiography: initial experience.

BACKGROUND AND PURPOSE: The criterion standard to diagnose and classify cranial DAVFs is DSA. Since this is invasive, relatively expensive and time-consuming, a noninvasive alternative is of interest. We aimed to evaluate the capabilities and pitfalls of 4D-CTA in a consecutive series of patients who presented with a newly diagnosed cranial DAVF, as demonstrated by conventional DSA. MATERIALS AND METHODS: Eleven patients were included in this study after biplane DSA demonstrated a cranial DAVF. They subsequently underwent 4D-CTA imaging by using a 320-detector CT scanner. DSA and 4D-CTA studies were independently read by 2 blinded observers, by using a standardized scoring sheet. 4D-CTA results were analyzed with DSA as the criterion standard. RESULTS: In 10 cases, there was full agreement between DSA and 4D-CTA regarding the Borden classification. However, in the remaining patient, a slow-filling DAVF with a low shunt volume was missed by both readers on 4D-CTA. In all 10 detected cases, ≥ 1 of the major contributing arteries could be identified with 4D-CTA. Although, by using DSA, the 2 observers identified additional arterial feeders in 7 and 8 cases, respectively, these discrepancies did not influence clinical decision making. CONCLUSIONS: Although novel 4D-CTA imaging may not rule out a small slow-flow DAVF, it appears to be a valuable new adjunct in the noninvasive diagnostic work-up, treatment planning, and follow-up of patients with cranial DAVFs.

Dynamic 320-section CT angiography in cranial arteriovenous shunting lesions.

Novel 320-section CT scanning equipment enables dynamic noninvasive angiographic imaging of the entire cranial vasculature (4D-CTA). We describe this technique and demonstrate its potential in arteriovenous shunting lesions. 4D-CTA imaging resulted in a correct diagnosis, lesion classification, and treatment-strategy selection in 3 patients, compared with CA. We think that 4D-CTA can further reduce the need for CA, sparing the patient the discomfort and risk associated with an invasive procedure.

Endovascular treatment of epistaxis.

Epistaxis is a common condition that can be managed conservatively in most cases. When these measures, including anterior and posterior packing of the nasal cavity, are unsuccessful at controlling the bleeding, interruption of the blood supply to the sinonasal area can be performed, either by surgical ligation or by transarterial embolization. Embolization should be preceded by thorough diagnostic angiography. Aside from aiding with subsequent selective catheterization and embolization, such angiography may reveal significant anatomic anomalies, anastomoses, or an unsuspected cause of epistaxis. Taking these findings into account, the interventionalist may decide to refrain from embolization or adjust the technique to minimize the risk of adverse events, which are mostly related to inadvertent embolization of the internal carotid artery or ophthalmic artery. We present a review of the various causes of epistaxis and the treatment options, with emphasis on endovascular embolization. We also describe the protocol of our institution for endovascular management of this condition.

Neuronavigation and surgery of intracerebral tumours.

Approximately four decades after the successful clinical introduction of framebased stereotactic neurosurgery by Spiegel and Wycis, frameless stereotaxy emerged to enable more elaborate image guidance in open neurosurgical procedures. Frameless stereotaxy, or neuronavigation, relies on one of several different localizing techniques to determine the position of an operative instrument relative to the surgical field, without the need for a coordinate frame rigidly fixed to the patients' skull. Currently, most systems are based on the optical triangulation of infrared light sources fixed to the surgical instrument. In its essence, a navigation system is a three-dimensional digitiser that correlates its measurements to a reference data set, i.e. a preoperatively acquired CT or MRI image stack. This correlation is achieved through a patient-to-image registration procedure resulting in a mathematical transformation matrix mapping each position in 'world space' onto 'image space'. Thus, throughout the remainder of the surgical procedure, the position of the surgical instrument can be demonstrated on a computer screen, relative to the CT or MRI images. Though neuronavigation has become a routinely used addition to the neurosurgical armamentarium, its impact on surgical results has not yet been examined sufficiently. Therefore, the surgeon is left to decide on a case-by-case basis whether to perform surgery with or without neuronavigation. Future challenges lie in improvement of the interface between the surgeon and the neuronavigator and in reducing the brainshift error, i.e. inaccuracy introduced by changes in tissue positions after image acquisition.

Frameless stereotactic subcaudate tractotomy for intractable obsessive-compulsive disorder.

Obsessive-compulsive disorder (OCD) is a chronic, disabling disorder. Psychosurgery may be indicated for a subset of patients for whom no conventional treatment is satisfactory. This paper focuses on the stereotactic subcaudate tractotomy (SST). Thus far, these procedures have been carried out using frame-based stereotactic techniques. However, modern - highly accurate - frameless stereotactic procedures have successfully been introduced in neurosurgical practice. We developed a novel frameless stereotactic subcaudate tractotomy procedure with promising initial results in a patient suffering from intractable OCD. This is the first report on frameless SST. Future studies should examine whether other ablative stereotactic psychosurgery procedures can be done using frameless stereotactic methods.

The analysis of intraoperative neurosurgical instrument movement using a navigation log-file.

BACKGROUND: The purpose of this study was to define the technical requirements of future (tele)robotic neurosurgical systems. We aimed to analyse the movements of surgical instruments during neurosurgical procedures. METHODS: A commercially available neuronavigation system (StealthStation TREON(plus), Medtronic, USA) was used to determine the position and orientation of the surgical instrument. A custom-made log-mode was implemented in the software to file instrument coordinates intraoperatively. Data was collected during the debulking of malignant primary brain tumours, temporal epilepsy surgery and skull base tumour surgery. RESULTS: Maximum tip displacement velocity varied, per procedure, in the range 6.6-12.7 cm/s and maximum rotational speed 21-40 degrees/s. Maximum instrument orientation differences within the volume of movement varied. The largest differences were detected during temporal epilepsy surgery (73 degrees and 52 degrees in the coronal and axial planes, respectively), while the smallest differences were detected in the debulking of an intraventricular tumour. CONCLUSIONS: In this study, we have demonstrated the feasibility of motion analysis in image-guided neurosurgery. To mimic ordinary open neurosurgery, future neurosurgical (tele)robotic systems should at least support translational speeds up to 12.7 cm/s, rotational speeds up to 40 degrees/s and differences in instrument orientation of up to 73 degrees.

Frameless stereotactic placement of ventriculoperitoneal shunts in undersized ventricles: a simple modification to free-hand procedures.

The aim of this report is to introduce a simple modification to the free-hand frameless stereotactic placement of ventriculoperitoneal shunts in undersized ventricles. In this technical note, we describe our experience with ventricular catheter placement in two children suffering from shunt dependent idiopathic intracranial hypertension using an image-guided instrument holder with a catheter guide. In both patients, the surgical procedure proved to be easy and accurate, with good initial clinical results. The use of an image-guided instrument holder is a modification to the free-hand frameless stereotactic placement of ventriculoperitoneal shunts in undersized ventricles.

The impact of auditory feedback on neuronavigation.

OBJECT: We aimed to develop an auditory feedback system to be used in addition to regular neuronavigation, in an attempt to improve the usefulness of the information offered by neuronavigation systems. INSTRUMENTATION: Using a serial connection, instrument co-ordinates determined by a commercially available neuronavigation system were transferred to a laptop computer. Based on preoperative segmentation of the images, the software on the laptop computer produced an audible signal whenever the instrument moved into an area the surgeon wanted to avoid. METHODS: To evaluate the impact of our setup on volumetric resections, phantom experiments were conducted. CT scans were acquired from eight blocks of floral foam. In each of these scans, a target-volume was segmented. This target-volume was subsequently resected using either regular neuronavigation or neuronavigation extended with auditory feedback. A 'postoperative' CT scan was used to compare the resection cavity to the preoperatively planned target-volume. FINDINGS: The resemblance between the resection cavity and the target-volume was greater each time auditory feedback had been used. This corresponded with more complete removal of the target-volume. However, it also corresponded with the removal of more non-target 'tissue' in two out of four cases. CONCLUSIONS: The usefulness of auditory feedback was made plausible and the use of a new type of navigation phantom was illustrated. Based on these results, we recommend incorporation of auditory feedback in commercially available neuronavigation systems, especially since this is relatively inexpensive.

Clinical evaluation of stereotactic brain biopsies with an MKM-mounted instrument holder.

OBJECT: The aim of this study was to assess the clinical usefulness and accuracy of robot-assisted frameless stereotactic brain biopsies with a recently introduced MKM-mounted instrument holder. METHODS: Twenty-three patients with intracranial lesions participated in this study. Depending on the size of the intracranial lesion, fiducials for image-to-patient co-ordinate transformation consisted either of bone screws or adhesive markers. Shortly after surgery, postoperative MRI-imaging was performed to demonstrate the location of the biopsy site. These images were compared with the preoperative images to assess the biopsy localisation error. RESULTS: Postoperative biopsy sites could be demonstrated in six patients with bone screws and in 14 with adhesive markers. These two subgroups yielded average biopsy localisation errors of 3.3 mm (SD 1.7 mm) and 4.5 mm (SD 2.0 mm) respectively. This difference was not statistically significant. One biopsy was located in a liquefied haematoma. All others yielded pathological tissue. There were two postoperative haemorrhages, of which only one was temporarily symptomatic. There was no mortality in the first 30 days after surgery. CONCLUSIONS: Robot-assisted frameless point-stereotactic techniques represent an alternative to frame-based techniques for the performance of stereotactic biopsies.