Cerebrospinal Fluid Leak after Transsphenoidal Surgery: A Systematic Review and Meta-analysis

Background Cerebrospinal fluid (CSF) leak is widely recognized as a challenging and commonly occurring postoperative complication of transsphenoidal surgery (TSS). The primary objective of this study is to benchmark the current prevalence of CSF leak after TSS in the adult population. Methods The authors followed the PRISMA guidelines. The PubMed, Embase, and Cochrane Library databases were searched for articles reporting CSF leak after TSS in the adult population. Meta-analysis was performed using the Untransformed Proportion metric in OpenMetaAnalyst. For two between-group comparisons a generalized linear mixed model was applied. Results We identified 2,408 articles through the database search, of which 70, published since 2015, were included in this systematic review. These studies yielded 24,979 patients who underwent a total of 25,034 transsphenoidal surgeries. The overall prevalence of postoperative CSF leak was 3.4% (95% confidence interval or CI 2.8–4.0%). The prevalence of CSF leak found in patients undergoing pituitary adenoma resection was 3.2% (95% CI 2.5–4.2%), whereas patients who underwent TSS for another indication had a CSF leak prevalence rate of 7.1% (95% CI 3.0–15.7%) (odds ratio [OR] 2.3, 95% CI 0.9–5.7). Patients with cavernous sinus invasion (OR 3.0, 95% CI 1.1–8.7) and intraoperative CSF leak (OR 5.9, 95% CI 3.8–9.0) have increased risk of postoperative CSF leak. Previous TSS and microscopic surgery are not significantly associated with postoperative CSF leak. Conclusion The overall recent prevalence of CSF leak after TSS in adults is 3.4%. Intraoperative CSF leak and cavernous sinus invasion appear to be significant risk factors for postoperative CSF leak. Keywords - complications - CSF leak - endonasal - liquorrhea - pituitary adenoma surgery - skull bas

Amide proton transfer (APT) imaging of brain tumors at 7 T : The role of tissue water T1 -Relaxation properties

PURPOSE: To provide insight into the effect of water T1 relaxation (T1wat ) on amide proton transfer (APT) contrast in tumors. Three different metrics of APT contrast-magnetization transfer ratio (MTRRex ), relaxation-compensated MTRRex (AREX), and traditional asymmetry (MTRasym )-were compared in normal and tumor tissues in a variety of intracranial tumors at 7 Tesla (T). METHODS: Six consented intracranial tumor patients were scanned using a low-power, three-dimensional (3D) APT imaging sequence. MTRRex and MTRasym were calculated in the region of 3 to 4 ppm. AREX was calculated by T1wat correction of MTRRex . Tumor tissue masks, which classify different tumor tissues, were drawn by an experienced neuroradiologist. ROI-averaged tumor tissue analysis was done for MTRRex , AREX, and MTRasym . RESULTS: MTRRex and MTRasym were slightly elevated in tumor-associated structures. Both metrics were positively correlated to T1wat . The correlation coefficient (R) was determined to be 0.88 (P < 0.05) and 0.92 (P < 0.05) for MTRRex and MTRasym , respectively. After T1wat correction (R = -0.21, P = 0.69), no difference between normal and tumor tissues was found for AREX. CONCLUSIONS: The strong correlation of MTRRex and MTRasym with T1wat and the absence thereof in AREX suggests that much of APT contrast in tumors for the low-power, 3D-acquisition scheme at 7 T originates from the inherent tissue water T1 -relaxation properties

Amide proton transfer (APT) imaging of brain tumors at 7 T: The role of tissue water T -Relaxation properties.

PURPOSE: To provide insight into the effect of water T1 relaxation (T1wat ) on amide proton transfer (APT) contrast in tumors. Three different metrics of APT contrast-magnetization transfer ratio (MTRRex ), relaxation-compensated MTRRex (AREX), and traditional asymmetry (MTRasym )-were compared in normal and tumor tissues in a variety of intracranial tumors at 7 Tesla (T). METHODS: Six consented intracranial tumor patients were scanned using a low-power, three-dimensional (3D) APT imaging sequence. MTRRex and MTRasym were calculated in the region of 3 to 4 ppm. AREX was calculated by T1wat correction of MTRRex . Tumor tissue masks, which classify different tumor tissues, were drawn by an experienced neuroradiologist. ROI-averaged tumor tissue analysis was done for MTRRex , AREX, and MTRasym . RESULTS: MTRRex and MTRasym were slightly elevated in tumor-associated structures. Both metrics were positively correlated to T1wat . The correlation coefficient (R) was determined to be 0.88 (P < 0.05) and 0.92 (P << 0.05) for MTRRex and MTRasym , respectively. After T1wat correction (R = -0.21, P = 0.69), no difference between normal and tumor tissues was found for AREX. CONCLUSIONS: The strong correlation of MTRRex and MTRasym with T1wat and the absence thereof in AREX suggests that much of APT contrast in tumors for the low-power, 3D-acquisition scheme at 7 T originates from the inherent tissue water T1 -relaxation properties. Magn Reson Med, 2016. (c) 2016 Wiley Periodicals, Inc

Petroclival meningiomas: the risk of post-operative cranial nerve deficits among different surgical approaches-a systematic review and meta-analysis

Background: The surgical resection of petroclival meningiomas (PCMs) remains a challenge. Both the relationship with neurovascular structures and the deep location of the tumor can affect the extent of resection and the rate of post-operative morbidity. Methods: The authors performed a systematic review and meta-analysis of the literature examining the rate of new cranial nerve (CN) deficits after resection of PCM. A systematic search of two databases was performed for studies published between 1990 and 2018. Random-effect meta-analysis was used to pool the rate of post-operative CN deficits, mortality rate, and rate of radical resection. Results: We included twelve studies and 334 patients harboring PCM. The overall rate of complete resection was 68% (95% CI 57.9-78.2%; p &lt; 0.01; I2 = 83%). The rate of early and late post-operative CN deficits was the following: 3.8 and 2.7% (III CN), 6.6 and 3% (IV), 7.3 and 5.5% (V CN), 8 and 3.6% (VI CN), 8.9 and 8.9%% (VIII), and 4 and 2.7% (IX-XI CNs) (I2 = 0%, and p &lt; 0.01 for all analyses). The risk of post-operative deficit of the IV CN was higher among the petrosal group (7.6%; I2 = 0% vs 2.1%; I2 = 0%), whereas the impairment of VII CN function was higher among retrosigmoid group (16.6%; I2 = 64.6% vs 11.4%; I2 = 52.8%), but it was transient in the majority of cases. Conclusions: This systematic review and meta-analysis provides a detailed overview of post-operative CN deficits ensuing surgical resection of PCMs. These findings should be acknowledged when counseling patients with PCMs regarding the more appropriate approach for their tumor

Validation of exposure visualization and audible distance emission for navigated temporal bone drilling in phantoms

BACKGROUND: A neuronavigation interface with extended function as compared with current systems was developed to aid during temporal bone surgery. The interface, named EVADE, updates the prior anatomical image and visualizes the bone drilling process virtually in real-time without need for intra-operative imaging. Furthermore, EVADE continuously calculates the distance from the drill tip to segmented temporal bone critical structures (e.g. the sigmoid sinus and facial nerve) and produces audiovisual warnings if the surgeon drills in too close vicinity. The aim of this study was to evaluate the accuracy and surgical utility of EVADE in physical phantoms. METHODOLOGY/PRINCIPAL FINDINGS: We performed 228 measurements assessing the position accuracy of tracking a navigated drill in the operating theatre. A mean target registration error of 1.33±0.61 mm with a maximum error of 3.04 mm was found. Five neurosurgeons each drilled two temporal bone phantoms, once using EVADE, and once using a standard neuronavigation interface. While using standard neuronavigation the surgeons damaged three modeled temporal bone critical structures. No structure was hit by surgeons utilizing EVADE. Surgeons felt better orientated and thought they had improved tumor exposure with EVADE. Furthermore, we compared the distances between surface meshes of the virtual drill cavities created by EVADE to actual drill cavities: average maximum errors of 2.54±0.49 mm and -2.70±0.48 mm were found. CONCLUSIONS/SIGNIFICANCE: These results demonstrate that EVADE gives accurate feedback which reduces risks of harming modeled critical structures compared to a standard neuronavigation interface during temporal bone phantom drilling

Implications of Extracranial Distortion in Ultra-High-Field Magnetic Resonance Imaging for Image-Guided Cranial Neurosurgery

BACKGROUND: Ultra-high-field magnetic resonance imaging (MRI) of the brain is attractive for image guidance during neurosurgery because of its high tissue contrast and detailed vessel visualization. However, high-field MRI is prone to distortion artifacts, which may compromise image guidance. Here we investigate intra- and extracranial distortions in 7-T MRI scans. METHODS: Five patients with and 5 patients without skin-adhesive fiducials received magnetization-prepared T1-weighted 7-T MRI and standard 3-T MRI scans. The 7- and 3-T images were rigidly coregistered and compared. Intracranial distortions were evaluated qualitatively, whereas shifts at the skin surface and shifts of the center positions of skin-adhesive fiducials were measured quantitatively. Moreover, we present an illustrative case of an ultra-high-field image-guided skull base meningioma resection. RESULTS: We found excellent intracranial correspondence between 3- and 7-T MRI scans. However, the average maximum skin shift was 6.8 ± 2.0 mm in group A and 5.2 ± 0.9 mm in group B. The average maximum difference between the skin-adhesive fiducial positions was 5.6 ± 3.1 mm in group B. In our tumor resection case, the meningioma blood supply could be targeted early thanks to 7-T image guidance, which made subsequent tumor removal straightforward. CONCLUSIONS: There are no visible intracranial distortions in magnetization-prepared T1-weighted 7-T MRI cranial images. However, we found considerable extracranial shifts. These shifts render 7-T images unreliable for patient-to-image registration. We recommend performing patient-to-image registration on a routine (computed tomography scan or 3-T magnetic resonance) image and subsequently fusing the 7-T magnetic resonance image with the routine image on the image guidance machine, until this issue is resolved

Drill Tracking Accuracy Results.

<p>This table displays results for four separate tracking accuracy experiments on the cylinder and ball phantom in the operating room. Average target registration errors are given in millimeters for the “Pointer” and a drill with “3 mm”, “4 mm” or “5 mm” drill bits attached, for each experiment. Additionally, overall average and maximum target registration errors for each of the instruments are displayed in millimeters in the row “Average” and “Maximum” respectively. “SD” means standard deviation.</p

Virtual Drill Bits.

<p>Drill bits were scanned with high resolution CT and represented as 3D point clouds. On the left is displayed a 3 mm match-head drill bit and on the right a 4 mm drill bit can be seen.</p

Exposure Visualization Accuracy Results.

<p>The mean and maximum over- and underestimation errors in virtually representing the drill cavity (i.e. the surgical exposure) are presented in millimeters (on the y-axis) for each temporal bone phantom (whose index is displayed on the x-axis). Note the differences in errors between the first three models and the last seven models in which higher resolution CT scans were used.</p