Electrical impedance tomography: a potential tool for intraoperative imaging of the tongue base

The presence of a tumor in the tongue is a pathology that requires surgical intervention from a certain stage. This type of surgery is difficult to perform because of the limited space available around the base of the tongue for the insertion of surgical tools. During the procedure, the surgeon has to stretch and then fix the tongue firmly in order to optimize the available space and prevent tissue movement. As a result, the preoperative images of the inside of the tongue no longer give a reliable indication of the position and shape of the cancerous tissue due to the deformation of the overall tissue in the area. Thus, new images are needed during the operation, but are very difficult to obtain using conventional techniques due to the presence of surgical tools. Electrical Impedance Tomography (EIT) is an imaging technique that maps the resistivity or difference of resistivity of biological tissues from electrical signals. The small size of the electrodes makes it a potentially interesting tool to obtain intraoperative images of the inside of the tongue. In this paper, the possibility of using EIT for this purpose is investigated. A detection method is proposed, including an original configuration of the electrodes, consistent with the anatomical specificities of the tongue. The proposed method is studied in simulation and then a proof of concept is obtained experimentally on a 3D printed test tank filled with saline solution and plant fibres.

Novel Intraoperative Imaging of Gastric Tube Perfusion during Oncologic Esophagectomy—A Pilot Study Comparing Hyperspectral Imaging (HSI) and Fluorescence Imaging (FI) with Indocyanine Green (ICG)

Background: Novel intraoperative imaging techniques, namely, hyperspectral (HSI) and fluorescence imaging (FI), are promising with respect to reducing severe postoperative complications, thus increasing patient safety. Both tools have already been used to evaluate perfusion of the gastric conduit after esophagectomy and before anastomosis. To our knowledge, this is the first study evaluating both modalities simultaneously during esophagectomy. Methods: In our pilot study, 13 patients, who underwent Ivor Lewis esophagectomy and gastric conduit reconstruction, were analyzed prospectively. HSI and FI were recorded before establishing the anastomosis in order to determine its optimum position. Results: No anastomotic leak occurred during this pilot study. In five patients, the imaging methods resulted in a more peripheral adaptation of the anastomosis. There were no significant differences between the two imaging tools, and no adverse events due to the imaging methods or indocyanine green (ICG) injection occurred. Conclusions: Simultaneous intraoperative application of both modalities was feasible and not time consuming. They are complementary with regard to the ideal anastomotic position and may contribute to better surgical outcomes. The impact of their simultaneous application will be proven in consecutive prospective trials with a large patient cohort.

Specimen Mammography for Intraoperative Margin Assessment in Breast Conserving Surgery: A Meta-Analysis

Specimen mammography is one of the widely used intraoperative methods assessing margin status in breast conserving surgery. We performed a meta-analysis to evaluate the diagnostic accuracy of specimen mammography. Literature databases including Pubmed, Cochrane Library, Web of Science and EMBASE were searched prior to May 2020. 18 studies with a total of 1142 patients were included. Data was extracted to perform pooled analysis, heterogeneity testing, threshold effect testing, sensitivity analysis, publication bias analysis and subgroup analyses. The pooled weighted values were a sensitivity of 0.55 (95% CI, 0.45–0.64), a specificity of 0.85 (95% CI, 0.77–0.90), a DOR of 7 (95% CI, 4–11) and a pooled positive likelihood ratio of 3.6 (95% CI 2.4-5.3). The area under the receiver operator characteristic curve was 0.75 (95% CI 0.71-0.78). In the subgroup analysis, the pooled specificity in the positive margin defined as tumor at margin subgroup was lower than the other positive margin definition subgroup (0.79 [95% CI: 0.66, 0.91] vs. 0.88 [95% CI: 0.81, 0.95], p = 0.01). Our findings indicated specimen mammography to be an accurate and intraoperative imaging technique for margin assessment in breast conserving surgery.

Initial Intraoperative Experience with Robotic-Assisted Pedicle Screw Placement with Cirq® Robotic Alignment: An Evaluation of the First 70 Screws

Background: Robot-guided spine surgery is based on a preoperatively planned trajectory that is reproduced in the operating room by the robotic device. This study presents our initial experience with thoracolumbar pedicle screw placement using Brainlab’s Cirq® surgeon-controlled robotic arm (BrainLab, Munich, Germany). Methods: All patients who underwent robotic-assisted implantation of pedicle screws in the thoracolumbar spine were included in the study. Our workflow, consisting of preoperative imagining, screw planning, intraoperative imaging with automatic registration, fusion of the preoperative and intraoperative imaging with a review of the preplanned screw trajectories, robotic-assisted insertion of K-wires, followed by a fluoroscopy-assisted insertion of pedicle screws and control iCT scan, is described. Results: A total of 12 patients (5 male and 7 females, mean age 67.4 years) underwent 13 surgeries using the Cirq® Robotic Alignment Module for thoracolumbar pedicle screw implantation. Spondylodiscitis, metastases, osteoporotic fracture, and spinal canal stenosis were detected. A total of 70 screws were implanted. The mean time per screw was 08:27 ± 06:54 min. The mean time per screw for the first 7 surgeries (first 36 screws) was 16:03 ± 09:32 min and for the latter 6 surgeries (34 screws) the mean time per screw was 04:35 ± 02:11 min (p < 0.05). Mean entry point deviation was 1.9 ± 1.23 mm, mean deviation from the tip of the screw was 2.61 ± 1.6 mm and mean angular deviation was 3.5° ± 2°. For screw-placement accuracy we used the CT-based Gertzbein and Robbins System (GRS). Of the total screws, 65 screws were GRS A screws (92.85%), one screw was a GRS B screw, and two further screws were grade C. Two screws were D screws (2.85%) and underwent intraoperative revision. There were no perioperative deficits. Conclusion: Brainlab’s Cirq® Robotic Alignment surgeon-controlled robotic arm is a safe and beneficial method for accurate thoracolumbar pedicle screw placement with high accuracy.

Intraoperative 3D imaging with cone-beam computed tomography leads to revision of pedicle screws in dorsal instrumentation: a retrospective analysis

Background Correct positioning of pedicle screws can be challenging. Intraoperative imaging may be helpful. The purpose of this study was to evaluate the use of intraoperative 3D imaging with a cone-beam CT. The hypotheses were that intraoperative 3D imaging (1) will lead to an intraoperative revision of pedicle screws and (2) may diminish the rate of perforated screws on postoperative imaging. Methods Totally, 351 patients (age 60.9 ± 20.3 a (15–96); m/f 203/148) underwent dorsal instrumentation with intraoperative 3D imaging with 2215 pedicle screws at a trauma center level one. This study first evaluates intraoperative imaging. After this, 501 screws in 73 patients (age 62.5 ± 19.7 a; m/f 47/26) of this collective were included in the study group (SG) and their postoperative computed tomography was evaluated with regard to screw position. Then, 500 screws in 82 patients (age 64.8 ± 14.4 a; m/f 51/31) as control group (CG), who received the screws with conventional 2D fluoroscopy but without 3D imaging, were evaluated with regard to screw position. Results During the placement of the 2215 pedicle screws, 158 (7.0%) intraoperative revisions occurred as a result of 3D imaging. Postoperative computed tomography of the SG showed 445 (88.8%) screws without relevant perforation (type A + B), of which 410 (81.8%) could be classified as type A and 35 (7.0%) could be classified as type B. Fifty-six (11.2%) screws in SG showed relevant perforation (type C–E). In contrast, 384 (76.8%) screws in the CG were without relevant perforation (type A + B), of which 282 (56.4%) could be classified as type A and 102 (20.4%) as type B. One hundred and sixteen (23.2%) screws in the CG showed relevant perforation (type C–E). Conclusion This study shows that correct placement of pedicle screws in spine surgery with conventional 2D fluoroscopy is challenging. Misplacement of screws cannot always be prevented. Intraoperative 3D imaging with a CBCT can be helpful to detect and revise misplaced pedicle screws intraoperatively. The use of intraoperative 3D imaging will probably minimize the number of revision procedures due to perforating pedicle screws.

Electrically evoked and spontaneous neural activity in the subthalamic nucleus under general anesthesia

OBJECTIVE Deep brain stimulation (DBS) surgery is commonly performed with the patient awake to facilitate assessments of electrode positioning. However, awake neurosurgery can be a barrier to patients receiving DBS. Electrode implantation can be performed with the patient under general anesthesia (GA) using intraoperative imaging, although such techniques are not widely available. Electrophysiological features can also aid in the identification of target neural regions and provide functional evidence of electrode placement. Here we assess the presence and positional variation under GA of spontaneous beta and high-frequency oscillation (HFO) activity, and evoked resonant neural activity (ERNA), a novel evoked response localized to the subthalamic nucleus. METHODS ERNA, beta, and HFO were intraoperatively recorded from DBS leads comprising four individual electrodes immediately after bilateral awake implantation into the subthalamic nucleus of 21 patients with Parkinson’s disease (42 hemispheres) and after subsequent GA induction deep enough to perform pulse generator implantation. The main anesthetic agent was either propofol (10 patients) or sevoflurane (11 patients). RESULTS GA reduced the amplitude of ERNA, beta, and HFO activity (p < 0.001); however, ERNA amplitudes remained large in comparison to spontaneous local field potentials. Notably, a moderately strong correlation between awake ERNA amplitude and electrode distance to an “ideal” therapeutic target within dorsal STN was preserved under GA (awake: ρ = −0.73, adjusted p value [padj] < 0.001; GA: ρ = −0.69, padj < 0.001). In contrast, correlations were diminished under GA for beta (awake: ρ = −0.45, padj < 0.001; GA: ρ = −0.13, padj = 0.12) and HFO (awake: ρ = −0.69, padj < 0.001; GA: ρ = −0.33, padj < 0.001). The largest ERNA occurred at the same electrode (awake vs GA) for 35/42 hemispheres (83.3%) and corresponded closely to the electrode selected by the clinician for chronic therapy at 12 months (awake ERNA 77.5%, GA ERNA 82.5%). The largest beta amplitude occurred at the same electrode (awake vs GA) for only 17/42 (40.5%) hemispheres and 21/42 (50%) for HFO. The electrode measuring the largest awake beta and HFO amplitudes corresponded to the electrode selected by the clinician for chronic therapy at 12 months in 60% and 70% of hemispheres, respectively. However, this correspondence diminished substantially under GA (beta 20%, HFO 35%). CONCLUSIONS ERNA is a robust electrophysiological signal localized to the dorsal subthalamic nucleus subregion that is largely preserved under GA, indicating it could feasibly guide electrode implantation, either alone or in complementary use with existing methods.

Risk factors for postoperative cerebellar mutism syndrome in pediatric patients: a systematic review and meta-analysis

OBJECTIVE A review article assessing all the risk factors reported in the literature for postoperative cerebellar mutism syndrome (pCMS) among children remains absent. The authors sought to perform a systematic review and meta-analysis to evaluate this issue. METHODS PubMed, Embase, and Web of Science were queried to systematically extract potential references. The articles relating to pCMS were required to be written in the English language, involve pediatric patients (≤ 18 years of age), and provide extractable data, which included a comparison group of patients who did not develop pCMS. The quality of the included studies was evaluated using the Newcastle-Ottawa Scale. Data were pooled using RevMan 5.4, and publication bias was assessed by visual inspection for funnel plot asymmetry. The study protocol was registered through PROSPERO (ID: CRD42021256177). RESULTS Overall, 28 studies involving 2276 patients were included. Statistically significant risk factors identified from univariate analysis were brainstem invasion (OR 4.28, 95% CI 2.23–8.23; p < 0.0001), fourth ventricle invasion (OR 12.84, 95% CI 4.29–38.44; p < 0.00001), superior cerebellar peduncle invasion (OR 6.77, 95% CI 2.35–19.48; p = 0.0004), diagnosis of medulloblastoma (OR 3.26, 95% CI 1.93–5.52; p < 0.0001), medulloblastoma > 50 mm (OR 8.85, 95% CI 1.30–60.16; p = 0.03), left-handedness (OR 6.57, 95% CI 1.25–34.44; p = 0.03), and a vermis incision (OR 5.44, 95% CI 2.09–14.16; p = 0.0005). On the other hand, a tumor located in the cerebellar hemisphere (OR 0.23, 95% CI 0.06–0.92; p = 0.04), cerebellar hemisphere compression (OR 0.23, 95% CI 0.11–0.45; p < 0.0001), and intraoperative imaging (OR 0.36, 95% CI 0.18–0.72; p = 0.004) reduced the risk of pCMS. CONCLUSIONS This study provides the largest and most reliable review of risk factors associated with pCMS. Although some risk factors may be dependent on one another, the data may be used by surgeons to better identify patients at risk for pCMS and for intervention planning.