To Örebro University

OBJECTIVE: To evaluate if intraoperative cone-beam CT (CBCT) provides equivalent image quality to postoperative multidetector CT (MDCT) in spine surgery, potentially eliminating unnecessary imaging and cumulative radiation exposure.

METHODS: Twenty-seven patients (16 men, 11 women; median age 39 years) treated with spinal fixation surgery were evaluated using intraoperative CBCT and postoperative MDCT. The images were independently evaluated by four neuroradiologists, utilizing a five-step Likert scale and visual grading characteristics (VGC) analysis. The area under the VGC curve (AUCVGC) quantified preferences between modalities. Intra- and inter-observer variability was evaluated using intraclass correlation coefficients (ICC). Image quality was objectively evaluated by contrast and signal-to-noise measurements (CNR, SNR).

RESULTS: In image quality, CBCT was the preferred modality in thoracolumbar spine (AUCVGC = 0.58, p < 0.001). Conversely, MDCT was preferred in cervical spine (AUCVGC = 0.38, p < 0.004). The agreement was good for inter-observer and moderate in intra-observer (ICC 0.76-0.77 vs 0.60-0.71), p < 0.001. SNR and CNR were comparable in thoracolumbar imaging, while MDCT provided superior and more consistent image quality in the cervical spine, p < 0.001.

CONCLUSION: In spine surgery, CBCT provides superior image quality for thoracolumbar imaging, while MDCT performs better for cervical imaging. Intraoperative CBCT could potentially replace postoperative MDCT in thoracolumbar spine procedures, while postoperative MDCT remains essential for cervical spine assessment.

KEY POINTS: Subjective assessment demonstrated that CBCT was the preferred modality for thoracolumbar spine imaging, while MDCT was favored for cervical spine imaging. Agreement between readers was good, while individual readings showed moderate consistency in repeated assessments. Objective assessment of image clarity and detail showed both modalities performed equally well in the thoracolumbar spine, while MDCT performed better in the cervical spine. Intraoperative CBCT proves superior to postoperative MDCT for thoracolumbar spine imaging, potentially eliminating redundant scans, and improving workflow. Postoperative MDCT remains essential for cervical spine procedures.

BACKGROUND: Dysphonia is one of the more common complications following anterior cervical discectomy and fusion (ACDF). ACDF is the gold standard for treating degenerative cervical spine disorders, and identifying high-risk patients is therefore crucial. PURPOSE: This study aimed to evaluate different machine learning models to predict persistent dysphonia after ACDF.

STUDY DESIGN: A retrospective review of the nationwide Swedish spine registry (Swespine) PATIENT SAMPLE: All adults in the Swespine registry who underwent elective ACDF between 2006 and 2020.

OUTCOME MEASURES: The primary outcome was self-reported dysphonia lasting at least one month after surgery. Predictive performance was assessed using discrimination and calibration metrics.

METHODS: Patients with missing dysphonia data at the one-year follow-up were excluded. Data preprocessing involved one-hot encoding categorical variables, scaling continuous variables, and imputing missing values. Four machine learning models (logistic regression, random forest (RF), gradient boosting, K-nearest neighbor) were employed. The models were trained and tested using an 80:20 data split and 5-fold cross-validation, with performance metrics guiding the selection of the best model for predicting persistent dysphonia.

RESULTS: In total, 2,708 were included in the study. Twelve key predictors were identified. Four machine learning models were tested, with the RF model achieving the best performance (AUC = 0.794). The most significant predictors across models included preoperative NDI, EQ5Dindex, preoperative neurology, number of operated levels, and use of a fusion cage. The RF model, chosen for its superior performance, showed high sensitivity and consistent accuracy, but a low specificity and positive predictive value.

CONCLUSIONS: In this study, machine learning models were employed to identify predictors of persistent dysphonia following ACDF. Among the models tested, the RF classifier demonstrated superior performance, with an AUC value of 0.790. The RF model identified NDI, EQ5Dindex, and number of fused vertebrae as key variables. These findings underscore the potential of machine learning models in identifying patients at increased risk for dysphonia persisting for more than one month after surgery.

External ventricular drain (EVD) insertion using the freehand technique is often associated with misplacements resulting in unfavorable outcomes. Augmented Reality (AR) has been increasingly used to complement conventional neuronavigation. The accuracy of AR guided EVD insertion has been investigated in several studies, on anthropomorphic phantoms, cadavers, and patients. This review aimed to assess the current knowledge and discuss potential benefits and challenges associated with AR guidance in EVD insertion. MEDLINE, EMBASE, and Web of Science were searched from inception to August 2023 for studies evaluating the accuracy of AR guidance for EVD insertion. Studies were screened for eligibility and accuracy data was extracted. The risk of bias was assessed using the Cochrane Risk of Bias Tool and the quality of evidence was assessed using the Newcastle-Ottawa-Scale. Accuracy was reported either as the average deviation from target or according to the Kakarla grading system. Of the 497 studies retrieved, 14 were included for analysis. All included studies were prospectively designed. Insertions were performed on anthropomorphic phantoms, cadavers, or patients, using several different AR devices and interfaces. Deviation from target ranged between 0.7 and 11.9 mm. Accuracy according to the Kakarla grading scale ranged between 82 and 96%. Accuracy was higher for AR compared to the freehand technique in all studies that had control groups. Current evidence demonstrates that AR is more accurate than free-hand technique for EVD insertion. However, studies are few, the technology developing, and there is a need for further studies on patients in relevant clinical settings.

INTRODUCTION: Peripheral nerve sheath tumors are the most common tumor of the peripheral nerves. In general, surgery has a favorable outcome and is the treatment of choice. However, postoperative neurologic deficits are not uncommon, and predictors of outcome are poorly defined.

OBJECTIVE: To evaluate clinical outcomes after surgical treatment of benign peripheral nerve sheath tumors and identify outcome predictors that may affect preoperative decision making and improve surgical outcomes.

METHOD: In this single center retrospective study, all patients surgically treated for a benign peripheral nerve sheath tumor between 2005 and 2020 were eligible for inclusion. Medical records and imaging data were reviewed. Studied outcomes were changes in neurological symptoms, pain, and tumor recurrence. Logistic regression was performed to identify possible outcome predictors.

RESULTS: In total, 81 patients undergoing 85 separate surgeries for benign peripheral nerve sheath tumors were included. The most common preoperative symptoms were local pain (90%) followed by a noticeable mass (78%), radiating pain (72%), sensory deficit (18%) and motor deficit (16%). A postoperative improvement of symptoms was seen in 94% of those with pain, 48% of those with sensory deficits and 78% of those with motor deficits. However, 35% and 9% developed new postoperative sensory and motor deficits, respectively. Multivariable analysis showed complete tumor removal as a predictor of reduced pain (p = 0.033), and younger age and larger tumors were risk factors for persistent or increased sensory deficits (p = 0.002 and p = 0.005, respectively). There were no significant predictors of motor deficits. Neurocutaneous syndromes were associated with increased odds of tumor recurrence on univariable analysis (p = 0.008).

CONCLUSION: Surgery of benign peripheral nerve sheath tumors is a safe procedure with a favorable outcome in most cases. Younger age and larger tumors were risk factors for persistent or increased sensory deficits, while complete tumor removal was associated with reduced pain. Patients with neurocutaneous syndromes had a higher rate of tumor recurrence. To further evaluate outcome predictors, we recommend future studies to focus on longer follow-up periods to assess the natural course of postoperative neurological deficits.

PURPOSE: The purpose of this study was to evaluate patient-reported outcome measures (PROMS) on dysphagia, health-related quality of life (HRQoL) and return to work after occipitocervical fixation (OCF). Postoperative radiographic measurements were evaluated to identify possible predictors of dysphagia.

METHODS: All individuals (≥ 18 years) who underwent an OCF at the study center or were registered in the Swedish spine registry (Swespine) between 2005 and 2019, and were still alive when the study was conducted, were eligible for inclusion. There was no overlap between the cohorts. Prospectively collected data on dysphagia (Dysphagia Short Questionnaire DSQ), HRQoL (EQ5D-3L) and return to work were used. Radiological and baseline patient data were retrospectively collected. In addition, HRQoL data of a matched sample of individuals was elicited from the Stockholm Public Health Survey 2006.

RESULTS: In total, 54 individuals were included. At long-term follow-up, 26 individuals (51%) had no dysphagia, and 25 (49%) reported some degree of dysphagia: 11 (22%) had mild dysphagia, and 14 (27%) had moderate to severe dysphagia. On a group level, the OCF sample scored significantly lower EQVAS and EQ-5Dindex values compared to the general population (60.0 vs. 80.0, p = 0.016; 0.43 vs. 0.80, p < 0.001). Individuals working preoperatively returned to work after surgery. Of those responding, 88% stated that they would undergo the OCF operation if it was offered today. No predictors of dysphagia based on radiographic measurements were identified.

CONCLUSION: Occipitocervical fixation results in a high frequency of long-term dysphagia. The HRQoL of OCF patients is significantly reduced compared to matched controls. However, most patients are satisfied with their surgery. No radiographic predictors of long-term dysphagia could be identified. Future prospective and systematic studies with larger samples and more objective outcome measures are needed to elucidate the causes of dysphagia in OCF.

PURPOSE: This bibliometric analysis of the top 100 cited articles on extended reality (XR) in neurosurgery aimed to reveal trends in this research field. Gender differences in authorship and global distribution of the most-cited articles were also addressed.

METHODS: A Web of Science electronic database search was conducted. The top 100 most-cited articles related to the scope of this review were retrieved and analyzed for trends in publications, journal characteristics, authorship, global distribution, study design, and focus areas. After a brief description of the top 100 publications, a comparative analysis between spinal and cranial publications was performed.

RESULTS: From 2005, there was a significant increase in spinal neurosurgery publications with a focus on pedicle screw placement. Most articles were original research studies, with an emphasis on augmented reality (AR). In cranial neurosurgery, there was no notable increase in publications. There was an increase in studies assessing both AR and virtual reality (VR) research, with a notable emphasis on VR compared to AR. Education, surgical skills assessment, and surgical planning were more common themes in cranial studies compared to spinal studies. Female authorship was notably low in both groups, with no significant increase over time. The USA and Canada contributed most of the publications in the research field.

CONCLUSIONS: Research regarding the use of XR in neurosurgery increased significantly from 2005. Cranial research focused on VR and resident education while spinal research focused on AR and neuronavigation. Female authorship was underrepresented. North America provides most of the high-impact research in this area.

Spinal schwannomas are the second most common primary intradural spinal tumor. This study aimed to assess health-related quality of life (HRQoL) and the frequency of return to work after the surgical treatment of spinal schwannomas. HRQoL was compared to a sample of the general population. Patients operated for spinal schwannomas between 2006 and 2020 were identified in a previous study and those alive at follow-up (171 of 180) were asked to participate. Ninety-four (56%) responded and were included in this study. Data were compared to the Stockholm Public Health Survey 2006, a cross-sectional survey of a representative sample of the general population. An analysis for any potential non-response bias was performed and showed no significant differences between the groups. HRQoL was equal between the spinal schwannoma sample and the general population sample in all but one dimension; men in the spinal schwannoma sample reported more moderate problems in the usual activities dimension than men in the general population (p = 0.020). In the schwannoma sample, there were no significant differences between men and women in either of the dimensions EQ-5Dindex or EQVAS. Before surgery, a total of 71 (76%) were working full-time and after surgery almost all (94%) returned to work, most of them within 3 months of surgery. Eighty-nine (95%) of the patients responded that they would accept the surgery for their spinal schwannoma if asked again today. To conclude, surgical treatment of spinal schwannomas is associated with good HRQoL and with a high frequency of return to work.

BACKGROUND: Intraoperative MRI (iMRI) has emerged as a useful tool in glioma surgery to safely improve the extent of resection. However, iMRI requires a dedicated operating room (OR) with an integrated MRI scanner solely for this purpose. Due to physical or economical restraints, this may not be feasible in all centers. The aim of this study was to investigate the feasibility of using a non-dedicated MRI scanner at the radiology department for iMRI and to describe the workflow with special focus on time expenditure and surgical implications.

METHODS: In total, 24 patients undergoing glioma surgery were included. When the resection was deemed completed, the wound was temporarily closed, and the patient, under general anesthesia, was transferred to the radiology department for iMRI, which was performed using a dedicated protocol on 1.5 or 3 T scanners. After performing iMRI the patient was returned to the OR for additional tumor resection or final wound closure. All procedural times, timestamps, and adverse events were recorded.

RESULT: The median time from the decision to initiate iMRI until reopening of the wound after scanning was 68 (52-104) minutes. Residual tumors were found on iMRI in 13 patients (54%). There were no adverse events during the surgeries, transfers, transportations, or iMRI-examinations. There were no wound-related complications or infections in the postoperative period or at follow-up. There were no readmissions within 30 or 90 days due to any complication.

CONCLUSION: Performing intraoperative MRI using an MRI located outside the OR department was feasible and safe with no adverse events. It did not require more time than previously reported data for dedicated iMRI scanners. This could be a viable alternative in centers without access to a dedicated iMRI suite.

Spinal schwannomas are the second most common form of primary intradural spinal tumor. Despite being benign, they may cause spinal cord compression and subsequently acute or chronic neurological dysfunction. The primary treatment is surgical resection. The aim of this study was to identify pre- and postoperative predictors of favorable outcomes after surgical treatment for spinal schwannoma. All adult patients surgically treated for spinal schwannoma between 2006 and 2020 were eligible for inclusion. Medical records and imaging data were retrospectively reviewed. The primary outcome measures were neurological improvement according to the modified McCormick Scale (mMC) and changes in motor deficit, sensory deficit, gait disturbance, bladder dysfunction, and pain at long-term follow-up. In total, 180 patients with a median follow-up time of 4.4 years were included. Pain was the most common presenting symptom (87%). The median time between symptom presentation and surgery was 12 months, while the median time between diagnosis (first MRI) and surgery was 3 months. Gross total resection (GTR) was achieved in 150 (83%) patients and the nerve root could be preserved in 133 (74%) patients. A postoperative complication occurred in 10 patients (5.6%). There were significant postoperative improvements in terms of motor, sensory, gait, and bladder functions, as well as pain (p < 0.001). Of these symptoms, bladder dysfunction was the one most often improved, with complete symptom resolution in all cases. However, no other predictors of improvement could be identified. There were three cases of recurrence after GTR and nine cases of regrowth after STR. Reoperation was performed in six (3.3%) cases. GTR was associated with a significant improvement in neurological status at long-term follow-up and increased the chance of progression-free survival.

Background: In brain tumor surgery, maximal tumor resection is typically desired. This is complicated by infiltrative tumor cells which cannot be visually distinguished from healthy brain tissue. Optical methods are an emerging field that can potentially revolutionize brain tumor surgery through intraoperative differentiation between healthy and tumor tissues.

Methods: This study aimed to systematically explore and summarize the existing literature on the use of Raman Spectroscopy (RS), Hyperspectral Imaging (HSI), Optical Coherence Tomography (OCT), and Diffuse Reflectance Spectroscopy (DRS) for brain tumor detection. MEDLINE, Embase, and Web of Science were searched for studies evaluating the accuracy of these systems for brain tumor detection. Outcome measures included accuracy, sensitivity, and specificity.

Results: In total, 44 studies were included, covering a range of tumor types and technologies. Accuracy metrics in the studies ranged between 54 and 100% for RS, 69 and 99% for HSI, 82 and 99% for OCT, and 42 and 100% for DRS.

Conclusions: This review provides insightful evidence on the use of optical methods in distinguishing tumor from healthy brain tissue.