Association Between the Serum α-Klotho Level and Insulin Resistance in Adults: NHANES 2007-2016.

OBJECTIVE: This study aimed to investigate the relationship between serum α-Klotho levels and insulin resistance (IR), a precursor to type 2 diabetes. METHODS: The study analyzed data from 4,758 adult participants in the National Health and Nutrition Examination Survey (NHANES) spanning from 2007 to 2016. The relationship between α-Klotho concentration and IR was assessed using the Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) and odds ratios (OR) derived from logistic regression models. RESULTS: Results showed that every 1-ln increase in α-Klotho concentration raised the HOMA-IR value by 0.55 (95% confidence interval 0.35-0.74) and the odds of IR by 64% (odds ratio 1.64; 95% confidence interval 1.28-2.1). The odds of IR was 40% greater in highest tertile than in the lowest tertile. CONCLUSION: The findings of this study underscore a significant correlation between increased serum α-Klotho levels and the prevalence of IR.

Quantitative Validation of the Correlation Between Optimized Pyramidal Tract Delineation After Brain Shift Compensation and Direct Electrical Subcortical Stimulation During Brain Tumor Surgery.

It remains unclear whether tractography of pyramidal tracts is correlated with the intraoperative direct electrical subcortical stimulation (DESS), and brain shift further complicates the issue. The objective of this research is to quantitatively verify the correlation between optimized tractography (OT) of pyramidal tracts after brain shift compensation and DESS during brain tumor surgery. OT was performed for 20 patients with lesions in proximity to the pyramidal tracts based on preoperative diffusion-weighted magnetic resonance imaging. During surgery, tumor resection was guided by DESS. A total of 168 positive stimulation points and their corresponding stimulation intensity thresholds were recorded. Using the brain shift compensation algorithm based on hierarchical B-spline grids combined with a Gaussian resolution pyramid, we warped the preoperative pyramidal tract models and used receiver operating characteristic (ROC) curves to investigate the reliability of our brain shift compensation method based on anatomic landmarks. Additionally, the minimum distance between the DESS points and warped OT (wOT) model was measured and correlated with DESS intensity threshold. Brain shift compensation was achieved in all cases, and the area under the ROC curve was 0.96 in the registration accuracy analysis. The minimum distance between the DESS points and the wOT model was found to have a significantly high correlation with the DESS stimulation intensity threshold (r = 0.87, P < 0.001), with a linear regression coefficient of 0.96. Our OT method can provide comprehensive and accurate visualization of the pyramidal tracts for neurosurgical navigation and was quantitatively verified by intraoperative DESS after brain shift compensation.

Optimized Tractography Mapping and Quantitative Evaluation of Pyramidal Tracts for Surgical Resection of Insular Gliomas: a Correlative Study with Diffusion Tensor Imaging-Derived Metrics and Patient Motor Strength.

We investigate the correlation between diffusion tensor imaging (DTI)-derived metric statistics and motor strength grade of insular glioma patients after optimizing the pyramidal tract (PT) delineation. Motor strength grades of 45 insular glioma patients were assessed. All the patients underwent structural and diffusion MRI examination before and after surgery. We co-registered pre- and post-op datasets, and a two-tensor unscented Kalman filter (UKF) algorithm was employed to delineate bilateral PTs after DWI pre-processing. The tractography results were voxelized, and their labelmaps were cropped according to the location of frontal and insular parts of the lesion. Both the whole and cropped labelmaps were used as regions of interest to analyze fractional anisotropy (FA) and Trace statistics; hence, their ratios were calculated (lesional side tract/contralateral normal tract). The combination of DWI pre-processing and two-tensor UKF algorithm successfully delineated bilateral PTs of all the patients. It effectively accomplished both full fiber delineation within the edema and an extensive lateral fanning that had a favorable correspondence to the bilateral motor cortices. Before surgery, correlations were found between patients' motor strength grades and ratios of PT volume and FA standard deviation (SD). Nearly 3 months after surgery, correlations were found between motor strength grades and the ratios of metric statistics as follows: whole PT volume, whole mean FA, and FA SD. We substantiated the correlation between DTI-derived metric statistics and motor strength grades of insular glioma patients. Moreover, we posed a workflow for comprehensive pre- and post-op DTI quantitative research of glioma patients.

Intraoperative visualisation of functional structures facilitates safe frameless stereotactic biopsy in the motor eloquent regions of the brain.

BACKGROUND: For stereotactic brain biopsy involving motor eloquent regions, the surgical objective is to enhance diagnostic yield and preserve neurological function. To achieve this aim, we implemented functional neuro-navigation and intraoperative magnetic resonance imaging (iMRI) into the biopsy procedure. The impact of this integrated technique on the surgical outcome and postoperative neurological function was investigated and evaluated. METHOD: Thirty nine patients with lesions involving motor eloquent structures underwent frameless stereotactic biopsy assisted by functional neuro-navigation and iMRI. Intraoperative visualisation was realised by integrating anatomical and functional information into a navigation framework to improve biopsy trajectories and preserve eloquent structures. iMRI was conducted to guarantee the biopsy accuracy and detect intraoperative complications. The perioperative change of motor function and biopsy error before and after iMRI were recorded, and the role of functional information in trajectory selection and the relationship between the distance from sampling site to nearby eloquent structures and the neurological deterioration were further analyzed. RESULTS: Functional neuro-navigation helped modify the original trajectories and sampling sites in 35.90% (16/39) of cases to avoid the damage of eloquent structures. Even though all the lesions were high-risk of causing neurological deficits, no significant difference was found between preoperative and postoperative muscle strength. After data analysis, 3mm was supposed to be the safe distance for avoiding transient neurological deterioration. During surgery, the use of iMRI significantly reduced the biopsy errors (p = 0.042) and potentially increased the diagnostic yield from 84.62% (33/39) to 94.87% (37/39). Moreover, iMRI detected intraoperative haemorrhage in 5.13% (2/39) of patients, all of them benefited from the intraoperative strategies based on iMRI findings. CONCLUSIONS: Intraoperative visualisation of functional structures could be a feasible, safe and effective technique. Combined with intraoperative high-field MRI, it contributed to enhance the biopsy accuracy and lower neurological complications in stereotactic brain biopsy involving motor eloquent areas.

Endoscopic endonasal transsphenoidal surgery of 1,166 pituitary adenomas.

AIM: To report the results of a series of patients undergoing pure endoscopic endonasal pituitary surgery and to evaluate the efficacy and safety of this procedure. MATERIALS AND METHODS: The data of 1,166 patients that underwent endoscopic endonasal transsphenoidal adenoma removal between December 2006 and June 2013 were retrospectively reviewed. Pre- and postoperative hormonal status (3 months after surgery) were analyzed and compared with the clinical parameters originally presented by the patients. The incidences of tumor removal, hormonal control, and tumor removal complications were retrospectively analyzed. RESULT: Out of 577 nonfunctioning adenomas, 180 were growth hormone (GH) secreting, 308 prolactin (PRL) secreting, 26 mixed GH/PRL adenomas, 68 adrenocorticotropin secreting, and 7 thyroid-stimulating hormone-secreting adenomas. The gross total removal of pituitary adenomas was achieved in 98 % of microadenomas, 92 % of macroadenomas, and 76 % of giant adenomas. Hormonal control was achieved in 47 (69 %) cases of ACTH adenomas, 119 (66 %) GH adenomas, 262 (85 %) PRL adenomas, and 6 (86 %) TSH adenomas. Postoperative complications were observed in 168 (14.4 %) patients. The most frequent complications were diabetes insipidus (7 %), epistaxis (1.7 %), hyposmia (1.5 %), anterior lobe insufficiency (1.3 %) ,and CSF leaks (0.6 %). CONCLUSION: The pure endoscopic approach is a safe, efficacious, and minimally invasive technique for the removal of pituitary adenomas. A higher gross total resection rate is vital for non-functional and functional adenomas. For patients with functional adenomas, while hormonal remission is unlikely to be achieved by surgery, the use of adjuvant therapy is advocated to obtain long-term hormonal control.

Facial and Cochlear Nerve Complications following Microsurgical Resection of Vestibular Schwannomas in a Series of 221 Cases.

BACKGROUND: Despite improvements in microsurgical technique and the use of intraoperative electrophysiological monitoring, the potential for facial and cochlear nerve injury remains a possibility in the resection of vestibular schwannomas (VS). We reviewed a series of 221 cases of VS resected via a retrosigmoid approach at our institution from October 2008 to April 2014 and determined the incidence of postoperative facial and cochlear deficits. MATERIAL AND METHODS: A total of 221 patients - 105 (47.5%) male and 116 (52.5%) female - with a mean age of 46.1 years (range 29-73 years), with VS ≥3 cm (n=183, 82.8%) and <3 cm (n=38, 17.2%) underwent surgical resection via a retrosigmoid approach and were evaluated for postoperative facial and cochlear nerve deficits. RESULTS: Near-total resection (>95% removal) was achieved in 199 cases (90%) and subtotal resection (>90% removal) in 22 cases (10%). At 6 month follow-up, House-Brackmann grades I-III were observed in 183 cases (82.8%), grade IV in 16 cases (7.2%), and grade V in 22 cases (10%). Of the 10 patients that had preoperative functional hearing, 3 (33%) retained hearing postoperatively. Cerebrospinal fluid leakage occurred in 6 patients (2.7%), lower cranial nerve palsies in 9 patients (4.1%), and intracranial hematomas 3 cases (1.4%). CONCLUSIONS: The observed incidence of persistent postoperative nerve deficits is very low. Meticulous microsurgical dissection of and around the facial and cochlear nerves with the aid of intraoperative electrophysiological nerve monitoring in the retrosigmoid approach allows for near-total resection of medium and large VS with the possibility of preservation of facial and cochlear nerve function.

Full-course resection control strategy in glioma surgery using both intraoperative ultrasound and intraoperative MRI.

Background: Intraoperative ultrasound(iUS) and intraoperative MRI (iMRI) are effective ways to perform resection control during glioma surgery. However, most published studies employed only one modality. Few studies have used both during surgery. How to combine these two techniques reasonably, and what advantages they could have for glioma surgery are still open questions. Methods: We retrospectively reviewed a series of consecutive patients who underwent initial surgical treatment of supratentorial gliomas in our center. We utilized a full-course resection control strategy to combine iUS and iMRI: IUS for pre-resection assessment and intermediate resection control; iMRI for final resection control. The basic patient characteristics, surgical results, iMRI/iUS findings, and their impacts on surgical procedures were evaluated and reported. Results: A total of 40 patients were included. The extent of resection was 95.43 ± 10.37%, and the gross total resection rate was 72.5%. The median residual tumor size was 6.39 cm3 (range 1.06-16.23 cm3). 5% (2/40) of patients had permanent neurological deficits after surgery. 17.5% (7/40) of patients received further resection after the first iMRI scan, resulting in four (10%) more patients achieving gross total resection. The number of iMRI scans per patient was 1.18 ± 0.38. The surgical time was 4.5 ± 3.6 hours. The pre-resection iUS scan revealed that an average of 3.8 borders of the tumor were beside sulci in 75% (30/40) patients. Intermediate resection control was utilized in 67.5% (27/40) of patients. In 37.5% (15/40) of patients, the surgical procedures were changed intraoperatively based on the iUS findings. Compared with iMRI, the sensitivity and specificity of iUS for residual tumors were 46% and 96%, respectively. Conclusion: The full-course resection control strategy by combining iUS and iMRI could be successfully implemented with good surgical results in initial glioma surgeries. This strategy might stabilize resection control quality and provide the surgeon with more intraoperative information to tailor the surgical strategy. Compared with iMRI-assisted glioma surgery, this strategy might improve efficiency by reducing the number of iMRI scans and shortening surgery time.

[High-field intraoperative magnetic resonance imaging suite with neuronavigation system: implementation and preliminary experience in the pituitary adenoma operation with transsphenoidal approach].

OBJECTIVES: To review the preliminary clinical experience with high-field-strength intraoperative magnetic resonance imaging (iMRI) suite with neuronavigation system in the pituitary adenoma operation with transsphenoidal approach. METHODS: From March 2009 to December 2010, 31 patients [range, 29 - 76 years, mean age (47 ± 11) years]of pituitary adenoma were operated with transsphenoidal approach and intraoperatively with a movable 1.5 T high-field-strength iMRI suite in combination with neuronavigation system. Tumor size was 1.8 - 7.3 cm, mean (3.5 ± 1.2) cm. Twenty-five cases were non-functional pituitary adenoma, 4 cases were prolactin-secreting pituitary adenoma, 2 cases were growth hormone-secreting pituitary adenoma. Thirty patients' resection with transnasal transsphenoidal approach were performed, one patient with transoral transsphenoidal approach was performed. RESULTS: In 12 cases of 30 patients who planed to totally remove tumor, iMRI had revealed residual lesions and resulted in the change of the surgical strategy, 2 invasive cavernous sinus cases no further resection of the tumor because of internal carotid artery encasement, the other 10 cases resected further, eventually. Finally, 8 cases were totally removed. The ratio of total removal tumor was enhanced to 86.7% (26/30) from 60.0% (18/30). There was no perioperative mortality. CONCLUSIONS: High-field-strength iMRI suite with neuronavigation system provides valuable information of tumor resection that allows intraoperative modification of the surgical strategy. It could be very helpful to maximize the resection of the pituitary adenoma and minimize the injury to neurological function.

[Implementation and preliminary experience of high-field intraoperative magnetic resonance imaging in the endoscopic chordoma operation with transsphenoidal or transoral approach].

OBJECTIVE: To review the preliminary clinical experience with high-field-strength intra-operative magnetic resonance imaging (iMRI) in the endoscopic chordoma operation with transsphenoidal or transoral approach. METHODS: From January 2009 to December 2010, 23 patients [range, 29 - 64 years, mean age (42 ± 3) years] of chordoma were operated with endoscopic transsphenoidal or transoral approach and examined intraoperatively with a movable 1.5 T iMRI magnet. Tumor size range was 2.0 - 5.7 cm, mean (3.5 ± 0.8) cm. A navigation system based on iMRI was used in 20 cases. RESULTS: iMRI scan were performed in each operation from 1 time to 5 times. Neuronavigation system were used in 20 operations and the data renewed in 12 cases by the information from iMRI. In 15 of 23 patients, iMRI had revealed residual lesions and resulted in 12 cases further treatment, eventually, 9 tumors were totally removed and 3 tumors were further removed. The ratio of total removal tumor was enhanced to 73.9% (17/23) from 34.8% (8/23). Among 15 cases of partial chordoma removal detected by scanning in operation, 9 were huge chordoma. The residual of huge chordoma detected by scanning in operation was 9/11, and other chordoma contributed to 6/12. There were no iMRI related safety issue or accident recorded in this study. CONCLUSIONS: High-field-strength iMRI provide high-quality images of tumor resection that allows intraoperative modification of the surgical strategy. Combined with the navigation system, iMRI is helpful to maximize the resection of the chordoma and benefit for the safety of endoscopic operation.

Multimodal Image-Based Virtual Reality Presurgical Simulation and Evaluation for Trigeminal Neuralgia and Hemifacial Spasm.

OBJECTIVE: To address the feasibility and predictive value of multimodal image-based virtual reality in detecting and assessing features of neurovascular confliction (NVC), particularly regarding the detection of offending vessels, degree of compression exerted on the nerve root, in patients who underwent microvascular decompression for nonlesional trigeminal neuralgia and hemifacial spasm (HFS). METHODS: This prospective study includes 42 consecutive patients who underwent microvascular decompression for classic primary trigeminal neuralgia or HFS. All patients underwent preoperative 1.5-T magnetic resonance imaging (MRI) with T2-weighted three-dimensional (3D) sampling perfection with application-optimized contrasts by using different flip angle evolutions, 3D time-of-flight magnetic resonance angiography, and 3D T1-weighted gadolinium-enhanced sequences in combination, whereas 2 patients underwent extra experimental preoperative 7.0-T MRI scans with the same imaging protocol. Multimodal MRIs were then coregistered with open-source software 3D Slicer, followed by 3D image reconstruction to generate virtual reality (VR) images for detection of possible NVC in the cerebellopontine angle. Evaluations were performed by 2 reviewers and compared with the intraoperative findings. RESULTS: For detection of NVC, multimodal image-based VR sensitivity was 97.6% (40/41) and specificity was 100% (1/1). Compared with the intraoperative findings, the κ coefficients for predicting the offending vessel and the degree of compression were >0.75 (P < 0.001). The 7.0-T scans have a clearer view of vessels in the cerebellopontine angle, which may have significant impact on detection of small-caliber offending vessels with relatively slow flow speed in cases of HFS. CONCLUSIONS: Multimodal image-based VR using 3D sampling perfection with application-optimized contrasts by using different flip angle evolutions in combination with 3D time-of-flight magnetic resonance angiography sequences proved to be reliable in detecting NVC and in predicting the degree of root compression. The VR image-based simulation correlated well with the real surgical view.

Endoscopic Evacuation of Basal Ganglia Hematoma: Surgical Technique, Outcome, and Learning Curve.

BACKGROUND: Minimally invasive endoscopic hematoma evacuation is a promising treatment option for intracerebral hemorrhage. However, the technique still needs improvement. We report our clinical experience of using this technique to evacuate deep-seated basal ganglia hematomas. METHODS: The frontal approach was used in most patients. The preoperative and postoperative hematoma volumes, Glasgow Coma Scale, hematoma evacuation rate, 30-day mortality, and long-term outcome defined by the modified Rankin Scale were analyzed retrospectively. The surgical duration per milliliter of clot (DPM) was calculated. The learning curve for this technique was determined based on the relation between the DPM and evacuation rate per the number of cases experienced. RESULTS: A total of 24 patients were enrolled. The evacuation rate was 87% ± 10%. The average Glasgow Coma Scale score recovered from 8 to 13 after surgery. Twenty-one patients had follow-up data. The follow-up time was 13 ± 6 months. The 30-day mortality after surgery was zero. Forty-eight percent of patients (10/21) achieved a favorable outcome. The DPM (P = 0.92) and evacuation rate (P = 0.64) did not change substantially with the number of cases experienced. CONCLUSIONS: Endoscopic port surgery for hematoma evacuation via the frontal approach is a safe surgical option for deep-seated basal ganglia hematomas. This technique is minimally invasive and may be helpful to provide better long-term outcomes for selected patients. For neurosurgeons, the learning curve for this technique is steep, which implies that the skills needed for our technique can be easily acquired.

Image-guided endoscopic surgery for spontaneous supratentorial intracerebral hematoma.

OBJECTIVE Endoscopic removal of intracerebral hematomas is becoming increasingly common, but there is no standard technique. The authors explored the use of a simple image-guided endoscopic method for removal of spontaneous supratentorial hematomas. METHODS Virtual reality technology based on a hospital picture archiving and communications systems (PACS) was used in 3D hematoma visualization and surgical planning. Augmented reality based on an Android smartphone app, Sina neurosurgical assist, allowed a projection of the hematoma to be seen on the patient's scalp to facilitate selection of the best trajectory to the center of the hematoma. A obturator and transparent sheath were used to establish a working channel, and an endoscope and a metal suction apparatus were used to remove the hematoma. RESULTS A total of 25 patients were included in the study, including 18 with putamen hemorrhages and 7 with lobar cerebral hemorrhages. Virtual reality combined with augmented reality helped in achieving the desired position with the obturator and sheath. The median time from the initial surgical incision to completion of closure was 50 minutes (range 40-70 minutes). The actual endoscopic operating time was 30 (range 15-50) minutes. The median blood loss was 80 (range 40-150) ml. No patient experienced postoperative rebleeding. The average hematoma evacuation rate was 97%. The mean (± SD) preoperative Glasgow Coma Scale (GCS) score was 6.7 ± 3.2; 1 week after hematoma evacuation the mean GCS score had improved to 11.9 ± 3.1 (p < 0.01). CONCLUSIONS Virtual reality using hospital PACS and augmented reality with a smartphone app helped precisely localize hematomas and plan the appropriate endoscopic approach. A transparent sheath helped establish a surgical channel, and an endoscope enabled observation of the hematoma's location to achieve satisfactory hematoma removal.

iPhone-Assisted Augmented Reality Localization of Basal Ganglia Hypertensive Hematoma.

OBJECTIVE: A low-cost, time-efficient technique that could localize hypertensive hematomas in the basal ganglia would be beneficial for minimally invasive hematoma evacuation surgery. We used an iPhone to achieve this goal and evaluated its accuracy and feasibility. METHODS: We located basal ganglia hematomas in 26 patients and depicted the boundaries of the hematomas on the skin. To verify the accuracy of the drawn boundaries, computed tomography (CT) markers surrounding the depicted boundaries were attached to 10 patients. The deviation between the CT markers and the actual hematoma boundaries was then measured. In the other 16 patients, minimally invasive endoscopic hematoma evacuation surgery was performed according to the depicted hematoma boundary. The deflection angle of the actual trajectory and deviation in the hematoma center were measured according to the preoperative and postoperative CT data. RESULTS: There were 40 CT markers placed on 10 patients. The mean deviation of these markers was 3.1 mm ± 2.4. In the 16 patients who received surgery, the deflection angle of the actual trajectory was 4.3° ± 2.1. The deviation in the hematoma center was 5.2 mm ± 2.6. CONCLUSIONS: This new method can locate basal ganglia hematomas with a sufficient level of accuracy and is helpful for minimally invasive endoscopic hematoma evacuation surgery.

A Low-Cost iPhone-Assisted Augmented Reality Solution for the Localization of Intracranial Lesions.

BACKGROUND: Precise location of intracranial lesions before surgery is important, but occasionally difficult. Modern navigation systems are very helpful, but expensive. A low-cost solution that could locate brain lesions and their surface projections in augmented reality would be beneficial. We used an iPhone to partially achieve this goal, and evaluated its accuracy and feasibility in a clinical neurosurgery setting. METHODOLOGY/PRINCIPAL FINDINGS: We located brain lesions in 35 patients, and using an iPhone, we depicted the lesion's surface projection onto the skin of the head. To assess the accuracy of this method, we pasted computed tomography (CT) markers surrounding the depicted lesion boundaries on the skin onto 15 patients. CT scans were then performed with or without contrast enhancement. The deviations (D) between the CT markers and the actual lesion boundaries were measured. We found that 97.7% of the markers displayed a high accuracy level (D ≤ 5mm). In the remaining 20 patients, we compared our iPhone-based method with a frameless neuronavigation system. Four check points were chosen on the skin surrounding the depicted lesion boundaries, to assess the deviations between the two methods. The integrated offset was calculated according to the deviations at the four check points. We found that for the supratentorial lesions, the medial offset between these two methods was 2.90 mm and the maximum offset was 4.2 mm. CONCLUSIONS/SIGNIFICANCE: This low-cost, image-based, iPhone-assisted, augmented reality solution is technically feasible, and helpful for the localization of some intracranial lesions, especially shallow supratentorial intracranial lesions of moderate size.

In vivo visualization of the facial nerve in patients with acoustic neuroma using diffusion tensor imaging-based fiber tracking.

OBJECTIVE Preoperative determination of the facial nerve (FN) course is essential to preserving its function. Neither regular preoperative imaging examination nor intraoperative electrophysiological monitoring is able to determine the exact position of the FN. The diffusion tensor imaging-based fiber tracking (DTI-FT) technique has been widely used for the preoperative noninvasive visualization of the neural fasciculus in the white matter of brain. However, further studies are required to establish its role in the preoperative visualization of the FN in acoustic neuroma surgery. The object of this study is to evaluate the feasibility of using DTI-FT to visualize the FN. METHODS Data from 15 patients with acoustic neuromas were collected using 3-T MRI. The visualized FN course and its position relative to the tumors were determined using DTI-FT with 3D Slicer software. The preoperative visualization results of FN tracking were verified using microscopic observation and electrophysiological monitoring during microsurgery. RESULTS Preoperative visualization of the FN using DTI-FT was observed in 93.3% of the patients. However, in 92.9% of the patients, the FN visualization results were consistent with the actual surgery. CONCLUSIONS DTI-FT, in combination with intraoperative FN electrophysiological monitoring, demonstrated improved FN preservation in patients with acoustic neuroma. FN visualization mainly included the facial-vestibular nerve complex of the FN and vestibular nerve.

Prediction of the location of the pyramidal tract in patients with thalamic or basal ganglia tumors.

BACKGROUND: Locating the pyramidal tract (PT) is difficult in patients with thalamic or basal ganglia tumors, especially when the surrounding anatomical structures cannot be identified using computed tomography or magnetic resonance images. Hence, we objected to find a way to predict the location of the PT in patients with thalamic and basal ganglia tumors METHODOLOGY/PRINCIPAL FINDINGS: In 59 patents with thalamic or basal ganglia tumors, the PTs were constructed by with diffusion tensor imaging (DTI)-based fiber tracking (FT). In axial slices crossing the foramen of Monro, the tumor position was classified according to three lines. Line 1 was vertical and crossed the vertex point of the anterior limbs of the internal capsule. Lines 2 and line 3 were horizontal and crossed the foramen of Monro and joint of the middle and lateral thirds of the posterior limbs, respectively. Six (10.17%) patients were diagnosed with type 1 tumor, six (10.17%) with type 2, seven (11.86%) with type 3a, five (8.47%) with type 3b, 17 (28.81%) with type 4a, six (10.17%) with type 4b, three (5.08%) with type 5, and nine (15.25%) with type 6. In type 1 tumors, the PTs were located at the 12 o'clock position of the tumor, type 2 at six o'clock, type 3a between nine and 12 o'clock, type 3 between six and nine o'clock, type 4a between 12 and three o'clock, type 4b at three o'clock, type 5 between six and nine o'clock, and type 6 between three and six o'clock. CONCLUSIONS/SIGNIFICANCE: The position of the PT relative to the tumor could be determined according to the tumor location. These results could prove helpful in determining the location of the PT preoperatively.