Xinguang Yu

Posterior realignment of irreducible atlantoaxial dislocation with C1–C2 screw and rod system: a technique of direct reduction and fixation

BACKGROUND CONTEXTnTreatment of chronic and irreducible atlantoaxial dislocation (AAD) with ventral compression is challenging for surgeons. The main procedures are occipitocervical/C1-C2 fusion after transoral odontoidectomy or release of the periodontoid tissues. These surgical procedures, which are performed simultaneously or intermittently, have many disadvantages that may discount their effectiveness. Therefore, a more effective way to achieve surgical reduction and to keep solid stability with only a single procedure is needed.nnnPURPOSEnWe describe a technique to reduce chronic and irreducible AAD with C1 lateral mass and C2 pedicle screw and rod system.nnnSTUDY DESIGNnThis was a retrospective case series.nnnPATIENT SAMPLEnOur sample comprised 26 patients (9 men and 17 women) with irreducible AAD who ranged in age from 15 to 54 years (mean, 35 years).nnnOUTCOME MEASURESnPatients neurologic status was evaluated with the Japanese Orthopedic Association (JOA) scale.nnnMETHODSnTwenty-six symptomatic patients underwent posterior realignment and reduction through the C1 lateral mass and C2 pedicle screw and rod system. The proposed mechanism of reduction is that the implanted screws and rods between C1 and C2 acting as a lever system drew C1 backward and pushed C2 downward and forward after removing circumambient obstruction and scars and thoroughly releasing the facet joints. The preoperative and postoperative JOA score, the extent of reduction, and the conditions of C1-C2 bony fusion were examined.nnnRESULTSnNo neurovascular injury occurred during surgery. Follow-up ranged from 6 to 40 months (mean 20.7 months). Radiographic evaluation showed that solid bony fusion was achieved in all patients, and that complete reduction was attained in 18 patients and partial reduction (>60% reduction) in 8 patients. The mean postoperative JOA score at last follow-up was 15.7, compared with the preoperative score of 12.1 (p<.01).nnnCONCLUSIONSnThis C1-C2 screw and rod system provides reliable stability and sufficient reduction of the anatomic malalignment at the craniovertebral junction and meanwhile retains the mobility of atlanto-occipital joints in the treatment of chronic and irreducible AAD. Sophisticated skills, thorough release of the facet joints, and intraoperative protection of the vertebral artery are key points to accomplish this technique.

Comparison of the Tada Formula With Software Slicer Precise and Low-Cost Method for Volume Assessment of Intracerebral Hematoma

Background and Purpose— The Tada (ABC/2) formula has been used widely for volume assessment of intracerebral hematoma. However, the formula is crude for irregularly shaped hematoma. We aimed to compare the accuracy of the ABC/2 formula with open source software Slicer. Methods— Computed tomographic images of 294 patients with spontaneous intracerebral hematoma were collected. Hematoma volumes were assessed with the ABC/2 formula and calculated with software 3D Slicer. Results of these 2 methods were compared with regard to hematoma size and shape. Results— The estimated hematoma volume was 58.41±37.83 cm3 using the ABC/2 formula, compared with 50.38±31.93 cm3 with 3D Slicer (mean percentage deviation, 16.38±9.15%). When allocate patients into groups according to hematoma size, the mean estimation error were 3.24 cm3 (17.72%), 5.85 cm3 (13.72%), and 15.14 cm3 (17.48%) for groups 1, 2, and 3, respectively. When divided by shape, estimation error was 3.33 cm3 (9.76%), 7.19 cm3 (18.37%), and 29.39 cm3 (39.12%) for regular, irregular, and multilobular hematomas. Conclusions— There is significant estimation error using the ABC/2 formula to calculate hematoma volume. Compared with hematoma size, estimation error is more significantly associated with hematoma shape.

Preoperative Prediction of Location and Shape of Facial Nerve in Patients with Large Vestibular Schwannomas Using Diffusion Tensor Imaging–Based Fiber Tracking

OBJECTIVEnPreserving the facial nerve (FN) during surgery for large vestibular schwannomas (VSs) is challenging because of the unpredictable locations and morphologic changes in the FN. Diffusion tensor imaging-based fiber tracking (DTI-FT) has been proposed to preoperatively visualize the FN. This study was performed to evaluate the efficacy of DTI-FT for predicting FN location and shape in patients with large VSs.nnnMETHODSnIn this prospective study, imaging data from 30 consecutive patients with large VSs were obtained using 3-T magnetic resonance imaging. The DTI-FT results included the location of the reconstructed FN relative to the tumor, and maximal fractional anisotropy (MFA) threshold values for FN tracking were determined with iPlan software. Intraoperative findings including the location of FN relative to the tumor and shape were determined by microscopic observations and electrophysiologic monitoring. A correlation analysis was performed between the DTI-FT results and intraoperative findings.nnnRESULTSnPreoperative visualization of the FN using DTI-FT was successful in all 30 patients. The location of the cisternal segment of the FN in relation to the tumors predicted by DTI-FT was consistent with the intraoperative findings in 29 (96.7%) of the 30 patients. The area under the curve of MFA for differentiation between the compact and flat FN was 0.84 (95% confidence interval [CI]: 0.69-0.98) (Pxa0= 0.002).nnnCONCLUSIONSnDTI-FT with modified tracking settings was useful to preoperatively predict the location of FN in patients with large VSs. The MFA of FN demonstrated moderate diagnostic performance for distinguishing compact from flat FNs.

Low-Cost Interactive Image-Based Virtual Endoscopy for the Diagnosis and Surgical Planning of Suprasellar Arachnoid Cysts

OBJECTIVEnTo investigate the feasibility and reliability of virtual endoscopy (VE) as a rapid, low-cost, and interactive tool for the diagnosis and surgical planning of suprasellar arachnoid cysts (SACs).nnnMETHODSnEighteen patients with SACs treated with endoscopic ventriculocystostomy were recruited, and 18 endoscopic patients treated with third ventriculostomy were randomly selected as a VE reconstruction control group. After loading their DICOM data into free 3D Slicer software, VE reconstruction was independently performed by 3 blinded clinicians and the time required for each reconstruction was recorded. Another 3 blinded senior neurosurgeons interactively graded the visibility of VE by watching video recordings of the endoscopic procedures. Based on the visibility scores, receiver operating characteristic curve analysis was used to investigate the reliability of VE to diagnose SACs, and Bland-Altman plots were used to assess the reliability of VE for surgical planning. In addition, the intraclass correlation coefficient was calculated to estimate the consistency among the results of 3 reconstruction performers.nnnRESULTSnAll 3 independent reconstructing performers successfully completed VE simulation for all cases, and the average reconstruction time was 10.2 ± 9.7 minutes. The area under the receiver operating characteristic curve of the cyst visibility score was 0.96, implying its diagnostic value for SACs. The Bland-Altman plot indicated good agreement between VE and intraoperative viewings, suggesting the anatomic accuracy of the VE for surgical planning. In addition, the intraclass correlation coefficient was 0.81, which revealed excellent interperformer consistency of our simulation method.nnnCONCLUSIONSnThis study substantiated the feasibility and reliability of VE as a rapid, low-cost, and interactive modality for diagnosis and surgical planning of SACs.

Functional Neuronavigation-Guided Transparieto-Occipital Cortical Resection of Meningiomas in Trigone of Lateral Ventricle

BACKGROUNDnThis study investigated whether functional neuronavigation can be used to remove lesions in the lateral ventricle while preserving patients neurologic functionality.nnnMETHODSnA total of 60 patients with lateral ventricular meningiomas were divided into study and control groups (n = 30 each). Diffusion tensor and blood oxygenation level-dependent functional magnetic resonance imaging were used for fiber tracking and eloquent cortex localization, respectively, in the study group. The surgical approach was based on coregistered data sets from 3-D lesion and brain structure reconstructions. Patients in the control group underwent anatomic neuronavigation-guided surgery. The patients demographics, degree of resection, visual field, language score, movement, preoperative and postoperative Karnofsky Performance Status (KPS) scores, and surgical complications were recorded.nnnRESULTSnTumors were completely removed in both groups. Patients in the study group had a higher rate of visual field preservation than controls (P = 0.01). The two groups had similar motor and language functions after surgery, except that fewer cases of transient aphasia were observed in the former (P < 0.05). KPS scores for the study and control groups were 80 (70-80) and 70 (60-70), respectively (P < 0.01), at 2 weeks and 90 (80-100) and 85 (70-90), respectively (P = 0.022), at 3 months after surgery.nnnCONCLUSIONSnFunctional neuronavigation preserved neurologic functionality and was especially beneficial for protecting optical functionality and for the rapid recovery of patients.

C1 lateral mass screw placement in occipitalization with atlantoaxial dislocation and basilar invagination: a report of 146 cases.

Study Design. Retrospective study of 146 patients with the diagnosis of occipitalization, atlantoaxial dislocation (AAD) and basilar invagination, using a novel surgical treatment strategy. Objective. To introduce a novel fixation and reduction technique. Summary of Background Data. Atlas occipitalization associated with basilar invagination often result in fixed AAD that need reduction and occipitocervical fixation. The widely used occipitocervical fixation with suboccipital screws has several limitations such as the poor screw purchase in maldevelopment of the occipital bone, limited area available for implants in previous suboccipital craniectomy. The placement of occipitalized C1 lateral mass screw is an alternative option. Methods. From June 2007 to June 2013, 146 patients of occipitalized atlas with fixed AAD and basilar invagination, underwent fixation and reduction via C1 lateral mass and C2 pars/pedicle screw. Results. A total of 143 patients achieved the follow-up in the range from 6 months to 4 years (average, 30 mo). Neurological improvement was seen in all the 143 patients, with the averaged Japanese Orthopedic Association scores increasing from 11.6 to 15.5. Radiographical evaluation showed that solid bony fusion was achieved in all patients, and complete reduction was attained in 95 patients, and partial reduction (>60%) in 40 patients, and no effective reduction in 8 patients who had additional transoral decompression. Magnetic resonance imaging demonstrated that the ventral cervicomedullary compression was relieved in all patients. Conclusion. Although technically demanding, the C1 lateral mass placement in occipitalization is very useful in the rescue situation where more conventional stabilization alternatives are not technically possible, or as routine occipitocervical stabilization. It provides firm stabilization offering an optimum situation for bony fusion, and meanwhile the effective reduction of fixed AAD and basilar invagination. An extremely high fusion rate can be expected with minimal complications and minimal postoperative immobilization with this technique. Level of Evidence: 4

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 patients 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 hematomas location to achieve satisfactory hematoma removal.

Impact of Virtual and Augmented Reality Based on Intraoperative Magnetic Resonance Imaging and Functional Neuronavigation in Glioma Surgery Involving Eloquent Areas.

BACKGROUNDnThe utility of virtual and augmented reality based on functional neuronavigation and intraoperative magnetic resonance imaging (MRI) for glioma surgery has not been previously investigated.nnnMETHODSnThe study population consisted of 79 glioma patients and 55 control subjects. Preoperatively, the lesion and related eloquent structures were visualized by diffusion tensor tractography and blood oxygen level-dependent functional MRI. Intraoperatively, microscope-based functional neuronavigation was used to integrate the reconstructed eloquent structure and the real head and brain, which enabled safe resection of the lesion. Intraoperative MRI was used to verify brain shift during the surgical process and provided quality control during surgery. The control group underwent surgery guided by anatomic neuronavigation.nnnRESULTSnVirtual and augmented reality protocols based on functional neuronavigation and intraoperative MRI provided useful information for performing tailored and optimized surgery. Complete resection was achieved in 55 of 79 (69.6%) glioma patients and 20 of 55 (36.4%) control subjects, with average resection rates of 95.2% ± 8.5% and 84.9% ± 15.7%, respectively. Both the complete resection rate and average extent of resection differed significantly between the 2 groups (P < 0.01). Postoperatively, the rate of preservation of neural functions (motor, visual field, and language) was lower in controls than in glioma patients at 2 weeks and 3 months (P < 0.01).nnnCONCLUSIONnCombining virtual and augmented reality based on functional neuronavigation and intraoperative MRI can facilitate resection of gliomas involving eloquent areas.

Posterior Reduction of Fixed Atlantoaxial Dislocation and Basilar Invagination by Atlantoaxial Facet Joint Release and Fixation: A Modified Technique With 174 Cases.

BACKGROUNDnTreatment of fixed atlantoaxial dislocation (AAD) with basilar invagination (BI) is challenging.nnnOBJECTIVEnTo introduce a modified technique to reduce fixed AAD and BI through a posterior approach.nnnMETHODSnFrom 2007 to 2013, 174 patients with fixed AAD and BI underwent surgical reduction by posterior atlantoaxial facet joint release and fixation technique.nnnRESULTSnThere was 1 death in the series, and 3 patients were lost to follow-up. The follow-up period ranged from 12 to 52 months (mean: 35.2 months) for the remaining 170 patients. Neurological improvement was observed in 168 of 170 patients (98.8%), and was stable in 1 (0.06%) and exacerbated in 1 (0.06%), with the Japanese Orthopedic Association scores increasing from 11.4 preoperatively to 15.8 postoperatively (P < .01). Radiologically, complete or >90% reduction was attained in 107 patients (62.9%), 60% to 90% reduction was attained in 51 patients (30%), and <50% reduction was attained in 12 patients (7.1%), who underwent additional transoral decompression. Complete decompression was demonstrated in all 170 patients. Solid bony fusion was demonstrated in 167 patients at follow-up (98.2%).nnnCONCLUSIONnThis series showed the safety and efficacy of the posterior C1-2 facet joint release and reduction technique for the treatment of AAD and BI. Most fixed AAD and BI cases are reducible via this method. In most cases, this method avoids transoral odontoidectomy and cervical traction. Compared with the occiput-C2 screw method, this short-segment C1-2 technique exerts less antireduction shearing force, guarantees longer bone purchase, and provides more immediate stabilization.

Indirect Revascularization for Non–Moyamoya Disease Anterior Circulation Arterial Steno-occlusion: Clinical Features, Surgical Treatment, and Medium-Term Outcomes in Adults

BACKGROUNDnSymptomatic anterior arterial steno-occlusion is often associated with neurofunctional deficits or a high risk of recurrent stroke or both. Although both medical and endovascular treatments are useful and suitable, few studies have investigated the continued use of indirect encephaloduroarteriosynangiosis (EDAS) bypass in patients with non-moyamoya disease ischemia. We retrospectively investigated clinical features, surgical treatments, and medium-term outcomes of indirect revascularization for patients with non-moyamoya disease anterior circulation arterial steno-occlusion in China.nnnMETHODSnEDAS without burr holes was performed in 51 adult patients with cerebral ischemic events and diagnosed nonmoyamoya anterior circulation arterial steno-occlusion. Preoperative, postoperative, and follow-up neurologic status was evaluated using the National Institutes of Health Stroke Scale; changes on angiography and perfusion-weighted magnetic resonance imaging were evaluated.nnnRESULTSnUnilateral EDAS was performed in 48 patients, and bilateral EDAS was performed in 3 patients. Four patients experienced complications before hospital discharge; only 23 patients underwent follow-up angiograms. Of the 51 patients, 44 (86.3%) exhibited improved muscle strength; 21 of 23 patients (91.3%) with follow-up angiography data exhibited evidence of new visible branches from the superficial temporal artery or middle meningeal artery or both. Preoperative and postoperative perfusion-weighted magnetic resonance imaging was performed for 5 patients. Despite clinical improvement in all patients, only 2 exhibited hemodynamic improvement.nnnCONCLUSIONSnIndirect revascularization may be safe and effective for improving blood flow to the ischemic region following nonmoyamoya anterior circulation arterial steno-occlusion, especially in patients with residual postinfarction neurologic deficits. Our study demonstrates that improvements in ischemic symptoms after EDAS correspond to neovascularization from the superficial temporal artery or middle meningeal artery in ischemic brain areas.