Computed Tomography Scan-Based Morphometric Analysis of Lateral Masses of Atlas Vertebrae in Normal Indian Population.

STUDY DESIGN: A cross-sectional observational study involved the analysis of computed tomography (CT) scan data from 125 Indian subjects of 18 years or older with normal imaging findings. Scans were obtained from patients with head injuries as a part of the screening process along with brain CT scans. PURPOSE: To establish the dimensions of lateral masses of the atlas vertebrae in normal disease-free Indian individuals. OVERVIEW OF LITERATURE: Lateral mass fixation has become the standard of care in fixation of the supra-axial cervical spine. Many studies have investigated the dimensions of lateral masses in cadaveric specimens; however, studies involving the radiological morphometric analysis of the lateral masses of the atlas vertebra in living patients are lacking. METHODS: Subjects underwent craniovertebral junction CT scans during evaluations of head injury. All had normal radiology reports. The CT scans were obtained using a CT Philips Brilliance 64 machine (Philips, Amsterdam, Netherlands) with a slice thickness of 1 mm and then analyzed using Horos software ver. 2.0.2 (Horos Project, Annapolis, MD, USA) on a MacBook. RESULTS: Lateral masses of the atlas vertebrae were found to be larger in males than females and larger on the right than the left side. The angle of permissible medialization was found to be larger on the right side. The analysis of the average dimensions indicated the conventionally described screw positions to be safe. CONCLUSIONS: The present study provides information that may help to establish standard dimensions of lateral masses of the atlas vertebrae among the normal Indian population. We demonstrate that there is no significant difference when compared with the Western population. The results presented here will be of use to clinicians as they may inform preoperative planning for lateral mass fixation surgeries.

Role of Additional Coronal Magnetic Resonance Imaging in Decompression and Reconstruction with or without Segment Salvage in Thoracic Spine Tuberculosis.

STUDY DESIGN: Retrospective and observational study. PURPOSE: The present study aimed to develop guidelines for segment salvage or sacrifice based on the amount and status of the remnant portion of the vertebra as assessed by coronal magnetic resonance imaging (MRI) in addition to sagittal and axial images in thoracic spine tuberculosis (TB). OVERVIEW OF LITERATURE: Indications for surgery have not changed significantly since the 'middle path regimen' was proposed by Tuli. Goals of modern surgical management of spinal TB include debridement of diseased vertebrae, spinal cord decompression, deformity correction, and spine stabilization. However, the extent of decompression has not been defined previously. Too less decompression will lead to compromised neurological recovery, whereas large extent of decompression is associated with increased surgical morbidity and longer segment to reconstruct. METHODS: Sixty-five patients with thoracic spine TB were divided into two groups (segment salvage/sacrifice) based on the thickness of the subchondral bone and endplate morphology of the vertebra as seen on MRI. The operative procedure in the form of instrumentation with Hartshill loop rectangle and sublaminar wire using the simultaneous anterior posterior approach in lateral position (versatile approach) was performed. The patients were analyzed for postoperative fusion, improvement in kyphosis angle, and followed up for development of complications. RESULTS: This method of deciding the level of fixation and segment salvage based on coronal MRI in addition to the sagittal and axial images provided good result in 64 of 65 patients, except for one patient in the segment sacrifice group who had graft buckling and resultant kyphosis. CONCLUSIONS: For segment salvage, having a clear three-dimensional idea about the viable remnant bone is important. Viable salvaged segment reduces the morbidity of the procedure, length of the construct, and unnecessary debridement without compromising on the neural recovery and fusion rate. Hence, additional cone down coronal cuts must be required when MRI is suggestive for spinal TB because it will help in the decision making.

Diffusion tensor imaging as an additional postoperative prognostic predictor factor in cervical myelopathy patients: An observational study.

INTRODUCTION: Multiple investigation modalities have been invented for diagnosis and for planning management of degenerative cervical myelopathy, which include magnetic resonance imaging (MRI), computed tomography scan, and plain X-rays. Diffusion tensor imaging (DTI) of the spinal cord is a special variety of MRI where diffusion of water molecules across and along the tracts is mapped. The changes in anisotropy at the stenotic level can be a postoperative prognostic factor. The aim of this study was to establish postoperative prognostic predictive value of DTI in cases of degenerative cervical myelopathy. MATERIALS AND METHODS: The study included 30 indoor patients in a tertiary care hospital diagnosed with degenerative compressive cervical myelopathy based on both clinical and radiological parameters with complete clinical data including follow-up. All patients with medical neurological diseases, cases who underwent repeat surgery, cases who developed surgical site infection, and those patients who were lost to follow-up were excluded from the study. The patients underwent operative decompression through either anterior or posterior approach with or without fixation with titanium implants as per indication. All patients underwent pre- and postoperative DTI. The fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were noted in both pre- and postoperative imaging. Epidemiological data such as age and sex were noted. Pre- and postoperative modified Japanese Orthopedic Association (mJOA) scores were calculated. RESULTS: There was a significant improvement in FA values postoperatively. Preoperatively, both FA and ADC values showed a significant correlation with preoperative Neurological status of the patient while postoperatively only FA values were found to be significantly correlated. The regression equations for determining postoperative mJOA score based on preoperative FA and ADC values revealed mJOA = 9.77 + 12.1 (FA), mJOA = 14.2 + 2408.4 (ADC), and mJOA = 9.54 + 11.2 (FA) +1575.5 (ADC). This means that postoperative mJOA score, i.e., postoperative clinical status improvement can be determined using DTI variables which are an objective preoperative data. However, relative strength of prediction for FA value is 66.7% and for ADC value is 28.7%. CONCLUSION: DTI tractography of the spinal cord will be a helpful objective prognostic factor for patients in whom surgery is planned. However, a study with larger subject size is required to increase the accuracy of determination of regression coefficient.