Prediction of facial nerve position in large vestibular schwannomas using diffusion tensor imaging tractography and its intraoperative correlation.

OBJECTIVE: Resection of large Vestibular Schwannomas (VSs) can be associated with postoperative facial nerve injury. Diffusion-based tractography has emerged as a powerful tool for three-dimensional imaging and reconstruction of white matter fibers; however, tractography of the cranial nerves has not been well studied. In this prospective study, we aim to predict the position of facial nerve in large VSs (>3 cm) using Diffusion Tensor Imaging (DTI) tractography and correlate it with the intraoperative finding of the position of facial nerve. MATERIALS AND METHODS: Twenty patients with a large VS (>3 cm) undergoing surgery were subjected to preoperative DTI to predict the position of the facial nerve in relation to the tumor. The surgeon was blinded to the results of the preoperative DTI tractography. A comparative analysis was then made during operation. The location of the facial nerve in relation to the tumor was recorded during surgery using facial nerve stimulator. RESULTS: Of the 20 patients who underwent DTI tractography, it was not possible to preoperatively identify facial nerve in one patient. In another patient, although DTI tractography predicted the position of facial nerve, it was not identified intraoperatively. In the remaining 18 patients, DTI tractography accurately predicted the facial nerve position. The predicted position was in synchronization with the intraoperative facial nerve position in 16 patients (89% concordance). It was discordant in two patients (11%), but this was not found to be statistically significant (P = -0.3679). CONCLUSION: This study validates the reliability of facial nerve DTI-based fiber tracking for prediction of the facial nerve position in patients with large VSs. The reliable preoperative visualization of facial nerve location in relation to the VS will allow surgeons to plan tumor removal accordingly and may increase the safety of surgery.

Clinical Features, Gender Differences, Disease Course, and Outcome in Neuromyelitis Optica Spectrum Disorder.

INTRODUCTION: Neuromyelitis optica spectrum disorder (NMOSD) is an astrocytopathy with a predilection for the optic nerve, spinal cord, and brainstem. In this ambispective study, we evaluate clinical characteristics, responses to therapy, and disability outcomes in patients with NMOSD. METHODS: Patients diagnosed as NMOSD and following up for at least 1 year at a tertiary care center in India were recruited. Patient data were collected ambispectively from January 2012 until December 2018. RESULTS: A total of 106 patients (29M/77F) with NMOSD were evaluated. The mean age of onset was 29 (±11.6) years. About 77 patients (72.64%) were positive for the AQP4 antibody. Age of onset was higher for those presenting with an opticospinal syndrome (34.2 years) as compared to either isolated longitudinally extensive transverse myelitis (LETM) (30 years) or optic neuritis (ON) (25.3 years). The most common syndrome at onset was LETM in 57 patients (53.77%) followed by ON in 31 patients (29.24%). Azathioprine was the most common immunotherapy (83.96%) prescribed followed by rituximab (7.54%) and mycophenolate mofetil (1.88%). There was a significant decrease in the number of relapses post-azathioprine (P < 0.001). Out of 67 patients with ON, 21 (31.34%) had complete recovery while 17 (25.37%) patients had a severe deficit at a 3-month follow-up. Out of 92 patients with a motor deficit, 49 (53.26%) patients had a partial motor deficit at a 6-month follow-up. The severe visual deficit at baseline and female gender predicted poor visual and motor recovery, respectively. CONCLUSION: This is the largest descriptive study on patients with NMOSD from India. Relapse rates were similar irrespective of the clinical presentation, age, gender, and disease course. Treatment with immunosuppressive treatment significantly affected the disease course.

Cervical alignment following laminoplasty for cervical spondylotic myelopathy.

BACKGROUND: Laminoplasty can result in the loss of cervical lordosis (LOCL) or the development of kyphosis after surgery. Here, we evaluated the clinical and radiological parameters involved in predicting the postoperative LOCL following laminoplasty in patients with cervical spondylotic myelopathy (CSM) and ossification of the posterior longitudinal ligament (OPLL). METHODS: For 50 patients with CSM and 35 with OPLL undergoing laminoplasty, preoperative and 1-year postoperative X-rays were obtained to determine the incidence and risk factors contributing to postoperative LOCL. The patients were divided into two groups depending on whether the preoperative T1 slope was above or below the median preoperative T1S (26°); Group A - high T1 slope group (n = 40) and Group B - low T1 slope group (n = 45). RESULTS: Following laminoplasty, Group A patients had significantly higher preoperative lordosis (C2-C7 Cobb's angle) (P = 0.001) and significantly higher LOCL (P = 0.02) versus Group B patients with low T1 slopes. The preoperative T1 slope was also found to be significantly correlated with the preoperative C2-C7 Cobb's angles (R = 0.619, P = 0.001), LOCL (R = 0.487, P = 0.001), and preoperative C2-C7 sagittal vertical axis (R = 0.480, P = 0.001). Utilizing multivariate analysis and a generalized linear model, the preoperative T1 slope significantly impacted the Oswestry disability index (ODI) index (P = 0.002) and frequency of LOCL (P = 0.001) following laminoplasty. CONCLUSION: The preoperative T1 slope is a significant predictor of the LOCL and change in ODI following laminoplasty for CSM/OPLL utilizing a cutoff value of 29.5°.

Cervical rotation before and after hinge-door cervical laminoplasty for cervical spondylotic myelopathy.

BACKGROUND: Hinge-Door Cervical laminoplasty is commonly performed procedure in patients with cervical spondylotic myelopathy. Most available studies have established restriction of flexion and extension motion post laminoplasty but the literature on post-laminoplasty axial rotation is sparse. OBJECTIVE: To study the axial neck rotation on either side following hinge door cervical laminoplasty. MATERIALS AND METHODS: Twenty consecutive patients of cervical spondylotic myelopathy planned for cervical laminoplasty were included in the study. Preoperative and postoperative radiological data was recorded for each patient and analysed by an experienced neuroradiologist. The clinical and radiological follow-up was recorded at 6 months post surgery. All patients underwent standard hinge door C3-C6 laminoplasty preserving the muscle attachments to C2 and C7 vertebra. RESULTS: There were 13 men and 7 women with a mean age of 60.5 years, age range 58-70 years. The mean preop C1 C2 rotation was 46.5 degrees and mean post-operative C1-C2 rotation was 44.3 degrees. The average subaxial cervical spine rotation was 11.66 degrees preoperatively and 12.47 degrees postoperatively. The global cervical spine rotation was 80.95 degrees preoperatively and 76.82 degrees postoperatively. There is no significant change in segmental, subaxial and global cervical spine rotation following hinge door C3-C6 laminoplasty preserving the muscle attachments to C2 and C7 vertebra. CONCLUSION: Cervical laminoplasty preserves cervical ROM and is a motion-preserving surgery as far as axial rotation is concerned.