A comparative study of early and late extubation following transoral odontoidectomy and posterior fixation.

BACKGROUND AND AIMS: Elective ventilation is the usual practice after transoral odontoidectomy (TOO) and posterior fixation. This practice of elective ventilation is not based on any evidence. The primary objective of our study was to find out the difference in oxygenation and ventilation in patients extubated early compared to those extubated late after TOO and posterior fixation. The secondary objectives were to compare the length of Intensive Care Unit (ICU)/hospital stay and pulmonary complications between the two groups. MATERIAL AND METHODS: After TOO and posterior fixation, patients were either extubated in the operating room (Group E) or extubated next day (Group D). The oxygenation (PaO2:FiO2 ratio) and ventilation (PaCO2) of the two groups before surgery, at 30 min and at 6/12/24 and 48 h after extubation were compared. Complications, durations of ICU and hospital stay were noted. RESULTS: The base-line PaO2:FiO2 and PaCO2 was comparable between the groups. No significant change in the PaO2:FiO2 was noted in the postoperative period in either group as compared to the preoperative values. Except for at 12 h after surgery, there was no significant difference between the two groups at various time intervals. No significant change in the PaCO2 level was seen during the study period in either group. PaCO2 measured at 30 min after surgery was more in Group E (37.5 ± 3.2 mmHg in Group E vs. 34.6 ± 2.9 mmHg in Group D), otherwise there was no significant difference between the two groups at various time intervals. One patient in Group E (7.1%) and two patients in Group D (13%) developed postoperative respiratory complication, but the difference was not statistically significant. The mean ICU stay (Group D = 42 ± 25 h vs. Group E = 25.1 ± 16.9 h) and mean hospital stay (Group D = 9.9 ± 4 days vs. Group E = 7.6 ± 2.2 days) were longer in Group D patients. CONCLUSION: Ventilation and oxygenation in the postoperative period in patients undergoing TOO and posterior fixation are not different between the two groups. However, the duration of ICU and hospital stay was prolonged in group D.

MAGAT gel and EBT2 film-based dosimetry for evaluating source plugging-based treatment plan in Gamma Knife stereotactic radiosurgery.

This work illustrates a procedure to assess the overall accuracy associated with Gamma Knife treatment planning using plugging. The main role of source plugging or blocking is to create dose falloff in the junction between a target and a critical structure. We report the use of MAGAT gel dosimeter for verification of an experimental treatment plan based on plugging. The polymer gel contained in a head-sized glass container simulated all major aspects of the treatment process of Gamma Knife radiosurgery. The 3D dose distribution recorded in the gel dosimeter was read using a 1.5T MRI scanner. Scanning protocol was: CPMG pulse sequence with 8 equidistant echoes, TR = 7 s, echo step = 14 ms, pixel size = 0.5mm × 0.5mm, and slice thickness of 2 mm. Using a calibration relationship between absorbed dose and spin-spin relaxation rate (R2), we converted R2 images to dose images. Volumetric dose comparison between treatment planning system (TPS) and gel measurement was accomplished using an in-house MATLAB-based program. The isodose overlay of the measured and computed dose distribution on axial planes was in close agreement. Gamma index analysis of 3D data showed more than 94% voxel pass rate for different tolerance criteria of 3%/2 mm, 3%/1 mm and 2%/2 mm. Film dosimetry with GAFCHROMIC EBT 2 film was also performed to compare the results with the calculated TPS dose. Gamma index analysis of film measurement for the same tolerance criteria used for gel measurement evaluation showed more than 95% voxel pass rate. Verification of gamma plan calculated dose on account of shield is not part of acceptance testing of Leksell Gamma Knife (LGK). Through this study we accomplished a volumetric comparison of dose distributions measured with a polymer gel dosimeter and Leksell GammaPlan (LGP) calculations for plans using plugging. We propose gel dosimeter as a quality assurance (QA) tool for verification of plug-based planning.

Telementoring Feasibility Using a Novel Low-cost Lazy Glass Microsurgical Simulator: A "Proof of Concept" Experimental Study.

BACKGROUND: In order to mitigate the challenges in microsurgical skill acquisition and training, especially in the COVID-19 era, we devised a novel microsurgical telementoring protocol for imparting microsurgical skill training in a socially distanced setting. We objectively analyzed its feasibility among neurosurgical trainees. METHODS: In a controlled experimental design, 8 residents at different stages of their tenure participated in a lazy glass microsurgical simulator-based telementoring exercise. Microsuturing with 4-0 silk, 10-0 nylon on silastic sheets, and eggshell peeling tasks were performed by the residents prior to and after a telementoring session by a panel of 4 neurosurgical experts. Impact of telementoring was assessed in terms of surgical accuracy, efficiency, and dexterity by providing objective (Performance score [PS]), subjective (Neurosurgery Education and Training School [NETS] score), and cumulative scores (CS). Subgroup analysis was performed to assess the impact at different stages of residency. RESULTS: PS, NETS score, and CS were significantly improved by telementoring sessions for 10-0 nylon micro-suturing (P < 0.001), and egg-hell peeling tasks (P < 0.01). PS and CS improved significantly (P = 0.01) after telementoring sessions for 4-0 silk microsuturing. Both pre- and post-training CS were similar across the 2 subgroups PGY 1-4 and PGY 5-6 (P > 0.05). CONCLUSIONS: Telementoring is a viable alternative for neurosurgical resident training in the COVID-19 era, where reduction in elective surgeries and social distancing norms preclude conventional teaching. Lazy glass microsurgical simulator-based structured telementoring protocol is a cost-effective tool to augment surgical proficiency and finesse, irrespective of stage of residency.

Single-Stage Posterior Only Approach for Unilateral Atlantoaxial Spondyloptosis with type-II odontoid Fracture in Pediatric Patients.

Objective: When there is a complete slippage of facet joints of C1 over C2 such that there is no contact between the articulating surfaces of C1 and C2, the condition is known as atlantoaxial spondyloptosis (AAS). AAS represents an extremely rare manifestation of atlantoaxial instability. This study was performed to highlight the presentation, radiological features, and management of unilateral AAS in pediatric patients. Material and Methods: We retrospectively identified four pediatric patients with AAS from our hospital records in the last 6 years (2014-2019). Results: Among the four patients with unilateral AAS, three were posttraumic and one was diagnosed with craniovertebral junction tuberculosis (CVJ TB). All the patients had a varying degree of spastic quadriparesis on presentation. One patient with CVJ TB presented with neck tilt. All patients with traumatic unilateral AAS were associated with an odontoid fracture. These patients underwent C1-C2 fixation with complete reduction of spondyloptosis using the techniques of joint manipulation and joint remodeling with a posterior only approach. Complete reduction of AAS in patients with trauma was also associated with the realignment of the odontoid fracture. All patients improved neurologically after surgery and achieved excellent correction of the deformity on a follow-up imaging. Conclusion: Pediatric unilateral AAS is an extremely rare phenomenon. A single-stage posterior approach with C1-C2 fixation is a feasible technique for the treatment of this seemingly difficult to correct deformity in pediatric patients and the clinical outcomes are excellent.

Endoscopic Anterior Odontoid Screw Fixation for the Odontoid Fracture: A Cadaveric Pilot Study.

INTRODUCTION: Anterior odontoid screw fixation technique for specific types of odontoid fracture has been proven to be an effective, yet challenging procedure because of threatened damage to the structures in the vicinity. There are few articles suggesting the role of percutaneous and endoscopic technique as an alternative approach to the standard microscopic way. This is the first cadaveric study using existing "EASY GO" endoscopic system-assisted odontoid screw placement. STUDY DESIGN: This was a cadaveric study. OBJECTIVE: The objective of the study is to use the endoscope as a safer minimally invasive approach than the standard microscopic anterior approach to odontoid. METHODOLOGY: This is a pilot study on 10 fresh-frozen formalin-fixed adult human cadavers. The cadaver was positioned in a way to simulate reduced odontoid fracture. Tubular dilators were used to dock at C2-3 disk space after identifying the landmarks through the microscopic method. The EASY GO endoscopic system was then introduced, and a handheld drill was used to mark the entry point and pass the K-wire through the planned trajectory. RESULTS: No vascular or adjacent vital structures' injury was observed in any of the cadavers. The initial difficulty in attaining the alignment was overcome by the appropriate positioning of the scope. CONCLUSIONS: Endoscopic-assisted technique for odontoid screw fixation shall provide a minimally invasive, safe, and easy surgery.

Perioperative Management of a Patient with Chin-On-Chest Deformity Presenting for Reconstructive Spine Surgery.

Chin-on- chest deformity is not uncommon sequelae of ankylosing spondylitis. Apart from difficult airway, several other considerations might include co-existing cardio-respiratory embarrassment, osteoporotic bones, and neurological perturbations. We describe the successful anesthetic management of a case of chin-on-chest deformity with no access to midline neck structures and extremely difficult airway posted for corrective spine surgery.

Anterior Odontoid Screw Fixation for Pediatric and Adolescent Odontoid Fractures: Single-Center Experience Over a Decade.

OBJECTIVE: Management of pediatric odontoid fractures is tricky and controversial. This study will enrich world literature with intricacies of anterior odontoid screw (OS) fixation in the pediatric population learned over the last decade. METHODS: In this retrospective study, all patients with pediatric odontoid fracture who underwent anterior odontoid screw fixation from January 2010 to December 2019 were included and evaluated for surgical outcome. RESULTS: Thirteen patients were included in this study (mean age, 15 years; range, 6-18 years; male/female, 11:2; type II, 10; type IIA, 1; type III, 2). Common causes of injury were motor vehicle accidents (61.5%) followed by fall from height (38.5%) and all were acute fractures (2-30 days). Five patients had neurologic deficits. Accurate placement of screw was achieved in 92.3% of patients, including all 9 patients who used intraoperative O-arm. K wire migration during bicortical drilling resulted in neurovascular injury, with 1 mortality (7.7%). The remaining 12 patients were available for follow-up (mean, 36 months; range, 20-72 months) and all had preservation of neck movements. Successful OS fixation was achieved in 84.6% of patients, including 1 patient (7.7%) who had a fibrous union. One patient (8.3%) had nonunion because of migration of the screw head in the C2 body. CONCLUSIONS: Anterior odontoid screw fixation in the pediatric population provides good functional outcomes with instant fixation by direct osteosynthesis. However, the surgeon should be meticulous in the surgical approach and should achieve a lag effect. The surgeon should stop after engaging the outer cortex of the odontoid peg with K wire to avoid cranial migration. Intraoperative O-arm guidance is useful.

Feasibility of Double Anterior Odontoid Screw: A CT-Based Morphometric Analysis of the Axis in Adult Indian Population.

BACKGROUND: The fractures of the odontoid process constitute 10% of all cervical spine injuries. Odontoid screw placement, although technically challenging, in indicated cases is the ideal treatment. Hence, a thorough knowledge of the odontoid dimensions is necessary prior to the surgical endeavor, more so for planning double odontoid screws. MATERIALS AND METHODS: A prospective morphometric analysis of retrospective data of 250 patients was acquired at our institute using Somatom Definition edge 128 slice 64-row detector Siemens CT scanner. The dimensions of the odontoid process were measured at the waist (narrowest portion), widest diameter both in anteroposterior and transverse diameters. The dimensions of the C2 vertebra were measured at the level of the superior and inferior endplate in both the planes. RESULTS: A total of 250 patients were evaluated with age ranging from 1 to 80 years. Males constituted 174 (69.6%) and 76 (30.4%) were females. The mean transverse diameter (TD) at the odontoid waist (narrowest diameter) was 8.66 mm. The mean TD at the widest point of odontoid was 9.68 mm. Mean anteroposterior (AP) diameter 2.5 mm away from the midline on the left side at the level of the waist was 9.51 mm and 2.5 mm on the right of midline was 9.01 mm. The mean AP diameter at the C2 base was 15.824 mm in males and 14.833 mm in females (P < 0.001). CONCLUSION: Double odontoid screw insertion is feasible in only 36% of Indians in the transverse plane, whereas 98.4% of the odontoids can accommodate double screws in the sagittal plane.

Have cranio-vertebral junction anomalies been overlooked as a cause of vertebro-basilar insufficiency?

STUDY DESIGN: A prospective controlled study using single photon emission computed tomography (SPECT) to assess cerebellar perfusion in a cohort of 19 patients with congenital cranio-vertebral junction (CVJ) anomalies, with or without vertebro-basilar insufficiency (VBI). OBJECTIVE: To correlate symptoms of VBI with the presence of posterior circulation ischemia in patients with congenital CVJ anomalies, using technetium 99m ethylene cystine dimer SPECT. SUMMARY OF BACKGROUND DATA: Patients with VBI are rarely investigated for CVJ anomalies, despite the fact that a significant number of patients with congenital CVJ anomalies has VBI. There are also no studies quantifying outcome of surgical interventions, such as like occipito-cervical fusion, in patients with VBI and CVJ anomalies. METHODS: There were 19 consecutive patients with congenital CVJ anomalies who were scheduled for combined transoral odontoidectomy and occipito-cervical fusion were included in the study. Technetium 99m ethylene cystine dimer brain SPECT and clinical assessment of all patients was performed in the preoperative period and at 4 weeks after surgery. Before surgery, patients were divided into 2 groups depending on the clinical findings: (1) symptomatic group, consisting of 12 patients having features suggestive of VBI (drop attacks, episodic vertigo, visual disturbances and dysarthria); and (2) control group, consisting of 7 patients without symptoms of VBI. RESULTS: SPECT showed decreased cerebellar perfusion in 75% (n = 9) of patients in the symptomatic group compared to 14% (n = 1) in the control group before surgery (Fisher exact 2-tailed test, P = 0.019). Following surgery, 8 patients (88.9%) in the symptomatic group and none in the control group had improvement in cerebellar perfusion. Two patients in the symptomatic group who had meningitis develop during the postoperative period had a decrease in cerebellar perfusion on follow-up SPECT. Clinically, all patients with improvement in cerebellar perfusion had improvement in the symptoms of VBI at 1 month of follow-up. CONCLUSIONS: A significant number of patients with congenital CVJ anomalies who have symptoms of VBI develop have decreased cerebellar perfusion shown by SPECT. Rigid internal fixation of the CVJ may alleviate symptoms and improve posterior circulation in some of these patients.