Safety and efficacy of the new modified technique for c2 nerve root resection in 3d fluoroscopy navigated instrumentation in the cranio-cervical junction.

PURPOSE: Instrumentation of the C1 vertebra requires either mobilization or transection of the C2 nerve root. This study investigates clinical and radiological outcomes and incidences of C2 neuropathic pain after posterior instrumented fusion in the cranio-cervical junction with or without division of the C2 nerve roots. METHODS: This retrospective study compared two cohorts of patients who underwent instrumented fusion in the cranio-cervical junction. Fifty patients (22 males and 28 females) were operated with complete resection of C2 nerve root ganglion (Ex group), and fifty-one patients (30 men, 21 women) with C2 nerve roots preservation (No group). RESULTS: The incidence of postoperative C2 neuropathy was eight times lower in the Ex group compared to the No group that was statistical significant, p = 0.039. Surgical time was significantly shorter in the No group (p = 0.001). The fusion rates were very high for both groups, without difference between groups (p = 1.0). Autografting from the iliac crest (p = 0.001) as well as postoperative immobilisation with a hard collar (p < 0.001) were required in fewer patients in the Ex group. Also, patients in the Ex group were mobilised faster after surgery (p = 0.49). Overall, complication rates were similar between groups, but the Ex group demonstrated fewer major medical complications (16% vs 31%). Male sex and iliac bone harvesting demonstrated significantly higher OR for development of postoperative complications (p = 0.023 and p = 0.034 respectively) and postoperative mobilization demonstrated significant higher OR for development of postoperative major complications (p = 0.042). CONCLUSIONS: Resection of the C2 nerve root ganglion during posterior instrumented fusion of the cranio-cervical junction is safe and rarely leads to C2 neuropathy. The technique tends to mitigate the odds of developing postoperative complications.

Biomechanical Assessment of Stabilization of Simulated Type II Odontoid Fracture with Case Study.

STUDY DESIGN: Researchers created a proper type II dens fracture (DF) and quantified a novel current posterior fixation technique with spacers at C1-C2. A clinical case study supplements this biomechanical analysis. PURPOSE: Researchers explored their hypothesis that spacers combined with posterior instrumentation (PI) reduce range of motion significantly, possibly leading to better fusion outcomes. OVERVIEW OF LITERATURE: Literature shows that the atlantoaxial joint is unique in allowing segmental rotary motion, enabling head turning. With no intervertebral discs at these joints, multiple ligaments bind the axis to the skull base and to the atlas; an intact odontoid (dens) enhances stability. The most common traumatic injury at these strong ligaments is a type II odontoid fracture. METHODS: Each of seven specimens (C0-C3) was tested on a custom-built six-degrees-of-freedom spine simulator with constructs of intact state, type II DF, C1-C2 PI, PI with joint capsulotomy (PIJC), PI with spacers (PIS) at C1-C2, and spacers alone (SA). A bending moment of 2.0 Nm (1.5°/sec) was applied in flexion-extension (FE), lateral bending (LB), and axial rotation (AR). One-way analysis of variance with repeated measures was performed. RESULTS: DF increased motion to 320%, 429%, and 120% versus intact (FE, LB, and AR, respectively). PI significantly reduced motion to 41%, 21%, and 8%. PIJC showed negligible changes from PI. PIS reduced motion to 16%, 14%, and 3%. SA decreased motion to 64%, 24%, and 54%. Reduced motion facilitated solid fusion in an 89-year-old female patient within 1 year. CONCLUSIONS: Type II odontoid fractures can lead to acute or chronic instability. Current fixation techniques use C1-C2 PI or an anterior dens screw. Addition of spacers alongside PI led to increased biomechanical rigidity over intact motion and may offer an alternative to established surgical fixation techniques.

Bilateral C-1 lateral mass reconstruction following radical resection of a giant osteoblastoma of the atlas: case report.

Osteoblastoma is a rare, benign, osteoid-producing, and slow-growing primary bone tumor, typically arising in long bones or in the spine, with a slight male predominance. This report describes the surgical treatment of a giant C-1 (atlantal) osteoblastoma diagnosed in a young male patient with neurofibromatosis Type 1. The authors describe the clinical presentation, the surgical procedure for complete excision and stabilization, and results as of the 1-year follow-up. They detail a bilateral occipitoaxial spinal interarticular stabilization technique that they used after complete tumor excision. To the best of their knowledge, this is the first case of bilateral C-1 lateral mass reconstruction by this technique to be reported in the literature.

A statistical shape model of the human second cervical vertebra.

PURPOSE: Statistical shape and appearance models play an important role in reducing the segmentation processing time of a vertebra and in improving results for 3D model development. Here, we describe the different steps in generating a statistical shape model (SSM) of the second cervical vertebra (C2) and provide the shape model for general use by the scientific community. The main difficulties in its construction are the morphological complexity of the C2 and its variability in the population. METHODS: The input dataset is composed of manually segmented anonymized patient computerized tomography (CT) scans. The alignment of the different datasets is done with the procrustes alignment on surface models, and then, the registration is cast as a model-fitting problem using a Gaussian process. A principal component analysis (PCA)-based model is generated which includes the variability of the C2. RESULTS: The SSM was generated using 92 CT scans. The resulting SSM was evaluated for specificity, compactness and generalization ability. The SSM of the C2 is freely available to the scientific community in Slicer (an open source software for image analysis and scientific visualization) with a module created to visualize the SSM using Statismo, a framework for statistical shape modeling. CONCLUSION: The SSM of the vertebra allows the shape variability of the C2 to be represented. Moreover, the SSM will enable semi-automatic segmentation and 3D model generation of the vertebra, which would greatly benefit surgery planning.

Occipitoaxial spinal interarticular stabilization with vertebral artery preservation for atlantal lateral mass failure.

The treatment of craniocervical instability caused by diverse conditions remains challenging. Different techniques have been described to stabilize the craniocervical junction. The authors present 2 cases in which tumoral destruction of the C-1 lateral mass caused craniocervical instability. A one-stage occipitoaxial spinal interarticular stabilization (OASIS) technique with titanium cages and posterior occipitocervical instrumentation was used to reconstruct the C-1 lateral mass and stabilize the craniocervical junction. The ipsilateral vertebral artery was preserved. The OASIS technique offers single-stage tumor resection, C-1 lateral mass reconstruction, and stabilization with a loadsharing construct. It could be an option in the treatment of select cases of C-1 lateral mass failure.

Markerless endoscopic registration and referencing.

Accurate patient registration and referencing is a key element in navigated surgery. Unfortunately all existing methods are either invasive or very time consuming. We propose a fully non-invasive optical approach using a tracked monocular endoscope to reconstruct the surgical scene in 3D using photogrammetric methods. The 3D reconstruction can then be used for matching the pre-operative data to the intra-operative scene. In order to cope with the near real-time requirements for referencing, we use a novel, efficient 3D point management method during 3D model reconstruction. The presented prototype system provides a reconstruction accuracy of 0.1 mm and a tracking accuracy of 0.5 mm on phantom data. The ability to cope with real data is demonstrated by cadaver experiments.

Pituitary apoplexy precipitating diabetes insipidus.

OBJECTIVE: To describe a case of pituitary apoplexy complicated by diabetes insipidus and to review management of patients with pituitary apoplexy and water excretion disturbances associated with transsphenoidal surgery. METHODS: We describe clinical, laboratory, and radiologic findings in a patient with pituitary apoplexy and central diabetes insipidus. RESULTS: A 74-year-old woman presented with severe headache and sudden loss of vision for 12 hours, accompanied by thirst and frequent urination. Visual field examination demonstrated bitemporal hemianopsia. Her laboratory findings were significant for a serum sodium level of 152 mEq/L and urine specific gravity of <1.005. A magnetic resonance imaging scan of her pituitary gland identified a 3.5-cm suprasellar mass compressing the optic chiasm. She subsequently underwent transsphenoidal pituitary surgery with subtotal resection of this mass. Microscopic evaluation of tumor tissue revealed a pituitary adenoma with evidence of recent infarct and hemorrhage. Her clinical and biochemical course was consistent with the triphasic response that may occur after pituitary surgery related to damage to the hypothalamus and supraopticohypophyseal tract. CONCLUSION: Pituitary apoplexy may be rarely associated with diabetes insipidus.