The surgical vascular anatomy of the minimally invasive lateral lumbar interbody approach: a cadaveric and radiographic analysis.

PURPOSE: The minimally invasive (MI) lateral lumbar interbody fusion (LLIF) approach has become increasingly popular for the treatment of degenerative lumbar spine disease. The neural anatomy of the lumbar plexus has been studied; however, the pertinent surgical vascular anatomy has not been examined in detail. The goal of this study is to examine the vascular structures that are relevant in relation to the MI-LLIF approach. METHODS: Anatomic dissection of the lumbar spines and associated vasculature was performed in three embalmed, adult cadavers. Right and left surgeon perspective views during LLIF were for a total of six approaches. During the dissection, all vascular elements were noted and photographed, and anatomical relationships to the vertebral bodies and disc spaces were analyzed. In addition, several axial and sagittal MRI images of the lumbar spine were analyzed to complement the cadaveric analysis. RESULTS: The aorta descends along the left anterior aspect of lumbar vertebra with an average distance of 2.1 cm (range 1.9-2.3 cm) to the center of each intervertebral disc. The vena cava descends along the right anterior aspect of lumbar vertebrates with average distance of 1.4 cm (range 1.3-1.6 cm) to the center of the intervertebral disc. Each vertebral body has two lumbar arteries (direct branches from the aorta); one exits to the left and one to the right side of the vertebral body. The lumbar arteries pass underneath the sympathetic trunk, run in the superior margin of the vertebral body and extend all the way across it, with average length of 3.8 cm (range 2.5-5 cm). The mean distance between the arteries and the inferior plate of the superior disc space is 4.2 mm (range 2-5 mm) and mean distance of 3.1 cm (range 2.8-3.8 cm) between two arteries in adjacent vertebrae. One of the cadavers had an expected normal anatomical variation where the left arteries at L3-L4 anastomosed dorsally of the vertebral bodies at the middle of the intervertebral disc. CONCLUSIONS: Understanding the vascular anatomy of the lateral and anterior lumbar spine is paramount for successfully and safely executing the LLIF procedure. It is imperative to identify anatomical variations in lumbar arteries and veins with careful assessment of the preoperative imaging.

Instability in Thoracolumbar Trauma: Is a New Definition Warranted?

STUDY DESIGN: Review of the articles. OBJECTIVE: The objective of this study was to review all articles related to spinal instability to determine a consensus statement for a contemporary, practical definition applicable to thoracolumbar injuries. SUMMARY OF BACKGROUND DATA: Traumatic fractures of the thoracolumbar spine are common. These injuries can result in neurological deficits, disability, deformity, pain, and represent a great economic burden to society. The determination of spinal instability is an important task for spine surgeons, as treatment strategies rely heavily on this assessment. However, a clinically applicable definition of spinal stability remains elusive. MATERIALS AND METHODS: A review of the Medline database between 1930 and 2014 was performed limited to papers in English. Spinal instability, thoracolumbar, and spinal stability were used as search terms. Case reports were excluded. We reviewed listed references from pertinent search results and located relevant manuscripts from these lists as well. RESULTS: The search produced a total of 694 published articles. Twenty-five articles were eligible after abstract screening and underwent full review. A definition for spinal instability was described in only 4 of them. Definitions were primarily based on biomechanical and classification studies. No definitive parameters were outlined to define stability. CONCLUSIONS: Thirty-six years after White and Panjabi's original definition of instability, and many classification schemes later, there remains no practical and meaningful definition for spinal instability in thoracolumbar trauma. Surgeon expertise and experience remains an important factor in stability determination. We propose that, at an initial assessment, a distinction should be made between immediate and delayed instability. This designation should better guide surgeons in decision making and patient counseling.

Prognostic factors in traumatic atlanto-occipital dislocation.

Traumatic atlanto-occipital dislocation (AOD) is an ominous injury with high mortality and morbidity in trauma patients. Improved survival has been observed with advancements in pre-hospital and hospital care. Furthermore, high quality imaging studies are accessible at most trauma centers; these are crucial for prompt diagnosis of AOD. The objective of this study is to perform a comprehensive literature review of traumatic AOD, with specific emphasis on identifying prognostic factors for survival. A review of the literature was performed using the Medline database for all traumatic atlanto-occipital articles published between March 1959 and June 2015; 141 patients from 60 total studies met eligibility criteria for study inclusion. A binary logistic regression model was utilized to identify prognostic factors. The analysis assessed age, sex, spinal cord injury (SCI), traumatic brain injury (TBI), polytrauma injury (PI), and Traynelis AOD Classification. Only TBI was statistically significantly associated with death (OR 8.05 p<0.05); SCI did not reach statistical significance for predicting mortality in AOD patients (OR 1.25 p>0.05). Age, sex, PI, and Traynelis AOD Classification did not meet significance to predict mortality in AOD patients. We found that patients with TBI are eight times more likely to die than patients without TBI. A high degree of suspicion for AOD during pre-hospital care, as well as, prompt diagnosis and management in the trauma center play a key role in the treatment of this devastating injury. The relationship between survival and factors such as TBI and SCI should be further explored.

Posterior atlantoaxial fixation: A cadaveric and fluoroscopic step-by-step technical guide.

BACKGROUND: Atlantoaxial surgical fixation is widely employed treatment strategy for a myriad of pathologies affecting the stability of the atlantoaxial joint. The most common technique used in adults, and in certain cases in children, involves a posterior construct with C1 lateral mass screws, and C2 pars or pedicle screws. This technical note aims to provide a step-by-step guide to this procedure using cadaveric and fluoroscopic images. METHODS: An embalmed, human, cadaveric, specimen was used for this study. The subject did not have obvious occipital-cervical pathology. Dissections and techniques were performed to mimic actual surgical technique. Photographs were taken during each step, and the critical aspects of each step were highlighted. Fluoroscopic images from a real patient undergoing C1/C2 fixation were also utilized to further highlight the anatomic-radiographic relationships. This study was performed without external or industry funding. RESULTS: Photographic and radiographic pictures and drawings are presented to illustrate the pertinent anatomy and technical aspects of this technique. The nuances of each step, including complication avoidance strategies are also highlighted. CONCLUSIONS: Given the widespread utilization of this technique, described step-by-step guide is timely for surgeons and trainees alike.

Anatomic considerations of the anterior upper cervical spine during decompression and instrumentation: a cadaveric based study.

We evaluated the anatomical considerations specific to the high anterior retropharyngeal approach to the cervical spine. Surgical exposure of the anterior upper cervical spine can sometimes be challenging due to the surrounding neurovascular structures. Using three adult cadavers, we performed high anterior retropharyngeal cervical dissection of the left and right side for a total of six approaches (six sides). During the dissection, all important neurovascular elements were noted and photographed, and anatomical relationships to the spinal vertebral bodies and disc spaces were analyzed. There are certain anatomic considerations that are unique to the high anterior cervical spine. The unique structures include the hypoglossal nerve and the superior thyroid artery/nerve. Only the superior thyroid artery in this region has numerous anatomical variations. Awareness of other structures, including the carotid artery, recurrent laryngeal nerve, and esophagus also remains important. Awareness of the anatomical structures in the anterior upper cervical spine is essential for performing safe anterior upper cervical spinal surgery, avoiding serious complications.

Peribrachiocephalic approaches to the anterior cervicothoracic spine.

This cadaveric study aims to reexamine the corridors to the anterior cervicothoracic junction, relative to the left brachiocephalic vein, and to present these working corridors as either supra- or infra-brachiocephalic. The anterior cervicothoracic junction incorporates the seventh cervical vertebrae through the fourth thoracic vertebrae (C7-T4) and involves critical anatomical structures. Operative approaches to this area are well described in the literature, with the predominant implementation of three surgical corridors. We used three embalmed, human, cadaveric specimens for this study. No pathology involving the cervicothoracic junction was noted. While dissecting, we tried to imitate the actual surgery. For each surgical step, photographs were taken, drawing attention to the critical structures and highlighting the different corridors to the spine relative to the left brachiocephalic vein. It is possible to access the cervicothoracic junction relative to the brachiocephalic vein from the left. The supra-brachiocephalic approach gives access to the C7-T4 vertebrae, whereas if T4-T5 is the goal, the infra-brachiocephalic approach may be utilized. In the supra-brachiocephalic approach, the brachiocephalic artery can be either medialized or lateralized as needed. A re-examination of the anterior cervicothoracic junction anatomy has allowed us to classify approaches relative to the left brachiocephalic vein. Identifying and understanding the approaches relative to this structure will assist in safe and effective spinal surgery in this area.

Fusion after intradural spine tumor resection in adults: A review of evidence and practices.

There is ample evidence supporting concomitant fusion after intradural spinal tumor resection in select pediatric patients. Unfortunately, the data are scarcer in adults. The objective of this work is to review the published literature and analyze practice patterns for stabilization and fusion after intradural tumor resection in adults. We performed a literature review via PubMed for information available regarding fusion in adults with intradural spine tumors. Additionally, we manually searched the references of selected articles to add relevant articles. Finally, we retrieved the criteria for fusion (if any) in the selected studies. A total of 639 articles were found and 35 were finally selected for analysis. Of those, three were literature reviews and 32 were retrospective case series. There were a total of 1288 patients on the series with 104 of them requiring fusion (8.1%). The median follow up of all the series was 24 months (range 1.5-180).The criteria for fusion that were common in most cases series were: previous deformity (i.e. kyphosis in the cervical spine), 3 or more levels of laminectomy, laminectomy encompassing a spinal junction, "young adults" (33 ± 4.2 years), facetectomy ≥ 50% (unilateral or bilateral), persistence of deformity after 1 year of the surgery and, C2 laminectomy. There appears to be some consistent practices for fusion after intradural tumor resection in adults, but this is based on retrospective analyses of case series. Prospective or randomized trials will likely provide more evidence based support for this practice.