Fernando Alonso

Aortic Arch Origin of the Left Vertebral Artery: An Anatomical and Radiological Study with Significance for Avoiding Complications with Anterior Approaches to the Cervical Spine

Complications from anterior approaches to the cervical spine are uncommon with normal anatomy. However, variant anatomy might predispose one to an increased incidence of injury during such procedures. We hypothesized that left vertebral arteries that arise from the aortic arch instead of the subclavian artery might take a more medial path in their ascent making them more susceptible to iatrogenic injury. Fifty human adult cadavers were examined for left vertebral arteries having an aortic arch origin and these were dissected along their entire cervical course. Additionally, two radiological databases of CTA and arteriography procedures were retrospectively examined for cases of aberrant left vertebral artery origin from the aortic arch over a two‐year period. Two cadaveric specimens (4%) were found to have a left vertebral artery arising from the aortic arch. The retrospective radiological database analysis identified 13 cases (0.87%) of left vertebral artery origin from the aortic arch. Of all cases, vertebral arteries that arose from the aortic arch were much more likely to not only have a more medial course (especially their preforaminal segment) over the cervical vertebral bodies but also to enter a transverse foramen that was more cranially located than the normal C6 entrance of the vertebral artery. Spine surgeons who approach the anterior cervical spine should be aware that an aortic origin of the left vertebral artery is likely to be closer to the midline and less protected above the C6 vertebral level. Clin. Anat. 30:811–816, 2017.

Lateral Transpsoas Approach to the Lumbar Spine and Relationship of the Ureter: Anatomic Study with Application to Minimizing Complications

BACKGROUND Complications from lateral lumbar interbody fusion procedures range from neurologic deficits to organ and blood vessel injuries. Injury to the ureter has been reported though uncommon. The present study was performed to elucidate the anatomic relationship of the ureter to this surgical approach. METHODS Eight adult cadavers (16 sides) were placed in the full lateral position, and the distal ureter was cannulated with a metal wire that was passed up to the kidney. Fluoroscopy was used to establish the position of the ureter in relation to the bony anatomy in this region. RESULTS In the lumbar region, there was a posterior to anterior course of the left and right ureter. From the direct lateral position, the ureter was found to lie at or posterior to the anterior edge of the lumbar vertebral bodies. On 87.5% of sides, the ureter was on average 2.5 cm posterior to the anterior border of the vertebral bodies at L2, 3 cm posterior at L3, 1.0 cm posterior at L4, and on the margin of the anterior vertebral bodies at L5. In general, the ureter, from a lateral perspective, crossed the posterior third of the upper lumbar vertebrae, approached the middle third at L3, and reached the anterior third at L4/L5 before descending into the pelvis. CONCLUSIONS Owing to the proximity of the ureter to the lumbar vertebral bodies, it is imperative to verify that this structure is not in the surgical trajectory during lateral lumbar interbody fusion procedures if injury is to be avoided.

Junctional neural tube defect in a newborn: report of a fourth case

IntroductionA discontinuous, functionally disconnected spinal cord is an extremely rare finding, with only three known reports in the literature. Titled junctional neural tube defect (JNTD), this newly reported dysraphism is believed to arise from a developmental error occurring during junctional neurulation, a transitory stage of development marked by the end of primary neurulation and the beginning of secondary neurulation. Herein, we report a newborn case of JNTD.Case reportWe report a newborn boy born with anorectal atresia. Physical examination revealed normal movement in the upper and lower extremities. Imaging revealed distal sacral agenesis and a spinal cord that was discontinuous at the thoracolumbar junction. Three vertebral segments inferiorly, at the L2 vertebral level, the distal end of the spinal cord (i.e., conus medullaris) were visualized. No signs of a tethered cord were identified.ConclusionsCharacterized by an error in junctional neurulation in which the primary and secondary NT fail to integrate appropriately, JNTD has been recently classified. We believe the current patient to represent only the fourth reported case of JNTD in the literature.

Microsurgical Anatomy of the Hypoglossal and C1 Nerves: Description of a Previously Undescribed Branch to the Atlanto-Occipital Joint

OBJECTIVE Distal branches of the C1 nerve that travel with the hypoglossal nerve have been well investigated but relationships of C1 and the hypoglossal nerve near the skull base have not been described in detail. Therefore, the aim of this study was to investigate these small branches of the hypoglossal and first cervical nerves by anatomic dissection. METHODS Twelve sides from 6 cadaveric specimens were used in this study. To elucidate the relationship among the hypoglossal, vagus, and first and cervical nerve, the mandible was removed and these nerves were dissected under the surgical microscope. RESULTS A small branch was found to always arise from the dorsal aspect of the hypoglossal nerve at the level of the transverse process of the atlas and joined small branches from the first and second cervical nerves. The hypoglossal and C1 nerves formed a nerve plexus, which gave rise to branches to the rectus capitis anterior and rectus capitis lateralis muscles and the atlanto-occipital joint. CONCLUSIONS Improved knowledge of such articular branches might aid in the diagnosis and treatment of patients with pain derived from the atlanto-occipital joint. We believe this to be the first description of a branch of the hypoglossal nerve being involved in the innervation of this joint.

Adult Apical Ligament of the Dens Lacks Notochordal Tissue: Application to Better Understanding the Origins of Skull Base Chordomas

INTRODUCTION The apical ligament has long been reported to contain notochord remnants and thus might serve as a site of origin of chordoma formation at the skull base. However, to our knowledge, the histologic study of the apical ligament using histologic staining specific for notochordal tissue has not been previously performed. Therefore the current study was undertaken. METHODS Fifteen apical ligament samples underwent histologic examination with specific markers for notochordal differentiation. RESULTS Across all samples, there was no indication of any notochordal remnants. CONCLUSIONS On the basis of our cadaveric study, the apical ligament does not contain notochord tissue and in adults should not be considered a remnant of this structure. Moreover, it is unlikely that the apical ligament gives rise to chordomas at the craniocervical junction under normal circumstances.

Injury to the Lumbar Plexus and its Branches After Lateral Fusion Procedures: A Cadaver Study

INTRODUCTION Neurologic deficits from lumbar plexus nerve injuries commonly occur in patients undergoing lateral approaches. However, it is not yet clear what types of injury occur, where anatomically they are located, or what mechanism causes them. We aimed to study 1) the topographic anatomy of lumbar plexus nerves and their injuries in human cadavers after lateral transpsoas approaches to the lumbar spine, 2) the structural morphology of those injuries, and 3) the topographic anatomy of the lumbar plexus throughout the mediolateral approach corridor. METHODS Fifteen adult fresh frozen cadaveric torsos (26 sides) underwent lateral approaches (L1-L5) by experienced lateral spine surgeons. The cadavers were subsequently opened and the entire plexus dissected and examined for nerve injuries. The topographic anatomy of the lumbar plexus and its branches, their injuries, and the morphology of these injuries were documented. RESULTS Fifteen injuries were found with complete or partial nerve transections (Sunderland IV and V). Injuries were found throughout the mediolateral approach corridor. At L1/2, the iliohypogastric, ilioinguinal, and subcostal nerves were injured within the psoas major muscle, the retroperitoneal space, or the outer abdominal muscles and subcutaneous tissues. Genitofemoral nerve injuries were found in the retroperitoneal space. Nerve root injuries occurred within the retroperitoneal space and psoas muscle. Femoral nerve injuries were found only within the psoas major muscle. No obturator nerve injuries occurred. CONCLUSIONS Lateral approaches can lead to structural nerve damage. Knowledge of the complex plexus anatomy, specifically its mediolateral course, is critical to avoid approach-related injuries.

The Decussating Fibers of the Lumbar Thoracolumbar Fascia: A Landmark for Identifying the L5 Spinous Process?

BACKGROUND The thoracolumbar fascia (TLF) has been well studied and is known to have crisscrossing fibers. Based on surgical experience, we hypothesized that the decussating fibers of the TLF may indicate a specific vertebral level and performed an anatomic study. METHODS Twenty adult fresh frozen cadavers aged 72-84 years at death were placed in the prone position, and the skin of the lumbar and upper sacrum was removed. Careful attention was given to the TLF and any fibers of it that grossly crossed the midline to interdigitate with its contralateral counterpart. Once such decussations were identified, a metal wire was laid on them at their center, and fluoroscopy was performed to verify the vertebral level. RESULTS Decussating fibers of the TLF were found on all but 1 specimen (95%). The central part of the decussation on the midline corresponded to the spinous process of L5 in 17/19 (89%) of specimens and the lower edge (L4-L5 interspace) of the spinous process of L4 in the remaining 2 specimens (11%). No specimens were found to have previous surgery in the area dissected or congenital anomalies of the spine. CONCLUSIONS In our cadaveric study, the decussating fibers of the TLF in the lumbar region helped predict the L5 spinous process in 89% of specimens and the L4 spinous process in 11% of specimens. This anatomic landmark might be used as an adjunct to palpation and intraoperative imaging during surgical exploration of the lower lumbar region.

Intracranial Facial Nerve Schwannomas: Current Management and Review of Literature

BACKGROUND Facial nerve schwannomas are rare, benign, nerve-sheath tumors. They can occur in any segment of the facial nerve and often clinically and radiographically mimic the common vestibular schwannoma when extending into the cerebellopontine angle. The optimal treatment strategy for intracranial facial nerve schwannomas remains controversial. METHODS We review the literature and discuss the natural history, clinical features, diagnosis and current management of facial nerve schwannoma. RESULTS Complete tumor resection with facial nerve preservation can be achieved in fewer cases. In most cases, the affected segment of facial nerve must be removed if the goal is to achieve complete tumor section. Regardless of type of facial nerve repair, patients can expect no better than an eventual HB grade III palsy. Stereotactic radiosurgery has good results in tumor control and facial function outcome. CONCLUSIONS Treatment for intracranial facial nerve schwannomas depends on clinical presentation, tumor size, preoperative facial, and hearing function. Conservative management is recommended for asymptomatic patients with small tumors. Stereotactic radiosurgery may be an option for smaller and symptomatic tumors with good facial function. If tumor is large or the patient has facial paralysis, surgical resection should be indicated. If preservation of the facial nerve is not possible, total resection with nerve grafting should be performed for those patients with facial paralysis, whereas subtotal resection is best for those patients with good facial function.

Failure Patterns in Standalone Anterior Cervical Discectomy and Fusion Implants

BACKGROUND Anterior cervical discectomy and fusion is commonly performed using an allograft or autograft implant and anterior screw-supported plate. There has been an increase in the use of standalone cage devices due to ease of use and studies suggesting a lower rate of acute postoperative dysphagia. We review our experience with standalone cage devices and identify risk factors, patterns of failure, and revision surgery approaches. METHODS We performed a retrospective case series of patients treated at a single tertiary care institution between March 2014 and March 2015. Inclusion criteria were aged 18-100 years, 1- or 2-level anterior cervical discectomy and fusion with a standalone cervical cage. Data collected included demographics, comorbidities, Charlson comorbidity score, primary diagnosis, and surgical characteristics. Descriptive statistics were performed for risk of readmission, implant failure, revision, and other complications. RESULTS We identified 211 patients who met our study criteria. Average surgical time was 107 ± 43 minutes, with an estimated blood loss of 84.6 ± 32.4 mL. There were 11 (5.2%) readmissions. There were 10 (4.74%) implant failures (5 involving single-level surgery and 5 involving 2-level surgery), with 7 cases of pseudoarthrosis. Mechanisms of failure included a C5 body fracture, fusion in a kyphotic alignment after graft subsidence, and acute spondylolisthesis. CONCLUSIONS Revision surgery after standalone anterior cervical implants can be complex. Posterior cervical fusion remains a valuable approach to avoid possible vertebral body fracture and loss of fusion area associated with the removal of implants secured through the endplates of adjacent vertebral bodies.

Trends in Spinal Surgery for Pott’s Disease (2000-2016): An Overview and Bibliometric Study

Study Design: Systematic review. Objectives: (1) What are the surgical indications? Have they changed over time since the year 2000? (2) What is the current surgical approaches of choice? Have they changed over time since the year 2000? Do they vary by geographical region? (3) What are the most common outcome measures following surgery? Methods: Electronic databases and reference lists of key articles were searched from database inception from January 1, 2000 to December 31, 2016 to identify studies specifically evaluating surgical indications, current surgical approaches, and outcome measures for spinal tuberculosis. Results: Six randomized controlled trials were identified from our search (1 excluded: no surgical arm identified after review) Neurological deficit, instability and deformity were common indications identified. Surgical approach included predominantly anterior for cervical spine and posterior for thoracic and lumbar spine. Combined approach was preferred in pediatric cases. Degree of deformity correction, neurological outcomes, and fusion formed the main bases of assessing surgical outcomes. Conclusions: Majority of the current literature is from South Asia. The presence of neurological compromise, deformity, and instability were the primary criteria for surgical intervention. The preferred approach varied with the anatomical region of the spine in adults. Outcome measures predominantly involved deformity correction, neurological deficit, and fusion.