Emre Yilmaz

Anatomical Study of the Extreme Lateral Transpsoas Lumbar Interbody Fusion with Application to Minimizing Injury to the Kidney

Objective Since the extreme lateral lumbar interbody fusion procedure was first reported by Ozgur in 2006, a large number of clinical studies have been published. Anatomical studies which explore methods to avoid visceral structures, such as the kidney, with this approach have not been examined in detail. We dissected the retroperitoneal space to analyze how the extreme lateral transpsoas approach to the lumbar spine could damage the kidney and related structures. Methods Eight sides from four fresh Caucasian cadavers were used for this study. The latissimus dorsi muscle and the thoracolumbar fascia were dissected to open the retroperitoneum. The fat tissue was removed. Steel wires were then put into the intervertebral disc spaces. Finally, the closest distance between kidney and wires on each interdiscal space was measured. Results The closest distance from the wire in the interdiscal space on L1/2, L2/3 and L3/4 to the kidney ranged from 13.2 mm to 32.9 mm, 20.0 mm to 27.7 mm, and 20.5 mm to 46.6 mm, respectively. The distance from the kidney to the interdiscal space at L4/5 was too great to be considered applicable to this study. Conclusions The results of this study might help surgeons better recognize the proximity of the kidney and avoid injury to it during the extreme lateral transpsoas approach to the lumbar spine.

Functional Neurorehabilitation using the Hybrid Assistive Limb (HAL): A First Experience in the United States

Introduction: The Hybrid Assistive Limb (HAL, Cyberdyne, Japan) facilitates voluntary, user-driven ambulation through a neurologically-controlled system based on bioelectrical signals derived from the user. This allows for the repeated execution of physiologically faithful gait patterns, crucial to recovery in cases of neurologic motor deficit. In this series, we present the first three patients in the United States to undergo HAL neurorehabilitation training. Patient and methods: A case series of three patients participating in a single-center prospective, interventional pilot study, suffering neurologic motor deficits secondary to spinal cord infarct following a pulmonary embolism (patient 1), multiple sclerosis (patient 2) and the surgical resection of a petroclival meningioma (patient 3). The patients underwent 60 sessions of body weight-supported treadmill training in the HAL over the course of 12 weeks. Measures of functional ambulation (10 Minute Walk Test, 10MWT) were performed out of the HAL before and after each session and at the 12 week and 6 month follow-up. Timed Up & Go (TUG) test was performed each week. Treadmill data (time, distance) while in HAL was recorded at each session. Measures of endurance (6 Minute Walk Test, 6MWT), risk of fall (TUG), balance impairment (Berg Balance Scale) and improvements in walking performance (Walking Index for Spinal Cord Injury II, WISCI II) were measured at baseline, after 12 weeks and at 6 months follow-up. Results: Patients 2 and 3 completed 60 visits, patient 1 completed 56 visits. All patients achieved markedly increased treadmill paces, improved functional scores, increased distance in the 6MWT and decreased TUG times at 6-month follow-up. In the 10MWT, all patients achieved a clinically significant decrease in time and steps and showed improvements in the required assistance level to perform the test. Patients 1 and 3 showed improvement on the Berg Balance Scale. Patient 2 had no change between baseline and 6-month follow-up. Only minor adverse effects were reported, including skin abrasions and irritation secondary to chaffing of the HAL unit and EMG electrodes. Conclusion: These data show that HAL training is both feasible and effective in the neurorehabilitation of patients suffering neurologic motor deficits secondary to trauma and/or pathological/neurodegenerative processes after they have undergone normal rehab. A greater number of patients are required to meaningfully assess the differences in improvement from baseline, based upon underlying pathologies.

Paramastoid Process: Literature Review of Its Anatomy and Clinical Implications

The paramastoid process is a rare variation found on the occipital bone as an extension of its jugular process. In the literature, this process has been called many names including the paraoccipital, paracondylar, or parajugular process. The paramastoid process can articulate with the lateral aspect of the transverse process of the atlas creating clinical consequences and potentially resulting in diminished range of motion of the head. Herein, we describe the anatomy, embryology, prevalence, imaging, and clinical consequences of the paramastoid process in order to improve our understanding of this rare anatomic variation.

Anatomic Study of Nutrient Foramina of Posterior Axis with Application to C2 Pedicle Screw Placement.

OBJECTIVEnPedicle screws placed into C2 necessitate a thorough understanding of this bones unique anatomy. Although multiple landmarks and measurements have been used by surgeons, these are often varied in the literature with no consensus. Herein, we studied one recently proposed landmark using the nutrient foramina of the posterior aspect of C2 for pedicle screw placement.nnnMETHODSnOn 19 (38 sides) C2 dry bone specimens, the presence, size, location, and distance from the midline of the nutrient foramina found at the junction between the isthmus and lamina were documented and measured. In addition, to discern the source of the artery entering such foramina, an injected adult cadaver was dissected.nnnRESULTSnThe number of foramina ranged from 0-5 with a mean of 1.84. On 3 sides, no foramina were identified. The mean diameter of the foramina was 0.57 mm. The location of the foramina was at position 1 on 9.5% of sides, position 2 on 66.4% of sides, and position 3 on 24.1% of sides. The mean horizontal distance from the midline of the spinous process of C2 to the foramina was 25.17 mm. In the cadaveric specimen, the source of the artery entering these C2 nutrient foramina was found to be distal branches of the deep cervical artery.nnnCONCLUSIONSnWe found the nutrient foramina of the C2 laminae are useful for pedicle screw placement. However, there are minor variations of the number and position of these structures. Lastly, on the basis of our study, 7.9% (nxa0= 3) of sides will not have such foramina.

A Novel Microsurgical Procedure for Revascularization of the Vertebral Artery

OBJECTIVEnA broad armamentarium of microsurgical techniques affords flexibility to surgeons when choosing a procedure that is best tailored to fit the anatomy of an individual. Herein, we report on the feasibility of using the deep cervical artery (DCA) to revascularize the vertebral artery (VA) via a DCA-V3 bypass graft.nnnMETHODSnFourteen DCAs from 7 injected cadaveric heads were located and traced. The diameter of the main trunk of the DCA was measured bilaterally at the C3 level. The proximal vertebral branches of each DCA were then severed and the main trunk of the DCA was transposed superiorly onto the V3 segment of the VA, which was also exposed bilaterally.nnnRESULTSnThe DCA was identified and traced bilaterally on all specimens. The diameter of the main trunk of the DCA at the C3 level ranged from 1.03 to 2.79 mm. The mean diameter of the main trunk of the DCA at this level was found to be 1.52 ± 0.60 mm for the right side and 1.46 ± 0.54 mm for the left side. After releasing the proximal vertebral branches of the DCA, all arteries were able to be transposed to the ipsilateral VA.nnnCONCLUSIONSnBased on the mean diameter of the DCA reported in extant literature and this study, the blood flow volume of the DCA makes it a viable candidate to bypass the proximal VA.

Neurovascular Relationships of S2AI Screw Placement: Anatomic Study

INTRODUCTIONnThe S2 alar-iliac (S2AI) screw is a modification of the traditional iliac fixation technique and has surgical and biomechanical benefits. However, there are significant regional neurovascular structures along the path of such screws. Therefore the current anatomic study was performed to better elucidate these relationships.nnnMETHODSnUsing fluoroscopy, S2AI screws were placed in 2 adult cadavers through a standard posterior midline exposure. The screw insertion point was placed 10 mm lateral to a line bisecting the S1 and S2 foramina, adjacent to the sacroiliac joint. Using 30- to 40-degree lateral angulation from the midline and 20- to 30-degree caudal angulation, a pedicle probe was directed toward the anterior inferior iliac spine. The final trajectory was positioned to sit 1-2 cm superior to the greater sciatic foramen. Lastly, the screws and surrounding bone were drilled in order to visualize both lateral and medial neurovascular relationships.nnnRESULTSnRemoving the bone around the S2AI-screw illustrated the close relationship to the medial (internal) neurovascular structures including the obturator nerve, lumbosacral trunk, sacral plexus and, specifically, the S1 ventral ramus and iliac vein and artery. By removing the outer cortex of the ilium, the close relationship to the superior gluteal artery, vein, and nerve was observed. In addition, we were able to identify the proximity to the iliopsoas muscle and internal iliac vessels.nnnCONCLUSIONSnA comprehensive knowledge of the surrounding neurovascular anatomy relevant to S2AI screw placement can decrease patient morbidity and allow spine surgeons to better diagnose potential postoperative complications.

Review of Treatment of Gunshot Wounds to Head in Late 19th Century

INTRODUCTIONnDuring the late 19th century, the seeds of modern neurosurgery were planted to bloom into what it is now known. Wars such as the American Civil War and Crimean War drove the need to find better ways of preventing mortality from gunshot wounds to the head. However, the mortality rate from all major surgical procedures to the head, neck, and face remained staggering. Herein, we describe the surgical treatments for head and neck injuries in order to improve our understanding of neurosurgical procedures performed during the late 19th century.nnnMETHODSnA literature search was conducted using PubMed and Google Books for available articles pertaining to treatment for gunshot wounds to the head during the 19th century. Search terms included Gunshot wounds, Treatment, Civil War, Gunshot wound, Treatment 19th century, and Gunshot wounds, Treatment, 1800s. Literature was excluded if not in English or if no translation was provided. Most of the information was taken from the International Encyclopedia of Surgery Volume II.nnnRESULTSnSurgical care for gunshot wounds to the cranium were based on depth and involved finding the bullet, controlling the bleeding, and preventing further brain injury. Surgical treatment for a gunshot wound to the face or neck involved controlling the bleeding, with a focus on maintaining the airway.nnnCONCLUSIONSnBecause of improved understanding of infectious processes and technologic advances in surgical equipment, the late 19th century was a major milestone in creating modern day neurosurgery. The methodology behind todays treatments is no different from that of the late 19th century.

Treatment of Gunshot Wounds to Spine During Late 19th Century

BACKGROUNDnThe demand for neurosurgical procedures increased drastically in the late 19th century owing to advances in ballistics during the American Civil War and Crimean War.nnnMETHODS AND RESULTSnSurgical care for a gunshot wound to the spine relied on skilled identification and removal of the fractured bone. Hemorrhage control and infection prevention were also imperative for improving survival rates.nnnCONCLUSIONSnAlthough new techniques were implemented, the mortality rate from spinal injuries during this period was staggering. Nevertheless, those 19th century procedural methods provided the basis for present-day treatment for spinal injury patients.

Autologous Bone Harvest in Anterior Cervical Spine Surgery: A Quantitative and Qualitative In Vitro Analysis of Cadaveric Tissue

BACKGROUNDnThe cervical spine may be used as a harvesting site of local autograft material during anterior cervical discectomy and fusion procedures. We analyzed the quality and composition of bone grafts obtained from different parts of the cervical vertebrae in a cadaveric model.nnnMETHODSnFive fresh adult human cadavers with intact cervical spines were used. Using a Smith-Robinson anterior approach to expose C4-5 and C5-6 vertebrae, samples from 4 vertebral sites were harvested under a microscope. Anterior osteophytes were removed piecemeal by a Leksell rongeur (sample A). A high-speed burr was used to drill the endplates of C4-5 and C5-6 (sample C) and uncovertebral joints of C4-5 (sample B) and C5-6 (sample D). Then 20 slides (4 per cadaver) were prepared and analyzed.nnnRESULTSnTissue fragmentation was associated with use of the high-speed burr. Sample A had minimal tissue fragmentation. Samples B-D showed moderate to high fragmentation. Cartilage was found in all samples. Of the 20 slides, 6 contained soft tissues (sample A in 4, sample D in 2). Disc material was identified in 6 slides (sample A in 1, sample B in 4, sample D in 1). Sample A had the greatest number of intact osteocytes and chondrocytes, and sample B had the least.nnnCONCLUSIONSnAnterior osteophytes provide the highest number of osteocytes, with the highest osteocyte/chondrocyte ratio. Osteocyte viability is a function of vertebral body site and collection technique, with fragmentation caused by use of a high-speed burr decreasing the number of viable osteocytes.

S2 Alar-Iliac Screw Insertion: Technical Note with Pictorial Guide

BACKGROUNDnThe S2 alar-iliac (S2AI) screw is a modification of the iliac fixation technique using the space between the neuroforamina of S1 and S2 as an insertion point to fix the sacrum to the ilium. To our knowledge, an anatomic review of the S2AI technique has not been described and the insertion point is vague and angles differ in reports from the literature. The purpose of the current anatomic illustration is to provide step-by-step techniques with fluoroscopic imaging to help confirm the safe placement of S2AI screws.nnnMETHODSnThe procedure was performed on the left and rights sides of a fresh, frozen, and thawed predissected male cadaver in a surgical training facility through a standard posterior midline exposure for placement of the S2AI screws. All screws were placed by a fellowship-trained spine surgeon and an attending spine surgeon.nnnRESULTSnThe specimen was placed prone, and a midline incision begun at the L4 or L5 spinous process. Using the anteroposterior and inlet views, the S1 dorsal sacral foramen, the S1 endplate, and the sacroiliac joint can be identified. The insertion point is 10 mm laterally between the S1 and S2 foramina and near to the sacroiliac joint. Aim toward the anterior inferior iliac spine is ensured by using a 30°-40° lateral angulation in the transverse plane and 20°-30° caudal angulation in the sagittal plane depending on the sacral angulation. Using lateral fluoroscopy, the acetabulum and greater sciatic notch can be identified and screw misplacement can be avoided. The screw length is measured and is usually between 60 and 90 mm (8- to 9-mm diameter). An elevator is used to identify the outer sacral cortex. Anteroposterior, obturator-outlet, and teardrop views are used to ensure correct screw insertion.nnnCONCLUSIONSnFluoroscopic guidance is crucial for optimal S2AI screw placement. Using the described technique allows a safe and correct insertion of the S2AI screw.