Edwin Ramos

Feasibility of occipital condyle screw placement for occipitocervical fixation: a cadaveric study and description of a novel technique.

Study Design Occipital-cervical (OC) stabilization using occipital condyle fixation with a polyaxial screw-rod construct is described. Objectives To describe a novel technique and initial radiographic results for posterior OC fixation using the occipital condyles for cranial fixation. Summary of Background Data Stabilization of the OC junction remains a challenge. Owing to the regional anatomy and the poor occipital bone purchase, multiple attachment points to the occipital bone are required to increase construct rigidity. To address these issues, we propose a novel OC fixation technique using polyaxial occipital condyle screws for cranial purchase. Methods The OC junction was exposed posteriorly in silicone-injected cadaver heads. Polyaxial titanium screws (3.5 mm) were inserted bicortically solely into the occipital condyles; C1 lateral masses and C2 pedicles, or transarticularly through C1-C2, followed by fixation to a 3-mm rod. Drilling was guided by anatomic landmarks and fluoroscopy. Computerized tomography scans were obtained. Condylar screw angles and lengths were analyzed with respect to historical morphometric condyle measurements and with respect to neurovascular structures. Results The condylar entry point was 4 to 5-mm lateral to the foramen magnum on the axial plane, and 1 to 2-mm rostral to the atlantooccipital joint. The mean angle of medialization was 17 degrees (range: 12 to 22 degrees). In the sagittal plane, the maximal superior screw angulation was 5 degrees. The mean screw length to obtain bicortical purchase was 22 mm (range: 20 to 24 mm). The hypoglossal canal was uninterrupted during its full course. The jugular bulb, carotid, and vertebral arteries were not injured by condyle screw placement. No fractures were identified. Conclusion Condyle screws can be placed without injury to neurovascular structures. OC junction fixation using polyaxial occipital condyle screws is feasible and can be considered a salvage technique or an alternative where other fixation techniques are not available.

Failure of temporal lobe resection for epilepsy in patients with mesial temporal sclerosis: results and treatment options

OBJECT The purpose of this study was to identify the causes of failed temporal lobe resection in patients with mesial temporal sclerosis (MTS) and the role of repeat surgery for seizure control. METHODS This is a retrospective study of 105 patients who underwent temporal lobe resection for MTS with unilateral electroencephalographic findings. The mean follow-up duration was 36 months (range 24-84 months). Surgeries were all performed by the senior author (F.L.V.). RESULTS Following initial surgical intervention, 97 patients (92%) improved to Engel Class I or II (Group A), and 8 (8%) did not have significant improvement (Engel Class III or IV; Group B). These 8 patients were restudied using video-electroencephalography (EEG) and MR imaging. All major surgical failures occurred within 1 year after initial intervention. Reevaluation demonstrated 3 patients (37.5%) with contralateral temporal EEG findings. Five patients (62.5%) had evidence of ipsilateral recurrent discharges. Four patients underwent extended neocortical resection along the previous resection cavity. Their outcomes ranged from Engel Class I to Class III. Only 1 patient (12.5%) who failed to improve after initial surgery was found to have incomplete resection of mesial structures. This last patient underwent reoperation to complete the resection and improved to Engel Class I. CONCLUSIONS Failure of temporal lobe resection for MTS is multifactorial. The cause of failure lies in the pathological substrate of the epileptogenic area. Complete seizure control cannot be predicted solely by conventional preoperative workup. Initial surgical failures from temporal lobe resection often benefit from reevaluation, because reoperation may be beneficial in selected patients. Based on this work, the authors have proposed a management and treatment algorithm for these patients.

Craniocervical fixation with occipital condyle screws: Biomechanical analysis of a novel technique

Study Design. A human cadaveric biomechanical study comparing craniocervical fixation techniques. Objective. To quantitatively compare the biomechanical stability of a new technique for occipitocervical fixation using the occipital condyles with an established method for craniocervical spine fusion. Summary of Background Data. Stabilization of the occipitocervical junction remains a challenge. The occiput does not easily accommodate instrumentation because of access and spatial constraints. In fact, the area available for the implant fixation is limited and can be restricted further when a suboccipital craniectomy has been performed, posing a challenge to current fixation techniques. Occipital screws are also associated with the potential for intracranial complications. Methods. Six fresh frozen cadaveric specimens occiput-C4 were tested intact, after destabilization and after fixation as follows: (1) occipital plate with C1 lateral mass screws and C2 pars screws and (2) occipital condyle screws with C1 lateral mass screws and C2 pars screws. Specimens were loaded in a custom spine testing apparatus and subjected to the following tests, all performed under 50-N unconstrained axial preload: flexion, extension, lateral bending, and axial rotation at 1.5 Nm. The constructs were statistically compared with a one-way analysis of variance and compared with the intact condition. Results. Motions were reduced by ∼80% compared with the intact condition for both configurations under all motions. There were no statistically significant differences in the range of motion (ROM) between the 2 instrumentation conditions. The mean values indicated decreased ROM with the novel occipital condyle screw construct in comparison with the standard occipital plate and rod system. Conclusion. Craniocervical stabilization using occipital condyle screws as the sole cephalad fixation point is biomechanically equivalent with regard to the modes tested (ROM and stiffness) to the standard occipital plate construct.

Complications of the mini-open anterolateral approach to the thoracolumbar spine

The mini-open anterolateral approach to the thoracolumbar spine is gaining popularity as a minimally-invasive alternative to traditional open thoracolumbar approaches. Published studies reporting and discussing the complications associated with this minimally invasive approach, however, are limited. We performed a retrospective review of patients undergoing the mini-open lateral approach to the thoracolumbar spine for corpectomy/fusion. Intraoperative and postoperative complications are reported and analyzed. Eighty consecutive patients underwent the mini-open lateral approach with corpectomy and fusion for trauma (71%), tumor (26%) and infection (3%). Total complication rate was 12.5% (dural tear 2.5%, intercostal neuralgia 2.5%, deep vein thrombosis 2.5%, pleural effusion 1.3%, wound infection 1.3%, hardware failure 1.3%, hemothorax 1.3%). Two patients needed a re-operation to address the complication (hardware failure, hemothorax). There were no postoperative neurological complications. The mini-open anterolateral approach to the thoracolumbar spine is an appealing alternative to the traditional open approaches. This technique, however, is technically demanding and requires proficiency in the use of minimally invasive spinal surgery instruments and retractors.

OCCIPITAL CERVICAL STABILIZATION USING OCCIPITAL CONDYLES FOR CRANIAL FIXATION: TECHNICAL CASE REPORT

OBJECTIVEPresentation of a successful case of craniocervical stabilization involving a novel surgical technique using the occipital condyles as the sole cranial fixation points. CLINICAL PRESENTATIONA 22-year-old man presented in a delayed fashion with neck pain after a motor vehicle accident. Evaluation revealed a type 2 odontoid fracture with pseudarthrosis and displacement of the dens superiorly and cranial settling of the dens. INTERVENTIONThe patient underwent posterior occipitocervical fixation with a polyaxial screw rod construct using the occipital condyle, C1 lateral mass, and C2 pars articularis for fixation. The patient had no immediate postoperative deficits. At the time of the 12-month follow-up examination, the patient was neurologically intact with a solid occipitocervical fusion. CONCLUSIONCraniocervical stabilization using occipital condyle screws as the sole cephalad fixation points is a feasible option and can be used safely without neurovascular complication in the treatment of craniocervical instability.

Occipital condyle screw placement and occipitocervical instrumentation using three-dimensional image-guided navigation

Occipital condyle (OC) screws are an alternative cephalad fixation point in occipitocervical fusion. Safe placement of occipital, C1 lateral mass, and C2 pars screws have been described previously, but not OC screws. The craniocervical junction is complex, and a thorough understanding of the anatomy is needed. Three-dimensional (3D) image-guided navigation was used in six patients. There were no complications related to image-guided navigation during the placement of 12 OC screws and we found that this navigation can serve as a useful adjunct when placing an OC screw. Technical considerations of placing OC and C1 lateral mass screws are discussed with particular reference to patient positioning and the StealthStation® S7™ image-guided navigational platform (Medtronic, Minneapolis, MN, USA). The reference arc is attached to the head-clamp and faces forward. The optical camera and monitor are positioned at the head of the table for a direct, non-obstructed line-of-sight. To minimize intersegmental movement, the OC should not be drilled until all other screws have been placed. We conclude that 3D image-guided navigation is a useful adjunct that can be safely and effectively used for placement of instrumentation of the upper cervical spine including the OC.

Interfascial technique for vertebral artery exposure in the suboccipital triangle: the road map.

BACKGROUND: The extradural portion of the vertebral artery (VA-V3) has a unique anatomy at the craniovertebral junction. The exposure of V3 can be accompanied by profuse bleeding from the venous plexus in addition to the potential risk of inadvertent injury of the VA during surgery at the craniovertebral junction. The natural tissue planes represent a road map to the safe exposure of the VA in the suboccipital triangle. OBJECTIVE: To describe the microsurgical anatomy of the tissue planes in the suboccipital region. METHODS: The suboccipital region was bilaterally dissected in 6 fresh silicone-injected cadaver heads. An interfascial technique was used to expose the VA-V3 following a tissue plane between the deep suboccipital muscular fascia dorsally and posterior atlantooccipital membrane, the C1 periosteal membrane, and the membrane covering the VA and venous plexus ventrally. The craniovertebral junction was harvested from 2 heads and prepared for histological sections. The same technique was applied in 25 operative cases. RESULTS: The anatomic dissections confirmed the existence of an interfascial plane that can be dissected in a blunt fashion to reach as far lateral as the transverse processes of C1 and C2. Application of the dissection technique did not require diathermy coagulation in the operating room. In 25 cases, there was no injury of the VA or bleeding from the venous plexus. CONCLUSION: Vertebral artery exposure in the suboccipital triangle (V3) can be achieved safely with minimal blood loss using a technique that follows the natural tissue plane between the deep suboccipital muscle fascia, the posterior atlantooccipital membrane, the membrane covering VA/venous plexus, and the periosteum of the C1 and C2 laminae.

Combined subgaleal/myocutaneous technique for temporalis muscle dissection.

Background The frontal branch of the facial nerve (FBFN) is the most susceptible neural structure to injury during frontotemporal craniotomies. The balance between adequate temporalis muscle mobilization and frontal branch protection with minimal anatomical alteration is the philosophy behind our approach to temporalis muscle dissection. Objective To describe a combined subgaleal/myocutaneous technique for dissection and mobilization of the temporalis muscle in anterolateral cranial approaches. Methods Interdisciplinary literature review of the anatomical course of the FBFN was performed. Retrospective analysis of anterolateral craniotomies performed at our institution in which the combined subgaleal/myocutaneous (CSGMC) technique was performed. Results A total of 71 cases of anterolateral craniotomies (excluding full variant orbitozygomatic) were performed with the successful application of a CSGMC technique (36 pterional, 31 orbitopterional, and 4 fronto-orbital). Partial frontalis weakness was transient in one case. Conclusion The CSGMC technique provides sufficient protection for the FBFN and allows for adequate mobilization for a variety of skull base exposures while minimally violating myofascial anatomy. This is the first reported technique that allows both adequate temporalis muscle mobilization with performance of the one-piece orbitofrontal and orbitopterional approaches, without disruption of the superficial/deep temporalis fascia and fat-pad complex.

Trend of Spine Surgeries in the Outpatient Hospital Setting versus Ambulatory Surgical Center

Study Design. Retrospective database review. Objective. The aim of the present study was to examine how often spine surgery is being performed in an outpatient hospital setting versus a more “true” ambulatory setting, specifically ambulatory surgery centers (ASCs) in which admission and discharge are required on the same calendar day. Summary of Background Data. Recent studies have assessed the safety, satisfactory clinical outcomes, and increasing utilization of both cervical and lumbar spinal surgeries performed in the outpatient setting. No studies have delineated between true ambulatory settings and outpatient hospitals when assessing the rates of these procedures. Methods. A retrospective review of the Truven Health Marketscan Research Databases was conducted for patients undergoing spine operations between 2003 and 2014. The frequency of each Common Procedural Terminology code was identified per year, and then categorized into each of “inpatient hospital,” “outpatient hospital,” or “ASC” in states that clearly define ASCs as facilities in which patients are discharged on the same calendar day of the operation, and do not stay overnight. Results. During the period between 2003 and 2014, the procedures that had the most dramatic increase as an outpatient hospital procedure included lumbar decompression laminotomy first level (18.7%–68.5%) and posterior cervical decompression laminectomy without facetectomy discectomy first level (0%–46.7%). ASC procedures had more modest increases during this time period with the most significant increases in lumbar decompression laminotomy first level (0.7%–10.6%) and posterior cervical decompression laminotomy first level (0%–23.4%). Conclusion. “True” ambulatory surgeries are not increasing at the same rate as outpatient procedures with 23-hour observation capacity. Although prior studies have demonstrated the safety of outpatient spine surgery, one possible reason for this trend may be that surgeons feel that this safety may not be comparable to that of other outpatient procedures. Level of Evidence: 3

Congenital dermoid tumor in a child at initial myelomeningocele closure: an etiological discussion

The authors report on a case of a full-term infant with lumbar myelomeningocele who was found to have an intramedullary mass at the time of surgical repair of the defect. The intramedullary mass was consistent with a dermoid tumor both macroscopically and microscopically. This case provides evidence that dermoid tumors occurring at the site of previous surgical myelomeningocele repair are not always a consequence of incomplete excision of the dermal elements.