Decompression Of Neural Elements Research Articles

Rates of Radiosurgical Decompression for High Grade Epidural Spinal Disease Due to Solid Tumor Metastases

A recent phase 2 study reported a significant difference in Bilsky grading of treated lesions before and after SBRT. This study reports rates of epidural downgrading following spine SBRT in a larger cohort of patients with high grade epidural disease. Patients with high grade epidural disease from solid spinal metastases treated with SBRT from 2009-2021 were retrospectively reviewed. High grade epidural disease was defined as Bilsky grade 1c-3 for lesions above the conus. A modified Bilsky grading was developed and used for lesions below the conus; grade 0 is spinal bone involvement only; grade 1 is epidural involvement without contact of cauda equina; grade 2 is contact of cauda equina with visible cerebrospinal fluid (CSF); grade 3 is compression of cauda equina with no visible CSF. High grade epidural disease below the conus was defined as a modified Bilsky grade 1-3. Patients who received upfront surgery were included in the current study if post-surgical grading met inclusion criteria. The first post-SBRT MRI was compared to the SBRT simulation imaging to evaluate the extent of epidural downgrading. Epidural disease grading pre- and post-SBRT were compared using the Wilcoxon signed-rank test. A total of 460 vertebral segments from 201 patients were included. The most common histologies were GI (19.3%), breast (16.0%), renal cell carcinoma (13.9%), and prostate (12.6%). Metastases were most often in the T-spine (45.8%), L-spine (34.8%), C-spine (11.8%), and Sacrum (7.6%). Most cases were treated with 3 (37.4%) or 5 (44.5%) fractions with a median prescription dose of 27 Gy or 30 Gy, respectively. 43.3% of cases were treated in the postoperative setting, while 18.5% of cases had prior radiation therapy at the same vertebral level. Median time to first post-SBRT MRI was 3.0 months (IQR 1.8-3.6). Among those with disease above the conus, 98 of the 139 cases (70.5%) had a pre-SBRT Bilsky grade of 2. For those with disease below the conus, 70 of the 99 cases (70.7%) had a pre-SBRT modified Bilsky grade of 1. Epidural downgrading was seen in 32.3% of all cases, 24.3% of postoperative cases, and 25.0% of reirradiation cases. The change in epidural grading was statistically different between pre- and post-SBRT evaluation for all cases (p<0.001), postoperative cases (p<0.001), and reirradiation cases (p = 0.01). We report the largest study to date exploring epidural downgrading following spine SBRT. Although surgery is typically deemed essential for decompression of neural elements, this study suggests that SBRT results in epidural downgrading in as many as one quarter to one third of patients, depending on the clinical scenario.

Apparent Provisional Diagnosis Validated by Histopathology: 2 Case Report that mimics TB Spine Conflict of interest: There is no Conflict of interest relevant to this paper to disclose

Background: The incidence of atypical clinic-radiological presentations of spinal TB is on the upsurge. Lesions that share similar features should be evaluated thoroughly. Tissue diagnosis remains the only foolproof investigation to confirm diagnosis before initiation of treatment. Methods: We present 2 cases who were provisionally diagnosed as a case of Tubercular spondylodiscitis based on clinic-radiological findings. After failure of response from anti tubercular drugs, they underwent operative management for decompression of neural elements and histological confirmation of the provisional diagnosis. Results: Clinical features like back pain, weight loss, gait abnormalities with radiological features like Magnetic resonance imaging and GeneXpert, CT guided FNAC helps in early detection and initiation of treatment of spinal TB. But in our case, 58year old female and 13 years old male presented with clinic-radiological features consistent with Spinal TB. Histopathology and immunohistochemistry confirm that first case is due to Aspergillus Spinal Epidural Abscess (ASEA) and second case due to round blue cell neoplasm consistent with Ewings Sarcoma. Conclusion: This article highlights the importance of awareness of the different clinic-radiographic features of spinal lesions, which can mimic a Tubercular Spondylodiscitis. In order to avoid delayed diagnosis, clinicians must be aware of differential diagnosis from common to rare entity which may interfere with other clinical conditions. Bang. J Neurosurgery 2022; 12(1): 29-36

Establishing the Swiss Spinal Tumor Registry (Swiss-STR): a prospective observation of surgical treatment patterns and long-term outcomes in patients with primary and metastatic spinal tumors.

Tumors of the vertebral column consist of primary spinal tumors and malignancies metastasizing to the spine. Although primary spine tumors are rare, metastases to the spine have gradually increased over past decades because of aging populations and improved survival for various cancer subtypes achieved by advances in cancer therapy. Metastases to the vertebral column occur in up to 70% of cancer patients, with 10% of patients demonstrating epidural spinal cord compression. Therefore, many cancer patients may face spinal surgical intervention during their chronic illness; such interventions range from simple cement augmentation over decompression of neural elements to extended instrumentation or spinal reconstruction. However, precise surgical treatment guidelines do not exist, likely due to the lack of robust, long-term clinical outcomes data and the overall heterogeneous nature of spinal tumors. Objectives of launching the Swiss Spinal Tumor Registry (Swiss-STR) are to collect and analyze high-quality, prospective, observational data on treatment patterns, clinical outcomes, and health-related quality of life (HRQoL) in adult patients undergoing spinal tumor surgery. This narrative review discusses our rationale and process of establishing this spinal cancer registry. A REDCap-based registry was created for the standardized collection of clinical, radiographic, surgical, histological, radio-oncologial and oncological variables, as well as patient-reported outcome measures (PROMs). We propose that the Swiss-STR will inform on the effectiveness of current practices in spinal oncology and their impact on patient outcomes. Furthermore, the registry will enable better categorization of the various clinical presentations of spinal tumors, thereby facilitating treatment recommendations, defining the socio-economic burden on the healthcare system, and improving the quality of care. In cases of rare tumors, the multi-center data pooling will fill significant data gaps to yield better understanding of these entities. Finally, our two-step approach first implements a high-quality registry with efficient electronic data capture strategies across hospital sites in Switzerland, and second follows with potential to expand internationally, thus fostering future international scientific collaboration to further push the envelope in cancer research.

Letter: Commentary: The Anatomy of Disvalued Codes: The 63047 and the 22633.

Letter: Commentary: The Anatomy of Disvalued Codes: The 63047 and the 22633.

Mimics of Spinal Tuberculosis

Background: The incidence of atypical clinicoradiological presentations of spinal tuberculosis (TB) is on the upsurge. Lesions that share similar features should be evaluated thoroughly. Tissue diagnosis remains the only foolproof investigation to confirm the diagnosis before initiation of treatment. Objectives: To evaluate the lesions of spine masquerading as tuberculosis Materials and Methods: We present two cases who were provisionally diagnosed with a case of tubercular spondylodiscitis based on clinicoradiological findings. After failure of response from anti-tubercular drugs, they underwent operative management for decompression of neural elements and histological confirmation of the provisional diagnosis. Results: Clinical features such as back pain, weight loss, gait abnormalities with radiology such as magnetic resonance imaging, computed tomography-guided fine-needle aspiration cytology and GeneXpert helps in the early detection and initiation of treatment of spinal TB. However, in our case, 58-year-old female and 13-year-old male presented with clinic-radiological features consistent with spinal TB. Histopathology and immunohistochemistry confirm that the first case is due to Aspergillus spinal epidural abscess and second case due to round blue cell neoplasm consistent with Ewing’s sarcoma. Conclusion: This article highlights the importance of awareness of the different clinic-radiographic features of spinal lesions, which can mimic a tuberculous spondylodiscitis. In order to avoid delayed diagnosis, clinicians must be aware of differential diagnosis from common to rare entity which may interfere with other clinical conditions.

Lumbar arthroplasty for treatment of primary or recurrent lumbar disc herniation.

Microdiscectomy is the current gold standard surgical treatment for primary lumbar disc herniations that fail non-surgical measures. Herniated nucleus pulposus is the manifestation of underlying discopathy that remains unaddressed with microdiscectomy. Therefore, risk remains of recurrent disc herniation, progression of the degenerative cascade, and on-going discogenic pain. Lumbar arthroplasty allows for complete discectomy, complete direct and indirect decompression of neural elements, restoration of alignment, restoration of foraminal height, and preservation of motion. In addition, arthroplasty avoids disruption of posterior elements and musculoligamentous stabilizers. The purpose of this study is to describe the feasibility of the use of lumbar arthroplasty in the treatment of patients with primary or recurrent disc herniations. In addition, we describe the clinical and peri-operative outcomes associated with this technique. All patients that underwent lumbar arthroplasty by a single surgeon at a single institution from 2015 to 2020 were reviewed. All patients with radiculopathy and pre-operative imaging demonstrating disc herniation that received lumbar arthroplasty were included in the study. In general, these patients were those with large disc herniations, advanced degenerative disc disease, and a clinical component of axial back pain. Patient-reported outcomes of VAS back, VAS leg, and ODI pre-operatively, at threemonths, oneyear, and at last follow-up were collected. Reoperation rate, patient satisfaction, and return to work were documented at last follow-up. Twenty-four patients underwent lumbar arthroplasty during the study period. Twenty-two (91.6%) patients underwent lumbar total disc replacement (LTDR) for a primary disc herniation. Two patients (8.3%) underwent LTDR for a recurrent disc herniation after prior microdiscectomy. The mean age was 40years. The mean pre-operative VAS leg and back pain were 9.2 and 8.9, respectively. The mean pre-operative ODI was 22.3. Mean VAS back and leg pain was 1.2 and 0.5 at threemonths post-operative. The mean VAS back and leg pain was 1.3 and 0.6 at oneyear post-operative. The mean ODI was 3.0 at oneyear post-operative. One patient (4.2%) underwent re-operation for migrated arthroplasty device which required repositioning. At last follow-up, 92% of patients were satisfied with their outcome and would undergo the same treatment again. The mean time for return-to-work was 4.8weeks. After returning to work, 89% of patients required no further leave of absence for recurrent back or leg pain at last follow-up. Forty-four percent of patients were pain free at last follow-up. Most patients with lumbar disc herniations can avoid surgical intervention altogether. Of those that require surgical treatment, microdiscectomy may be appropriate for certain patients with preserved disc height and extruded fragments. In a subset of patients with lumbar disc herniation that require surgical treatment, lumbar total disc replacement is an effective option by performing complete discectomy, restoring disc height, restoring alignment, and preserving motion. The restoration of physiologic alignment and motion may result in durable outcomes for these patients. Longer follow-up and comparative and prospective trials are needed to determine how the outcomes of microdiscectomy may differ from lumbar total disc replacement in the treatment of primary or recurrent disc herniation.

Value of Direct Decompression of Lumbosacral Roots in Sacral Fractures with Neurologic Deficit: Is It Mandatory?

The value of direct decompression of neural structures to treat lumbosacral plexus injury associated with sacral fractures is still debatable. Direct decompression allows decompression of nerve roots by sacral laminectomy and removal of bone fragments in the spinal canal. In contrast, indirect decompression may offer similar neurological outcomes if good fracture reduction and correction of sacral kyphosis are achieved. In this comparative retrospective study, we analyzed differences between direct and indirect neurological decompression in terms of neurological recovery, complications, and functional outcome. This study included 33 cases with spinopelvic dissociation with variable degrees of lumbosacral plexus injury. All cases were managed by spinopelvic fixation. Eighteen patients (group 1) had direct decompression of lumbosacral nerve roots while 15 patients (group 2) had indirect decompression. Initial sacral kyphosis, quality of fracture reduction, and postoperative residual kyphosis were the main factors that significantly affected functional and neurological outcome in both groups. The final neurological improvement was similar in both groups. No significant difference was observed between both groups in the residual Gibbons' score recorded in the last visit (p = 0.206). The final Majeed score also showed no significant difference between the two groups (p = 0.869). Indirect decompression of sacral fractures showed similar final functional outcome and neurological recovery compared to direct decompression. Restoration of lumbosacropelvic stability and anatomic reduction seem to be the cornerstone for better functional outcome and neurological recovery rather than direct decompression of neural elements.

Fifty-year history of the evolution of spinal metastatic disease management.

Spine metastases are a significant source of morbidity in oncology. Treatment of these spine metastases largely remains palliative, but advances over the past 50 years have improved the effectiveness of interventions for preserving functional status and obtaining local control while minimizing morbidity. While the field began with conventional external beam radiation as the primary treatment modality, a series of paradigm shifts and technological advances in the 2000s led to a change in treatment patterns. These advances allowed for an increased role of surgical decompression of neural elements, a shift in the stereotactic capabilities of radiation oncologists, and an improved understanding of the radiobiology of metastatic disease. The result was improved local control while minimizing treatment morbidity. These advances fit within the larger framework of metastatic spine tumor management known as the Neurologic, Oncologic, Mechanical, and Systemicdisease decision framework. This dynamic framework takes into account the neurological function of the patient, the radiobiology of their tumor, their degree of mechanical instability, and their systemic disease control and treatment options to help determine appropriate interventions based on the individual patient. Herein, we describe the 50-year evolution of metastatic spine tumor management and the impact of various advances onthe field.

Technical Note on Unilateral Biportal Lumbar Endoscopic Interbody Fusion

Unilateral biportal lumbar endoscopic interbody fusion is a relatively new technique in the field of minimally invasive spine surgery. It combines the benefits of preservation of the normal anatomy of the spine with direct visualization of the decompression of neural elements and endplate preparation for fusion. This results in high union rates and excellent outcomes for patients with back pain and lumbar spinal stenosis from spondylolisthesis while reducing the risk of injuries to the neural elements, endplate fractures and the theoretical rate of adjacent segment disease from disruption of the musculature. In this paper, we describe the steps and technical pearls pertaining to this technique and methods to avoid common pitfalls and complications. In conclusion, this technique would be a good tool in the armamentarium of a spinal surgeon specializing in minimally invasive spinal surgery.

Predictors of subsidence after lateral lumbar interbody fusion.

Lateral lumbar interbody fusion (LLIF) facilitates the restoration of disc height and the indirect decompression of neural elements. However, these benefits are lost when the graft subsides into the adjacent endplates. The factors leading to subsidence after LLIF are poorly understood. This article presents a case series of patients who underwent LLIF and reports factors correlating with subsidence. A retrospective review of a consecutive, prospectively collected, single-institution database of patients who underwent LLIF over a 29-month period was performed. The degree of subsidence was measured on the basis of postoperative imaging. The timing of postoperative subsidence was determined, and intraoperative fluoroscopic images were reviewed to determine whether subsidence occurred as a result of endplate violation. The association of subsidence with age, sex, cage size and type, bone density, and posterior instrumentation was investigated. One hundred thirty-one patients underwent LLIF at a total of 204 levels. Subsidence was observed at 23 (11.3%) operated levels. True subsidence, attributable to postoperative cage settling, occurred for 12 (5.9%) of the levels; for the remaining 11 (5.4%) levels, subsidence was associated with intraoperative endplate violation noted on fluoroscopy during cage placement. All subsidence occurred within 12 weeks of surgery. Univariate analysis showed that the prevalence of true subsidence was significantly lower among patients with titanium implants (0 of 55; 0%) than among patients with polyetheretherketone cages (12 of 149; 8.1%) (p = 0.04). In addition, the mean ratio of graft area to inferior endplate area was significantly lower among the subsidence levels (0.34) than among the nonsubsidence levels (0.42) (p < 0.01). Finally, subsidence among levels with posterior fixation (4.4% [6/135]) was not significantly different than among those without posterior fixation (8.7% [6/69]) (p = 0.23). Multivariate analysis results showed that the ratio of cage to inferior endplate area was the only significant predictor of subsidence in this study (p < 0.01); increasing ratios were associated with a decreased likelihood of subsidence. Overall, the prevalence of subsidence after LLIF was low in this clinical series. Titanium cages were associated with a lower prevalence of observed subsidence on univariate analysis; however, multivariate analysis demonstrated that this effect may be attributable to the increased surface area of these cages relative to the inferior endplate area.

Osteoporosis as a Risk Factor for Intraoperative Complications and Long-term Instrumentation Failure in Patients With Scoliotic Spinal Deformity.

A retrospective review study. This study aims to determine the effect of osteoporosis on spine instrumentation. Osteoporosis is a common skeletal pathology that affects systemic cortical bone maintenance and remodeling. This disease accelerates the degeneration of the spine, often necessitating spinal surgery for progressive vertebral deformity, pathologic fracture, bony canal stenosis, and/or neural element decompression. There is a paucity of literature describing the role of osteoporosis as it relates to both perioperative complications and outcomes after spine fusion surgery. A retrospective review was conducted of a prospectively maintained database for patients undergoing spine surgery between January 1, 2006 and October 3, 2017. Inclusion criteria included age 18 years and above and surgery performed for the correction of thoracolumbar scoliosis. Data collected included various demographic, clinical, and operative variables. A total of 532 patients met inclusion criteria, including 144 (27%) patients with a diagnosis of osteoporosis. Osteoporosis was significantly associated with increased blood volume loss (P=0.003). Postoperatively, osteoporosis was associated with increased rates of instrumentation failure (19% vs. 10%; P=0.008) and the need for revision surgery (33% vs. 16%; P<0.001). Multivariate analysis confirmed osteoporosis to be an independent risk factor for increased mean number of spinal segments fused (P<0.05), mean blood volume loss (P<0.05), rate of postoperative deep venous thrombosis/pulmonary embolism (P<0.05), rate of instrumentation failure (P<0.05), and need for revision surgery (P<0.05). Osteoporosis is a significant risk factor for instrumentation failure and need for revision surgery following arthrodesis for scoliosis correction. Furthermore, patients with osteoporosis have a significantly higher risk of intraoperative blood volume loss and postoperative thromboembolic events.

Creation of a Proof-of-Concept 3D-Printed Spinal Lateral Access Simulator.

BackgroundMinimally invasive lateral lumbar interbody fusion (LLIF) offers advantages over traditional approaches, providing indirect decompression of neural elements and deformity correction while avoiding many challenges and risks of anterior and posterior approaches. Mastering this technique requires a specialized team, advanced equipment, and sufficient case exposure. Current training is limited to the classic educational model, and alternative training methods such as cadaver labs can be inconvenient, inaccessible, expensive, and incompatible with intraoperative neuromonitoring (IONM) systems.ObjectiveThe aim of this study was to create a proof-of-concept, low-cost, fully synthetic lateral lumbar surgical simulator and to increase awareness of the lack of current training alternatives.MethodsStandard engineering design and expert interviews of attending neurosurgeons, nurses, engineers, and medical device representatives (n=20) were utilized to determine key elements for the simulator, physical characteristics of the components, and translational strategy. Physical and radiographic testing was performed on multiple thermoplastics to determine appropriateness for inclusion in the simulator. For evaluation of the concept, a descriptive slide deck and questionnaire were sent to 15 U.S. and 15 international surgeons who perform LLIF.ResultsThe lateral access training model (LATM) features the following three components: torso casing, spine module, and IONM feature. This model utilizes operable ABS (acrylonitrile butadiene styrene) 3D-printed lumbar vertebrae, verified for anatomical accuracy and compatibility with fluoroscopy. Additionally, a novel neuromonitoring simulation algorithm was developed to train junior residents on neurological complications. To further highlight the need for lateral training models, 30/30 polled surgeons felt that this simulator has value for the field, 29/30 noted that they would have used the LATM if they had access during training, and 30/30 responded that they would encourage trainees to practice on the LATM.ConclusionThe LATM is a first step to provide reliable and inexpensive basic lateral lumbar spine training. While this model is lacking some anatomical features, our simulator offers novel training elements for lateral lumbar transpsoas approaches, which lay the foundation for future models to be built. The need for this training exists, and current gaps in the approach to learning these complex techniques need to be filled due to the inconvenience, cost, and impracticability of standard cadaveric models.

Expandable vs Static Interbody Devices for Lateral Lumbar Interbody Fusion.

Lateral lumbar interbody fusion (LLIF) has paved a way for minimally invasive surgical treatment of a wide variety of spine pathologies. Interbody devices are used to stabilize painful disc levels, provide indirect decompression of neural elements, correct deformity, restore lordosis, and provide a sound durable fusion. Through the years, new static and expandable interbody devices have been developed in an attempt to improve radiographic and clinical outcomes in lumbar spine surgery. The purpose of this article is to explore the advantages and disadvantages between static and expandable interbody devices when used in LLIF. Specifically, this article addresses the differences in subsidence, indirect decompression, restoration of lumbar lordosis, complications, patient-reported outcomes, and cost between static and expandable interbody devices.

Functional Outcome of Instrumentation and Interbody Cage Fusion in Cases of Lumbar Spondylolisthesis

Background: Primary lumbar vertebral instability or “spondylolisthesis” is perhaps one of the commonest radiological sign associated with lumbo-sacral pain after the third decade of life. Aims and Objectives: To find out the functional outcome in terms of clinical improvement in cases of single level lumbar spondylolisthesis by bone grafting and interbody cage fusion and pedicle screw fixation after decompression of neural elements. Materials and Methods: All the patients were evaluated by anteroposterior and lateral radiographs of the lumbosacral spine centered at the appropriate level. In all cases flexion and extension views were taken to assess the instability. More than 4 to 5 mm of sagittal translation and 10 degrees of rotation were considered as instability. All cases were evaluated further by MRI to evaluate facet joint pathology, sacralization/lumbarisation and to find the associated disc changes and the nerve root involvement. All patients were treated by decompression and interbody fusion with cage and bone graft by either Transforaminal or Posterior approach and instrumentation done with pedicle screws. Post operatively all patients were assessed for the functional outcome using the Oswestry Disability Index at 1 month, 3 month and 6 months Results: There is statistically significant difference in ODI Scores (Oswestry Disability Index) post operatively at 1 month, 3 month and 6 months. Conclusion: In agreement with good results, found in our study, we strongly believe that this technique of fusion and instrumentation is very useful in management of lumbar spondylolisthesis. However, this study should further be extended to a wider sample of patients with a longer follow-up.

Chapter 12 - Intraoperative neuromonitoring during surgery for lumbar stenosis

The indications for neuromonitoring during lumbar stenosis surgery are defined by the risks associated with patient positioning, the approach, decompression of neural elements, deformity correction, and instrument implantation. The routine use of EMG and SEP alone during lumbar stenosis surgery is no longer supported by the literature. Lateral approach neuromonitoring with EMG only is also suspect. Lumbar stenosis patients often present with multiple co-morbidities which put them at risk during routine pre-surgical positioning. Frequently encountered morbid obesity and/or diabetes mellitus may play a role in monitorable and preventable brachial plexopathy after "superman" positioning or femoral neuropathy from groin pressure after prone positioning, for example. Deformity correction in lumbar stenosis surgery often demands advanced implementation of multiple neuromonitoring modalities: EMG, SEP, and MEP. Because the bulbocavernosus reflex detects the function of the conus medullaris and sacral somato afferent/efferent fibers of the cauda equina, it may also be recorded. The recommendation to record pedicle screw thresholds has become more nuanced as surgeon dependence on 3D imaging, navigation, and robotics has increased. Neuromonitoring in lumbar stenosis surgery has been subject mainly to uncontrolled case series; prospective cohort trials are also needed.

Chapter 14 - Monitoring spinal surgery for extramedullary tumors and fractures

Meningiomas are the most common intradural extramedullary tumors, followed by nerve sheath tumors that can also grow extradurally. Metastases are the most frequent extradural tumors and most commonly affect the thoracic vertebrae. Spinal fractures with column dislocation and/or instability require surgical fixation. Spine surgery for an extramedullary tumor or fracture usually involves decompression of neural elements and instrumentation for stabilization. These procedures risk spinal cord and nerve root injury. The incidence of nerve root deficits after resection of nerve sheath tumors is particularly high since the tumor grows from the rootlets. Intraoperative neurophysiologic monitoring and mapping techniques have been introduced to prevent iatrogenic neurologic deficits. These include motor and sensory evoked potentials, electromyography, compound muscle action potentials, and the bulbocavernosus reflex. The combination of techniques chosen for a particular procedure depends on the surgical level and the character of the lesion.

Ten-Step Minimally Invasive Treatment of Lumbar Giant Disc Herniation via Unilateral Tubular Laminotomy for Bilateral Decompression: 2-Dimensional Operative Video.

Giant disc herniation (GDH) is generally defined as a lumbar disc herniation that obstructs 50% or more of the space in the spinal canal.1-3 Common treatment options for GDH include unilateral interlaminar approach, bilateral approach, or open full laminectomy.4,5 Surgical treatment of GDH may be challenging because severe bilateral compression of neural elements in the spinal canal increases the risk of iatrogenic injury to nerve roots and dura. The surgical approach can be further complicated by calcification, hardening, and dehydration of the GDH tissue. The prevailing opinion in the literature is that giant disc herniations cannot safely be treated via tubular minimally invasive approaches.5-7 In this video, we present a case of a 52-yr-old male patient with a history of progressive low back pain that radiates bilaterally from the buttocks toward the posterior legs and knees for 2 yr because of a GDH at the L4-5 level. The patient was treated via a tubular "over-the-top" minimally invasive decompression in order to first provide generous bilateral decompression of neural elements and dura.8,9 After sufficient decompression at the surgical level, the discectomy was performed via an ipsilateral piecemeal resection of the GDH. The "over-the-top" contralateral mobilization of disc herniation was also achieved with this approach, which facilitated the removal of the entire disc fragment. Patient consent was obtained prior to performing the procedure. Therefore, GDH should not be considered as a contraindication for tubular decompression when this modified technique is performed.

Enhanced Safety of Pedicle Subtraction Osteotomy Using Intraoperative Ultrasound

Pedicle subtraction osteotomy (PSO) can improve sagittal alignment but carries risks, including iatrogenic spinal cord and nerve root injury. Critically, during the reduction phase of the technique, medullary kinking or neural element compression can lead to neurologic deficits. We describe 3 cases of thoracic PSO and evaluate the feasibility, findings, and utility of intraoperative ultrasound in this setting. Intraoperative ultrasound can provide a visual assessment of spinal cord morphology before and after PSO reduction and influences surgical decision making with regard to the final amount of sagittal plane correction. This modality is particularly useful for confirming ventral decompression of disc-osteophyte complex before reduction and also after reduction maneuvers when there is kinking of the thecal sac but uncertainty about the underlying status of the spinal cord. Intraoperative ultrasound is a reliable modality that fits well into the technical sequence of PSO, adds a minimal amount of operative time, and has few limitations. We propose that intraoperative ultrasound is a useful supplement to standard neuromonitoring modalities for ensuring safe PSO reduction and decompression of neural elements.

INDIRECT DECOMPRESSION BY LATERAL FUSION: ANALYSIS OF SAGITAL ALIGNMENT

ABSTRACT Objective: To verify the effectiveness of indirect decompression after lateral access fusion in patients with high pelvic incidence. Methods: A retrospective, non-comparative, non-randomized analysis of 22 patients with high pelvic incidence who underwent lateral access fusion, 11 of whom were male and 11 female, with a mean age of 63 years (52-74), was conducted. Magnetic resonance exams were performed within one year after surgery. The cross-sectional area of the thecal sac, anterior and posterior disc heights, and bilateral foramen heights, measured pre- and postoperatively in axial and sagittal magnetic resonance images, were analyzed. The sagittal alignment parameters were measured using simple radiographs. The clinical results were evaluated using the ODI and VAS (back and lower limbs) questionnaires. Results: In all cases, the technique was performed successfully without neural complications. The mean cross-sectional area increased from 126.5 mm preoperatively to 174.3 mm postoperatively. The mean anterior disc height increased from 9.4 mm preoperatively to 12.8 mm postoperatively, while the posterior disc height increased from 6.3 mm preoperatively to 8.1 mm postoperatively. The mean height of the right foramen increased from 157.3 mm in the preoperative period to 171.2 mm in the postoperative period and that of the left foramen increased from 139.3 mm in the preoperative to 158.9 mm in the postoperative. Conclusions: This technique is capable of correcting misalignment in spinal deformity, achieving fusion and promoting the decompression of neural elements. Level of evidence III; Retrospective study.

Clinical Outcome Assessment following Open Reduction and Instrumented Posterior Interbody Fusion of Adult Single-Level Lumbar Spondylolisthesis

Background Data: Posterior lumbar decompression combined with instrumented posterior lumbar interbody fusion (PLIF) is the gold standard management of adult spondylolisthesis. Complete anatomic surgical reduction of slippage, although controversial, is associated with encouraging results. Purpose: This study aims to assess the clinical outcome of complete open surgical reduction and instrumented PLIF in adult single-level lumbar spondylolisthesis. Study design: Retrospective clinical case study. Patients and Methods: Retrospective review of standing data and radiographs of adult patients with single-level lumbar spondylolisthesis (regardless of the aetiology) from January 2018 to January 2020. All patients have undergone posterior lumbar decompression, pedicle screw instrumentation, complete reduction of the slippage, and PLIF. All patients were assessed at six and 12 months postoperatively by Visual Analogue Scale (VAS), Oswestry Disability Index (ODI), and the Odom criteria. Results: A total of 118 patients met the inclusion criteria. There was no neurologic deterioration in any of the patients postoperatively. There was a significant change in VAS, ODI, and Odom’s criteria at six and 12 months postoperatively (p < 0.001). The mean value for VAS and ODI were 0.61 ± 1.03 and 4.52 ± 7.02, respectively, at the last follow-up. There was a significant change in Odom’s criteria as 61.9% of patients had excellent outcomes at the last follow-up. Conclusion: Complete surgical reduction of single-level lumbar spondylolisthesis combined with instrumented PLIF offers adequate neural element decompression and satisfactory clinical outcome. (2020ESJ227)