Evolution of Cervical Endoscopic Spine Surgery: Current Progress and Future Directions-A Narrative Review.

Cervical endoscopic spine surgery is rapidly evolving and gaining popularity for the treatment of cervical radiculopathy and myelopathy. This approach significantly reduces muscular damage and blood loss by minimizing soft tissue stripping, leading to less postoperative pain and a faster postoperative recovery. As scientific evidence accumulates, the efficacy and safety of cervical endoscopic spine surgery are continually affirmed. Both anterior and posterior endoscopic approaches have surfaced as viable alternative treatments for various cervical spine pathologies. Newer techniques, such as endoscopic-assisted fusion, the anterior transcorporeal approach, and unilateral laminotomy for bilateral decompression, have been developed to enhance clinical outcomes and broaden surgical indications. Despite its advantages, this approach faces challenges, including a steep learning curve, increased radiation exposure for both surgeons and patients, and a relative limitation in addressing multi-level pathologies. However, the future of cervical endoscopic spine surgery is promising, with potential enhancements in clinical outcomes and safety on the horizon. This progress is fueled by integrating advanced imaging and navigation technologies, applying regional anesthesia for improved and facilitated postoperative recovery, and incorporating cutting-edge technologies, such as augmented reality. With these advancements, cervical endoscopic spine surgery is poised to broaden its scope in treating cervical spine pathologies while maintaining the benefits of minimized tissue damage and rapid recovery.

Advancing Prone-Transpsoas Spine Surgery: A Narrative Review and Evolution of Indications with Representative Cases.

The Prone Transpsoas (PTP) approach to lumbar spine surgery, emerging as an evolution of lateral lumbar interbody fusion (LLIF), offers significant advantages over traditional methods. PTP has demonstrated increased lumbar lordosis gains compared to LLIF, owing to the natural increase in lordosis afforded by prone positioning. Additionally, the prone position offers anatomical advantages, with shifts in the psoas muscle and lumbar plexus, reducing the likelihood of postoperative femoral plexopathy and moving critical peritoneal contents away from the approach. Furthermore, operative efficiency is a notable benefit of PTP. By eliminating the need for intraoperative position changes, PTP reduces surgical time, which in turn decreases the risk of complications and operative costs. Finally, its versatility extends to various lumbar pathologies, including degeneration, adjacent segment disease, and deformities. The growing body of evidence indicates that PTP is at least as safe as traditional approaches, with a potentially better complication profile. In this narrative review, we review the historical evolution of lateral interbody fusion, culminating in the prone transpsoas approach. We also describe several adjuncts of PTP, including robotics and radiation-reduction methods. Finally, we illustrate the versatility of PTP and its uses, ranging from 'simple' degenerative cases to complex deformity surgeries.

Machine learning for automated and real-time two-dimensional to three-dimensional registration of the spine using a single radiograph.

OBJECTIVE: The goal of this work was to methodically evaluate, optimize, and validate a self-supervised machine learning algorithm capable of real-time automatic registration and fluoroscopic localization of the spine using a single radiograph or fluoroscopic frame. METHODS: The authors propose a two-dimensional to three-dimensional (2D-3D) registration algorithm that maximizes an image similarity metric between radiographic images to identify the position of a C-arm relative to a 3D volume. This work utilizes digitally reconstructed radiographs (DRRs), which are synthetic radiographic images generated by simulating the x-ray projections as they would pass through a CT volume. To evaluate the algorithm, the authors used cone-beam CT data for 127 patients obtained from an open-source de-identified registry of cervical, thoracic, and lumbar scans. They systematically evaluated and tuned the algorithm, then quantified the convergence rate of the model by simulating C-arm registrations with 80 randomly simulated DRRs for each CT volume. The endpoints of this study were time to convergence, accuracy of convergence for each of the C-arm's degrees of freedom, and overall registration accuracy based on a voxel-by-voxel measurement. RESULTS: A total of 10,160 unique radiographic images were simulated from 127 CT scans. The algorithm successfully converged to the correct solution 82% of the time with an average of 1.96 seconds of computation. The radiographic images for which the algorithm converged to the solution demonstrated 99.9% registration accuracy despite utilizing only single-precision computation for speed. The algorithm was found to be optimized for convergence when the search space was limited to a ± 45° offset in the right anterior oblique/left anterior oblique, cranial/caudal, and receiver rotation angles with the radiographic isocenter contained within 8000 cm3 of the volumetric center of the CT volume. CONCLUSIONS: The investigated machine learning algorithm has the potential to aid surgeons in level localization, surgical planning, and intraoperative navigation through a completely automated 2D-3D registration process. Future work will focus on algorithmic optimizations to improve the convergence rate and speed profile.

Minimally invasive modification of the Goel-Harms atlantoaxial fusion technique: a case series and illustrative guide.

OBJECTIVE: The Goel-Harms atlantoaxial screw fixation technique for the treatment of atlantoaxial instability and unstable odontoid fractures is reliable and reproducible for a variety of anatomies. The drawbacks of the technique are the potential for significant bleeding from the C2 nerve root venous plexus and the risks associated with posterior midline exposure and retraction, such as pain and wound complications. The authors developed a minimally invasive surgical (MIS) modification of the Goel-Harms technique using intra-articular grafting to facilitate placement of percutaneous lateral mass and pars screws with extended tabs for minimally invasive subfascial rod placement. The objective of this study was to present the authors' first series of 5 patients undergoing minimally invasive modification in comparison with 51 patients undergoing open atlantoaxial fusion. METHODS: A retrospectiveanalysis of patient comorbid conditions, blood loss, length of surgery, and length of stay was performed on patients undergoing Goel-Harms instrumented fusion (GHIF) for unstable odontoid fractures performed between 2016 and 2021. RESULTS: Patients undergoing the minimally invasive procedure showed significantly less blood loss than those undergoing the open atlantoaxial fusion procedure, with a median blood loss of 30 ml compared with 150 ml using the open technique (p < 0.01). The patients showed no significant differences in length of stay (2 days for MIS vs 4 days for open atlantoaxial fusion, p = 0.25). There were no significant differences in length of surgery for MIS, but a possible trend toward increased operative duration (234 vs 151 minutes, p = 0.112). CONCLUSIONS: In this small pilot study, it was shown that MIS-GHIF can be performed with decreased blood loss in atlantoaxial instability and odontoid fractures. This technique may allow for greater and safer application of the procedure in the elderly and infirm.

Case report: Minimally invasive modification of the Goel-Harms atlantoaxial fusion utilizing percutaneous screws and intra-articular cage is feasible and results in decreased blood loss.

Treatment of atlantoaxial pathology is often associated with significant morbidity and mortality. While surgical techniques for fixation are well established, approaches that minimize blood loss and muscle dissection are advantageous for expediting recovering and minimizing surgical risk. We present a 34-year-old female who presented with a Type III odontoid fracture requiring surgical fixation. She underwent a C1-2 fusion employing a novel minimally invasive modification of the Goel-Harms atlantoaxial fusion using percutaneous screws and intra-articular cage.

Novel use of percutaneous cervical pedicle inlet screws for supplemental posterior fixation after anterior cervical deformity correction.

INTRODUCTION: Correction of cervical deformity can be achieved using anterior cervical fixation and fusion techniques. However, supplemental posterior fixation is a critical component for ensuring biomechanical longevity and favorable patient outcomes. We present a novel percutaneous technique for posterior cervical fixation in patients where cervical pedicle (CP) screws may not be feasible and midline muscle dissection is not needed. METHODS: Three patients presented to our hospital with cervical pathology amendable to circumferential cervical fusion. After adequate deformity correction was performed through an anterior cervical decompression and fusion, staged posterior supplemental fixation was achieved using percutaneous CP inlet (CPI) screws using a percutaneous muscle-sparing approach. RESULTS: All three patients underwent CPI screw placement without postoperative neurovascular complications. Postoperative radiographic follow-up showed the desired, proper screw placement, with continued maintained cervical alignment. CONCLUSIONS: CPI screw placement may be alternative hybrid screw that achieves a advantageous safety profile while also avoiding an open midline exposure.

Gender Disparities in Surgical Treatment of Axis Fractures in Older Adults.

STUDY DESIGN: Retrospective cohort study. OBJECTIVES: Gender appears to play in important role in surgical outcomes following acute cervical spine trauma, with current literature suggesting males have a significantly higher mortality following spine surgery. However, no well-adjusted population-based studies of gender disparities in incidence and outcomes of spine surgery following acute traumatic axis injuries exist to our knowledge. We hypothesized that females would receive surgery less often than males, but males would have a higher 1-year mortality following isolated traumatic axis fractures. METHODS: We performed a retrospective cohort study using Medicare claims data that identified US citizens aged 65 and older with ICD-9 (International Classification of Diseases, Ninth Revision) code diagnosis corresponding to isolated acute traumatic axis fracture between 2007 and 2014. Our primary outcome was defined as cumulative incidence of surgical treatment, and our secondary outcome was 1-year mortality. Propensity weighted analysis was performed to balance covariates between genders. Our institutional review board approved the study (IRB #16-0533). RESULTS: There was no difference in incidence of surgery between males and females following acute isolated traumatic axis fractures (7.4 and 7.5 per 100 fractures, respectively). Males had significantly higher 1-year weighted mortality overall (41.7 and 28.9 per 100 fractures, respectively, P < .001). CONCLUSION: Our well-adjusted data suggest there was no significant gender disparity in incidence of surgical treatment over the study period. The data also support previous observations that males have worse outcomes in comparison to females in the setting of axis fractures and spinal trauma regardless of surgical intervention.

1-Year Mortality and Surgery Incidence in Older US Adults with Cervical Spine Fracture.

BACKGROUND: Traumatic cervical spinal cord injuries (SCIs) can be lethal and are especially dangerous for older adults. Falls from standing and risk factors for a cervical fracture and spinal cord injury increase with age. This study estimates the 1-year mortality for patients with a cervical fracture and resultant SCI and compares the mortality rate with that from an isolated cervical fracture. METHODS: We performed a retrospective cohort study of U.S. Medicare patients older than 65 years of age. International Classification of Diseases (ICD)-9 codes were used to identify patients with a cervical fracture without SCI and patients with a cervical fracture with SCI between 2007 and 2014. Our primary outcome was 1-year mortality cumulative incidence rate; our secondary outcome was the cumulative incidence rate of surgical intervention. Propensity weighted analysis was performed to balance covariates between the groups. RESULTS: The SCI cohort had a 1-year mortality of 36.5%, compared with 31.1% in patients with an isolated cervical fracture (risk difference 5.4% (2.9%-7.9%)). Patients with an SCI were also more likely to undergo surgical intervention compared with those without a SCI (23.1% and 10.3%, respectively; risk difference 12.8% (10.8%-14.9%)). CONCLUSIONS: Using well-adjusted population-level data in older adults, this study estimates the 1-year mortality after SCI in older adults to be 36.5%. The mortality after a cervical fracture with SCI was 5 percentage points higher than in patients without SCI, and this difference is smaller than one might expect, likely representing the frailty of this population and unmeasured covariates.

Comparative Propensity-Weighted Mortality After Isolated Acute Traumatic Axis Fractures in Older Adults.

INTRODUCTION: In older patients with axis fractures, the survival benefit from surgery is unclear due to high baseline mortality. Comparative effectiveness research can provide evidence from population level cohorts. Propensity weighting is the preferred methodology for reducing bias when analyzing national administrative cohort data for these purposes but has not yet been utilized for this important surgical conundrum. We estimate the effect of surgery on mortality after isolated acute traumatic axis fracture in older adults. MATERIALS AND METHODS: We used a retrospective population-based cohort of Medicare patients and generated a propensity score-weighted nonsurgical cohort and compared mortality with and without surgery. This balanced the comorbid conditions of the treatment groups. Incident fractures were defined using a predetermined algorithm based on enrollment, code timing, and billing location. The primary outcome was adjusted all-cause 1-year mortality. RESULTS: From 12 372 beneficiaries with 1-year continuous enrollment and a coded axis fracture, 2676 patients met final inclusion/exclusion criteria. Estimated incidence was 16.5 per 100 000 person-years overall in 2014 (95% confidence interval [CI]: 15.0-18.0) and was stable from 2008 through 2014. Patients with axis fracture had a mean age of 82.8 years, 30.2% were male, and 91.9% were Caucasian. Mortality was 3.8 times higher (CI 3.6-4.1) compared with the general population of older US adults. Propensity-weighted mortality at 1 year for nonsurgical patients was 26.7 of 100 (CI: 24.5-29.0). Mortality for surgical patients was significantly lower (19.7/100; CI 14.5-25.0). Risk difference was 7.0 fewer surgical deaths per 100 patients (CI: 1.3-12.7). Surgical patients aged 65 to 74 years had the largest difference in mortality with 11.2 fewer deaths per 100 (CI: 1.1-21.3). DISCUSSION: Patients with axis fractures are predominantly older Caucasian women and have a higher mortality rate than the general population. Propensity-weighted mortality at 1-year was lower in the surgical patients with the largest risk difference occurring in patients 65 to 74 years old. CONCLUSIONS: Surgery may provide an independent survival benefit in patients aged 65 to 75 years, and the mortality difference diminishes thereafter.

Use of C2 vertebroplasty and stereotactic radiosurgery for treatment of lytic metastasis of the odontoid process.

Improvements in cancer therapy have led to increased patient survival times in spite of metastatic spinal disease in many forms of cancer. Conventional treatment methods often employ radiotherapy with or without surgery depending on the neurological status, mechanical instability, and the extent of tumor. Percutaneous vertebroplasty as well as stereotactic radiosurgery (SRS) have arisen as common modalities of treatment of spinal metastasis in which neurological compromise or spinal instability and deformity is not of significant concern. These treatments, when used in combination, have been shown to provide early pain relief and effective tumor control while avoiding surgical resection, fixation, and lengthy recovery times. We present a case unique in the literature for the use of this combination treatment for tumors of the C2 vertebral body. While limited in application to patients without overt atlantoaxial instability or significant spinal canal compromise, we believe it provides a significant benefit in decreasing morbidity and improving early adherence to systemic therapy.

Biomechanical analysis of the upper thoracic spine after decompressive procedures.

BACKGROUND CONTEXT: Decompressive procedures such as laminectomy, facetectomy, and costotransversectomy are routinely performed for various pathologies in the thoracic spine. The thoracic spine is unique, in part, because of the sternocostovertebral articulations that provide additional strength to the region relative to the cervical and lumbar spines. During decompressive surgeries, stability is compromised at a presently unknown point. PURPOSE: To evaluate thoracic spinal stability after common surgical decompressive procedures in thoracic spines with intact sternocostovertebral articulations. STUDY DESIGN: Biomechanical cadaveric study. METHODS: Fresh-frozen human cadaveric spine specimens with intact rib cages, C7-L1 (n=9), were used. An industrial robot tested all spines in axial rotation (AR), lateral bending (LB), and flexion-extension (FE) by applying pure moments (±5 Nm). The specimens were first tested in their intact state and then tested after each of the following sequential surgical decompressive procedures at T4-T5 consisting of laminectomy; unilateral facetectomy; unilateral costotransversectomy, and subsequently instrumented fusion from T3-T7. RESULTS: We found that in all three planes of motion, the sequential decompressive procedures caused no statistically significant change in motion between T3-T7 or T1-T12 when compared with intact. In comparing between intact and instrumented specimens, our study found that instrumentation reduced global range of motion (ROM) between T1-T12 by 16.3% (p=.001), 12% (p=.002), and 18.4% (p=.0004) for AR, FE, and LB, respectively. Age showed a negative correlation with motion in FE (r = -0.78, p=.01) and AR (r=-0.7, p=.04). CONCLUSIONS: Thoracic spine stability was not significantly affected by sequential decompressive procedures in thoracic segments at the level of the true ribs in all three planes of motion in intact thoracic specimens. Age appeared to negatively correlate with ROM of the specimen. Our study suggests that thoracic spinal stability is maintained immediately after unilateral decompression at the level of the true ribs. These preliminary observations, however, do not depict the long-term sequelae of such procedures and warrant further investigation.

Minimally invasive, robot-assisted, anterior lumbar interbody fusion: a technical note.

BACKGROUND: Minimally invasive techniques in spine surgery have gained significant popularity due to decreased tissue dissection and destruction, postoperative pain, and hospital stay. The laparoscopic anterior lumbar interbody fusion (ALIF), an innovation in minimally invasive spine surgery, is rarely done because it has marginal benefit over the mini-open ALIF technique in rates of retrograde ejaculation and vascular complications. We propose these outcomes can be improved with enhanced robotic-assisted dissection and exposure for ALIF. PATIENTS: Two patients with single-level degenerative spine disease at L5-S1, associated with mechanical back pain, underwent anterior spinal exposure using the da Vinci S Surgical Robot during ALIF. RESULTS: In this report, we provide the first description of the use of a surgical robot in the dissection and exposure for ALIF in patients with degenerative spine disease. We demonstrate successful use of the da Vinci Surgical Robot in separating the presacral nervous plexus from retroperitoneal structures without postoperative vascular or urological complications over a 1-year follow-up period. CONCLUSION: Use of the robotic assistance in the performance of ALIF is possible without significant operative complications. This technique may provide added benefit over conventional laparoscopic approaches to the spine.

Salvage C2 ganglionectomy after C2 nerve root decompression provides similar pain relief as a single surgical procedure for intractable occipital neuralgia.

OBJECTIVE: To determine the effectiveness of C2 nerve root decompression and C2 dorsal root ganglionectomy for intractable occipital neuralgia (ON) and C2 ganglionectomy after pain recurrence following initial decompression. METHODS: A retrospective review was performed of the medical records of patients undergoing surgery for ON. Pain relief at the time of the most recent follow-up was rated as excellent (headache relieved), good (headache improved), or poor (headache unchanged or worse). Telephone contact supplemented chart review, and patients rated their preoperative and postoperative pain on a 10-point numeric scale. Patient satisfaction and disability were also examined. RESULTS: Of 43 patients, 29 were available for follow-up after C2 nerve root decompression (n = 11), C2 dorsal root ganglionectomy (n = 10), or decompression followed by ganglionectomy (n = 8). Overall, 19 of 29 patients (66%) experienced a good or excellent outcome at most recent follow-up. Among the 19 patients who completed the telephone questionnaire (mean follow-up 5.6 years), patients undergoing decompression, ganglionectomy, or decompression followed by ganglionectomy experienced similar outcomes, with mean pain reduction ratings of 5 ± 4.0, 4.5 ± 4.1, and 5.7 ± 3.5. Of 19 telephone responders, 13 (68%) rated overall operative results as very good or satisfactory. CONCLUSIONS: In the third largest series of surgical intervention for ON, most patients experienced favorable postoperative pain relief. For patients with pain recurrence after C2 decompression, salvage C2 ganglionectomy is a viable surgical option and should be offered with the potential for complete pain relief and improved quality of life (QOL).

Treatment of pediatric atlantoaxial instability with traditional and modified Goel-Harms fusion constructs.

There are several treatment options for rigid fixation at C1-C2 including Brooks and Gallie type wired fusions and C1-2 transarticular screws. The use of a Goel-Harms type fusion, a construct with C1 lateral mass screws and C2 pedicle screws, has not been extensively described in pediatric patients. Here, we describe its relatively safe and effective use for treating pediatric patients by retrospective chart review of patients treated by the senior author for atlantoaxial instability with a Goel-Harms-type constructs during a 3-year period (2005-2007). Six patients were treated using Goel-Harms-type constructs. Five patients were treated utilizing a construct containing C1 lateral mass screws and C2 pedicle screws; one patient was treated using construct containing C1 lateral mass screws and C2 trans-laminar screws. The patients ranged in age from 7 to 17 years old (mean 12.7). All patients had findings of an os odontoideum on CT scans and three of the six patients had T2 hyperintensity on MRI. Three of the six patients presented with transient neurologic deficits: quadraplegia in two patients and paresthesias in two patients. In each patient C1 lateral mass and C2 screws were placed and the subluxation was reduced to attain an anatomical alignment. No bone grafts were harvested from the iliac crest or rib. Local morsalized bone and sub-occipital skull graft was used. All patients tolerated the procedure well and were discharged home on post-operative day 3-4. The patients wore a hard cervical collar and no halo-vests were needed. All patients had solid fusion constructs and normal alignment on post-operative imaging studies performed on average 14 months post-operatively (range: 7-29). The results demonstrated that Goel-Harms fusions are a relatively safe and effective method of treating pediatric patients with atlantoaxial instability and are not dependent on vertebral anatomy or an intact ring of C1. Follow-up visits and studies in this limited series of patients demonstrated solid fusion constructs and anatomical alignment in all patients treated.

Symptomatic high-flow arteriovenous fistula after a C-2 fracture. Case report.

Spinal arteriovenous fistulas (AVFs) are relatively uncommon lesions that are often diagnosed in a delayed fashion. The authors present a cause of a symptomatic high-flow AVF that developed in a patient after traumatic injury to the upper cervical spine. The patient presented to the trauma bay after a motor vehicle collision, and was found to have a C-2 fracture involving the transverse foramen. Although the patient was neurologically intact on presentation, 6 hours after admission weakness developed on his left side. Imaging studies demonstrated complete transection of the distal cervical aspect of the right vertebral artery (VA) at the base of C-2, with antegrade and retrograde flow into a direct AVF, resulting in early filling of the right internal jugular vein and other external draining veins. The patient was treated endovascularly with coil occlusion of the VA both proximal and distal to the transection. The patient's weakness improved over the next 7 days. At the 12-week follow-up examination, the patient's fractures had healed and he was neurologically intact.

Congenital cystic hemangioblastomas of the cerebral hemisphere in a neonate without alteration in the VHL gene.

A 4-week-old child presented with lethargy, emesis, decreased spontaneous movements, and a bulging fontanelle. Neuroimaging demonstrated a large, hemispheric, multicystic lesion with multiple enhancing nodules, which, on pathological examination, proved to be multiple, distinct hemangioblastomas. Careful molecular analysis failed to reveal alterations of the VHL gene. This represents an uncommon presentation for these tumors and suggests that genes other than VHL may be important in the genesis of these tumors.

Protein patterns and proteins that identify subtypes of glioblastoma multiforme.

Glioblastoma multiforme (GBM) has been subdivided into two types based on clinical and genetic findings: primary tumors, which arise de novo, and secondary tumors, which progress from lower grade gliomas to GBMs. To analyse this dichotomy at the protein level, we employed selective tissue microdissection to obtain pure populations of tumor cells, which we studied using two-dimensional protein gel electrophoresis (2-DGE) and protein sequencing of select target proteins. Protein patterns were analysed in a blinded manner from the clinical and genetic data. 2-DGE clearly identified two distinct populations of tumors. 2-DGE was reproducible and reliable, as multiple samples analysed from the same patient gave identical results. In addition, we isolated and sequenced 11 proteins that were uniquely expressed in either the primary or the secondary GBMs, but not both. We demonstrate that specific proteomic patterns can be reproducibly identified by two-dimensional gel electrophoresis from limited numbers of selectively procured, microdissected tumor cells and that two patterns of GBMs, primary versus secondary, previously distinguished by clinical and genetic differences, can be recognized at the protein level. Proteins that are expressed distinctively may have important implications for the diagnosis, prognosis, and treatment of patients with GBM.

A functional polymorphism in the EGF gene is found with increased frequency in glioblastoma multiforme patients and is associated with more aggressive disease.

Glioblastoma multiforme, the most aggressive form of primary brain tumor in adults, is nearly universally fatal, with 5-year survivals of <5% (P. Kleihues and W. K. Cavenee, eds., pp. 1-314, Lyon: IARC, 2000). Alterations in the epidermal growth factor receptor (EGFR) are common events in many glioblastoma. We hypothesized that a polymorphism in the 5'-untranslated region of the epidermal growth factor (EGF) gene, a natural ligand of the EGFR, may play a role in the genesis of these malignant gliomas. We find that patients with the GA or GG genotype have higher tumoral levels of EGF, irrespective of EGFR status, that they are more likely to recur after surgery, and that they have a statistically significant shorter overall progression-free survival than patients with the AA genotype. These findings suggest that a single nucleotide polymorphism in EGF may play a role in the formation of glioblastomas, is a useful and powerful prognostic marker for these patients, and may be a target for tumor therapy.