Dentate Ligament Research Articles

Percutaneous and open anterolateral cordotomy for intractable cancer pain: a technical note

IntroductionAnterolateral cordotomy (AL-C) is a long-established treatment for alleviating intractable cancer pain. However, AL-C has progressively fallen into desuetude, leading to the risk of a definitive loss of expertise within neurosurgical teams. Our objective was therefore to provide an update on percutaneous and open AL-C, with special emphasis on contemporary operative technique. Material and methodsPatient selection, indications, outcomes and up-to-date operative technique are reviewed through illustrative cases, including intraoperative photographs and video. ResultsMain indications are represented by unilateral, nociceptive pain refractory to best pharmacological treatment in patients with limited life expectancy. Percutaneous AL-C is performed under cooperative sedation at C1-C2 level. CT myelography guidance and intraoperative electrophysiology allow accurate targeting of the spinothalamic tract (STT). Thermocoagulation is performed at 80 °C for 60 s during a Mingazzini maneuver, in order to promptly detect the potential onset of a motor weakness. Open AL-C is performed under general anesthesia at T2-T3 level. The dentate ligament is suspended to gently rotate the spinal cord and expose the anterolateral column. Section of the STT is made with a micro scalpel blade at a depth of 4−5 mm, from the dentate ligament to the emergence of ventral rootlets. Success rate after AL-C is high and allows a marked reduction in antalgic drugs intake. Main limitations include failure in achieving long-standing pain relief and the new occurrence of spontaneous, mirror pain. ConclusionAL-C is a safe and effective option for the management of opioid-resistant cancer pain, which should be part of the neurosurgeon’s armamentarium.

Minimally Invasive Transpedicular Approach with Stereotactic Navigation for Evacuation and Fusion of Thoracic Ventral Epidural Abscess of Thoracic Spine: an illustrative case

Background: Surgical treatment of ventral thoracic pathologies can be challenging due to anatomical restrictions limiting corridor access, need for extensive spinal cord manipulation and limited experience for most spine surgeons’ due rarity of ventral thoracic pathologies. There is growing evidence that creation of a ventrolateral operative corridor through minimal invasive (MIS) transpedicular approach is safe and effective for accessing and treating of ventral thoracic spinal lesions [ 1-6] However, poor visualization with difficulty of spinal cord manipulation due to tubular retractor restriction remains changeling for MIS transpedicular approach. Objective: The authors illustrate a case of concurrent utilization of MIS tubular approach and stereotactic navigation to ensures safe and effective removal of epidural abscess and subsequent fusion. Conclusion: Addressing any lesion located anteriorly to the dentate ligament can be challenging and often necessitates either an antero-lateral or an anterior approach. This choice may depend on various factors, including the availability of an access surgeon. Utilization of stereotactic navigation with MIS transpedicular approach for ventral thoracic lesions, allows for real time intraoperation localization and visualization increasing lesion targeting accuracy and less cord manipulation. It also provides immediate post instrumentation checks and less radiation exposure for operating personals.

Diagnosis and Management of Thoracic Myelopathy.

Thoracic myelopathy can be a challenging condition to diagnose and treat. Successful outcomes depend on early recondition of the pathology and appropriate surgical referral in cases of progressive neurologic deterioration. The thoracic cord is tethered in kyphosis by the dentate ligaments and contains a tenuous blood supply. These conditions make the thoracic cord particularly susceptible to external compression and ischemic damage. Careful preoperative planning with specific attention to the location and source of thoracic stenosis is critical to successful decompression and complication avoidance. The purpose of this discussion is to outline the common sources of thoracic myelopathy and current recommendations regarding diagnosis and management. The review concludes with an overview of the most up-to-date literature regarding clinical outcomes.

Posterior Transdural Approach for Thoracic Corpectomies in the Setting of Complex Spine Deformity Reconstruction.

There are many surgical approaches for execution of a thoracic corpectomy. In cases of challenging deformity, traditional posterior approaches might not be sufficient to complete the resection of the vertebral body. In this technical note, we describe indications and technique for a transdural multilevel high thoracic corpectomy. A 25-year-old man with a history of neurofibromatosis type 1 presented with instrumentation failure after a previous T1-T12 posterior spinal fusion, extensive laminectomy, and tumor resection. The patient presented with progressive back pain, had broad dural ectasia, and a progressive kyphotic rotational and anteriorly translated spinal deformity. To resect the medial-most aspect of the vertebral body, a bilateral extracavitary approach was attempted, but was found insufficient. A transdural approach was subsequently performed. A left paramedian durotomy was made, followed by generous arachnoid dissection, bilateral dentate ligament division, and T4 rootlet sacrifice to mobilize the spinal cord. A ventral durotomy was then made and the ventral dura was reflected over the spinal cord to protect it while drilling. The corpectomy was then completed. The ventral and dorsal durotomies were closed primarily and reinforced with fibrin glue and fibrin sealant patch. The corpectomy defect was filled with nonstructural autograft. The focal kyphosis was corrected with a combination of rod contouring, compression, and in situ bending. During the surgery, the patient had stable neuromonitoring data, and postoperatively had no neurological deficits. On follow-up until 1 year, the patient presented with no signs of cerebrospinal spinal leaks, no motor or sensory deficits, minimal incisional pain, and significantly improved posture. Complex high thoracic (T3-5) ventral pathology inaccessible via a bilateral extracavitary approach may be accessed via a transdural approach as opposed to an anterior/lateral transthoracic approach that requires mobilization of cardiovascular structures or scapula.

Differentiation between Anterior and Posterior Roots Using Compound Muscle Action Potential in Intradural Extramedullary Spinal Tumor Surgery.

This study aims to determine the cutoff values for the compound muscle action potential (CMAP) stimulus in anatomically identified anterior (motor nerve) and posterior roots (sensory nerve) during cervical intradural extramedullary tumor surgery. The connection between CMAP data from nerve roots and postoperative neurological symptoms in thoracolumbar tumors was compared with data from cervical lesions. The participants of the study included 22 patients with intradural extramedullary spinal tumors (116 nerve roots). The lowest stimulation intensity to the nerve root at which muscle contraction occurs was defined as the minimal activation intensity (MAI) in the CMAP. In cervical tumors, the MAI was measured after differentiating between the anterior and posterior roots based on the anatomical placement of the dentate ligament and nerve roots. The MAIs for 20 anterior roots in eight cervical tumors were between 0.1 and 0.3 mA, whereas those for 19 posterior roots were between 0.4 and 2.0 mA. The cutoff was <0.4 mA for both the anterior and posterior roots, and sensitivity and specificity were both 100%. In thoracolumbar tumors, the nerve root was severed in 12 of 14 cases. All MAIs were determined to be at the dorsal roots as their scores were higher than the cutoff and did not indicate motor deficits. The MAIs of the anatomically identified anterior and posterior root CMAPs were found to have a cutoff value of <0.4 mA in the cervical lesions. Similar MAI cutoffs were also applicable to thoracolumbar lesions. Thus, CMAP may be useful in detecting anterior and posterior roots in spinal tumor surgery.

Idiopathic Ventral Spinal Cord Herniation: An Illustrative Case and Literature Review

Background and Importance: Idiopathic spinal cord herniation (ISCH), or spontaneous spinal cord herniation, is a rare but serious condition that can cause progressive myelopathy and irreversible neurological deficits if left untreated. The condition is marked by the gradual herniation of the spinal cord through a ventral defect in the dura, leading to compromised blood flow and neurological deficits. Common symptoms include Brown-Séquard syndrome or asymmetrical paraparesis. Treatment options typically focus on reducing the strangulated spinal cord and closing the dural defect with a synthetic patch. Case Presentation: We present the case of an adult woman with progressive asymmetrical weakness of the lower limbs compatible with spastic paraparesis. Thoracic magnetic resonance imaging (MRI) revealed characteristic features of ISCH at the T3-T4 level. Intraoperative neurophysiological monitoring was used during the surgical intervention, which involved a 3-level laminectomy, dura opening, excision of the dentate ligament, and reduction of the cord across the dural defect. The defect was then filled with an autogenous piece of muscle, followed by the closure of the defect with an artificial dural patch and dural closure. At the 6-month follow-up, the patient showed favorable improvement. Conclusion: Patients with slowly progressive paraparesis or Brown-Séquard syndrome should consider the possibility of ISCH as a potential cause, despite its rarity. In symptomatic cases, the preferred treatment option often involves reducing the incarcerated spinal cord followed by covering the dural defect.

Modified Unilateral Approach for Ventrally Located Spinal Tumors.

Surgery on spinal tumors becomes challenging when the tumor is ventral to the spinal cord. Conventionally, we approach it posteriorly through bilateral laminectomy and rotate the cord after sectioning the dentate ligament and nerve roots. However, manipulating the cord can be hazardous, and a long bilateral laminectomy can be invasive. Meanwhile, a narrow operative field and a limited lateral viewing angle in a unilateral approach constrained the surgeon. To overcome these problems, we previously reported a technique of modified unilateral approach where we incised the skin and the fascia horizontally and placed a pair of retractors longitudinally.The current article reports our experience applying this approach in 15 patients with ventrally located spinal tumors. The approach was performed on 10 schwannomas, 2 meningiomas, and 3 others. We evaluated paraspinal muscle atrophy on postoperative magnetic resonance imaging.The modified unilateral approach provided an excellent surgical field for removing ventrally located tumors. Gross total removal was achieved in 11 patients (92% of benign tumors). No neurological complications occurred except for one case of transient weakness. We encountered no wound-related late complications such as pain or deformity. The reduction of the cross-sectional area of the paraspinal muscles on the approach side (compared to the nonapproach side) was 0.93 (95% confidence interval: 0.72-1.06), indicating 7% atrophy (statistically nonsignificant, p = 0.48).We believe this simple technique can be useful for removing spinal tumors located ventral to the spinal cord.

Location-specific technical nuances of spinal meningioma resection: an operative video case series.

The objective of this video was to demonstrate technical nuances of intradural spinal meningioma (ISM) resection through a high-quality surgical video. The authors describe 3 patients with ISM in the cervicomedullary, cervical, and thoracic regions. Patients underwent surgery in the prone position with laminectomy, dorsal durotomy, and then resection of the mass. Case 1 required a suboccipital craniectomy and dissection of the tumor away from the vertebral artery. In case 2, special emphasis is placed on sectioning the dentate ligament with cord rotation. Case 3 highlights meticulous circumferential arachnoid release and the use of ultrasound. Patients saw significant neurological improvement postoperatively. This video provides clear instruction on location-specific technical nuances of ISM removal.

Open thoracic cordotomy for intractable cancer pain: a how I do it.

Some cancers of the lower extremity involve nerves and plexuses and can produce extreme drug-resistant noceptive pain. In these cases, open thoracic cordotomy can be proposed. This procedure involves disruption of the spinothalamic tract, which sustains nociceptive pathways. After placement in the prone position, selection of the side to be operated on (contralateral to the pain), and dura exposure, microsurgery is used to section the anterolateral spinal cord quadrant previously exposed by gently pulling on the dentate ligament. Open thoracic cordotomy is a moderate invasive, safe, and effective option for the management of drug-resistant unilateral lower extremity cancer pain in well-selected patients.

659 Minimally Invasive Surgery for Spinal CSF-Leaks in Spontaneous Intracranial Hypotension—Technical Aspects and Complications

INTRODUCTION: Spinal cerebrospinal fluid (CSF)-leaks cause spontaneous intracranial hypotension (SIH). In persisting symptoms despite treatment, surgical closure of spinal CSF-leaks is the treatment of choice. METHODS: Since April 2019 SIH patients were operated using the minimal invasive technique of tubular retractors. Leaks were sealed using an interlaminar dorsal access and if necessary a transdural route. Neuromonitoring was used for ventral leaks in the first 16 cases. The primary outcome was the benefit of surgery with respect to orthostatic symptoms; secondary outcome was the occurrence of complications. RESULTS: Between April 2019 and December 2020 we included 58 patients, mean age 46 years (IQR 36-55), 65% female, with the diagnosis of SIH. We treated 38 ventral leaks, 17 dorsal/lateral leaks, 2 CSF-venous fistulas. In all but two patients (96.6%) the leak could be approached, identified and closed via the tubular retractor. Leaks were visualized via a transdural approach, after cutting the dentate ligament and lateralization of the ventral dura. Microspurs were removed and leaks were closed by sandwich patch using a fibrin sealant patch (ventral leaks) or clipping of the respective nerve root (lateral leaks, CSF-venous fistula). At a median follow up of 21.5 months (IQR 16-28), eight patients were lost to follow up and 45 reported a benefit from surgery with respect to orthostatic symptoms. Mild permanent neurologic deficits occurred in 1.7%, the revision rate due to persisting or recurring leak was 3.4% and the overall revisioin rate was 10.3%. CONCLUSIONS: Minimally invasive surgery using tubular retractors of 18-20mm diameter can be safely and effectively performed for closure of spinal dural CSF-leaks in specialized centers.

A Classification Proposal for Spinal Vascular Lesions.

A Classification Proposal for Spinal Vascular Lesions.

Compromised Cranio-Spinal Suspension in Chiari Malformation Type 1: A Potential Role as Secondary Pathophysiology.

In Chiari Malformation Type I (CM1), low-lying tonsils obstruct the cisterna magna at the foramen magnum, thereby compromising the essential juncture between the cranial and spinal compartments. The anatomical obstruction of the cisterna magna inhibits bi-directional CSF flow as well as CSF pulse pressure equilibration between the intracranial compartment and the intraspinal compartment in response to instances of increased intracranial pressure. Less understood, however, are the roles of the spinal cord suspension structures at the craniocervical junction which lend viscoelastic support to the spinal cord and tonsils, as well as maintain the anatomical integrity of the cisterna magna and the dura. These include extradural ligaments including the myodural bridges (MDBs), as well as intradural dentate ligaments and the arachnoid framework. We propose that when these elements are disrupted by the cisterna magna obstruction, tonsillar pathology, and altered CSF dynamics, there may arise a secondary pathophysiology of compromised and dysfunctional cranio-spinal suspension in CM1. We present intraoperative images and videos captured during surgical exposure of the craniocervical junction in CM1 to illustrate this proposal.

Far Lateral Approaches: Far Lateral Approach With Minimal Condylectomy for C2 Schwannoma: 3-Dimensional Operative Video

Upper cervical schwannomas are rare lesions and together with meningiomas constitute around 5% of spinal tumors. The approach to these lesions is difficult because of the close proximity of the medulla and cervical spinal cord, lower cranial nerves, and the vertebral artery. Schwannomas in the upper cervical area typically arise from the dorsal roots and are located posterior to the dentate ligament. Nevertheless, a far lateral approach is often required for these lesions because of their lateral extent through the neural foramen and the proximity of both the V3 and V4 segments of the vertebral artery. With these lesions, an extensive condylectomy is rarely required. We present a case of a 40-yr-old woman who presented with an 8-mo history of deteriorating mobility and feeling of heaviness in the lower limbs with a further acute deterioration 1 wk before admission. She had a dissociated sensory loss and myelopathy in keeping with a partial hemicord syndrome. Imaging revealed a right-sided C2 intradural lesion extending through the C2 foramen in keeping with a C2 schwannoma. The patient was counseled on the treatment options, and informed consent for surgery was obtained. We describe a right-sided far lateral approach with minimal condylectomy for gross total resection of this lesion. We demonstrate the relationship of the tumor with the C2 nerve root, the spinal accessory nerve, and the cervical cord. We supplement the discussion with a 3D surgical video.

Far Lateral Approaches: C1 Meningioma With Vertebral Artery Involvement: 3-Dimensional Operative Video.

Tumors around the cervicomedullary junction are rare and constitute 5% of spinal tumors and 1% of cranial tumors. The approach to these lesions is difficult because of the close proximity of the medulla and cervical spinal cord, lower cranial nerves, and vertebral artery (VA) as well as the complex articulation between occipital condyle, C1 and C2. Cervicomedullary junction meningiomas are commonly classified based on their origin in relation to the dentate ligament, but the relationship to the VA typically plays an important role in deciding the surgical approach. For lesions located dorsal to the dentate ligament and not involving the VA, a midline approach is typically sufficient. However, when the VA is involved a far lateral approach is preferred as it offers better access to the V4 segment. We describe a case of a 55-yr-old man who presented with accessory nerve palsy and mild upper motor neuron signs and was found to have a C1 meningioma encasing and narrowing the VA at the V3/V4 segment. Informed consent was obtained. The patient was treated with a right far lateral approach with limited condylectomy to gain access to the V4 segment. We described the steps used for safe resection of the tumor around the VA from distal to proximal. We demonstrate the relationship of the tumor to the VA and the need to completely skeletonize the VA to achieve a gross total resection. We supplement the discussion with a 3D surgical video.

The AIUM Practice Parameter for the Performance of an Ultrasound Examination of the Neonatal and Infant Spine.

The AIUM Practice Parameter for the Performance of an Ultrasound Examination of the Neonatal and Infant Spine.

Posterolateral trans dentate approach to anterior extensive extramedullary tumor of the cervical spine in a pediatric case: how I do it.

Extramedullary anterior cervical canal tumors can be challenging lesions to reach. The posterolateral trans dentate approach offers an alternative route. Classic posterior laminoplasty is done to expose the medulla; the dentate ligament is identified as a fibrous structure running from the lateral pial surface of the medulla to the lateral dura between nerve roots spaces. Once the ligament is cut, the medulla can be gently rotated to access the anterior cervical canal. Intraoperative neurophysiological stimulation is mandatory. This approach allows a safe route, without the need for corpectomies. It should be considered especially in children where multilevel corpectomies could be challenging.

Dissecting Fusiform PICA Aneurysm Repair With Trapping and an Unconventional End-to-Side Reanastomosis: 2-Dimensional Operative Video.

Dissecting fusiform posterior inferior cerebellar artery (PICA) aneurysms are rare and challenging.1,2 One common treatment is occlusion of the aneurysm and parent artery via an endovascular approach without revascularization.3 Revascularization of the artery requires an open microsurgical bypass or endovascular placement of a newer-generation flow diverter.4 We present an end-to-side reanastomosis of the PICA for treatment of a dissecting fusiform left PICA aneurysm with anatomy deemed unfavorable for endovascular treatment in a 62-yr-old man with subarachnoid hemorrhage. After discussions regarding risks, benefits, and alternatives to the procedure, the family consented to surgical treatment. A far-lateral craniotomy was performed, with partial condylectomy to widen the exposure. The cisterna magna was opened, and the dentate ligament was cut to visualize the vertebral artery. The PICA was identified and traced distally to the aneurysmal segment, which was circumferentially diseased. Perforators were noted immediately distal to the aneurysm. The aneurysm was then trapped, and the afferent artery was transected and brought to the sidewall of the distal artery. The recipient site was trapped with temporary clips, and a linear arteriotomy was made. An end-to-side reanastomosis was performed, temporary clips were removed, and hemostasis was achieved. Postoperative angiography confirmed bypass patency and preservation of the PICA perforators. Conventional reanastomosis of the parent artery after aneurysm excision is achieved by end-to-end reanastomosis. In contrast, we performed an unconventional end-to-side reanastomosis to revascularize the PICA while leaving the efferent artery in situ to protect its medullary perforators. This bypass is an example of a fourth-generation bypass.5,6 Used with permission from the Barrow Neurological Institute, Phoenix, Arizona.

Minimally invasive intrathecal spinal cord imaging with optical coherence tomography.

.Significance: Imaging of the spinal cord is challenging due to the surrounding bony anatomy, physiologic motion, and the small diameter of the spinal cord. This precludes the use of non-invasive imaging techniques in assessing structural changes related to trauma and evaluating residual function.Aim: The purpose of our research was to apply endovascular technology and techniques and construct a preclinical animal model of intrathecal spinal cord imaging using optical coherence tomography (OCT).Approach: Five animals (2 Yorkshire Swine and 3 New Zealand Rabbits) were utilized. Intrathecal access was gained using a 16-guage Tuohy, and an OCT catheter was advanced under roadmap technique into the cervical canal. The OCT catheter has a motorized pullback, and a total length of 54 mm of the spinal canal is imaged.Results: Image acquisition was successful for all animals. There were no instances of difficult catheter navigation, enabling OCT imaging rostrally to C2. The thecal sac provided excellent thoroughfare for the OCT catheter. The clear cerebrospinal fluid also provided an excellent medium for image acquisition, with no detectable artifact from the contents of the cerebrospinal fluid. The anatomical space of the spinal canal could be readily appreciated including: dural lining of the thecal sac, epidural veins, pial lining of the spinal cord, arachnoid bands, dentate ligaments, and nerve rootlets/roots.Conclusion: Minimally invasive intrathecal imaging using endovascular OCT was feasible in this preclinical animal study. The repurposing of an endovascular device for spinal imaging comes with limitations, and a spine-specific device is necessary.

Microsurgical resection of foramen magnum meningioma: multi-institutional retrospective case series and proposed surgical risk scoring system.

Foramen magnum meningiomas (FMMs) are a major surgical challenge, due to relevant surgical morbidity and mortality. The paper aims to review the clinical (symptomatic improvement, complication rate, length of hospital stay) and radiological outcome (completeness of resection) of microsurgical resection of FMMs, and to identify predictors of complications. A multi-institutional retrospective review of prospectively maintained database of FMMs included 51 patients (74.5% females) with a median tumor volume of 8.18cm3 (range, 1.77-57.9cm3) and median follow-up of 36months (range, 0.30-180.0months). Tumors were resected though suboccipital approach (58.8%) or posterior-lateral approaches (39.3%), including far-lateral, extreme lateral and transcondylar approaches. Gross-total resection (GTR) was achieved in 80.4% and 98% of cases did not present tumor regrowth or recurrence. Clinical symptoms improved in 34 patients (66.7%) and worsened in 5 (9.8%). The median length of hospital stay was 5days. Mortality was null. Postoperative complications developed in 15 patients (29.4%), with cerebrospinal fluid leak (7.8%) and lower cranial nerves deficits (7.8%) as the most frequent. Craniospinal location (p = 0.03), location anterior to the dentate ligament (DL) (p = 0.02), involvement of vertebral artery (VA) (p = 0.03) were significantly associated with complication rate. These three elements allow calculating the Foramen Magnum Meningioma Risk Score (FRMMRS), to estimate the risk of post-operative complications. Microsurgical resection allows for high GTR rate and low rate of tumor regrowth or recurrence, despite complications in one third of the patients. The FMMRS allows classifying FMMs and estimating the risk of post-operative complications.

Challenges in Using the Posterior Inferior Cerebellar Artery for Revascularization of the Anterior Inferior Cerebellar Artery: A Microsurgical Anatomic Study

A bypass is usually required to prevent ischemia during the treatment of anterior inferior cerebellar artery (AICA) aneurysms. The intracranial (IC)-to-IC bypass provides several advantages over the extracranial-to-IC bypass in the posterior fossa. However, there are only 2 case reports about AICA revascularization with the posterior inferior cerebellar artery (PICA). We aimed to investigate the microsurgical anatomical challenges for PICA to AICA anastomosis. Ten cadaveric heads injected with colored silicone were inspected on both sides using a lateral transcondylar approach. After the donor and recipient arteries were examined from the posterior side, neurovascular contents of the posterior fossa were excised and the origin, course, and variations of both arteries were investigated from the anterior view. The diameters of the AICA and PICA segments and the intersegment distance were measured. PICA variations and posteromedial origins from the vertebral artery were identified in 8 of the 20 right and 6 of the 20 left sides, and the first segment of the PICA was not present in 7 sides. Furthermore, in 18 sides, the PICA was trapped between the lower cranial nerves and dentate ligaments. Therefore the donor artery could not be brought closer than 1 cm to the recipient artery in 19 sides. Moreover, AICA variations were identified in 6 sides, and in 12 sides, the diameter of the recipient artery was <1 mm. The mostly PICA-related issues made PICA-to-AICA anastomosis unfeasible in all cadaveric heads included in the study.