Percutaneous aspiration of spinal terminal ventricle cysts using real-time magnetic resonance imaging and navigation

The Impact of Navigation in Lumbar Spine Surgery: A Study of Historical Aspects, Current Techniques and Future Directions

Background/Objectives: We sought to improve accuracy while minimizing radiation hazards, improving surgical outcomes, and preventing potential complications. Despite the increasing popularity of these systems, a limited number of papers have been published addressing the historical evolution, detailing the areas of use, and discussing the advantages and disadvantages, of this increasingly popular system in lumbar spine surgery. Our objective was to offer readers a concise overview of navigation system history in lumbar spine surgeries, the techniques involved, the advantages and disadvantages, and suggestions for future enhancements to the system. Methods: A comprehensive review of the literature was conducted, focusing on the development and implementation of navigation systems in lumbar spine surgeries. Our sources include PubMed-indexed peer-reviewed journals, clinical trial data, and case studies involving technologies such as computer-assisted surgery (CAS), image-guided surgery (IGS), and robotic-assisted systems. Results: To develop more practical, effective, and accurate navigation techniques for spine surgery, consistent advancements have been made over the past four decades. This technological progress began in the late 20th century and has since encompassed image-guided surgery, intraoperative imaging, advanced navigation combined with robotic assistance, and artificial intelligence. These technological advancements have significantly improved the accuracy of implant placement, reducing the risk of misplacement and related complications. Navigation has also been found to be particularly useful in tumor resection and minimally invasive surgery (MIS), where conventional anatomic landmarks are lacking or, in the case of MIS, not visible. Additionally, these innovations have led to shorter operative times, decreased radiation exposure for patients and surgical teams, and lower rates of reoperation. As navigation technology continues to evolve, future innovations are anticipated to further enhance the capabilities and accessibility of these systems, ultimately leading to improved patient outcomes in lumbar spine surgery. Conclusions: The initial limited utilization of navigation system in spine surgery has further expanded to encompass almost all fields of lumbar spine surgeries. As the cost-effectiveness and number of trained surgeons improve, a wider use of the system will be ensured so that the navigation system will be an indispensable tool in lumbar spine surgery. However, continued research and development, along with training programs for surgeons, are essential to fully realize the potential of these technologies in clinical practice.

Cystic dilatation of the ventriculus terminalis: A narrative review

Introduction

The terminal ventricle, also known as the fifth ventricle, is a tiny relic cavity in the conus medullaris of the human spinal cord. Our purpose in bringing attention to this condition is to get the word out about the signs and symptoms, diagnostic hurdles, and therapeutic options available for it.

Methods

All relevant studies involving patients diagnosed with ventriculus terminalis (VT) were retrieved from PubMed, Google Scholar, and Scopus. Studies published in complete English language reports were included. The terms VT, terminal ventricle, and 5th ventricle. Age, gender, presenting symptoms, magnetic resonance imaging findings, treatment, and outcome of patients with ventriculus terminalis were all included and recorded.

Results

The average age of the patients was 39 years, and there were 13 men among them (14.4%). Motor deficits and sciatica were the most commonly reported symptoms in 38 and 34 patients (42.2%, 37.7%), respectively. In 48 patients (53.3%), cyst fenestration was performed, and in 25 patients (27.7%), myelotomy was performed. Fifty-eight patients (64.4%) saw a reduction in cyst size after surgery. The majority of patients reported an improvement in their symptoms in 64 cases (51.1%), with only three cases (3.3%) reporting a worsening.

Conclusions

In cases where the VT is the source of symptoms such as motor, sensory, or bladder dysfunction, surgical intervention is recommended. This review compiles information from the available literature to shed light on the anatomy, clinical presentation, imaging, and treatment options for this variant. It also aims to pinpoint any potential drawbacks or restrictions connected to the surgical techniques.

Cystic Dilatation of the Ventriculus Terminalis: Examining the Relevance of the Revised Operative Classification Through a Systematic Review of the Literature, 2011-2021

The literature features limited evidence on the natural history of the cystic dilatation of the ventriculus terminalis (CDVT) and its response to treatment. The goal of this study is to ascertain which impact the revised operative classification of CDVT had on the management of patients diagnosed over the past 10 years.Ten new clinical articles presenting a total of 30 cases of CDVT were identified and included for qualitative analysis. Two take-home messages can be identified: (1) Adequate consideration should be given to designing national pathways for referral to tertiary centers with relevant expertise in the management of lesions of the conus medullaris, and (2) we suggest that type Ia should be, at least initially, treated conservatively, whereas we reckon that the signs and symptoms described in types Ib, II, and III seem to benefit, although in some patients only partially, from surgical decompression in the form of cystic fenestration, cyst-subarachnoid shunting, or both.While the level of evidence gathered in this systematic review remains low because the literature on CDVT consists only of retrospective studies based on single-center series (level of evidence 4 according to the Oxford Centre for Evidence-Based Medicine (OCEBM)), the strength of recommendation for adopting the revised operative classification of CDVT is moderate.

Toward the End of the Funnel: The Ventriculus Terminalis-The State of Art of an Ancient Entity with a Recent History

PURPOSE

The ventriculus terminalis (VT), also called the fifth ventricle, is a small cavity containing cerebrospinal fluid (CSF) that is in the conus medullaris in continuity with the central canal of the spinal cord. In adults, persistent VT is a very rare entity, and the diagnosis is incidental in most cases. Rarely, VT may become symptomatic for still-uncertain reasons but most often for its cystic dilatation. The management of these selected cases is still controversial and sometimes associated with unsatisfactory outcomes.

METHODS

We performed a critical review of the existing literature on the management of symptomatic VT in adults. The etiology, pathophysiology, and treatment of VT are presented and discussed, focusing on the best timing for surgery.

RESULTS

Conservative management, marsupialization, or the placement of a T drain have been reported. The existing classifications describe the most correct approach for each clinical presentation, but scarce importance has been given to the delay from symptoms' onset to surgical treatment.

CONCLUSION

Although different cases have been described in the literature, this rare pathology remains unknown to most neurosurgeons.

Evaluation of an Ultrasound-Based Navigation System for Spine Neurosurgery: A Porcine Cadaver Study

BACKGROUND

With the growing incidence of patients receiving surgical treatment for spinal metastatic tumours, there is a need for developing cost-efficient and radiation-free alternatives for spinal interventions. In this paper, we evaluate the capabilities and limitations of an image-guided neurosurgery (IGNS) system that uses intraoperative ultrasound (iUS) imaging for guidance.

METHODS

Using a lumbosacral section of a porcine cadaver, we explored the impact of CT image resolution, ultrasound depth and ultrasound frequency on system accuracy, robustness and effectiveness. Preoperative CT images with an isotropic resolution of , and were acquired. During surgery, vertebrae L1 to L6 were exposed. For each vertebra, five iUS scans were acquired using two depth parameters (5 cm and 7 cm) and two frequencies (6 MHz and 12 MHz). A total of 120 acquisition trials were evaluated. Ultrasound-based registration performance is compared to the standard alignment procedure using intraoperative CT. We report target registration error (TRE) and computation time. In addition, the scans' trajectories were analyzed to identify vertebral regions that provide the most relevant features for the alignment.

RESULTS

For all acquisitions, the median TRE ranged from 1.42 mm to 1.58 mm and the overall computation time was 9.04 s ± 1.58 s. Fourteen out of 120 iUS acquisitions (11.66%) yielded a level-to-level mismatch (and these are included in the accuracy measurements reported). No significant effect on accuracy was found with CT resolution (F (2,10) = 1.70, p = 0.232), depth (F (1,5) = 0.22, p= 0.659) nor frequency (F (1,5) = 1.02, p = 0.359). While misalignment increases linearly with the distance from the imaged vertebra, accuracy was satisfactory for directly adjacent levels. A significant relationship was found between iUS scan coverage of laminae and articular processes, and accuracy.

CONCLUSION

Intraoperative ultrasound can be used for spine surgery neuronavigation. We demonstrated that the IGNS system yield acceptable accuracy and high efficiency compared to the standard CT-based navigation procedure. The flexibility of the iUS acquisitions can have repercussions on the system performance, which are not fully identified. Further investigation is needed to understand the relationship between iUS acquisition and alignment performance.

Open-source software for ultrasound-based guidance in spinal fusion surgery

Spinal instrumentation and surgical manipulations may cause loss of navigation accuracy requiring an efficient re-alignment of the patient anatomy with pre-operative images during surgery. While intra-operative ultrasound (iUS) guidance has shown clear potential to reduce surgery time, compared with clinical computed tomography (CT) guidance, rapid registration aiming to correct for patient misalignment has not been addressed. In this article, we present an open-source platform for pedicle screw navigation using iUS imaging. The alignment method is based on rigid registration of CT to iUS vertebral images and has been designed for fast and fully automatic patient re-alignment in the operating room. Two steps are involved: first, we use the iUS probe's trajectory to achieve an initial coarse registration; then, the registration transform is refined by simultaneously optimizing gradient orientation alignment and mean of iUS intensities passing through the CT-defined posterior surface of the vertebra. We evaluated our approach on a lumbosacral section of a porcine cadaver with seven vertebral levels. We achieved a median target registration error of 1.47 mm (100% success rate, defined by a target registration error <2 mm) when applying the probe's trajectory initial alignment. The approach exhibited high robustness to partial visibility of the vertebra with success rates of 89.86% and 88.57% when missing either the left or right part of the vertebra and robustness to initial misalignments with a success rate of 83.14% for random starts within ±20° rotation and ±20 mm translation. Our graphics processing unit implementation achieves an efficient registration time under 8 s, which makes the approach suitable for clinical application.

The state-of-the-art in ultrasound-guided spine interventions

During the last two decades, intra-operative ultrasound (iUS) imaging has been employed for various surgical procedures of the spine, including spinal fusion and needle injections. Accurate and efficient registration of pre-operative computed tomography or magnetic resonance images with iUS images are key elements in the success of iUS-based spine navigation. While widely investigated in research, iUS-based spine navigation has not yet been established in the clinic. This is due to several factors including the lack of a standard methodology for the assessment of accuracy, robustness, reliability, and usability of the registration method. To address these issues, we present a systematic review of the state-of-the-art techniques for iUS-guided registration in spinal image-guided surgery (IGS). The review follows a new taxonomy based on the four steps involved in the surgical workflow that include pre-processing, registration initialization, estimation of the required patient to image transformation, and a visualization process. We provide a detailed analysis of the measurements in terms of accuracy, robustness, reliability, and usability that need to be met during the evaluation of a spinal IGS framework. Although this review is focused on spinal navigation, we expect similar evaluation criteria to be relevant for other IGS applications.

Cystic dilation of the ventriculus terminalis

The ventriculus terminalis (VT) is a virtual cavity of the conus medullaris that appears during embryonic life. We presented a case with the cystic dilation of the ventriculus terminalis (CDVT) in a symptomatic patient. A 66-year-old female suffered from disturbance while walking evolving for the past 2 years. An MR image revealed a cystic dilatation of ventriculus terminalis. The patient experienced marked improvement of lower extremity strength by a fenestration of cyst and cyst-subarachnoid shunt. Treatment for asymptomatic patients seems to be the best conducted conservatively, whereas patients with focal neurological deficits seem to be best handled surgically.

Surgical treatment for symptomatic ventriculus terminalis: case series and a literature review

BACKGROUND

Ventriculus terminalis is a cystic embryological remnant within the conus medullaris that normally regresses after birth. In rare cases, it may persist into adulthood and give rise to neurological symptoms, for which the optimal treatment remains uncertain. The aim of this study was to present our experience from a population-based cohort of patients with ventriculus terminalis and discuss our management strategy as compared to the existing literature.

METHODS

A retrospective review was conducted of all adult (≥ 15 years) patients with ventriculus terminalis who were referred to the Karolinska University Hospital between 2010 and 2018.

RESULTS

Fourteen patients were included. All patients were symptomatic at the time of referral, and the most common symptom was lower limb weakness (n = 9). Microsurgical cyst fenestration was offered to all patients and performed in thirteen. Postoperative imaging confirmed cyst size reduction in all surgically treated patients. No surgical complications were reported. Eleven of the surgically treated patients showed clinical improvement at long-term follow-up. One patient declined surgery, with progression of the cyst size and clinical deterioration observed at follow-up.

CONCLUSIONS

Surgery for ventriculus terminalis seems to be a safe and effective option for relief of symptoms. We propose that surgery should be offered to all patients with symptomatic ventriculus terminalis.

The cystic dilation of ventriculus terminalis with neurological symptoms: Three case reports and a literature review

CONTEXT

The ventriculus terminalis (VT) is a very small ependymal-lined residual lumen in the conus medullaris. It is normally present in all subjects during fetal development. VT in adults appears as an unusual pathology with an uncertain pathogenesis.

FINDINGS

In this paper, we described three case reports of symptomatic fifth ventricle cystic dilations. All of them were female and their mean age was 59 years. We treated them surgically and all three patients were improved based on clinical and imaging assessments.

CONCLUSION

Our cases suggested that surgical decompression was a safe and effective treatment in symptomatic patients and the neurosurgeons should be aware of such rare situations. A complete list of differential diagnosis about other cystic dilations of the conus medullaris should be emphasized to select the correct clinical approach.

Surgery or not? A case of ventriculus terminalis in an adult patient

The ventriculus terminalis (VT) is an intramedullary cavity containing cerebrospinal fluid (CSF), usually located at the conus, and represents an unsuccessful regression of a normal embryological phase of the development of the neural tube. Symptoms are not univocal and may vary from aspecific signs to sphincter dysfunctions and focal neurological deficits. The correct management of this condition is still an object of debate due to its rarity and its unpredictable behaviour in adult patients. Two different studies have proposed a distinction for patients with cystic dilatation of VT based on their symptoms, suggesting that only those patients with neurological deficits clearly related to the terminal ventricle could benefit from surgery. We describe a case of an adult patient with a progressive dilatation of a diagnosed VT that we treated surgically. A management flowchart for this condition is also proposed based on our experience and a review of the literature.

Cystic dilation of a ventriculus terminalis. Case report and review of the literature

The ventriculus terminalis (VT) is a small ependyma-lined cavity within the conus medullaris that is in direct continuity with the central canal of the spinal cord. Cystic dilatation of the ventriculus terminalis on its own is an extremely rare pathological event in adults whose pathogenesis is uncertain. VT has been described in children as a normal developmental phenomenon. These lesions are often diagnosed incidentally during imaging and are in most cases asymptomatic, especially in children. Symptomatic dilatation of VT in adults is a rare condition with 61cases being reported to date. Symptomatic dilatation of VT in children has not been reported till now. We present a 5 year-old-boy with a sphincteric and walking disorder. The patient was assessed by clinical, electrophysiological and urodynamic investigations as well as magnetic resonance imaging (MRI) of the lumbar-sacral segment with and without gadolinium enhancement. Lumbar-sacral MRI demonstrated the presence of a cystic lesion containing cerebrospinal fluid (CSF), which did not enhance after gadolinium, compatible with the diagnosis of the ventriculus terminalis dilation.The patient underwent laminectomy and the cyst wall was fenestrated with a midline myelotomy. In 6-month of follow-up, urinary problems and gait disturbance improved.

Cystic Dilation of the Ventriculus Terminalis: Report of 6 Surgical Cases Treated with Cyst-Subarachnoid Shunting Using a T-Catheter

BACKGROUND

Cystic dilation of the ventriculus terminalis (CDVT) is a rare anatomic variation that and may become symptomatic. Literature regarding CDVT is limited, and thus the clinical characteristics and management strategy of CDVT are unclear. Here we report 6 cases of CDVT seen in our institution, and provide a review of the current literature.

METHODS

The study cohort comprised 6 patients with CDVT seen at Beijing Tiantan Hospital between September 2010 and June 2015. All 6 patients were managed surgically. Data on age, sex, clinical presentation, radiologic features, operative methods, and surgical outcomes were reviewed retrospectively. We evaluated the clinical outcomes and postoperative radiologic changes of these patients and compared them with findings of similar previous reports.

RESULTS

All 6 patients were female, with a median age of 50.0 years (interquartile range [IQR], 25.8-54.0 years). Surgical management of cyst-subarachnoid shunting using T-catheter after myelotomy was successfully performed in all patients. During an average follow-up of 41 months, relief of clinical symptoms, especially low-back pain and sciatica, were observed in all 6 patients. No patients experienced symptom recurrence during follow-up, and postoperative magnetic resonance imaging revealed no regrowth of the lesion. Patients with focal neurologic deficits and sphincter disorders also achieved symptom relief from the procedure.

CONCLUSIONS

CDVT is an extremely rare cause of conus medullaris syndrome with an unclear treatment strategy. Our successful surgical management of 6 cases through cystic-subarachnoid shunting using a T-catheter for CDVT drainage provides a potential option for treating CDVT.

Image guidance based on MRI for spinal interstitial laser thermotherapy: technical aspects and accuracy

OBJECTIVE

Image guidance for spinal procedures is based on 3D-fluoroscopy or CT, which provide poor visualization of soft tissues, including the spinal cord. To overcome this limitation, the authors developed a method to register intraoperative MRI (iMRI) of the spine into a neuronavigation system, allowing excellent visualization of the spinal cord. This novel technique improved the accuracy in the deployment of laser interstitial thermal therapy probes for the treatment of metastatic spinal cord compression.

METHODS

Patients were positioned prone on the MRI table under general anesthesia. Fiducial markers were applied on the skin of the back, and a plastic cradle was used to support the MRI coil. T2-weighted MRI sequences of the region of interest were exported to a standard navigation system. A reference array was sutured to the skin, and surface matching of the fiducial markers was performed. A navigated Jamshidi needle was advanced until contact was made with the dorsal elements; its position was confirmed with intraoperative fluoroscopy prior to advancement into a target in the epidural space. A screenshot of its final position was saved, and then the Jamshidi needle was exchanged for an MRI-compatible access cannula. MRI of the exact axial plane of each access cannula was obtained and compared with the corresponding screenshot saved during positioning. The discrepancy in millimeters between the trajectories was measured to evaluate accuracy of the image guidance

RESULTS

Thirteen individuals underwent implantation of 47 laser probes. The median absolute value of the discrepancy between the location predicted by the navigation system and the actual position of the access cannulas was 0.7 mm (range 0–3.2 mm). No injury or adverse event occurred during the procedures.

CONCLUSIONS

This study demonstrates the feasibility of image guidance based on MRI to perform laser interstitial thermotherapy of spinal metastasis. The authors' method permits excellent visualization of the spinal cord, improving safety and workflow during laser ablations in the epidural space. The results can be extrapolated to other indications, including biopsies or drainage of fluid collections near the spinal cord.

Neuronavigation in minimally invasive spine surgery

OBJECT

Parallel advancements in image guidance technology and minimal access techniques continue to push the frontiers of minimally invasive spine surgery (MISS). While traditional intraoperative imaging remains widely used, newer platforms, such as 3D-fluoroscopy, cone-beam CT, and intraoperative CT/MRI, have enabled safer, more accurate instrumentation placement with less radiation exposure to the surgeon. The goal of this work is to provide a review of the current uses of advanced image guidance in MISS.

METHODS

The authors searched PubMed for relevant articles concerning MISS, with particular attention to the use of image-guidance platforms. Pertinent studies published in English were further compiled and characterized into relevant analyses of MISS of the cervical, thoracic, and lumbosacral regions.

RESULTS

Fifty-two studies were included for review. These describe the use of the iso-C system for 3D navigation during C1-2 transarticular screw placement, the use of endoscopic techniques in the cervical spine, and the role of navigation guidance at the occipital-cervical junction. The authors discuss the evolving literature concerning neuronavigation during pedicle screw placement in the thoracic and lumbar spine in the setting of infection, trauma, and deformity surgery and review the use of image guidance in transsacral approaches.

CONCLUSIONS

Refinements in image-guidance technologies and minimal access techniques have converged on spinal pathology, affording patients the ability to undergo safe, accurate operations without the associated morbidities of conventional approaches. While percutaneous transpedicular screw placement is among the most common procedures to benefit from navigation, other areas of spine surgery can benefit from advances in neuronavigation and further growth in the field of image-guided MISS is anticipated.

Clinical characteristics and surgical outcomes of spinal intramedullary ependymal cysts

OBJECT

Intramedullary ependymal cysts are exceedingly rare lesions, and have been previously reported in the literature as case reports. The aim of this study was to discuss the clinical presentation and the outcomes of microsurgery for these benign lesions.

METHODS

The authors retrospectively reviewed the records of ten patients who underwent microsurgery for intramedullary ependymal cysts. All patients had preoperative and postoperative magnetic resonance imaging. The surgical treatment included gross total resection and biopsy plus a cyst-subarachnoid shunt. The diagnosis of intramedullary ependymal cysts was based on radiological and pathological criteria. All patients were followed up, with a mean duration of 47.6 months.

RESULTS

Intramedullary ependymal cysts were hypointense on T1-weighted images and hyperintense on T2-weighted images. Contrast-enhanced T1-weighted images showed no enhancement. Gross total resection was achieved in one case. Biopsy of the cyst wall plus cyst-subarachnoid shunt placement was achieved in nine cases. Long-term neurological function was improved in eight patients. No recurrence was observed on magnetic resonance imaging.

CONCLUSIONS

Ependymal cysts should be considered in the differential diagnosis of intramedullary cysts. For symptomatic patients, early surgery should be performed before neurological deficits deteriorate. Complete decompression and cyst-subarachnoid shunt placement is the optimal treatment and the outcome may be favorable.

Multilobed cystic dilation of the ventriculus terminalis (CDVT)

The cystic dilation of ventriculus terminalis (CDVT) is a rare anatomical variant in adulthood. In this report we describe a new case of an adult with multilobed CDVT, causing low-back pain and subjective disturbances in walking. A myelotomy with fenestration of the cyst was performed with a good clinical and radiological outcome.

Computer-assisted fluoroscopic navigation of percutaneous spinal interventions

PURPOSE

Percutaneous spine procedures may occasionally be difficult and subject to complications. Navigation using a dynamic reference base (DRB) may ease the procedure. Yet, besides other shortcomings, its fixation demands additional incisions and thereby defies the percutaneous character of the procedure.

METHODS

A new concept of atraumatic referencing was invented including a special epiDRB. The accuracy of navigated needle placement in soft tissue and bone was experimentally scrutinised. Axial and pin-point deviations from the planned trajectory were investigated with a CT-based 3D computer system. Clinical evaluation in a series of ten patients was also done.

RESULTS

The new epiDRB proved convenient and reliable. Its fixation to the skin with adhesive foil provided a stable reference for navigation that improves the workflow of percutaneous interventions, reduces radiation exposure and helps avoid complications.

CONCLUSIONS

Percutaneous spine interventions can be safely and accurately navigated using epiDRB with minimal trauma or radiation exposure and without additional skin incisions.