Biomechanical comparison of traditional and minimally invasive intradural tumor exposures using finite element analysis

Does Minimally Invasive Hemilaminectomy for Intradural Extramedullary Tumor Resection Prevent Postlaminectomy Kyphosis or Lordosis Loss?

BACKGROUND

Minimally invasive hemilaminectomy is a safe and effective alternative to open laminectomy for treating intradural extramedullary tumors. There are no reports of postoperative kyphosis after this approach. This study aims to determine whether performing minimally invasive spine surgery hemilaminectomy for intradural extramedullary tumors can prevent the development of postlaminectomy kyphosis (PLK) or lordosis loss.

MATERIAL AND METHODS

Sixty-five patients with spinal intradural extramedullary tumors who underwent minimally invasive hemilaminectomy surgery and complete pre and postoperative radiologic imaging were included. The effect of the surgical approach on the spinal sagittal axis was assessed by comparing pre- versus postoperative segmental and local Cobb angles at different spinal levels, considering anatomical localization (cervical, thoracic, lumbar, and transition segments) and functional features (mobile, semi-rigid, and transition segments), as well as the extent of the surgical approach (1, 2, or 3 levels) and follow-up.

RESULTS

None of the patients had an increase in thoracic kyphosis nor a loss of cervical or lumbar lordosis greater than or equal to 10° after undergoing the minimally invasive spine surgery hemilaminectomy approach. More than 5° of increase in kyphosis was detected on 7.4% and 11.1%, for the segmental and the local angles, respectively; meanwhile, for patients with loss of lordosis, this deviation was detected in 5.3%, for both angles. The occurrence of PLK was more common than that of lordosis loss, but mainly manifested in postoperative angle impairment of less than 5°. No significant differences were evidenced, considering the approach length.

CONCLUSIONS

Hemilaminectomy represents a promising approach for preventing PLK and postlaminectomy lordosis loss following intradural extramedullary tumor resection.

Functional outcome after introduction of hemilaminectomy in management of spinal schwannomas and meningiomas

Background

Schwannomas and meningiomas are intradural extramedullary spinal tumors which are regularly encountered in the neurosurgical clinic. These tumors cause neurological deficit by compression on the spinal cord and commonly pain when affecting the cauda equina. The traditional treatment with standard laminectomy (SL) can cause instability to the dorsal segments of the spinal column, and the less invasive option of hemilaminectomy (HL) has therefore been developed. We aim in this study to investigate transition from SL to HL in a population-based cohort.

Methods

Adult patients (18 years and older) undergoing primary surgery due to spinal meningioma or schwannoma between 2007 and 2022 at the neurosurgical clinic were included. Data related to clinical, surgical and outcome variables were retrospectively collected.

Results

A total of 187 patients were identified: 155 in the SL group, 26 in the HL group and in 6 patients a combination of SL and HL. The mean age of the SL group was 62.7 years (SD14.2) compared to 58.0 (SD15.7) in the HL group (p = 0.16). Preoperative motor deficit was more common in SL group compared to HL group (76.8 % and 61.5 %, respectively, p = 0.14). Thoracal location was most common for both groups (SL 65.8 % and HL 61.5 %). Postoperative change in McCormick grades and early complications were similar between groups.

Conclusion

Outcome after hemilaminectomy due to intradural extramedullary schwannoma or meningioma is comparable to standard laminectomy with regards to postoperative complications and neurological improvement. Our findings support the transition to hemilaminectomy in selected cases.

Single-Center Experience of Resection of 120 Cases of Intradural Spinal Tumors

BACKGROUND

Our study presents a single-center experience of resection of intradural spinal tumors either with or without using intraoperative computed tomography-based registration and microscope-based augmented reality (AR). Microscope-based AR was recently described for improved orientation in the operative field in spine surgery, using superimposed images of segmented structures of interest in a two-dimensional or three-dimensional mode.

METHODS

All patients who underwent surgery for resection of intradural spinal tumors at our department were retrospectively included in the study. Clinical outcomes in terms of postoperative neurologic deficits and complications were evaluated, as well as neuroradiologic outcomes for tumor remnants and recurrence.

RESULTS

112 patients (57 female, 55 male; median age 55.8 ± 17.8 years) who underwent 120 surgeries for resection of intradural spinal tumors with the use of intraoperative neuromonitoring were included in the study, with a median follow-up of 39 ± 34.4 months. Nine patients died during the follow-up for reasons unrelated to surgery. The most common tumors were meningioma (n = 41), schwannoma (n = 37), myopapillary ependymomas (n = 12), ependymomas (n = 10), and others (20). Tumors were in the thoracic spine (n = 46), lumbar spine (n = 39), cervical spine (n = 32), lumbosacral spine (n = 1), thoracic and lumbar spine (n = 1), and 1 tumor in the cervical, thoracic, and lumbar spine. Four biopsies were performed, 10 partial resections, 13 subtotal resections, and 93 gross total resections. Laminectomy was the common approach. In 79 cases, patients experienced neurologic deficits before surgery, with ataxia and paraparesis as the most common ones. After surgery, 67 patients were unchanged, 49 improved and 4 worsened. Operative time, extent of resection, clinical outcome, and complication rate did not differ between the AR and non-AR groups. However, the use of AR improved orientation in the operative field by identification of important neurovascular structures.

CONCLUSIONS

High rates of gross total resection with favorable neurologic outcomes in most patients as well as low recurrence rates with comparable complication rates were noted in our single-center experience. AR improved intraoperative orientation and increased surgeons' comfort by enabling early identification of important anatomic structures; however, clinical and radiologic outcomes did not differ, when AR was not used.

Hemilaminectomy for the removal of the spinal tumors: An analysis of 901 patients

Objective

We report our experience with the use of hemilaminectomy approach for the removal of benign intraspinal tumors.

Method

A retrospective review of 1,067 patients who underwent hemilaminectomy in our hospital between 2013 and 2019 was analyzed. Baseline medical data were collected. One hundred sixteen patients were excluded due to degenerative diseases, spinal bone tumors, and malignant tumors. The remaining 901 patients (916 tumors) were enrolled. The Dennis Pain Scale (DPS) was used to assess improvement in pain before surgery and during long-term follow-up. Neurological status was assessed using the American Spinal Injury Association (ASIA) impairment scale.

Results

The age of the patients was 48.7 ± 15.3 years, the duration of symptoms was 16.5 ± 32.0 months, and the tumor size was 2.6 ± 1.4 cm. Three hundred two tumors were located in the cervical region, 42 in the cervicothoracic region, 234 in the thoracic region, 57 in the thoracolumbar region, and 281 in the lumbar and lumbosacral region. Twenty-three tumors were ventrally located, 677 were dorsal or dorsolateral, 63 were intramedullary, 87 were epidural, and the rest were dumbbell-shaped. The most common pathologies were schwannomas (601, 66.7%) and meningiomas (172, 19.1%). Total excision was achieved at 97.8%. The operative time was 94.3 ± 32.6 min and the blood loss during surgery was 96.9 ± 116.5 ml. The symptom of pain improved in 87.0% of patients during long-term follow-up, neurological function improved in 68.3% and remained unchanged at 30.5%.

Conclusion

The hemilaminectomy approach was a rapid and safe procedure to remove intradural and extradural tumors. This approach has offered several advantages. It could be used for the resection of most extradural or intradural extramedullary lesions, even some intramedullary tumors.

Endoscopic intradural extramedullary lesion excision: Results of augmented duroplasty with artificial dura

Objectives

Prevailing techniques of dural closure in endoscopic spine surgery (ESS) for intradural extramedullary (IDEM) tumor excision increase the steep learning curve and operative time. We aimed to assess the efficacy of augmented duroplasty with artificial dura and share our initial experience of ESS for IDEM excision.

Materials and Methods

We retrospectively analyzed 18 (n = 18) consecutive patients of IDEM tumors operated by ESS using Destandau's endoscopic system. The pre-operative, post-operative, and at the latest follow-up clinical status were recorded in terms of Nurick's grades and the Oswestry Disability Index. Immediate post-operative complications and intraoperative findings were noted from hospital information system and patient records.

Results

The mean (± SD) age of patients was 40.3 ± 14.9 (range 19-64) years, with M: F ratio of 2:1. All the lesions were intradural and present at lumber (n = 6), thoracic (n = 9), and cervical (n = 3) regions. The average duration of surgery, blood loss, hospital stay, and duration of follow-up were 157 ± 45.3 (90-240) min, 168.8 ± 78.8 (30-300) mL, 4.29 ± 1.4 (2-7) days, and 19.3 ± 7.2 (7-36) months, respectively. There were no CSF leaks, wound-related complications, or material-induced adverse events.

Conclusion

In endoscopic IDEM excision, dural closure with artificial dura is efficient in preventing CSF leak. It shortens the steep learning curve and improves the surgical outcome due to technical ease.

Microsurgical Tubular Resection of Intradural Extramedullary Spinal Tumors With 3-Dimensional-Navigated Localization

BACKGROUND

The safety and efficacy of minimally invasive spine surgical (MISS) approaches have stimulated interest in adapting MISS principles for more complex pathology including intradural extramedullary (IDEM) tumors. No study has characterized a repeatable approach integrating the MISS surgical technique and 3-dimensional intraoperative navigated localization for the treatment of IDEM tumors.

OBJECTIVE

To describe a safe and reproducible technical guide for the navigated MISS technique for the treatment of benign intradural and extradural spinal tumors.

METHODS

Retrospective review of prospectively collected data on 20 patients who underwent navigated microsurgical tubular resection of intradural extramedullary tumors over a 5-year period. We review our approach to patient selection and report demographic and outcomes data for the cohort.

RESULTS

Our experience demonstrates technical feasibility and safety with a 100% rate of gross total resection with no patients demonstrating recurrence during an average follow-up of 20.2 months and no instances of perioperative complications. We demonstrate favorable outcomes regarding blood loss, operative duration, and hospital length of stay.

CONCLUSION

Navigated localization and microsurgical tubular resection of IDEM tumors is safe and effective. Adherence to MISS principles and thoughtful patient selection facilitate successful management of these patients.

One step excision combined with unilateral transforaminal intervertebral fusion via minimally invasive technique in the surgical treatment of spinal dumbbell-shaped tumors: A retrospective study with a minimum of 5 years’ follow-up

Introduction

Spinal dumbbell-shaped tumors are rare, usually benign tumors with intraspinal and paravertebral components connected through intervertebral foramen. Complete excision is often performed through traditional open surgery (TOS). The efficacy and long-term outcomes of minimally invasive surgery (MIS) have not been reported to date in resection of dumbbell-shaped spinal tumors.

Purpose

The purpose was to evaluate the efficacy and long-term outcomes of minimally invasive resection combined with unilateral transforaminal intervertebral fusion (TIF) through comparing with TOS in the treatment of spinal dumbbell-shaped tumors.

Methods

Fifteen patients underwent MIS and 18 patients underwent TOS. Thoracic dumbbell-shaped tumors were directly exposed after removal of costotransverse joints, adjacent rib components, unilateral hemilamina, and facet joints. Lumbar dumbbell-shaped tumors were completely exposed after removal of transverse processes, unilateral hemilamina, and facet joints. Whether for minimally invasive resection or traditional open removal, dumbbell-shaped tumors were completely excised and unilateral TIF was performed to guarantee spinal stability. All patients were followed up for 5 years at least.

Results

The mean length of surgical incision for two groups was 3.47 ± 0.37 vs. 6.49 ± 0.39 cm (p < 0.05). The average duration of the operation was 131.67 ± 26.90 vs. 144.17 ± 23.59 min (p > 0.05). The mean blood loss was 172.00 ± 48.79 vs. 285.83 ± 99.31 ml (p < 0.05). No blood transfusions were required in the two groups. The median length of hospitalization was 6 vs. 10 days (range: 5–8 vs. 7–14 days). The patients of two groups were monitored for an average of 65.93 ± 3.88 vs. 65.78 ± 3.56 months. At 5-year follow-up, all patients presented with normal neurological function (American Spinal Injury Association scale E). The Oswestry Disability Index in the MIS group decreased significantly more than the TOS group. No spondylolisthesis or spinal instability were found in the follow-up period. There was no recurrence of any spinal tumor 5 years after surgery.

Conclusions

Spinal dumbbell-shaped tumors can be safely and effectively treated with minimally invasive resection combined with unilateral TIF. Compared with TOS, MIS offers a reduced length of surgical incision, blood loss, hospital stay, and postoperative pain. This surgical protocol might provide an alternative for the treatment of spinal dumbbell-shaped tumors.

Biomechanical effect of posterior ligament repair in lamina repair surgery

Cervical laminectomy has usually been applied in treating cervical spinal cord tumour. However, spinal instability after laminectomy was observed with high occurrence rate, due to excising of posterior structures. This study was to investigate the biomechanical performances of ligament repair on the cervical stability in lamina repair surgery. A finite element of cervical spine model (C2-C7) was developed, and lamina repair surgery with and without ligament repair was simulated at C3-C6 segments. All models were loaded with pure moment of 1.5 Nm to produce flexion, extension, lateral blending and axial torsion. Compared to intact model, the range of motion (ROM) at C2-C3, C6-C7 increased by 12.8%-113.6% in lamina repair model (LRM), while the change of ROM in other segments was less than 9.2%. The change of ROM in all segments in the lamina and ligament repair model (LLRM) was less than 7.2%. The maximal intradiscal pressure (IDP) in adjacent segment (C2-C3 and C6-C7) increased by 73.7%, and the maximal stresses in capsular ligament increased by 168.6% in LRM model. By the other hand, the change of facet joint contact stress, IDP and stresses in capsular ligament in LLRM model were less than 11.5%. The differences of stresses on bone-screw interface and screw-plate system in C4,C5 between LRM and LLRM were less than 5.9 MPa (2.7%), but this value in C3 and C6 were up to 105.7 MPa (41.8%). Laminectomy without reconstruction of posterior ligament resulted larger mobility in the adjacent segments, which might induce spinal instability as postoperative complications. Repairing or preserving the posterior ligament in the lamina repair is benefit to spinal integrity and stability.

Minimally Invasive Removal of Extra- and Intradural Spinal Tumors Using Full Endoscopic Visualization

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

To evaluate the clinical efficacy of minimally invasive endoscopic surgery in patients with spinal extradural and intradural-extramedullary tumors.

METHODS

This was a study of 15 consecutive patients with spinal extradural or intradural-extramedullary tumors up to 2 levels treated by minimal invasive surgery using a full endoscopic visualization and Caspar's retraction system (for cervical, thoracic, and lumbar tumors) over a 4-year period between January 2015 to April 2019 at a tertiary center.

RESULTS

A gross total remove was achieved in all patients (100%), determined by postoperative contrast computed tomography scans and magnetic resonance imaging. There was no postoperative spinal instability. All patients had equal or better neurologic functions after surgery at follow-up. The average preoperative Nurick's grade mean was 1.9 and the postoperative was 1.1. The average preoperative McCormick's grade mean was 2.9 versus 1.3 in the postoperative period.

CONCLUSIONS

Selective extradural or intradural-extramedullary tumors well localized and up to 2 levels can be safely and effectively treated by minimally invasive surgery using a full endoscopic visualization and the Caspar's retractor. However, there is insufficient evidence to recommend this approach over the classical or other microsurgical approach described.

Feasibility of unilateral hemilaminectomy utilizing a Williams retractor for the resection of intradural-extramedullary spinal neoplasms

BACKGROUND

While open approaches have historically been used in the surgical treatment of intradural-extramedullary spine tumors, minimally-invasive surgical (MIS) techniques are frequently applied to minimize post-operative complications associated with open surgery. Tubular retractor systems in particular have been employed in combination with the unilateral hemilaminectomy (UHL) approach. Here we describe the use of a Williams retractor as a safe and effective minimally-invasive alternative to tubular retractor systems with similar post-operative outcomes.

METHODS

We retrospectively reviewed a cohort of eight patients who underwent unilateral hemilaminectomy using a Williams retractor for the minimally-invasive resection of intradural-extramedullary neoplasms at a large tertiary academic center from 2017 to 2019. Patient demographics, pathologic specimens, radiographic studies, and intraoperative parameters were collected and analyzed.

RESULTS

In our series, gross total resection was achieved in all cases. Average operative time was 158±40minutes, the mean estimated blood loss (EBL) was 44.4±30.4mL, and mean length of stay was three days. All patients reported symptomatic improvement at follow-up as reported by Visual Analog Scale scores.

CONCLUSION

A Williams retractor yields similar outcomes with respect to post-operative pain, operative time, and EBL as it maintains the advantages of the UHL approach in the resection of intradural-extramedullary spine tumors while enhancing feasibility and providing significant cost savings.

Minimally Invasive Resection of Spinal Tumors with Tubular Retractor: Case Series, Surgical Technique, and Outcome

BACKGROUND

Traditional laminectomy for excision of spinal tumors involves extensive dissection of the midline spinous ligaments, greater blood loss, and risk of delayed segmental instability. The minimally invasive technique of spinal tumor resection using tubular retractors can achieve safe and complete tumor resection while preserving the structural and functional integrity. The authors present their experience of minimally invasive spinal surgery for spinal tumors in this case series.

METHODS

The authors retrospectively reviewed 41 consecutive spinal tumor cases operated by the MISS-Key Hole technique using the tubular retractor system at Sree Utharadom Thirunal Hospital, Kerala, India between January 2015 and January 2020. Preoperative clinical findings, surgical technique, operative statistics, complications, and patient outcomes were analyzed in detail.

RESULTS

We could successfully achieve gross total resection in 39 cases (95.12%) and subtotal resection in 2 cases. There were 4 cervical, 1 craniovertebral junction, 20 thoracic, 14 lumbar, and 2 sacral lesions, of which 4 were extradural, 1 extradural foraminal, 33 intradural, and 3 dumbbell lesions. The Modified McCormick Scale at 12 weeks had improved by 1-2 scales in all but 2 patients. There was no cerebrospinal fluid leak, pseudomeningocele, or infection in our series.

CONCLUSIONS

This series demonstrates the feasibility, safety and effectiveness of the keyhole approach for excision of intradural and extradural spinal tumors extending up to 2 levels. Careful case selection, good preoperative planning, meticulous microsurgical resection, and watertight dural closure are crucial for successful outcome. Early mobilization, less blood loss, and avoidance of delayed instability are the advantages of minimally invasive spinal surgery when compared with open surgery.

Abordaje mínimamente invasivo para el tratamiento de tumores espinales intradurales extramedulares: Nota Técnica

Objetivo:

Describir la técnica de abordaje mínimamente invasiva para el tratamiento de tumores intradurales extramedulares en los diferentes segmentos espinales.

Material y Métodos:

Se detallan la planificación, posicionamiento, marcación, pasos técnicos del abordaje mínimamente invasivo, exéresis lesional y cierre de lesiones ID-EM a nivel cervical, dorsal, lumbar y sacro. Se proporcionan recomendaciones para descomplejizar maniobras quirúrgicas, acortar el tiempo operativo y evitar potenciales complicaciones.

Conclusiones:

El abordaje MISS es una opción segura y eficaz para el tratamiento quirúrgico de determinados tumores ID-EM.

Radiologic Efficacy and Patient Satisfaction after Minimally Invasive Unilateral Laminotomy and Bilateral Decompression in Patients with Lumbar Spinal Stenosis: A Retrospective Analysis

BACKGROUND AND STUDY AIMS

 Lumbar spinal stenosis (LSS) is the most common spinal disease in older adults. Although surgical modalities are recommended in patients who are unresponsive to conservative treatment, the most appropriate minimally invasive surgical procedure for patients with LSS remains controversial. Moreover, few previous studies have focused on patient-centered outcomes with radiologic correlation. In the present study, we aimed to investigate radiologic efficacy and patient satisfaction following bilateral decompression via unilateral laminotomy.

MATERIALS AND METHODS

 We performed a retrospective analysis of radiologic efficacy and patient satisfaction in a series of surgical patients treated at our institution. We classified patients into two groups based on the primary pathology (i.e., central or lateral recess stenosis). Medical records were analyzed retrospectively for radiologic outcomes and clinical parameters including pain and changes in quality of life. Data related to outcomes were collected at 2 weeks, 3 months, and 12 months after surgery in the outpatient clinic.

RESULTS

 Among the 122 patients enrolled in this study, 51 had central spinal stenosis; 71 had lateral recess stenosis. Radiologically, we observed significant improvements in the anteroposterior diameter and cross-sectional area of the dural sac (central stenosis) and the lateral width of the central canal and depth of the lateral recess (lateral recess stenosis). Two weeks and 12 months after the surgical procedure, we observed significant improvements in the extent of symptoms, patient satisfaction, and quality of life (including physical function).

CONCLUSION

 Our findings suggest that bilateral decompression via a unilateral approach shows improved radiologic outcomes, varying based on the type of stenosis. Furthermore, patient satisfaction significantly improved regardless of the type of disease.

[Biomechanical changes of sheep cervical spine after unilateral hemilaminectomy and different degrees of facetectomy]

OBJECTIVE

To establish animal models and investigate the impact of unilateral hemilaminectomy (ULHL) and different degrees of facetectomy (FT) on the cervical spinal biomechanics.

METHODS

Twenty sheep were randomly and evenly divided into 4 groups. No operation was performed for group A, right C4-C6 ULHL was performed for group B, right C4-C6 ULHL and 50% ipsilateral C4-C5 FT was performed for group C, right C4-C6 ULHL and 100% ipsilateral C4-C5 FT was performed for group D. Animals of group A, B, C and D were sacrificed 24 weeks after operating and fresh cervical spine specimens were acquired, biomechanically tested and these data were compared to determine whether ULHL and different degrees of FT led to long-term differences in range of motion.

RESULTS

(1) Changes of the total range of motion of cervical spine 24 weeks after surgery: the total range of motion of group D (60.2°±8.6°) was significantly greater than group A (40.7°±6.4°) and group B (41.2°±13.1°) under flexion-extension station, the total range of motion of group D (81.5°±15.7°) was significantly greater than that of group A (56.7°±12.2°) and group B (57.7°±12.8°) under lateral bending station, and the total range of motion of group D (38.5°±17.5°) had no obvious increase compared with group A (26.4°±9.9°) and group B (27.1°±10.9°) under axial rotation station. The total range of motion of group C had no obvious increase compared with group A and group B under flexion-extension station (44.1°±11.7°), lateral bending station (73.6°±11.4°) and axial rotation station (31.3°±11.5°). (2) Changes of the intersegmental motion 24 weeks after surgery: the intersegmental motion of group D (20.3°±4.6°) at C4-C5 was significantly greater than that of group A (11.7°±3.4°) and group B (11.9°±2.1°) under flexion-extension station, the intersegmental motion of group D (26.8°±3.5°) at C4-C5 was significantly greater than that of group A (15.2°±3.1°) and group B (16.2°±3.2°) under lateral bending station, the intersegmental motion of group D (15.2°±3.5°) at C4-C5 was significantly greater than that of group A (6.6°±2.3°) and group B (7.1°±1.9°) under axial rotation station. The intersegmental motion of group C (21.2°±4.1°) at C4-C5 was significantly greater than that of group A and group B under lateral bending station, the intersegmental motion of group C at C4-C5 had no obvious increase compared with group A and group B under flexion-extension station (15.7°±3.7°) and axial rotation station (10.3°±3.1°).

CONCLUSION

ULHL does not affect cervical stability, ULHL and 50% ipsilateral FT does not affect the long-term cervical stability, ULHL and 100% ipsilateral FT can lead to long-term instability under lateral bending and flexion-extension station.

Microscopic Keyhole Technique for Surgical Removal of Thoracic Spinal Meningiomas

OBJECTIVE

The aim of this study was to evaluate the safety and efficacy of the microscopic minimally invasive keyhole technique for surgical resection of thoracic spinal meningiomas.

METHODS

Seventeen consecutive patients with thoracic spinal meningiomas were included in the series from May 2015 to August 2017. All patients were treated using a microscopic keyhole technique through a tubular retractor system. The demographic data and perioperative variables were recorded. At last follow-up, clinical outcome was assessed using the visual analog scale for pain and the American Spinal Injury Association scale for motor and sensory outcome.

RESULTS

All patients underwent microscopic keyhole surgery and complete resection was achieved. Mean operative time was 153.2 minutes (range 115-300 minutes). Mean blood loss during surgery was 110.3 mL (range 50-175 mL). No infection or aggravation of spinal cord injury occurred after operation, except for 2 patients who had postoperative cerebrospinal fluid leakage that recovered after conservative treatment. The mean duration of hospital stay was 6.8 days (range 5-10 days). At the last follow-up, all patients had a reduced level of pain as suggested by an average visual analog scale score that improved from 7.6 to 0.2. The American Spinal Injury Association grade improved or remained normal in all patients except 1. No evidence of tumor recurrence or secondary spinal deformity was observed in any patients during the postoperative follow-up period, and spinal stabilities were found to be satisfactory.

CONCLUSIONS

Based on our results, the microscopic minimally invasive keyhole technique can be used safely and effectively for resection of thoracic spinal meningiomas.

Hemilaminectomy for Spinal Cord Intradural Tumors: An Institutional Experience

Introduction:

Laminectomy is the workhorse of spinal cord tumor surgery. This procedure is not without the debilitating sequelae of postoperative pain and delayed kyphosis. Hemilaminectomy is an alternate option to laminectomy which offers the advantage of preserving the posterior supporting structures of the spine on the contralateral side. In this study, we analyze the outcome of hemilaminectomy clinically with improvement in pain scores and Nurick's grade as well as radiologically by assessing for the development of delayed kyphosis. We also discuss the technique and operative nuances of hemilaminectomy in intradural extramedullary tumors of the spinal cord.

Materials and Methods:

All patients with intradural spinal cord tumors were included in the study. All patients underwent unilateral hemilaminectomy (UHL) depending on the laterality of the tumor on the preoperative magnetic resonance imaging. Preoperative neurologic status was assessed with Nurick's grade for tumors involving the cervicothoracic region tumors, and visual analog scale scores were recorded for tumors of Thoracic, Lumbar and Lumbosacral regions. The postoperative outcomes were assessed by improvement in respective scales on follow-up. The occurrence of delayed spinal deformity was assessed by follow-up X-rays. Any complications whether intraoperative or postoperative were recorded.

Results:

There were a total of 34 cases of intradural extramedullary tumors in this study. Patient population consisted of 11 males and 23 females. Total excision was achieved in 31 patients. In three patients, we were unable to achieve complete removal through UHL. In these patients the procedure was converted to total laminectomy. They were excluded from analysis. The distribution of the tumors was in cervical, cervicothoracic, thoracic, lumbar, and lumbosacral region. All patients presented with pain or varying degrees or neurologic deficits. Sixteen patients underwent UHL from the right side, while 18 from the left. There were no intraoperative complications. The neurological status and pain scores of all patients improved postoperatively at 3 and 6 months of follow-up. There was no radiological evidence of kyphosis of the involved segment.

Conclusion:

With a small learning curve, UHL is a good corridor for the removal of intradural extramedullary spinal cord tumors. This approach offers the advantage of less postoperative pain and no postoperative deformity.

[Surgical treatment of intradural extramedullary lesions by hemilaminectomy]

OBJECTIVE

To evaluate the usefulness of hemilaminectomy as a surgical approach in patients with intradural-extramedullary tumors.

METHODS

Retrospective analysis of patients in which hemilaminectomy was as surgical approach in intradural-extramedullary tumors between June 2006 and December 2015. Demographics, preoperative symptoms, imaging characteristics, intraoperative findings, histological lineage, and postsurgical complications were analyzed. The average follow-up was 48.9 months (6-120 months).

RESULTS

Fifty-three patients underwent hemilaminectomy. Tumor was located in the cervical level in 5 cases, in the dorsal level in 24, and in the lumbar region in 24 cases. Histological analysis revealed 28 neuromas, 11 meningiomas, 7 ependymomas, and 7 "multiple injuries." Total resection without postsurgical neurologic deficit was possible in 96% of the patients. There were no recurrences on follow-up.

CONCLUSION

Hemilaminectomy is an effective approach for the resection of lateralized cervicodorsal intradural-extramedullary tumors. It can also be used to treat midline lesions located in the lumbar level.

Minimally Invasive Excision of Thoracic Arachnoid Web

OBJECTIVE

Arachnoid webs are rare intradural lesions that can cause direct spinal cord compression or alteration of the cerebrospinal fluid flow with syringomyelia. Surgery has been historically performed through wide-open laminectomies. The aim of this study is to prove the feasibility of minimally invasive techniques for the excision of arachnoid webs.

METHODS

A retrospective review of two cases of minimally invasive excision of thoracic arachnoid webs was performed. Surgery was undertaken through expandable tubular retractors.

RESULTS

Complete excision was achieved through the described approach, with minimal bony removal and soft tissue disruption. There were no intraoperative or perioperative complications. Both patients were mobilized early and discharged home within 24 hours after surgery. Postoperative imaging showed good re-expansion of the spinal cord, with no evidence of residual compression or tethering.

CONCLUSIONS

For symptomatic arachnoid webs, surgery remains the only definitive treatment. In expert hands, the excision of arachnoid webs can be achieved with tubular retractors and minimally invasive techniques.

Assessment of Paraspinal Muscle Cross-sectional Area After Lumbar Decompression: Minimally Invasive Versus Open Approaches

STUDY DESIGN

A retrospective, blinded analysis of imaging studies.

SUMMARY OF BACKGROUND DATA

To evaluate changes in paraspinal muscle cross-sectional area (CSA) after surgical treatment for lumbar stenosis and to compare these changes between minimally invasive and standard open approaches. The open approach to lumbar stenosis is effective, but it involves retraction and resection of muscle from the spinous process, which can result in ischemia and denervation of paraspinal musculature and may lead to muscle atrophy and pain.

OBJECTIVE

It is hypothesized that the microendoscopic decompression of stenosis (MEDS) technique will better preserve the paraspinal muscles compared with the open procedure.

MATERIALS AND METHODS

A total of 18 patients underwent a 1-level posterior decompression for lumbar stenosis, (9 open, 9 MEDS). Lumbar magnetic resonance imaging was obtained before surgery and after surgery (open approach average 16.3 mo; MEDS average 16.6 mo). CSA of paraspinal muscles were averaged over the distance of the surgical site.

RESULTS

The mean age of patients treated with the open and MEDS approaches were 55.2 and 66.4 years, respectively (P=0.07). Paraspinal muscle CSA decreased by an average of 5.4% (SD=10.6%; range, -24.5% to +7.7%) in patients treated with the open approach and increased by an average of 9.9% (SD=14.4%; range, -9.8% to +33.1%) in patients treated with MEDS (P=0.02). For the open approach, changes in CSA did not differ significantly between the left and right sides for erector spinae (P=0.35) or multifidus muscles (P=0.90). After the MEDS approach there were no significant differences between the dilated and contralateral sides with regard to change in CSA for erector spinae (P=0.85) or multifidus muscles (P=0.95).

CONCLUSIONS

Compared with the open approach for lumbar stenosis, MEDS had significantly less negative impact on the paraspinal muscle CSA. Previous reports have documented negative effects of paraspinal muscle injury, including weakness, disability, and pain. Collectively, these data suggest that the MEDS approach for lumbar decompression is less destructive to the paraspinous muscles than the open approach and may facilitate better clinical outcomes.

Minimally invasive surgery for resection of ossification of the ligamentum flavum in the thoracic spine

Introduction

Thoracic ossification of the ligamentum flavum (TOLF) is a common cause of progressive thoracic myelopathy. Surgical decompression is commonly used to treat TOLF.

Aim

To evaluate the clinical outcomes of microsurgical decompression of TOLF via a paraspinal approach, using a percutaneous tubular retractor system.

Material and methods

First, three-dimensional (3D) image reconstruction and printed models were made from thin computed tomography scans for each patient. Then, 3D computer-assisted virtual surgery was performed using the 3D reconstruction to calculate the precise location and sizes of the bone window and the angle of insertion of the percutaneous tubular retractor system. In total, 13 patients underwent the surgery through the percutaneous micro channel unilateral vertebral approach under electrophysiological monitoring. Five days after the surgery, increased creatine phosphokinase levels returned to preoperative levels. The Japanese Orthopedic Association (JOA) score was improved and computed tomography reconstruction and magnetic resonance imaging of the thoracic spine showed that decompression was achieved without injuries to the spinal cord or nerve root. The stability of the spine was not affected, nor were any deformities of the spine detected. Finally, nerve functional recovery was achieved with minimal injury to the paraspinal muscle, articulum, spinous process and ligament.

Results

The mean operative time was 98.23 ±19.10 min, and mean blood loss was 19.77 ±5.97 ml. At a mean follow-up of 13.3 months (median: 12 months), the mean JOA score was 7.54 ±1.13 at the final follow-up, yielding a mean RR of 49.10 ±15.71%. Using The recovery rate, 7 (53.85%) patients had good outcomes, 5 (38.46%) patients had a fair outcome, and 1 (7.69%) patient had poor outcomes, indicating significant improvement by the final follow-up examination (p < 0.05).

Conclusions

The 3D printed patient model-based microsurgical resection of TOLF via the paraspinal approach can achieve decompression of the spinal canal with minimal complications, faster recovery and improved stability of the vertebral body.

Unilateral Hemilaminectomy for Intradural Lesions

OBJECTIVE

Unilateral hemilaminectomy (UHIL), an alternative surgical approach to intradural lesions, involves a unilateral approach to meningeal opening that provides an adequate window for tumor extraction while leaving most of the vertebral structures intact. The techniques and results of a modified hemilaminectomy technique with spinal endoscopy is discussed and limited unilateral hemilaminectomy for intradural tumors (UHIT) evaluated prospectively.

METHODS

Relevant clinical variables, operative reports, histological findings, pre- and post-operative imaging, and follow-up data for 11 consecutive patients (five males, six females; mean age 63.36 ± 20.69 years) who underwent modified hemilaminectomy over a 3 year time period were analyzed. Contrast-enhanced MRI was used to demonstrate the side, size and location of the suspected tumor or intradural lesion and CT to evaluate the bone anatomy. Post-operative MRI and CT allowed evaluation of anatomy following resection.

RESULTS

Lesions included meningiomas (n = 2), neuromas (n = 3), and metastases, cysts or gliomas (n = 6). Pre-operative indications in order of incidence included cord compression, claudication, lower back pain, radiculopathy, paraplegia, weakness, incontinence, and generalized neuro-deterioration. There were no major complications, and no spinal deformity or instability at final follow up (mean, 13 months; range, 3-36 months).

CONCLUSION

Our data suggest that there is a place for the UHIT approach. This minimally invasive approach is useful for resecting all intradural tumors. UHIL is a useful minimally invasive technique for resecting intradural spinal tumors with maximal preservation of musculoligamentous attachments and posterior bony elements and should be considered an improvement on currently employed techniques.

Anterior retroperitoneal approach for removal of L5-S1 foraminal nerve sheath tumor-case report

BACKGROUND CONTEXT

Extradural lumbar schwannomas are a rare form of nerve sheath tumors (NSTs). The typical management approach for extradural foraminal NSTs is total gross resection, which involves a midline incision and muscle exposure, followed by laminectomy and facetectomy to access the tumor for resection. Following tumor removal, spinal fusion is often indicated to reduce postoperative deformity, pain, and neurologic deficits.

PURPOSE

We report the case of a 34-year-old woman who presented with a 2-year history of progressive dysesthesia and left foot drop. Magnetic resonance imaging revealed a lesion in the lateral L5/S1 foramen. A novel anterior-retroperitoneal approach was used to access the tumor, via muscle splitting, retraction of peritoneum medially and psoas muscle or iliac vessels laterally.

STUDY DESIGN/SETTING

This study is a case report of a novel approach for extradural lumbar schwannomas.

METHODS

The methods involve a description of the approach and reporting of clinical findings.

RESULTS

The schwannoma was successfully resected without requiring additional fusion surgery. The patient recovered uneventfully and was discharged on day 2 post operation.

CONCLUSION

We propose that the anterior-retroperitoneal approach is a viable technique for resection of lumbar foraminal NSTs without the need for fusion surgery.

Perioperative Cost Analysis of Minimally Invasive vs Open Resection of Intradural Extramedullary Spinal Cord Tumors

BACKGROUND:

Minimally invasive spinal surgery (MIS) has emerged as a clinically effective tool but its cost-effectiveness remains unclear. No studies have compared MIS vs open surgical techniques for the treatment of intradural extramedullary (IDEM) tumors.

OBJECTIVE:

To analyze and compare open and MIS techniques for resection of IDEM tumors, with focus on perioperative costs.

METHODS:

Retrospective analysis of a prospectively collected database including 35 IDEM patients (18 open, 17 MIS). Perioperative data, hospital costs, and hospital and physician charges for in-hospital services associated with the index surgical procedure and readmissions within 90 days were compared.

RESULTS:

Mean estimated blood loss, operative time, preoperative hospital charges, and physician fees were similar between open and MIS techniques. Patient and tumor characteristics were similar between groups. MIS cases were associated with shorter intensive care unit and floor stay. There were 3 complications in the open group, requiring 2 readmissions and 1 reoperation. Hospital costs ($21 307.80 open, $15 015.20 MIS, P &lt; .01), and postoperative ($75 383.48 open, $56 006.88 MIS, P &lt; .01) and total charges ($100 779.38 open, $76 100.92 MIS, P &lt; .01) were significantly lower in the MIS group. There were no tumor recurrences in either group. All patients except for one in the open group maintained or improved their Nurick score.

CONCLUSION:

Both MIS and open techniques were able to adequately treat IDEM tumors. Reductions in complication rate and intensive care unit and hospital stay led to a decrease in hospital costs of almost 30% in the MIS group. MIS resection of IDEM tumors is not only an effective and safe option, but allows faster hospital discharge and significant cost savings.

Outcomes after minimally invasive lumbar decompression: a biomechanical comparison of unilateral and bilateral laminotomies

Background

The unilateral approach for bilateral decompression was developed as an alternative to laminectomy. Unilateral laminotomy has been rated technically considerably more demanding and associated with more perioperative complications than bilateral laminotomy. Several studies have indicated that bilateral laminotomy are associated with a substantial benefit in most outcome parameters and thus constituted a promising treatment alternative. However, no complete kinematic data and relative biomechanical analysis for evaluating spinal instability treated with unilateral and bilateral laminotomy are available. Therefore, the purpose of this study was to compare the stability of various decompression methods.

Methods

Ten porcine lumbar spines were biomechanically evaluated regarding their strain and range of motion, and the results were compared following unilateral or bilateral laminotomies and laminectomy. The experimental protocol included flexion and extension in the following procedures: intact, unilateral or bilateral laminotomies (L2–L5), and full laminectomy (L2–L5). The spinal segment kinematics was captured using a motion tracking system, and the strain was measured using a strain gauge.

Results

No significant differences were observed during flexion and extension between the unilateral and bilateral laminotomies, whereas laminectomy yielded statistically significant findings. Regarding strain, significant differences were observed between the laminectomy and other groups. These results suggest that laminotomy entails higher spinal stability than laminectomy, with no significant differences between bilateral and unilateral laminotomies.

Conclusions

The laminectomy group exhibited more instability, including the index of the range of motion and strain. However, bilateral laminotomy seems to have led to stability similar to that of unilateral laminotomy according to our short-term follow-up. In addition, performing bilateral laminotomies is easier for surgeons than adopting a unilateral approach for bilateral decompression. The results provide recommendations for surgeons regarding final decision making. Future studies conducting long-term evaluation are required.

Comparison of open and minimally invasive surgery for intradural-extramedullary spine tumors

OBJECT

Patients with symptomatic intradural-extramedullary (ID-EM) tumors may be successfully treated with resection of the lesion and decompression of associated neural structures. Studies of patients undergoing open resection of these tumors have reported high rates of gross-total resection (GTR) with minimal long-term neurological deficit. Case reports and small case series have suggested that these patients may be successfully treated with minimally invasive surgery (MIS). These studies have been limited by small patient populations. Moreover, there are no studies directly comparing perioperative outcomes between patients treated with open resection and MIS. The objective of this study was to compare perioperative outcomes in patients with ID-EM tumors treated using open resection or MIS.

METHODS

A retrospective review was performed using data collected from 45 consecutive patients treated by open resection or MIS for ID-EM spine tumors. These patients were treated over a 9-year period between April 2003 and October 2012 at Northwestern University and the University of Chicago. Statistical analysis was performed to compare perioperative outcomes between the two groups.

RESULTS

Of the 45 patients in the study, 27 were treated with the MIS approach and 18 were treated with the open approach. Operative time was similar between the two groups: 256.3 minutes in the MIS group versus 241.1 minutes in the open group (p = 0.55). Estimated blood loss was significantly lower in the MIS group (133.7 ml) compared with the open group (558.8 ml) (p < 0.01). A GTR was achieved in 94.4% of the open cases and 92.6% of the MIS cases (p = 0.81).

The mean hospital stay was significantly shorter in the MIS group (3.9 days) compared with the open group (6.1 days) (p < 0.01). There was no significant difference between the complication rates (p = 0.32) and reoperation rates (p = 0.33) between the two groups. Multivariate analysis demonstrated an increased rate of complications in cervical spine tumors (OR 15, p = 0.05).

CONCLUSIONS

Thoracolumbar ID-EM tumors may be safely and effectively treated with either the open approach or an MIS approach, with an equivalent rate of GTR, perioperative complication rate, and operative time. Patients treated with an MIS approach may benefit from a decrease in operative blood loss and shorter hospital stays.

Two one-stage posterior approaches for treating thoracic and lumbar spinal tuberculosis: A retrospective case-control study

The aim of this retrospective study was to analyze the results of two surgical treatments for thoracic and lumbar spinal tuberculosis. A total of 73 patients with monosegmental thoracic or lumbar spinal tuberculosis were enrolled from January 2006 to April 2011. The patients were divided into two groups. Patients in group A (n=34) underwent one-stage posterior debridement, limited decompression, bone grafting and internal fixation combined with lamina reconstruction, while those in group B (n=39) underwent one-stage posterior debridement, decompression, bone grafting and posterior instrumentation. Clinical and radiographic results were analyzed and compared between the groups. Patients were followed for a mean 31.3 months (range, 21-42 months). Fusion occurred at 4-12 months (mean, 7.7 months). Surgical complications affected one and five patients in groups A and B, respectively. There was extraction of internal fixation in two group B patients. Postoperatively, there was significant Cobb angle correction in the two groups. By the last follow-up, the Cobb angle and correction loss in group A were significantly better than that in group B; the group A Oswestry Disability Index and Frankel grade were better than that in group B. In conclusion, one-stage posterior limited decompression, bone grafting and internal fixation combined with lamina reconstruction enables rapid management of monosegmental thoracic and lumbar spinal tuberculosis with fewer complications and minimal invasion.

Surgical Excition of Spinal Intradural Meningiomas through a Single-Sided Minimally Invasive Approach: Key-Hole Laminotomy

Study Design

Eight patients who underwent surgery through a single-sided keyhole laminotomy due to intradural extramedullary (IDEM) meningiomas were retrospectively investigated.

Purpose

To present the surgical outcomes of single-sided keyhole laminotomies aimed to excise large ventral IDEM spinal cord menengiomas.

Overview of Literature

Less invasive procedures, such as laminotomies and osteoplastic laminotomies, have been previously described in the literature, but an approach that interferes with spinal stability to an even lesser extent would be more desirable.

Methods

Tumors were removed through a slit-like space between the dura and spinal cord without retraction of the spinal cord. The neurological conditions of patients were evaluated pre- and postoperatively with the Nurick grading system. Pathologic subtypes, preoperative symptom duration, tumor location on the sagittal and axial planes, and the percentage of tumor occupying the intradural space were investigated. On follow-up, magnetic resonance imaging was conducted to evaluate whether the tumor had recurred.

Results

All tumors were localized either ventrally or ventrolaterally. Of the spinal menengiomas, four were cervical and four were thoracic. All lesions were completely excised, and the neurological condition improved in six patients. The remaining two patients already had preoperative Nurick grades of 0, and this score was maintained postoperatively. Neither kyphotic changes nor instability developed in any patient during the follow-up period.

Conclusions

Total resection of anterior and anterolateral IDEM menengiomas, without introducing new neurological deficits, can be performed by an isolated posterior approach through a single-sided keyhole laminotomy. However, this approach should be applied cautiously and with a thorough understanding of its limitations.

Retrospective observational comparative study of Hemilaminectomy versus Laminectomy for intraspinal tumour resection; Shorter Stays, Lower Analgesic Usage and Less Kyphotic Deformity

INTRODUCTION

Intraspinal tumours are rare and principally managed surgically. Laminectomy, employed for access to the spinal canal, destroys the posterior tension band leading to a risk of kyphosis. Hemilaminectomy as an alternative may be less destructive, potentially reducing the risk of deformity and causing less post-operative pain.

METHOD

We investigated this hypothesis by retrospectively reviewing a case series of 56 surgeries for a disparate and unselected group of intraspinal tumours utilizing a laminectomy or hemilaminectomy approach.

RESULTS

No difference was found in length of operation, completeness of resection, complication rate and Frankel-score improvements. Hemilaminectomy (n = 22) is associated with reduced hospital stay (post-op days) 4.5 (2-6) versus 6 (3-8), (p = 0.026, Mann-Whitney), and a reduction in post-operative morphine use (mg) 10 (3.5-28) versus 30 (10-90), (p = 0.005, Mann-Whitney). Post-operative kyphosis was measured with the Harrison posterior tangent method on T2-weighted sagittal MR images. The average change in kyphosis angle was greater in the laminectomy group compared with the hemilaminectomy group, 3.6 (0.8-6.2) versus 0.4 (-0.2-1.2), statistically significant (p = 0.004, Mann-Whitney).

CONCLUSION

Hemilaminectomy is as effective an access procedure for the resection of unselected intraspinal tumours as laminectomy, but is associated with shorter post-operative stays, lower analgesic requirements and less post-operative kyphosis.

Treatment results in the different surgery of intradural extramedullary tumor of 122 cases

Study Design

A retrospective study of intradural extramedullary tumor.

Objective

To compare the treatment results in the different surgeries of spinal intradural extramedullary tumor.

Methods

The study retrospectively reviewed 122 patients. The minimally invasive surgery (MIS) group was divided into Group A (hemilaminectomy + tumor microscopic excision) and Group B (laminectomy + tumor microscopic excision + pedicle screw fixation). Meanwhile, the non-MIS group was divided into Group C (hemilaminectomy + tumor excision), Group D (laminectomy + tumor excision), and Group E (laminectomy + tumor excision + pedicle screw fixation). In order to study postoperative spinal stability, we simultaneously divided all of the subjects into three categories, namely Group HE: hemilaminectomy + tumor excision; Group LE: laminectomy + tumor excision; and Group LEPSF: laminectomy + tumor excision + pedicle screw fixation.

Results

The MIS group exhibited fewer postoperative complications (p<0.05), better short-term clinical efficacy (p<0.05) and less non-surgical cost (p<0.05) than in non-MIS group. The rate of postoperative spinal instability in hemilaminectomy was lower than in laminectomy in a single spinal segment (p<0.05). The rate of postoperative spinal instability in laminectomy + pedicle screw fixation was lower than in hemilaminectomy and laminectomy in two or more spinal segments (p<0.05).

Conclusion

In the case of appropriate surgical indications, minimally invasive surgery for intradural extramedullary tumor is a useful method that can successfully produce good clinical results and reduce non-surgical cost. In addition, pedicle screw fixation helps avoid spinal postoperative instability.

Minimally invasive resection of an extradural far lateral lumbar schwannoma with zygapophyseal joint sparing: surgical nuances and literature review

Introduction. Spinal schwannomas are benign nerve sheath tumors. Completely extradural schwannomas of the lumbar spine are extremely rare lesions, accounting for only 0,7–4,2% of all spinal NSTs. Standard open approaches have been used to treat these tumors, requiring extensive muscle dissection, laminectomy, radical foraminotomy, and facetectomy. In this paper the authors present the case of a minimally invasive resection of a completely extradural schwannoma. Operative technique literature review is presented. Material & Methods. A 50-year-old woman presented with progressive complains of chronic right leg pain and paresthesia. The magnetic resonance imaging revealed a giant well-encapsulated dumbbell-shaped extradural lesion at the L3-L4 level. The patient underwent a minimally invasive gross total resection of the tumor using a tubular expandable retractor system. Results. The patient had complete resolution of radiculopathy in the immediate postoperative period and she was discharged home, neurologically intact, on the second postoperative day. Postoperative MRI demonstrated no evidence of residual tumor. At latest follow-up (18 months) the patient remains asymptomatic. Conclusion. Although challenging, this minimally invasive procedure is safe and effective, being an appropriate alternative, with many potential advantages, to the open approach.

Biomechanical effects of a unilateral approach to minimally invasive lumbar decompression

Minimally invasive (MI) lumbar decompression became a common approach to treat lumbar stenosis. This approach may potentially mitigate postoperative increases in segmental motion. The goal of this study was to evaluate modifications to segmental motion in the lumbar spine following a MI unilateral approach as compared to traditional facet-sparing and non-facet sparing decompressions. Six human lumbar cadaveric specimens were used. Each specimen was tested in flexion-extension 0 N and 400 N of follower preload), axial rotation, and lateral bending. Each testing condition was evaluated following three separate interventions at L4–L5: 1) Minimally invasive decompression, 2) Facet-sparing, bilateral decompression, and 3) Bilateral decompression with a wide facetectomy. Range of motion following each testing condition was compared to intact specimens. Both MI and traditional decompression procedures create significant increases in ROM in all modes of loading. However, when compared to the MI approach, traditional decompression produces significantly larger increase in ROM in flexion-extension (p<0.005) and axial rotation (p<0.05). It additionally creates increased ROM with lateral bending on the approach side (p<0.05). Lateral bending on the non-approach side is not significantly changed. Lastly, wide medial facet removal (40% to 50%) causes significant hypermobility, especially in axial rotation. While both MI and traditional lumbar decompressions may increase post-operative ROM in all conditions, a MI approach causes significantly smaller increase in ROM. With an MI approach, increased movement with lateral bending is only toward the approach side. Further, non-facet sparing decompression is further destabilizing in all loading modes.

Minimally invasive approach for the treatment of intradural spinal pathology

OBJECT

A wide variety of spinal intradural pathology traditionally has been treated from a midline posterior laminectomy using standard microsurgical techniques. This approach has been successful in treating the pathology; however, it carries a risk of postoperative complications including CSF leakage, wound infection, and spinal instability. The authors describe a minimally invasive surgical (MIS) approach to treating spinal intradural pathology with a low rate of postoperative complications.

METHODS

Through a retrospective review of a prospectively collected surgical database, the authors identified 26 patients who underwent 27 surgeries via an MIS approach for intradural pathology of the spine. Using a tubular retractor system and an operative microscope, the authors were able to treat all patients with a unilateral, paramedian, and muscle-splitting technique. They then collected data regarding operative blood loss, length of stay, imaging characteristics, and outcomes.

RESULTS

Eight cervical, 8 thoracic, and 11 lumbar intradural pathological entities, which included 14 oncological lesions, 4 Chiari I malformations, 4 arachnoid cysts, 3 tethered cords, 1 syrinx, and 1 chronic visceral pain, were treated via an MIS approach. The average blood loss was 197 ml and the average hospital stay was 3 days. One patient had to return to the operating room for noninfectious wound dehiscence. One patient required reoperation 18 months after the initial surgery for recurrence of the initial pathology. There was no CSF leak, no infection, and no spinal instability associated with the initial surgery on follow-up.

CONCLUSIONS

Intradural spinal pathology can be safely and effectively treated with MIS approaches without an increased risk of neurological injury. This approach may also offer a reduced postoperative length of stay, risk of CSF leak, and risk of future spinal instability.

The use of minimally invasive approaches to resect intradural extramedullary spinal cord tumors

AIM

To conduct a comparative analysis of outcomes in patients with extramedullary tumors operated on using a minimally invasive approach and traditional laminectomy.

MATERIAL AND METHODS

The study included 40 patients (13 males and 27 females) who underwent surgical treatment at the Department of Spinal Neurosurgery of the Burdenko Neurosurgical Institute. The mean age of patients was 47 years (range: 41-60 years). Tumors were located in the cervical, thoracic and lumbar spine. All patients were divided into two groups. In the control group, 20 patients underwent traditional laminectomy using a yard retractor or an Egorov-Freidin retractor. In the study group, 20 patients underwent hemilaminectomy using a retractor for minimally invasive surgery (Caspar and MAST Qudrant). The outcomes were evaluated 3, 6, and 12 months after surgery. The McCormik and VAS scales were used for the evaluation. MRI data were also evaluated.

RESULTS

Total tumor resection was reached in all cases. The mean surgery duration was 247 min (range: 180-320 min) for the first group and 105.25 min (range: 60-190 min) for the second one. The volume of blood loss was 297 mL (range: 100-600 mL) for the first group and 210 mL (50 to 400 mL) for the second group. The histological nature of the tumors was as follows: neurinoma, meningioma, and ependymomas of the cauda equina. The evaluation of the pain syndrome in the early postoperative period revealed that the pain syndrome intensity according to VAS was reduced in patients of the second group compared to that in patients of the first group. The evaluation using the McCormik scale revealed no obvious difference in the results between the study and control groups. MRI studies performed in the postoperative period showed no tumor recurrence.

CONCLUSION

Surgical treatment of patients with intradural extramedullary tumors can be safely and effectively performed using minimally invasive approaches. A potential reduction in surgery duration, intraoperative blood loss, the amount of anesthetic drugs and reduction in the pain syndrome in the early postoperative period allow us to conclude that, when performed by an experienced surgeon, the method of minimally invasive surgery may be an alternative to the traditional removal of an extramedullary tumor.

Minimally invasive removal of thoracic and lumbar spinal tumors using a nonexpandable tubular retractor

Object

Resection of spinal tumors traditionally requires bilateral subperiosteal muscle stripping, extensive laminectomy, and, in cases of foraminal extension, partial or radical facetectomy. Fusion is often warranted in cases of facetectomy to prevent deformity, pain, and neurological deterioration. Recent reports have demonstrated safety and efficacy of mini-open removal of these tumors using expandable tubular retractors. The authors report their experience with the minimally invasive removal of extradural foraminal and intradural-extramedullary tumors using the nonexpandable tubular retractor.

Methods

A retrospective chart review of consecutive patients who underwent minimally invasive resection of spinal tumors at Notre Dame Hospital was performed.

Results

Between December 2005 and March 2012, 13 patients underwent minimally invasive removal of spinal tumors at Notre Dame Hospital, Montreal. There were 6 men and 7 women with a mean age of 55 years (range 20–80 years). There were 2 lumbar and 2 thoracic intradural-extramedullary tumors and 7 thoracic and 2 lumbar extradural foraminal tumors. Gross-total resection was achieved in 12 patients. Subtotal resection (90%) was attained in 1 patient because the tumor capsule was adherent to the diaphragm. The average duration of surgery was 189 minutes (range 75–540 minutes), and the average blood loss was 219 ml (range 25–500 ml). There were no major procedure-related complications. Pathological analysis revealed benign schwannoma in 8 patients and meningioma, metastasis, plasmacytoma, osteoid osteoma, and hemangiopericytoma in 1 patient each. The average equivalent dose of postoperative narcotics after surgery was 66.3 mg of morphine. The average length of hospitalization was 66 hours (range 24–144 hours). All working patients returned to normal activities within 4 weeks. The average MRI and clinical follow-up were 13 and 21 months, respectively (range 2–68 months). At last follow-up, 92% of patients had improvement or resolution of pain with a visual analog scale score that improved from 7.8 to 1.2. All patients with neurological impairment improved. The American Spinal Injury Association grade improved in all but 1 patient.

Conclusions

Intradural-extramedullary and extradural tumors can be completely and safely resected through a minimally invasive approach using the nonexpandable tubular retractor. This approach may be associated with even less tissue destruction than mini-open techniques, translating into a quicker functional recovery. In cases of foraminal tumors, by eliminating the need for facetectomy, this minimally invasive approach may decrease the incidence of postoperative deformity and eliminate the need for adjunctive fusion surgery.

Minimally invasive thoracic decompression for multi-level thoracic pathologies

We describe our experience using a minimal access approach for multi-level dorsal decompression of the thoracic spine that may limit approach-related soft-tissue injury and spinal destabilization. Additionally, three patients, each with unique compressive thoracic pathology, are discussed. A single minimal access technique, using multi-level hemilaminotomies, was used to address these unique pathologies via a similar approach. The three patients in this study had a mean age of 49.3 years (range: 45-55 years), mean estimated blood loss of 750 cc (range: 350-1000 cc), mean operative time of 3.8 hours (range: 3-5 hours), and a mean post-operative hospital stay of 2.3 days (range: 2-3 days). Complete decompression was achieved with resolution of symptoms in all patients. Long-term follow-up averaged 26.7 months (range: 15-36 months). Radiographic decompression was demonstrated in all patients. Minimal access techniques using muscle-splitting tubular retractor systems can effectively treat multi-level dorsal compression of the thoracic cord, while potentially limiting morbidity and long-term spinal instability.

Biomechanical comparison of laminectomy, hemilaminectomy and a new minimally invasive approach in the surgical treatment of multilevel cervical intradural tumour: a finite element analysis

PURPOSE

The objective of this study was to investigate the impact of the less invasive procedures of hemilaminectomy and unilateral multilevel interlaminar fenestration (UMIF) on the cervical spinal biomechanics.

METHODS

A validated nonlinear finite element model of the intact cervical spine (C2-C7) was modified to study the biomechanical changes as a result of surgical alteration for treatment of intradural tumours at C3-6 using multilevel laminectomy (ML), multilevel hemilaminectomy (MHL) and UMIF with or without unilateral graded facetectomy.

RESULTS

Under the load-controlled method, the greatest biomechanical changes occurred at the surgical segments. The largest increases occurred in flexion motions following ML approach with 70, 62 and 60 % increase at C3-4, C4-5 and C5-6, respectively. The increases were significantly reduced to no more than 14 % under MHL and UMIF. When combined with graded facetectomy, the changes in flexion under ML approach have a significantly further increase, up to 110 % at C3-4. The further increase was not significantly following MHL and UMIF, with no more than 31 % increase at C3-4, C4-5 and C5-6. The motion following UMIF was only slightly smaller in axial rotation than MHL. The maximum stresses in the annulus occurred during flexion in ML model, with 39, 34 and 38 % more stress than the intact at C3-4, C4-5 and C5-6, respectively. The increases of stress were significantly reduced to 5-7 % under MHL and UMIF.

CONCLUSIONS

The less invasive approaches of UMIF and MHL greatly preserved the flexion motion (more than 48 %) of the cervical spine compared with laminectomy, and the preserved motion mean the low-risk of postoperative spinal instability. UMIF and MHL also reduced the increased stress of annulus caused by ML, and the lesser stress will lower the risk of postoperative disc degeneration. The posterior bone elements play a slight role in spinal stability after removal of the attached ligaments.

Microendoscopic decompression for cervical spondylotic myelopathy

Object

Cervical spondylotic myelopathy (CSM) is a common cervical degenerative disease that affects the elderly population. Spinal cord decompression is achieved through various anterior and posterior approaches including anterior cervical decompression and fusion, laminectomy, laminoplasty, and combined approaches. The authors describe another option, minimally invasive endoscopically assisted decompression of stenosis (MEDS), which obviates the need for muscle dissection and disruption of the posterior tension band, a cause of postlaminectomy kyphosis.

Methods

The authors conducted a retrospective study of 10 patients with CSM who underwent MEDS from January 2002 through July 2012. Data were collected on demographics, preoperative and postoperative Nurick scores, postoperative Odom scores, and preoperative and postoperative Cobb angles.

Results

The mean patient age (± SD) was 67 ± 7.7 years; 8 patients were male. The average number of disc levels operated on was 2.2 (range 1–4). The mean Nurick score was 1.6 ± 0.7 preoperatively and improved to 0.3 ± 0.7 postoperatively (p < 0.0005). The postoperative Odom scores indicated excellent outcomes for 4 patients, good for 3, fair for 2, and poor for 1. The average preoperative focal Cobb angle at the disc levels operated on was −0.43º ± 1.9º. The average Cobb angle at the last follow-up visit was 0.25° ± 1.6° (p = 0.6). The average follow-up time was 18.9 ± 32.1 months. There were no intraoperative or postoperative complications.

Conclusions

For selected patients with CSM, whose pathologic changes are primarily posterior and who have acceptable preoperative lordosis, MEDS is an alternative to open laminectomy and laminoplasty.

Minimally invasive surgery for benign intradural extramedullary spinal meningiomas: experience of a single institution in a cohort of elderly patients and review of the literature

Meningiomas of the spine are the most common benign intradural extramedullary lesions and account for 25%–46% of all spinal cord tumors in adults. The goal of treatment is complete surgical resection while preserving spinal stability. Usually, these lesions occur in the thoracic region and in middle-aged women. Clinical presentation is usually nonspecific and the symptoms could precede the diagnosis by several months to years, especially in older people, in whom associated age-related diseases can mask the tumor for a long time. We report a series of 30 patients, aged 70 years or more, harboring intradural extramedullary spinal meningiomas. No subjects had major contraindications to surgery. A minimally invasive approach ( hemilaminectomy and preservation of the outer dural layer) was used to remove the tumor, while preserving spinal stability and improving the watertight dural closure. We retrospectively compared the outcomes in these patients with those in a control group subjected to laminectomy or laminotomy with different dural management. In our experience, the minimally invasive approach allows the same chances of complete tumor removal, while providing a better postoperative course than in a control group.

The microendoscopic decompression of lumbar stenosis: a review of the current literature and clinical results

Lumbar stenosis is a well-defined pathologic condition with excellent surgical outcomes. Empiric evidence as well as randomized, prospective trials has demonstrated the superior efficacy of surgery compared to medical management for lumbar stenosis. Traditionally, lumbar stenosis is decompressed with open laminectomies. This involves removal of the spinous process, lamina, and the posterior musculoligamentous complex (posterior tension band). This approach provides excellent improvement in symptoms, but is also associated with potential postoperative spinal instability. This may result in subsequent need for spinal fusion. Advances in technology have enabled the application of minimally invasive spine surgery (MISS) as an acceptable alternative to open lumbar decompression. Recent studies have shown similar to improved perioperative outcomes when comparing MISS to open decompression for lumbar stenosis. A literature review of MISS for decompression of lumbar stenosis with tubular retractors was performed to evaluate the outcomes of this modern surgical technique. In addition, a discussion of the advantages and limitations of this technique is provided.

Paradigm changes in spine surgery: evolution of minimally invasive techniques

Minimally invasive spine surgery (MISS) techniques were developed to address morbidities associated with open spinal surgery approaches. MISS was initially applied for indications such as the microendoscopic decompression of stenosis (MEDS)-an operation that has become widely implemented in modern spine surgery practice. Minimally invasive surgery for MEDS is an excellent example of how an MISS technique has improved outcomes compared with the use of traditional open surgical procedures. In parallel with reports of surgeon experience, accumulating clinical evidence suggests that MISS is favoured over open surgery, and one could argue that the role of MISS techniques will continue to expand. As the field of minimally invasive surgery has developed, MISS has been implemented for the treatment of increasingly difficult and complex pathologies, including trauma, spinal malignancies and spinal deformity in adults. In this Review, we present the accumulating evidence in support of minimally invasive techniques for established MISS indications, such as lumbar stenosis, and discuss the need for additional level I and level II data to demonstrate the benefit of MISS over traditional open surgery. The expanding utility of MISS techniques to address an increasingly broad range of spinal pathologies is also highlighted.

Minimally invasive removal of a giant extradural lumbar foraminal schwannoma

Background:

Purely extradural lumbar schwannomas are rare lesions. Resection traditionally requires an open laminectomy and ipsilateral complete facectomy. Recent reports have demonstrated safety and efficacy of removal of these tumors using mini-open access devices with expandable retractors. We report a case of a giant L3 schwannoma successfully resected through a minimally invasive approach using the non-expandable Spotlight tubular retrator (Depuy Spine).

Case Description:

A 77-year-old woman presented with a history of chronic right leg pain, paresthesias and proximal right leg weakness. Magnetic Resonance imaging (MRI) scan revealed a large dumbbell-shaped extradural foraminal lesion at the L3–L4 level with significant extraforaminal extension. The patient underwent a minimally invasive gross total resection (GTR) of the tumor using an 18-mm Spotlight tubular retractor system. Pathology confirmed the lesion to be a benign schwannoma. Postoperatively, the patient's symptoms resolved and she was discharged from the hospital on the second postoperative day. Postoperative MRI showed no residual tumor. The patient returned to normal activities after 2 weeks and remained asymptomatic with no neurological deficits at final 6 months follow-up.

Conclusion:

Giant lumbar extradural schwannomas can be safely and completely resected using minimally invasive surgery without the need for facectomy or subsequent spinal fusion.

Unilateral hemilaminectomy for patients with intradural extramedullary tumors

A modified hemilaminectomy was introduced in an attempt to explore the operative techniques and the values of the limited approach to spinal cord tumors. Forty-five consecutive patients with intradural extramedullary lesions, who underwent modified hemilaminectomy, were studied retrospectively. The intraspinal tumors were removed via the limited bone window with a 3.3-cm mean length (range: 2.0-6.5 cm) and a 1.2-cm mean width (range: 0.6-1.5 cm), in which the inner parts of the medial and lateral laminae were mostly undercut for wider view. Spinal lesions were cervical in 21 cases, thoracic in 12 cases, lumbar in 10 cases, and multiple in 2 cases. Forty-three cases were completely excised via hemilaminectomy alone. Two subjects with dumbbell neurinoma underwent two-stage tumor removal via anterolateral cervical approach following hemilaminectomy. With respect to neurological status, the percentage of good Frankel scale (D+E grade) was markedly improved from 22.2% on admission to 93.3% at follow-up. At the median 26-month follow-up evaluation by magnetic resonance imaging (MRI), none of the subjects showed spinal deformity or instability. By preserving musculoligamentous attachments and posterior bony elements as much as possible, the modified approach is minimally invasive and may be routinely used to remove intradural and extramedullary tumors, especially in patients with meningiomas and neurinomas.

Minimally invasive approach for the resection of spinal neoplasm

STUDY DESIGN

Retrospective Case Series.

OBJECTIVE

To determine if extradural, intradural extramedullary, and intramedullary spinal neoplasms can be safely resected through a minimally invasive corridor.

SUMMARY OF BACKGROUND DATA

The use of minimally invasive approaches for resection of spinal neoplasms has been described for intradural schwannomas and ependymomas. We demonstrate that this approach can be extended to the resection of a variety of extradural, intradural and intramedullary spinal tumors.

METHODS

We undertook a retrospective review of all patients presenting with clinical and radiographic evidence of spinal neoplasm that subsequently underwent a minimally invasive approach for resection of the tumor using the METRx MAST QUADRANT Retractor System (Medtronics, Memphis, TN). Primary endpoints analyzed include completeness of resection, postoperative neurologic status, operative time, blood loss, postoperative pain, length of hospital stay, and operative complications.

RESULTS

Two cervical, seven thoracic and 13 lumbar neoplasms were identified in 20 patients operated on between September 2005 and May 2009. Mean intraoperative time was 210 minutes, blood loss 428 mL and average length of hospital stay was 3 days. Four patients required postoperative patient-controlled analgesia for pain control and an average of 5.8 doses of narcotic were given per patient. Two patients developed postoperative complications. Fifteen of 22 tumors (68%) were completely resected, with only one patient requiring repeat operation for residual tumor. All but one patient were improved from preoperative status at 6 months.

CONCLUSION

Intramedullary, intradural and extradural spinal neoplasms can be resected through a minimally invasive approach without increased risk for adverse neurologic outcome. This technique may be an appropriate alternative to the open approach for well-circumscribed extramedullary lesions spanning one or two spinal levels. With increasing experience, reduced operative time, blood loss, complications, length of hospital stay, postoperative pain, and spinal instability may be seen.

Safety and efficacy of intradural extramedullary spinal tumor removal using a minimally invasive approach

BACKGROUND

Although minimally invasive surgery for intradural tumors offers the potential benefits of less postoperative pain, a quicker recovery, and the avoidance of long-term instability from multilevel laminectomy, there are concerns over whether one can safely and effectively remove intradural extramedullary tumors in a fashion comparable to open techniques and whether the advantages of minimally invasive surgery are clinically significant.

OBJECTIVE

To review our early experience with minimally invasive techniques for intradural extramedullary tumors of the spine.

METHODS

Thirteen intradural tumors (1 cervical, 6 thoracic, 6 lumbar) in 11 patients were operated on using a muscle-splitting, tube-assisted paramedian oblique approach with hemilaminectomy to access the spinal canal while preserving the spinous process and ligaments. Fluoroscopy and navigation were used to determine the surgical level in all thoracic and lumbar cases.

RESULTS

Satisfactory tumor resection using standard microsurgical techniques was achieved in all but 1 case using a minimally invasive approach. Surgical time and intraoperative blood loss were favorable compared with our open technique cases. There was no postoperative morbidity with the minimally invasive approach, although in 2 patients with tumors in the mid- and upper thoracic spine, the surgical incision was inaccurately placed by 1 level. In 1 case, the approach was converted to open when the tumor could not be found, and postoperatively there was a cerebrospinal fluid leak with infection that required readmission.

CONCLUSION

Intradural extramedullary tumors can be safely and effectively removed using minimally invasive techniques. The pros and cons of minimally invasive vs open surgery are discussed.