Drop metastasis from the extradural to the intradural space in spinal Ewing's sarcoma - a novel case report.

Spinal Ewing's Sarcoma is a rare tumour predominantly affecting children and adolescents. We describe the case of an 18-year-old male patient who first presented with a primary extradural cervical Ewing's sarcoma tumour, and 5 years later had a recurrence with thoracolumbar and lumbosacral intradural extramedullary Ewing's sarcoma tumours. Both presentations were successfully treated by surgical resection and adjuvant chemo- and radiotherapy, and he remains disease-free at 12 months follow-up. This is the first reported case of seeding of tumour from an extradural primary Ewing's sarcoma to intradural metastases. Total surgical resection of his initial cervical tumour, performed at another centre, was complicated by a dural tear and CSF leak. Thus, we propose that isolated drop metastasis via CSF fistula is the most likely mechanism for tumour spread in this case. Thus, clinicians may wish to counsel patients on the possibility of such spread if a CSF leak is encountered, and potentially increase the frequency of imaging surveillance of the whole spine in this context.

A modified vertebroplasty technique for intraoperative thoracic spine localisation: a technical report.

The aim is to illustrate the modified vertebroplasty technique as a fixed marker for intraoperative thoracic spine localisation. Open and minimally invasive surgery in the thoracic spine has been correlated with a disproportionately high rate of wrong-level spinal surgery in pathologies where a focal deformity or fracture is absent. Spinal markers have evolved with time, and vertebroplasty as a spinal marker was initially described in 2008. A significant disadvantage is that the cement in the vertebral body and pedicle may preclude a more extensive osteotomy or subsequent instrumentation at the level of interest. We demonstrate the modified vertebroplasty technique, which introduces percutaneous polymethylmethacrylate cement two levels below the thoracic disc herniation on the contralateral side to the surgical approach using standard vertebroplasty methods. The vertebroplasty was performed as an outpatient procedure, and the radiopaque cement was instantaneously located on intraoperative fluoroscopy, identifying the correct level above. The modified vertebroplasty technique is a quick, safe and accurate method of thoracic spine localisation, facilitating the room required for the bony exposure and instrumentation if needed.

Surgical Management of Giant Thoracic Paraspinal Schwannomas.

BACKGROUND: Giant paraspinal thoracic schwannomas (GPTSs) are benign, slow-growing, encapsulated lesions. They can be intracanalicular, span more than 2 vertebral bodies, and/or have a foraminal component with extraspinal extension >2.5 cm. They pose surgical challenges because of the often unfamiliar complex regional anatomy. We report the largest series of GPTSs and discuss regional surgical strategies for tumors in the thoracic spine. METHODS: We conducted a retrospective review of GPTSs operated at a national spinal referral center between December 2008 and October 2019. Inclusion criteria included World Health Organization grade 1 GPTS. Patient demographics, clinical features, radiology, and histopathology were assessed. RESULTS: Seventeen patients (12 females, 5 males) had a mean age of 48.1 years (range 21-65 years). Five GPTS (29%) were located at T1-T3, 6 (35%) at T4-6, and 6 (35%) below T6. The mean maximum diameter was 58.5 ± 19.1 mm (range 30-91 mm). Mean volume was 90.9 cm3 (range 19.1-350.6 cm3). Twelve (70%) had a fluorodeoxyglucose positron emission tomography scan showing low (25%) or moderate to high (75%) uptake. Six patients (35%) had preoperative computed tomography-guided biopsy. Surgical approaches included 1) manubriotomy and variations (4/17); 2) high lateral thoracotomy (4/17); 3) posterior parascapular (1/17); 4) standard lateral thoracotomy (3/16); 5) posterior/posterolateral (2/17); and 6) combined posterior and thoracotomy (3/17). All patients had gross total resection and were grade 1 cellular schwannomas. No recurrence at final follow-up (mean 36.1 months, range 8-130 months). CONCLUSIONS: A number of approaches are available to resect GPST in specific locations in the thoracic spine. Total resection is achievable despite complex regional anatomy, location, and tumor extension but often requires anterior or combined approaches.

Hybrid Bone SPECT/CT Imaging in Evaluation of Chronic Low Back Pain: Correlation with Facet Joint Arthropathy.

BACKGROUND: Evidence to support the use of bone hydroxydiphosphonate (HDP) single photon emission computed tomography (SPECT/CT) in patients with facetogenic low back pain (LBP) is still limited. In this study we compared the scintigraphic patterns on bone SPECT/CT with the degree of structural facet joint (FJ) degeneration on CT in patients with LBP. METHODS: Ninety-nine consecutive patients with LBP were prospectively evaluated. Patients with known or suspected malignancy, trauma, infectious processes, chronic inflammatory diseases, and previous surgery were excluded. The effect of LBP on the daily quality of life was assessed with the Oswestry disability index (ODI). The Pathria grading system was used to score FJ degeneration on CT scans. The correlation between the degree of FJ degeneration and osteoblastic activity on SPECT/CT was analyzed with Kappa statistics. RESULTS: Ninety-nine patients were included (59 female, mean age 56.2 years). The mean ODI score was 38.5% (range, 8% to 72%). In all, 792 FJ (L2-3 to L5-S1) were examined. Of the FJs, 49.6% were Pathria grade 0-1 (normal to mild degeneration) on CT, 35% were grade 2 (moderate degeneration), and 16% were grade 3 (severe degeneration). Sixty-seven percent of the patients had scintigraphically active FJs on SPECT/CT. Sixty-nine percent of Pathria grade 3 FJs were scintigraphically active; 5.5% and 16.8% of Pathria grade 0-1 and Pathria grade 2, respectively, were active. Of the metabolically active FJs, 71.4% were at the L4-5/L5-S1 levels. CONCLUSIONS: The ability of SPECT/CT to precisely localize scintigraphically active FJs may provide significant improvement in the diagnosis and treatment of patients with LBP. In this study we demonstrate that in >40% of FJs, the scintigraphic patterns on SPECT/CT did not correlate with the degree of degeneration on CT.

Hybrid Bone Single Photon Emission Computed Tomography Imaging in Evaluation of Chronic Low Back Pain: Correlation with Modic Changes and Degenerative Disc Disease.

BACKGROUND AND OBJECTIVE: Multiple radiologic modalities are used in the evaluation of patients with low back pain (LBP). Only limited evidence currently exists to support the use of bone hydroxydiphosphonate single photon emission computed tomography (SPECT/CT) in patients with Modic changes (MCs) and degenerative disc disease. The aim of this study was to assess the value of the hybrid bone SPECT/CT imaging in patients with chronic LBP. We evaluate the correlation of hybrid bone SPECT/CT imaging patterns with MCs and disc abnormalities on magnetic resonance imaging (MRI). METHODS: This was a prospective study. Ninety-nine consecutive patients with LBP from a single center. The degree of lumbar intervertebral disc and endplate degeneration on MRI and osteoblastic activity was shown on SPECT/CT. These 99 consecutive patients with LBP were prospectively evaluated. Patients with contemporary lumbosacral spine MRI and bone SPECT/CT were included. Patients with known or suspected malignancy, trauma, infectious processes, and previous surgery were excluded. The effect of LBP on the daily quality of life was assessed using Oswestry disability index. We analyzed the correlation between the degenerative changes at the intervertebral disc spaces and endplates on MRI and bone SPECT/CT findings using receiver operating characteristic curve analysis and Kappa statistics. The Pfirrmann grading system was used to score the severity of disc space degeneration on MRI scans. RESULTS: A total of 99 patients were included in the study (58 women, 41 men; mean age, 56.2 years). Mean Oswestry disability index score was 38.5% (range, 8%-72%). The L2-3 through to L5-S1 levels were studied. MCs were found in 54% of patients. Of the 396 levels examined 85 were found to have MCs (21.5%). The most affected levels were L4-5 (31.3%) and L5-S1 (40.9%). Pfirrmann grade 5 disc space (72.9%) was associated with MC (Pp<0.001). MC (70.6%) and Pfirrmann grade 5 disc spaces (73%) resulted in scintigraphically active endplate/disc space on SPECT/CT (P< 0.001). Bone SPECT/CT showed high metabolic activity in 96.1% of endplates with MC type I, 56% with MC type II, and 77.8% with MC type III. CONCLUSIONS: In this study we found a high agreement between MCs and increased metabolic activity on bone SPECT/CT imaging. MC type 1 and Pfirrmann grade 5 were the best binary predictors for positivity on bone SPECT/CT and had equivalent correlations. Lower vertebral levels in the lumbar spine were associated with higher degree of disc degeneration, high frequency of MCs, and positivity on bone SPECT/CT.

Spontaneous cervical intradural disc herniation presenting with Brown-Séquard and Horner's syndrome: lesson learned from a very unique case.

PURPOSE: Cervical spontaneous intradural disc herniation (IDH) is an extremely rare condition. We describe a unique case of a patient presenting with a Brown-Séquard syndrome (BSS) and Horner's syndrome (HS). This study aimed to report an unusual case of spontaneous cervical intradural disc herniation that presented with Horner's and Brown-Séquard syndrome (BSS) and discuss difficulties in preoperative diagnosis and treatment difficulties of intradural cervical disc. METHODS: Notes and images review, and analysis of the relevant literature. RESULTS: A 45-year old female presented with acute Horner's syndrome and Brown-Séquard syndrome. The magnetic resonance imaging of cervical spine revealed C4-5 disc extrusion with cord compression. The patient underwent urgent decompression through an anterior cervical corpectomy and fusion. Patient fully recovered 6 months after disease onset. CONCLUSION: We would like to emphasize that prompt and anterior cervical decompression is the treatment of choice, as it directly address the problem and allows dura repair in spontaneous cervical disc herniation.

Joint arthropathy at the cranio-vertebral junction. Scintigraphic patterns on bone SPECT/CT.

Osteoarthritic degeneration at the cranio-vertebral junction (CVJ) is an underrecognized source of suboccipital and neck pain, limited range of motion and cervicogenic headaches. Correlation of radiographic findings with clinical symptoms is often difficult. Limited evidence currently exists to support the use of bone single-photon emission computed tomography/computed tomography (SPECT/CT) in this subgroup of patients. The aim of this study was to describe the scintigraphic patterns of joint arthropathy at the CVJ on bone SPECT/CT in patients with suboccipital/neck pain and cervicogenic headache. Patients with more than 3 months of suboccipital/neck pain/cervicogenic headache and abnormal SPECT/CT findings at the CVJ were included. Patients with known/suspected malignancy, trauma, infectious processes and previous surgery at the CVJ were excluded. Neck disability index (NDI), visual analogue scale (VAS) and treatment were recorded for each patient. Patterns of osteoblastic activity at the CVJ on bone SPECT/CT were described and correlated with arthritic changes on conventional scans. Eighteen patients were included (10 females, mean age 68). Mean NDI score was 22. Mean VAS was 7.5. On bone SPECT/CT, it was found that 13 patients had high osteoblastic activity unilaterally at the atlanto-axial joint (AAJ); two patients at the atlanto-dental joint (ADJ), one at the occipito-atlantal joint (OAJ), one at both OAJ and ADJ and one at the level of C2 pars/pedicle unilaterally. Metabolic activity on SPECT/CT was associated with severe degenerative changes on CT scans. The ability of hybrid bone SPECT/CT to precisely localize osteoblastic activity at the CVJ may provide significant improvement in the diagnosis and treatment of patients with suboccipital/neck pain and joint arthropathy at the CVJ. Further clinical studies are needed to establish the real clinical impact of bone SPECT/CT in the treatment of patients with suboccipital neck pain.

Minimally invasive supracondylar transtubercular (MIST) approach to the lower clivus.

OBJECTIVE: Drawbacks of the far-lateral approach to the lower clivus and pontomedullary region include the morbidity of a large incision extending into the cervical musculature and tedious exposure of the vertebral artery (VA), particularly when performing the transcondylar and transtubercular extensions. The authors describe a minimally invasive alternative to the far-lateral approach that has the potential to minimize operative morbidity and decrease the need for VA manipulation. METHODS: The minimally invasive supracondylar transtubercular (MIST) and far-lateral supracondylar transtubercular (FLST) approaches were performed in 10 adult cadaveric specimens (20 sides). The microsurgical anatomy of each step and the surgical views were analyzed and compared. In addition, the endoscopic view through the MIST was examined in five fresh cadaveric specimens (10 sides). RESULTS: The MIST approach provided exposure of the inferior-middle clivus, the anterolateral brainstem, and the premedullary cisterns, including the PICA-VA and vertebrobasilar junctions. The endoscope provided a clear view of cranial nerves III through XII, as well as the vertebrobasilar system. The FLST approach increased visualization of the anterolateral margin of the foramen magnum; otherwise, the surgical view is similar between the MIST and FLST approaches. CONCLUSIONS: The MIST approach could be considered as a potential alternative to the FLST approach in the treatment of lesions involving the inferior and middle clivus, and anterolateral lower brainstem; it does not require a C1 laminectomy, significant disruption of the atlanto-occipital joint, nor extensive exposure of the extracranial VA. Moreover, the MIST approach is an ideal companion to endoscope-assisted neurosurgery.

The V(2) segment of the vertebral artery: anatomical considerations and surgical implications.

OBJECT: Iatrogenic injury of the V(2) segment of the vertebral artery (VA) is a rare but serious complication and can be catastrophic. The purpose of this study was to characterize the relationship of the V(2) segment of the VA to the surrounding anatomical structures and to highlight the potential site and mechanisms of injury that can occur during common neurosurgical procedures involving the subaxial cervical spine. METHODS: Ten adult cadaveric specimens (20 sides) were included in this study. Quantitative anatomical measurements between selected landmarks and the VA were obtained. In addition, lateral mass screws were placed bilaterally, from C-3 to C-7, reproducing either the Magerl technique or a modified technique. The safety angle, defined as the axial deviation from the screw trajectory needed to injure the VA, and the distance from the entry point to the VA were measured at each level for both techniques. RESULTS: The VA coursed closer to the midline at C3-4 and C4-5 (mean distance [SD] 14.9 ± 1.1 mm) than at C2-3 or C5-6. Within the intertransverse space it coursed closer to the uncinate processes of the vertebral bodies (1.8 ± 1.1 mm) than to the anterior tubercle of the transverse processes (3.4 ± 1.6 mm). The distance between the VA and the uncinate process was less at C3-6 (1.3 ± 0.7 mm) than at C2-3 (3.3 ± 0.8 mm). The VA coursed on average at a distance of 11.9 ± 1.7 mm from the anterior and 4.2 ± 2.6 mm from the posterior aspect of the intervertebral disc space. Lateral mass screw angles were 25° lateral and 39.1° cranial for the Magerl technique, and 36.6° lateral and 46.1° cranial for the modified technique. The safety angle was greater and screw length longer when using this modified technique. CONCLUSIONS: The relation of the V(2) segment of the VA to anterior procedures and lateral mass instrumentation at the subaxial cervical spine was reviewed in this study. A detailed anatomical knowledge of the V(2) segment of the VA combined with careful preoperative imaging is mandatory for safe cervical spine surgery.

High anterior cervical approach to the clivus and foramen magnum: a microsurgical anatomy study.

BACKGROUND: Surgical exposure of lesions located along the ventral foramen magnum (FM) and clivus poses a unique set of challenges to neurosurgeons. Several approaches have been developed to access these regions with varying degrees of exposure and approach-related morbidity. OBJECTIVE: To describe the microsurgical anatomy of the high anterior cervical approach to the clivus and foramen magnum, and describe novel skull base extensions of the approach. METHODS: Eight adult cadaveric specimens were included in this study. The high anterior cervical approach includes a minimal anterior clivectomy and its lateral skull base extensions: the extended anterior far-lateral clivectomy and the inferior petrosectomy. The microsurgical anatomy and exposure of the various extensions of the approach were analyzed. In addition, the capability of complementary endoscopy was evaluated. RESULTS: With proper positioning, the minimal anterior clivectomy exposed the vertebrobasilar junction, proximal basilar artery, anteroinferior cerebellar arteries, and 6th cranial nerve. The lateral skull base extensions provided access to the anterior FM, mid-lower clivus, and petroclival region, up to the Meckel cave, contralateral to the side of the surgical approach. CONCLUSION: The high anterior cervical approach with skull base extensions is an alternative to the classic approaches to the ventral FM and mid-lower clivus. A minimal anterior clivectomy provides access to the midline mid-lower clivus. The addition of an extended anterior far-lateral clivectomy and an inferior petrosectomy extends the exposure to the anterior FM and cerebellopontine angle lying anterior to the cranial nerves. The approach is also ideally suited for endoscopic-assisted techniques.

Normal anatomical variations of the V3 segment of the vertebral artery: surgical implications.

OBJECT: The authors undertook this cadaveric and angiographic study to examine the microsurgical anatomy of the V3 segment of the vertebral artery (VA) and its relationship to osseous landmarks. A detailed knowledge of these variations is important when performing common neurosurgical procedures such as the suboccipital craniotomy and the far-lateral approach and when placing atlantoaxial instrumentation. METHODS: A total of 30 adult cadaveric specimens (59 sides) were studied using magnification × 3 to × 40 after perfusion of the arteries and veins with colored silicone. Seventy-three vertebral angiograms were also analyzed. The morphological detail of the V3 segment was described and measured in both the cadavers and angiograms. Transarticular screws were placed into 2 cadavers and the relationship of the trajectory to the V3 segment was analyzed. RESULTS: The authors identified 4 sites along the V3 segment that are anatomically the most likely to be injured during surgical approaches to the craniovertebral junction. In 35% of the cadaveric specimens the vertical portion of V3 formed a posteriorly oriented loop that could be injured during surgical exposures of the dorsal surface of C-2. The mean distance from the midline to the most posteromedial edge of the loop was 25.6 ± 3.5 mm (range 20-35 mm) on the left side and 30.4 ± 3.8 mm (range 23-36 mm) on the right side. On lateral angiograms, this loop projected posteriorly, with a mean distance of 9.8 ± 3.5 mm (range 0-15.7 mm) on the right side and 11.7 ± 1.2 mm (range 10-13.6 mm) on the left side. The horizontal segment of V3 can be injured when exposing the lower lateral occipital bone and when the C-1 arch is exposed. The mean distance from the inferior border of the occipital bone to the superior surface of the horizontal segment of V3 was 6 ± 2.8 mm on the right side and 5.6 ± 2.3 mm on the left. In 12% of cases the authors found no space between the horizontal portion of V3 and the occipital bone. The medial edge of the horizontal segment of V3 was located 23 ± 5.5 mm (range 10-30 mm) from the midline on the right side and 24 ± 5.7 mm (range 15-32 mm) on the left side. The transition between the V2-V3 segments after exiting the C-2 vertebral foramen is the most likely site of injury when placing C1-2 transarticular screws or C-2 pars screws. CONCLUSIONS: The normal variation of the V3 segment of the VA has been described with quantitative measurements. An awareness of the anatomical variations and the relationships to the surrounding bony anatomy will aid in reducing VA injury during suboccipital approaches, exposure of the dorsal surfaces of C-1 and C-2, and when placing atlantoaxial spinal instrumentation.