Lateral-PLIF for spinal arthrodesis: concept, technique, results, complications, and outcomes.

BACKGROUND: Posterior lumbar interbody fusion (PLIF) surgery represents an effective option to treat degenerative conditions in the lumbar spine. To reduce the drawbacks of the classical technique, we developed a variant, so-called Lateral-PLIF, which we then evaluated through a prospective consecutive series of patients. METHODS: All adult patients treated at our institute with single or double level Lateral-PLIF for lumbar degenerative disease from January to December 2017 were prospectively collected. Exclusion criteria were patients < 18 years of age, traumatic patients, active infection, or malignancy, as well as unavailability of clinical and/or radiological follow-up data. The technique consists of insert the cages bilaterally through the transition zone between the central canal and the intervertebral foramen, just above the lateral recess. Pre- and postoperative (2 years) questionnaires and phone interviews (4 years) assessed pain and functional outcomes. Data related to the surgical procedure, postoperative complications, and radiological findings (1 year) were collected. RESULTS: One hundred four patients were selected for the final analysis. The median age was 58 years and primary symptoms were mechanical back pain (100, 96.1%) and/or radicular pain (73, 70.2%). We found a high fusion rate (95%). A statistically significant improvement in functional outcome was also noted (ODI p < 0.001, Roland-Morris score p < 0.001). Walking distance increased from 812 m ± 543 m to 3443 m ± 712 m (p < 0.001). Complications included dural tear (6.7%), infection/wound dehiscence (4.8%), and instrument failure (1.9%) but no neurological deterioration. CONCLUSIONS: Lateral-PLIF is a safe and effective technique for lumbar interbody fusion and may be considered for further comparative study validation with other techniques before extensive use to treat lumbar degenerative disease.

Cysts associated with intramedullary ependymomas of the spinal cord: clinical, MRI and oncological features.

PURPOSE: Few published articles have explicitly focused on cysts associated with intramedullary (IM) ependymomas. The objective was to assess the clinical, MRI, and oncological results of patients operated for an IM ependymoma associated with a cystic portion. METHODS: During the study period, 23 IM tumors resected were cystic ependymomas. The modified McCormick scale was used to assess the neurological function of patients. The diagnosis of cystic spinal cord tumor was made on preoperative MRI. RESULTS: Two types of cysts were identified according to their location: either intra-tumoral cysts (ITC) or satellite cysts (SC). ITC (52.2%) were more frequent than SC (21.7%), but 26.1% of patients presented both. ITC were enhanced by gadolinium while SC were not. The solid portion of ependymomas with ITC was significantly larger than the one of ependymomas with SC (p = 0.002). The mean time to the first occurrence of symptoms was significantly shorter in patients with neurological deficit than those without a deficit (p = 0.04). GTR was achieved in 78.2% of cases. Complete excision of the cysts was easier when they were larger (p = 0.006). Sixty percent of cysts disappear postoperatively. Persistence of satellite cysts despite GTR of the tumor, and with no recurrence of a tumor on the post-operative MRI, was observed for 3 patients. CONCLUSION: ITC and SC are different in location, volume, gadolinium enhancement. Their surgical management is different since ITC are resected while SC are drained. Cystic recurrence and/or persistence are not synonymous with tumor recurrence.

Sacrifice of Involved Nerve Root during Surgical Resection of Foraminal and/or Dumbbell Spinal Neurinomas.

Even if usually needed to achieve the gross total resection (GTR) of spinal benign nerve sheath tumors (NSTs), nerve root sacrifice remains controversial regarding the risk of neurological deficit. For foraminal NSTs, we hypothesize that the involved root is poorly functional and thus can be safely sacrificed. All spinal benign NSTs with foraminal extension that underwent surgery from 2013 to 2021 were reviewed. The impacts of preoperative clinical status and patient and tumor characteristics on long-term outcomes were analyzed. Twenty-six patients were included, with a mean follow-up (FU) of 22.4 months. Functional motor roots (C5-T1, L3-S1) were involved in 14 cases. The involved nerve root was routinely sacrificed during surgery and GTR was obtained in 84.6% of cases. In the functional root subgroup, for patients with a pre-existing deficit (n = 5/14), neurological aggravation persisted in one case at last FU (n = 1/5), whereas for those with no preop deficit (n = 9/14), a postoperative deficit persisted in one patient only (n = 1/9). Preoperative radicular pain was the only characteristic significantly associated with an immediate postoperative motor deficit (p = 0.03). The sacrifice of an involved nerve root in foraminal NSTs seems to represent a reasonable and relevant option to resect these tumors, permitting one to achieve tumor resection in an oncologic fashion with a high rate of GTR.

Clipping Test of a Radiculomedullary Artery During Resection of a Dorsal Spinal Meningioma.

Arterial supply of the spinal cord is derived from the anterior spinal artery (ASA) and 2 posterior spinal arteries. In the thoracic spine, a few segmental arteries give origins to radiculomedullary arteries (RMAs) that supply the ASA and posterior spinal arteries.1 In the lower thoracic spine, the supply is provided by the Adamkiewicz artery. Spinal meningiomas may be embedded and/or supplied by the RMA, which may be sacrificed to obtain complete resection. Safety of the thoracic RMA occlusion is controversial,2 especially if the Adamkiewicz artery is involved.3 Somatosensory evoked potentials (SSEPs) and motor evoked potentials (MEP) are proposed to detect spinal cord ischemia.4 The RMA supplies the anterior spinal cord, and MEPs seem to be more sensitive than SSEPs to test RMA occlusion.2 SSEP and MEP monitoring during temporary occlusion has been described and significantly changes at 2 and 7 minutes of occlusion.5-8 Safe occlusion with unchanged MEPs after 10-minute temporary occlusion of 32 segmental arteries was reported by Salame et al.9 We intraoperatively discovered an anterior T10 RMA supplying the adjacent meningioma (Video 1). We temporary clipped the artery for 8 minutes. MEPs were recorded before clipping and every 2 minutes. No changes were observed, and the artery was sacrificed. RMA or segmental artery ligature may be required and is frequently performed in deformity, oncologic, and vascular spine surgery. The clipping test with MEP monitoring is a useful and simple intraoperative tool to identify the critical afferents of the ASA. It doesn't require planification or supplementary materials. Further study might be performed to validate the technique.

Pure lumbar foraminal cavernous malformation in a patient with Cowden syndrome-a case report.

Background: Spinal cavernous malformations (CMs) are slow flow venous vascular malformations which can occur in vertebral body, epidural space or intramedullary. Only 7 cases were described confined in foraminal space. Cowden syndrome (CS) is an autosomal dominant genodermatosis that may present and develop vascular malformations, which include CM. They were found intracranial, and rarely visceral. No association with spinal CM and CS has been reported to date. Case Description: A 46-year-old patient with CS came to our attention with a L5 radiculopathy secondary to a slow-growing intra-foraminal mass lesion, with bony scalloping. The lesion mimicked a schwannoma at radiological imaging and intraoperative findings. En bloc resection with root sacrifice was performed. No excessive bleeding was observed. After surgical resection, anatomical pathology demonstrated a CM. Postoperative review of neuroimaging revealed features compatible with chronic resolved peripheral haemorrage. The patient had no intra- or post-operative complications, and an immediate relief of symptoms was observed. The follow-up spinal magnetic resonance imaging (MRI) obtained 3 months after surgery, demonstrated the total removal of the lesion. Conclusions: CMs can be confined to foraminal space and associated with CS. They may mimic peripheral nerve sheath tumors. Diagnosis may be challenging. No pathognomonic imaging features were found. Complete resection with root sacrifice seems to be a safe and efficient technique.

Predictors of functional outcome after spinal cord surgery: Relevance of intraoperative neurophysiological monitoring combined with preoperative neurophysiological and MRI assessments.

OBJECTIVES: To assess the accuracy of intraoperative neurophysiological monitoring (IONM) in predicting immediate and 3-month postoperative neurological new deficit (or deterioration) in patients benefiting from spinal cord (SC) surgery; and to identify factors associated with a higher risk of postoperative clinical worsening. METHODS: Consecutive patients who underwent SC surgery with IONM were included. Pre and postoperative clinical (modified McCormick scale), radiological (lesion-occupying area ratio), and electrophysiological features were collected. RESULTS: A total of 99 patients were included: 14 (14.1%) underwent extradural surgery, 50 (50.5%) intradural extramedullary surgery, and 35 (35.4%) intramedullary surgery. Cumulatively, multimodal IONM (motor and somatosensory evoked potentials, D-wave whenever possible) significantly predicted postoperative deficits (p<0.001), with a sensitivity, specificity, positive predictive value, and negative predictive value of 0.81, 0.93, 0.83, and 0.92, respectively. Sixty (60.6%) patients displayed no IONM change, whereas 39 (39.4%) displayed IONM worsening. In multivariate analysis, predictors for postoperative clinical worsening were: abnormal preoperative electrophysiological assessment (p=0.03), intramedullary tumor (p<0.001), lesion-occupying area ratio ≥0.7 (p<0.001), and IONM alterations (p<0.001). Three months after the surgical procedure, in patients presenting at least one of the risk factors described above, 45/81 (55.6%) and 19/81 (23.5%) were clinically and electrophysiologically improved, respectively; while 13/81 (16.0%) and 10/81 (12.3%) were clinically and electrophysiologically worsened. CONCLUSION: Multimodal IONM is an essential tool to guide SC surgery, and enables the accurate prediction of postoperative neurological outcome. Specific attention should be given to patients presenting with preoperative electrophysiological abnormalities, large tumor volume, and intramedullary tumor location.

Transdural Spinal Cord Herniation: An Exceptional Complication of Thoracoscopic Discectomy: 2-Dimensional Operative Video.

Thoracic disc herniation is a rare and severe condition, whose treatment may have complications including dural tears. Although benign in most cases, dural tears may induce iatrogenic transdural herniation of the spinal cord. The video demonstrates the diagnosis and surgical treatment of iatrogenic transdural herniation of the spinal cord. Here, we report a case of spinal cord herniation after thorascopic treatment of a thoracic disc herniation (DH). A 28-yr-old male presented with several years of left lower extremity weakness and was found to have a T6-7 DH. He underwent DH resection through video assisted mini-thoracotomy at another institution. In the immediate postoperative period, he developed a Brown-Sequard syndrome with left leg weakness. The surgeon decided not to reoperate and the patient improved with rehabilitation, allowing him to walk again. At 6 mo postop, he experienced sudden neurologic worsening but did not present to our clinic until 6 mo later. At this time, he had near complete paraplegia with bilateral lower extremity spasticity and central neuropathic pain. MRI showed a pseudo-meningocele and features suggesting a lateral spinal cord herniation. After a multidisciplinary meeting, we elected to perform a posterolateral approach with costo-arthro-pediculectomy and durotomy to repair the SC herniation. Immediately postop, the patient had a slight improvement in right lower extremity function, with decreased pain and spasticity. This case shows a transdural SC herniation, a rare complication after resection of DH. It is possible that an unreported or unrecognized dural tear at the time of the initial surgery, combined with the negative pressure of the thoracic cavity, put the patient at risk for this particular complication. The authors state that the patient gave his informed consent.

Odontoid screw placement for Anderson type II odontoid fractures: how do duration from injury to surgery and clinical and radiological factors influence the union rate? A multicenter retrospective study.

OBJECTIVE: Anderson type II odontoid fractures are severe conditions, mostly affecting elderly people (≥ 70 years old). Surgery can be performed as a primary treatment or in cases of failed conservative management. This study aimed to investigate how duration from injury to surgery, as well as clinical, radiological, and surgical risk factors, may influence the union rate after anterior odontoid screw placement for Anderson type II odontoid fractures. METHODS: The authors conducted a retrospective multicenter study. Demographic, clinical, surgical, and radiological data of patients who underwent anterior odontoid screw placement for Anderson type II fractures were retrieved from institutional databases. Study exclusion criteria were prolonged corticosteroid drug therapy (> 4 weeks), polytraumatic injuries, oncological diagnosis, and prior cervical spine trauma. RESULTS: Eighty-five patients were included in the present investigation. The union rate was 76.5%, and 73 patients (85.9%) did not report residual instability. Age ≥ 70 years (p < 0.001, OR 6), female gender (p = 0.016, OR 3.61), osteoporosis (p = 0.009, OR 4.02), diabetes (p = 0.056, OR 3.35), fracture diastasis > 1 mm (p < 0.001, OR 8.5), and duration from injury to surgery > 7 days (p = 0.002, OR 48) independently influenced union rate, whereas smoking status (p = 0.677, OR 1.24) and odontoid process angulation > 10° (p = 0.885, OR 0.92) did not. CONCLUSIONS: Although many factors have been reported as influencing the union rate after anterior odontoid screw placement for Anderson type II fractures, duration from injury to surgery > 7 days appears to be the most relevant, resulting in a 48 times higher risk for nonunion. Early surgery appears to be associated with better radiological outcomes, as reported by orthopedic surgeons in other districts. Prospective comparative clinical trials are needed to confirm these results.

Patient-specific Rods for Surgical Correction of Sagittal Imbalance in Adults: Technical Aspects and Preliminary Results.

STUDY DESIGN: This was an innovative concept and a preliminary prospective series. OBJECTIVE: The aim of this study was to present the concept and the technical aspects of patient-specific rods (PSR), and compare preoperative and postoperative sagittal parameters (after PSR implantation), with a special focus on the difference pelvic incidence (PI)-lumbar lordosis (LL). BACKGROUND: Despite established techniques for planning and proven correlations between quality of life and sagittal alignment, some patients do not achieve optimal radiologic outcomes after surgery and are still hypolordotic and imbalanced. We hypothesize that the use of PSR could improve the correspondence between planning and surgical realization. METHODS: The planning was based on spinopelvic parameters evaluated on a full-spine x-ray. The surgical procedure including osteotomies was simulated using a dedicated program to reach the following objectives: PI-LL<10 degrees, a pelvic tilt <20 degrees, and sagittal vertical axis <50 mm. From the virtually corrected spine, the rod curvature and length were defined. Two PSRs were thus precisely manufactured and bent to this specification. Adults with degenerative spinal disorders requiring a construct ≥5 levels were implanted with PSR and prospectively included. We compared ratios through the χ test. RESULTS: A total of 60 patients (mean age of 64.4 years old; range, 34-83) were included. Follow-up was carried out over a period of 1 year. Average pedicle screws construct was of 6.4 levels (range, 5-9). Eight patients underwent a pedicle subtraction osteotomy. PI-LL was <10 degrees at baseline in 29/60 patients, and at follow-up in 50/60 (odds ratio=5, P=E-5). CONCLUSIONS: The ratio of patients with optimal PI-LL improved significantly from PSR implantation. In comparison with published data for conventional surgery, patients implanted with PSR were 2.6 times more likely to be optimally corrected. The expected benefits of PSR include the optimal execution of the plan, decreased mechanical complications, and reduced operating time, no longer requiring the bending of rods during surgery. A randomized trial on sagittal correction using PSR is ongoing.

Biomechanical evaluation of pedicle screw-based dynamic stabilization devices for the lumbar spine: a systematic review.

STUDY DESIGN: This study is a systematic review of published biomechanical studies involving pedicle screw-based posterior dynamic stabilization devices (PDS) with a special focus on kinematics and load transmission through the functional spine unit (FSU). METHODS: A literature search was performed via the PubMed online database from 1990 to 2008 using the following key words: "biomechanics," "lumbar dynamic stabilization," "Graf system," "Dynesys," and "posterior dynamic implant." Citations were limited to papers describing biomechanics of pedicle screw-based PDS devices currently available for clinical use. Studies describing clinical experience, radiology, and in vivo testing were excluded from the review. Parameters measured included kinematics of the FSU (range of motion (ROM), neutral zone (NZ), and location of the center of rotation) and load transmission through the disk, facets, and instrumentation. RESULTS: A total of 27 publications were found that concerned the biomechanical evaluation of lumbar pedicle screw-based dynamic stabilization instrumentation. Nine in vitro experimental studies and 4 finite element analyses satisfied the inclusion criteria. The Dynesys implant was the most investigated pedicle screw-based PDS system. In vitro cadaveric studies mainly focused on kinematics comparing ROM of intact versus instrumented spines whereas finite element analyses allowed analysis of load transmission at the instrumented and adjacent levels. CONCLUSION: Biomechanical studies demonstrate that pedicle screw-based PDS devices limit intervertebral motion while unloading the intervertebral disk. The implant design and the surgical technique have a significant impact on the biomechanical behavior of the instrumented spinal segment. The posterior placement of such devices results in non-physiologic intervertebral kinematics with a posterior shift of the axis of rotation. Biomechanical studies suggest that the difference at the adjacent level between investigated dynamic devices and rigid stabilization systems may not be as high as reported. Finally, additional investigations of semirigid devices are needed to further evaluate their biomechanical properties compared to soft stabilization PDS systems.