An in vitro evaluation of sagittal alignment in the cervical spine after insertion of supraphysiologic lordotic implants.

PURPOSE: Cervical spine malalignment can develop as a consequence of degenerative disc disease or following spinal surgery. When normal sagittal alignment of the spine is disrupted, further degeneration may occur adjacent to the deformity. The purpose of this study was to investigate changes in lordosis and sagittal alignment in the cervical spine after insertion of supraphysiologic lordotic implants. METHODS: Eight cadaveric cervical spines (Occiput-T1) were tested. The occiput was free to translate horizontally and vertically but constrained from angular rotation. The T1 vertebra was rigidly fixed with a T1 tilt of 23°. Implants with varying degrees of lordosis were inserted starting with single-level constructs (C5-C6), followed by two (C5-C7), and three-level (C4-C7) constructs. Changes in sagittal alignment, Occ-C2 angle, cervical lordosis (C2-7), and segmental lordosis were measured. RESULTS: Increasing cage lordosis led to global increases in cervical lordosis. As implanted segmental lordosis increased, the axial levels compensated by decreasing in lordosis to maintain horizontal gaze. An increase in cage lordosis also corresponded with larger changes in SVA. CONCLUSION: Reciprocal compensation was observed in the axial and sub-axial cervical spine, with the Occ-C2 segment undergoing the largest compensation. Adding more implant lordosis led to larger reciprocal changes and changes in SVA. Implants with supraphysiologic lordosis may allow for additional capabilities in correcting cervical sagittal plane deformity, following further clinical evaluation.

Reliability of a Novel Classification System for Thoracic Disc Herniations.

STUDY DESIGN: This is a cross-sectional survey. OBJECTIVE: The aim was to assess the reliability of a proposed novel classification system for thoracic disc herniations (TDHs). SUMMARY OF BACKGROUND DATA: TDHs are complex entities varying substantially in many factors, including size, location, and calcification. To date, no comprehensive system exists to categorize these lesions. METHODS: Our proposed system classifies 5 types of TDHs using anatomic and clinical characteristics, with subtypes for calcification. Type 0 herniations are small (≤40% of spinal canal) TDHs without significant spinal cord or nerve root effacement; type 1 are small and paracentral; type 2 are small and central; type 3 are giant (>40% of spinal canal) and paracentral; and type 4 are giant and central. Patients with types 1 to 4 TDHs have correlative clinical and radiographic evidence of spinal cord compression. Twenty-one US spine surgeons with substantial TDH experience rated 10 illustrative cases to determine the system's reliability. Interobserver and intraobserver reliability were determined using the Fleiss kappa coefficient. Surgeons were also surveyed to obtain consensus on surgical approaches for the various TDH types. RESULTS: High agreement was found for the classification system, with 80% (range 62% to 95%) overall agreement and high interrater and intrarater reliability (kappa 0.604 [moderate to substantial agreement] and kappa 0.630 [substantial agreement], respectively). All surgeons reported nonoperative management of type 0 TDHs. For type 1 TDHs, most respondents (71%) preferred posterior approaches. For type 2 TDHs, responses were roughly equivalent for anterolateral and posterior options. For types 3 and 4 TDHs, most respondents (72% and 68%, respectively) preferred anterolateral approaches. CONCLUSIONS: This novel classification system can be used to reliably categorize TDHs, standardize description, and potentially guide the selection of surgical approach. Validation of this system with regard to treatment and clinical outcomes represents a line of future study.

Can intraoperative neurophysiologic monitoring during cervical spine decompression predict post-operative segmental C5 palsy?

BACKGROUND: C5 nerve root palsy is a known complication after cervical laminectomy or laminoplasty, characterized by weakness of the deltoid and bicep brachii muscles. The efficacy of intraoperative monitoring of these muscles is currently unclear. In the current prospective study, intraoperative monitoring through somatosensory (SSEPs), motor (TcMEPs) evoked potentials and real-time electromyography activity (EMG) were analyzed for their ability to detect or prevent deltoid muscle weakness after surgery. METHODS: One hundred consecutive patients undergoing laminectomy/laminoplasty with or without fusion were enrolled. Intraoperative SSEPs, TcMEPs and EMGs from each patient were studied and analyzed. RESULTS: Intraoperative EMG activity of the C5 nerve root was detected in 34 cases, 10 of which demonstrated a sustained and repetitive EMG activity lasting 5 or more minutes. Paresis of the unilateral deltoid muscle developed in 5 patients, all from the group with sustained C5 EMG activity. None of the patients with weakness of deltoid muscle after surgery demonstrated any abnormal change in TcMEP or SSEP. CONCLUSIONS: Real-time EMG recordings were sensitive to C5 nerve root irritation, whilst SSEPs and TcMEPs were not. Sustained EMG activity of the C5 nerve root during surgery is a possible warning sign of irritation or injury to the nerve.

Reliability assessment of a novel cervical spine deformity classification system.

OBJECT: Despite the complexity of cervical spine deformity (CSD) and its significant impact on patient quality of life, there exists no comprehensive classification system. The objective of this study was to develop a novel classification system based on a modified Delphi approach and to characterize the intra- and interobserver reliability of this classification. METHODS: Based on an extensive literature review and a modified Delphi approach with an expert panel, a CSD classification system was generated. The classification system included a deformity descriptor and 5 modifiers that incorporated sagittal, regional, and global spinopelvic alignment and neurological status. The descriptors included: "C," "CT," and "T" for primary cervical kyphotic deformities with an apex in the cervical spine, cervicothoracic junction, or thoracic spine, respectively; "S" for primary coronal deformity with a coronal Cobb angle ≥ 15°; and "CVJ" for primary craniovertebral junction deformity. The modifiers included C2-7 sagittal vertical axis (SVA), horizontal gaze (chin-brow to vertical angle [CBVA]), T1 slope (TS) minus C2-7 lordosis (TS-CL), myelopathy (modified Japanese Orthopaedic Association [mJOA] scale score), and the Scoliosis Research Society (SRS)-Schwab classification for thoracolumbar deformity. Application of the classification system requires the following: 1) full-length standing posteroanterior (PA) and lateral spine radiographs that include the cervical spine and femoral heads; 2) standing PA and lateral cervical spine radiographs; 3) completed and scored mJOA questionnaire; and 4) a clinical photograph or radiograph that includes the skull for measurement of the CBVA. A series of 10 CSD cases, broadly representative of the classification system, were selected and sufficient radiographic and clinical history to enable classification were assembled. A panel of spinal deformity surgeons was queried to classify each case twice, with a minimum of 1 intervening week. Inter- and intrarater reliability measures were based on calculations of Fleiss k coefficient values. RESULTS: Twenty spinal deformity surgeons participated in this study. Interrater reliability (Fleiss k coefficients) for the deformity descriptor rounds 1 and 2 were 0.489 and 0.280, respectively, and mean intrarater reliability was 0.584. For the modifiers, including the SRS-Schwab components, the interrater (round 1/round 2) and intrarater reliabilities (Fleiss k coefficients) were: C2-7 SVA (0.338/0.412, 0.584), horizontal gaze (0.779/0.430, 0.768), TS-CL (0.721/0.567, 0.720), myelopathy (0.602/0.477, 0.746), SRS-Schwab curve type (0.590/0.433, 0.564), pelvic incidence-lumbar lordosis (0.554/0.386, 0.826), pelvic tilt (0.714/0.627, 0.633), and C7-S1 SVA (0.071/0.064, 0.233), respectively. The parameter with the poorest reliability was the C7-S1 SVA, which may have resulted from differences in interpretation of positive and negative measurements. CONCLUSIONS: The proposed classification provides a mechanism to assess CSD within the framework of global spinopelvic malalignment and clinically relevant parameters. The intra- and interobserver reliabilities suggest moderate agreement and serve as the basis for subsequent improvement and study of the proposed classification.

The impact of preinjury anticoagulants and prescription antiplatelet agents on outcomes in older patients with traumatic brain injury.

BACKGROUND: Anticoagulants and prescription antiplatelet (ACAP) agents widely used by older adults have the potential to adversely affect traumatic brain injury (TBI) outcomes. We hypothesized that TBI patients on preinjury ACAP agents would have worse outcomes than non-ACAP patients. METHODS: This was a 5.5-year retrospective review of patients 55 years and older admitted to a Level I trauma center with blunt force TBI. Patients were categorized as ACAP (warfarin, clopidogrel, dipyridamole/aspirin, enoxaparin, subcutaneous heparin, or multiple agents) or non-ACAP. ACAP patients were further stratified by class of agent (anticoagulant or antiplatelet). Initial and subsequent head computerized tomographic results were examined for type and progression of TBI. Patient preadmission living status and discharge destination were identified. Primary outcome was in-hospital mortality. Secondary outcomes were progression of initial TBI, development of new intracranial hemorrhage (remote from initial), and the need for an increased level of care at discharge. RESULTS: A total of 353 patients met inclusion criteria: 273 non-ACAP (77%) and 80 ACAP (23%). Upon exclusion of three patients taking a combination of agents, 350 were available for advanced analyses. ACAP status was significantly related to in-hospital mortality. After adjustment for patient and injury characteristics, anticoagulant users were more likely than non-ACAP patients to show progression of initial hemorrhage and develop a new hemorrhagic focus. However, compared with non-ACAP users, antiplatelet users were more likely to die in the hospital. Among survivors to discharge, anticoagulant users were more likely to be discharged to a care facility, but this finding was not robust to adjustment. CONCLUSION: Older TBI patients on preinjury ACAP agents experience a comparatively higher rate of inpatient mortality and other adverse outcomes caused by the effects of antiplatelet agents. Our findings should inform decision making regarding prognosis and caution against grouping anticoagulant and antiplatelet users together in considering outcomes. LEVEL OF EVIDENCE: Therapeutic study, level IV.

Shunt-related intracranial abscess caused by Staphylococcus lugdunensis in a hydranencephalic patient.

BACKGROUND: Staphylococcus lugdunensis is a coagulase-negative staphylococcus with aggressive and rapidly progressive infectious behavior. This organism has emerged as an important pathogen implicated in both community-acquired and nosocomial infections, including meningitis, brain abscess, catheter-related bacteremia, and ventriculoperitoneal shunt infection. CASE DESCRIPTION: We report the first known case of Staphylococcus lugdunensis intracranial abscess in a pediatric hydranencephalic patient, caused by a ventriculoperitoneal shunt-related infection. Further magnetic resonance imaging (MRI) confirmed a large abscess within the cranium that demonstrated multiple loculations. The patient received externalization of the right occipital ventricular catheter with evacuation of the brain abscess. Medical management included one week of intrathecal antibiotic treatment, and she was discharged on long-term intravenous rifampin and vancomycin, leading to cure of the infection. CONCLUSION: This case suggests that if Staphylococcus lugdunensis is identified, a virulent and prolonged clinical course with the production of destructive lesions, similar to those with S. aureus, should be expected. A course of antibiotic therapy and aggressive management that may include surgical treatment will be needed.

Osteoid osteomas: intraoperative bone scan-assisted resection. Clinical article.

OBJECT: Osteoid osteomas (OOs) are benign lesions of the spine, but can cause significant pain and spinal deformity in the pediatric population. They are often surgically elusive, and may require multiple surgical procedures to ensure complete resection. Nuclear medicine intraoperative bone scans (IOBSs) are highly sensitive for lesion localization and verification of complete surgical extirpation. METHODS: A retrospective review of 20 consecutive patients who had undergone resection of a spinal OO at the authors' institution was undertaken. In all cases, IOBSs were used for lesion localization and verification of resection. Postoperative imaging and clinical follow-up were obtained. RESULTS: The average length of follow-up was 56 months, with a range of 8-156 months. Five patients had undergone a total of 12 unsuccessful prior procedures for resection at other institutions where IOBSs were not used. In these patients, complete resection was accomplished with the use of IOBSs at the authors' institution. Of the 15 patients who presented to this institution with a newly diagnosed OO and who underwent IOBS-assisted resection, 14 had complete resection without recurrence. One patient, however, was found to have a discrete recurrence adjacent to the initial resection bed at the time of follow-up. CONCLUSIONS: Osteoid osteomas are benign lesions of the spine, and complete resection is curative. If resection is incomplete, then recurrence is likely. The IOBS modality is highly sensitive for detecting OO and for guiding complete resection. The IOBS modality should be considered as a first-line surgical adjunct in cases of suspected OO.