NG2+ progenitors derived from embryonic stem cells penetrate glial scar and promote axonal outgrowth into white matter after spinal cord injury.

The glial scar resulting from spinal cord injury is rich in chondroitin sulfate proteoglycan (CSPG), a formidable barrier to axonal regeneration. We explored the possibility of breaching that barrier by first examining the scar in a functional in vitro model. We found that embryonic stem cell-derived neural lineage cells (ESNLCs) with prominent expression of nerve glial antigen 2 (NG2) survived, passed through an increasingly inhibitory gradient of CSPG, and expressed matrix metalloproteinase 9 (MMP-9) at the appropriate stage of their development. Outgrowth of axons from ESNLCs followed because the migrating cells sculpted pathways in which CSPG was degraded. The degradative mechanism involved MMP-9 but not MMP-2. To confirm these results in vivo, we transplanted ESNLCs directly into the cavity of a contused spinal cord 9 days after injury. A week later, ESNLCs survived and were expressing both NG2 and MMP-9. Their axons had grown through long distances (>10 mm), although they preferred to traverse white rather than gray matter. These data are consistent with the concept that expression of inhibitory CSPG within the injury scar is an important impediment to regeneration but that NG2+ progenitors derived from ESNLCs can modify the microenvironment to allow axons to grow through the barrier. This beneficial action may be partly due to developmental expression of MMP-9. We conclude that it might eventually be possible to encourage axonal regeneration in the human spinal cord by transplanting ESNLCs or other cells that express NG2.

Biopsy of the superficial cortex: predictors of effectiveness and outcomes.

BACKGROUND: Brain biopsies of superficial cortex are performed for diagnosis of neurological diseases, but preoperative predictors of successful diagnosis and risks are lacking. OBJECTIVE: We evaluated effectiveness and outcomes of superficial cortical biopsies and determined preoperative predictors of diagnosis, outcomes, morbidities, and mortality. METHODS: A single-institution retrospective analysis of 170 patients who underwent open brain biopsies of superficial cortex was performed. Clinical predictors of effectiveness and outcomes were determined using univariate/multivariate analyses and a system for risk-benefit stratification was created and tested. RESULTS: Brain biopsies led to successful diagnosis in 122 of 170 (71.8%) and affected management in 97 of 170 (57.1%) cases. Factors increasing the odds of diagnostic pathology included age older than 45 years (odds ratio [OR]: 2.67, 95% confidence interval [CI]: 1.34-5.27, P < .01), previous cancer diagnosis (OR: 3.64, 95% CI: 1.69-7.85, P < .001), focal (OR: 3.90, 95% CI: 1.91-8.00, P < .001) and enhancing (OR: 5.03, 95% CI: 2.41-10.52, P < .001) lesions on magnetic resonance imaging, biopsy of specific lesions on magnetic resonance imaging (OR: 9.34, 95% CI: 4.29-20.33, P < .001), and use of intraoperative navigation (OR: 6.59, 95% CI: 3.04-14.28, P < .001). Brain biopsies led to symptomatic intracranial hemorrhage, seizures, other significant morbidities, and perioperative mortality in 12.4%, 16.2%, 37.1%, and 8% of cases, respectively. Risk of postoperative intracranial hemorrhage was increased by a history of aspirin use (OR: 2.51, 95% CI: 1.23-5.28, P < .05) and age older than 60 years (OR: 2.66, 95% CI: 1.36-5.18, P < .01). CONCLUSION: Effectiveness and risk of morbidity/mortality can be estimated preoperatively for patients undergoing open brain biopsies of the superficial cortex. Older age and specific imaging characteristics increase the odds of diagnostic biopsy. Conversely, older age and aspirin use increases the risk of postoperative complications.

The natural history and clinical presentation of cervical spondylotic myelopathy.

Cervical spondylotic myelopathy (CSM) refers to impaired function of the spinal cord caused by degenerative changes of the cervical spine resulting in spinal cord compression. It is the most common disorder in the United States causing dysfunction of the spinal cord. A literature review of the natural history of mild cervical myelopathy is undertaken. Clinical presentation and current concepts of pathophysiology are also discussed. While many patients with mild signs of CSM will stabilize or improve over time with conservative treatment, the clinical course of a specific individual patient cannot be predicted. Asymptomatic patients with cervical stenosis and abnormalities on electrophysiologic studies may be at higher risk for developing myelopathy.

Circumferential vertebrectomy with reconstruction for holocervical aneurysmal bone cyst at C4 in a 15-year-old girl.

STUDY DESIGN: The authors describe the unique case of a 15-year-old girl with a holovertebral aneurysmal bone cyst at C4, causing anterolisthesis and kyphosis, who underwent circumferential vertebrectomy with reconstruction and rigid fusion. OBJECTIVE: To report an unusual manifestation of aneurysmal bone cyst, requiring special considerations for surgery. The discussion highlights emerging principles for treatment of this lesion, and cervical spine fusion, in the pediatric population. SUMMARY OF BACKGROUND DATA: There is no previous report of a holovertebral aneurysmal bone cyst of the pediatric cervical spine. The potential for neurologic or vascular compromise from this lesion is substantial if left untreated, and the risk of recurrence or other morbidity is significantly higher unless completely resected. METHODS: A 15-year-old white female presented with a 4-month history of neck pain after a mild injury, but was neurologically intact. Diagnostic imaging revealed a holovertebral, multicystic, and osteolytic lesion with multiple fluid-fluid levels in the fourth cervical vertebra. Total vertebrectomy and repair were performed with fibular strut grafts and placement of rigid anterior and posterior instrumentation. This was accomplished in a single anteroposterior operative pass. RESULTS: Surgical treatment produced a stable bony fusion with no neurologic or vascular sequelae. This approach minimizes the risk of recurrence and the possibility of postoperative spinal instability. CONCLUSION: Spinal aneurysmal bone cyst in children presents diverse challenges. These lesions should be treated with complete resection to minimize the chance of recurrence. In pediatric cases, defects created by resection should be corrected by fusion to minimize the risk of postoperative instability and growth abnormality. One-year followup demonstrated a stable construct, and the patient remains neurologically at her baseline.

Multiple level discectomy and fusion.

The ventrolateral approach for surgical decompression of the cervical spine is widely used and well known to most spinal surgeons. Because compression of the spinal cord and nerve roots usually occurs ventral to the spinal cord, and the spinal cord does not tolerate traction, this approach allows safe and direct decompression of most compressive pathology. This article reviews the indications, diagnostic evaluation, and technique for multiple level discectomy and fusion. It further addresses the advantages and disadvantages of this technique compared with alternate surgical procedures.

Cervical deformity correction.

Subaxial cervical deformities most often occur in the sagittal plane, primarily as kyphosis. Kyphosis may develop secondary to advanced degenerative disease, trauma, neoplastic disease, or after surgery. Whatever the cause, the development of cervical deformity should be avoided and corrected when appropriate because the greater the deformity, the greater the probability of an associated neurological deficit or chronic pain. Patients usually present with mechanical type cervical pain, with or without neurological deficit (i.e., myelopathy). They may also be relatively asymptomatic. Work-up includes appropriate imaging studies, such as radiographs, including dynamic images, and magnetic resonance imaging or computed tomography myelography. The deformity may be accurately assessed and an appropriate surgical strategy undertaken. Depending on flexibility of the deformity and the presence or absence of facet ankylosis, a dorsal, ventral, or combined approach may be used. All approaches are unique in their ability to correct a deformity and in their associated complications. A comprehensive discussion of each is undertaken.

Techniques for the ventral correction of postsurgical cervical kyphotic deformity.

Progressive kyphotic deformity of the cervical spine may be a late sequela of congenital cervical anomalies, degenerative disc disease, neoplasm, cervical trauma, and surgical procedures. Of these, postsurgical kyphosis is the most common and can occur after ventral and dorsal surgeries of the cervical spine. The purpose of this article is to review the causes and clinical presentation of postsurgical cervical kyphosis and to focus on the operative planning and ventral correction techniques.