Amer F. Samdani

GRAFTING OF HUMAN BONE MARROW STROMAL CELLS INTO SPINAL CORD INJURY: A COMPARISON OF DELIVERY METHODS

Study Design. Three groups of 6 rats received subtotal cervical spinal cord hemisections followed with marrow stromal cell (MSC) transplants by lumbar puncture (LP), intravenous delivery (IV), or direct injection into the injury (control). Animals survived for 4 or 21 days. Objective. Cell therapy is a promising strategy for the treatment of spinal cord injury (SCI). The mode of cell delivery is crucial for the translation to the clinic. Injections directly into the parenchyma may further damage already compromised tissue; therefore, less invasive methods like LP or IV delivery are preferable. Summary of Background Data. Human MSC are multipotent mesenchymal adult stem cells that have a potential for autologous transplantation, obviating the need for immune suppression. Although previous studies have established that MSC can be delivered to the injured spinal cord by both LP and IV, the efficacy of cell delivery has not been directly compared with respect to efficacy of delivery and effects on the host. Methods. Purified MSC from a human donor were transplanted into the CSF at the lumbar region (LP), into the femoral vein (IV), or directly into the injury (control). After sacrifice, spinal cord sections were analyzed for MSC graft size, tissue sparing, host immune response, and glial scar formation, using specific antibodies and Nissl-myelin staining. Results. LP delivery of MSC to the injured spinal cord is superior to IV delivery. Cell engraftment and tissue sparing were significantly better after LP delivery, and host immune response after LP delivery was reduced compared with IV delivery. Conclusion. LP is an ideal minimally invasive technique to deliver cellular transplants to the injured spinal cord. It is superior to IV delivery and, together with the potential for autologous transplantation, lends itself for clinical application.

Vertebral body stapling: a fusionless treatment option for a growing child with moderate idiopathic scoliosis.

Study Design. Retrospective review. Objective. To report the results of vertebral body stapling (VBS) with minimum 2-year follow-up in patients with idiopathic scoliosis. Summary of Background Data. While bracing for idiopathic scoliosis is moderately successful, its efficacy has been called into question, and it carries associated psychosocial ramifications. VBS has been shown to be a safe, feasible alternative to bracing for idiopathic scoliosis. Methods. We retrospectively reviewed 28 of 29 patients (96%) with idiopathic scoliosis treated with VBS followed for a minimum of 2 years. Inclusion criteria: Risser sign of 0 or 1 and coronal curve measuring between 20° and 45°. Results. There were 26 thoracic and 15 lumbar curves. Average follow-up was 3.2 years. The procedure was considered a success if curves corrected to within 10° of preoperative measurement or decreased >10°. Thoracic curves measuring <35° had a success rate of 77.7%. Curves which reached ≤20° on first erect radiograph had a success rate of 85.7%. Flexible curves >50% correction on bend film had a success rate of 71.4%. Of the 26 curves, 4 (15%) showed correction >10°. Kyphosis improved in 7 patients with preoperative hypokyphosis (<10° of kyphosis T5–T12). Of the patients, 83.5% had remaining normal thoracic kyphosis of 10° to 40°. Lumbar curves demonstrated a success rate of 86.7%. Four of the 15 lumbar curves (27%) showed correction >10°. Major complications include rupture of a unrecognized congenital diaphragmatic hernia and curve overcorrection in 1 patient. Two minor complications included superior mesenteric artery syndrome and atelectasis due to a mucous plug. There were no instances of staple dislodgement or neurovascular injury. Conclusion. Analysis of patients with idiopathic scoliosis (IS) with high-risk progression treated with vertebral body stapling (VBS) and minimum 2-year follow-up shows a success rate of 87% in all lumbar curves and in 79% of thoracic curves <35°. Thoracic curves >35° were not successful and require alternative treatments.

Intra-operative magnetic resonance imaging in neurosurgery.

SummaryIntra-operative MRI (iMRI) has been incorporated into modern neurosurgical operating rooms as a guide for neurosurgical interventions for almost ten years. This technology has been shown to be a useful modality in brain tumour surgery and biopsy; its use in spine, vascular and epilepsy surgery has been evolving. It is particularly useful in low-grade gliomas, pituitary adenomas and pediatric tumors.We evaluate currently available iMRI systems and their applications in neurosurgery. Future possibilities related to iMRI systems are mentioned in the light of current advances.

Autofusion in the immature spine treated with growing rods.

Study Design. Retrospective case review of skeletally immature patients treated with growing rods. Patients received an average of 9.6 years follow-up care. Objective. (1) to identify the rate of autofusion in the growing spine with the use of growing rods; (2) to quantify how much correction can be attained with definitive instrumented fusion after long-term treatment with growing rods; and (3) to describe the extent of Smith-Petersen osteotomies required to gain correction of an autofused spine following growing rod treatment. Summary of Background Data. The safety and use of growing rods for curve correction and maintenance in the growing spine population has been established in published reports. While autofusion has been reported, the prevalence and sequelae are not known. Methods. Nine skeletally immature children with scoliosis were identified who had been treated using growing rods. A retrospective review of the medical records and radiographs was conducted and the following data collected: complications, pre- and postoperative Cobb angles at time of initial surgery (growing rod placement), pre- and postoperative Cobb angles at time of final surgery (growing rod removal and definitive fusion), total spine length as measured from T1–S1, % correction since initiation of treatment and at definitive fusion, total number of surgeries, and number of patients found to have autofusion at the time of device removal. Results. The rate of autofusion in children treated with growing rods was 89%. The average percent of the Cobb angle correction obtained at definitive fusion was 44%. On average, 7 osteotomies per patient were required at the time of definitive fusion due to autofusion. Conclusion. Although growing rods have efficacy in the control of deformity within the growing spine, they also have adverse effects on the spine. Immature spines treated with a growing rod have high rates of unintended autofusion which can possibly lead to difficult and only moderate correction at the time of definitive fusion.

Accuracy of frameless and frame-based image-guided stereotactic brain biopsy in the diagnosis of glioma: comparison of biopsy and open resection specimen

Abstract Objectives: Tissue heterogeneity and rapid tumor progression may decrease the accuracy a prognostic value of stereotactic brain biopsy in the diagnosis of gliomas. Correct tumor grading is therefore dependent on the accuracy of biopsy needle placement. There has been a dramatic increase in the utilization of frameless image-guided stereotactic brain biopsy; however, its accuracy in the diagnosis of glioma remains unstudied. Methods: The diagnoses of 21 astrocytic brain tumors were derived using image-guided stereotactic biopsy (12 frame-based, nine frameless) and followed by open resection of the lesion 1.5 (0.5–4) months later. The histologic diagnoses yielded by the biopsy were compared with subsequent histologic diagnosis from open tumor resection. Results: Histology of 21 stereotactic biopsies accurately represented the greater lesion at open resection a median of 45 days later in 16 (76%) cases and correctly guided therapy in 19 (91%) cases. Biopsy accuracy of frameless versus frame-based stereotaxis was similar (89 versus 66%, p=0.21). In three (14%) cases, biopsy specimens were adequate to diagnose glioma; however, histology was insufficient for definitive tumor grading. Anaplastic oligodendroglioma (ODG) was under-graded as low-grade ODG in one (5%) case. Biopsy of new onset glioblastoma multiforme (GBM) yielded necrosis/gliosis and was termed non-diagnostic in one patient. Tumors <50 cm3 were 8-fold less likely to accurately represent the grade of the entire lesion at resection compared with lesions <50 cm3 (OR, 8.8; 95% CI, 0.9–100, p=0.05). Discussion: Both frameless and frame-based MRI-guided stereotactic brain biopsy are safe and accurately represent the larger glioma mass sufficiently to guide subsequent therapy. Large tumor volume had a higher incidence of non-concordance. Increasing the number of specimens taken through the long dimension of large tumors may improve diagnostic accuracy.

Computed Tomography Evaluation of Rotation Correction in Adolescent Idiopathic Scoliosis : A Comparison of an All Pedicle Screw Construct Versus a Hook-Rod System

Study Design. Retrospective review with historical cohort. Objective. Our study measures axial rotation of the apical vertebral bodies of patients with adolescent idiopathic scoliosis treated with an all pedicle screw (APS) construct versus a hook-rod (HR) construct using computed tomography (CT). Summary of Background Data. Ecker et al (Spine 1988;13:1141–4) observed a 22% derotation of the apical vertebrate of the thoracic spine and 33% of the apical vertebra of the lumbar spine when using an HR system (CD instrumentation). More recently Lee et al (Spine 2004;29:343–9) reported 42.5% derotation of the apical vertebra (both thoracic and lumbar) in a series of APS constructs. Currently, there is no comparison series reported between the 2 types of constructs. Methods. From a database of 193 patients with adolescent idiopathic scoliosis and posterior spinal fusions, 32 patients were identified as having all APS constructs with pre- and postoperative CT scans. This cohort of patients was compared with a historical published cohort of patients treated with HR constructs by Ecker et al (Spine 1988;13:1141–4) Comparison of the groups showed no statistically significant differences for age and preoperative Cobb angle of the main curve (P > 0.05); however, there was a statistically significant difference (P < 0.05) in postoperative correction values. The apical vertebral rotation for the major curve was measured from the pre- and postoperative axial CT using the methods described by Aaro and Dahlborn (Spine 1981;6:460–7). Result. The average preoperative rotation was similar between the 2 groups (thoracic: HR = 22.6, APS = 21.3, P = 0.6; lumbar: HR = 19.4, APS = 20.6, P = 0.7). The postoperative correction had a significant difference (thoracic: HR = 16, APS = 8.5, P = 0.015; lumbar: HR = 13.4, APS = 7.0, P = 0.032). The percent correction of the apical vertebrae showed a significant difference, with 22% correction in the HR group and 60% in APS group (P < 0.001). Conclusion. Our study finds axial rotation correction using APSs and a direct vertebral body derotation technique was significantly greater than that obtained with the HR construct.

Cervical sagittal plane decompensation after surgery for adolescent idiopathic scoliosis: an effect imparted by postoperative thoracic hypokyphosis

OBJECT Several studies have characterized the relationship among postoperative thoracic, lumbar, and pelvic alignment in the sagittal plane. However, little is known of the relationship between postoperative thoracic kyphosis and sagittal cervical alignment in patients with adolescent idiopathic scoliosis (AIS) treated with all pedicle screw constructs. The authors examined this relationship and associated factors. METHODS A prospective database of pediatric patients with AIS undergoing spinal fusion between 2003 and 2005 was reviewed for those who received predominantly pedicle screw constructs for Lenke Type 1 or Type 2 curves. Parameters analyzed on pre- and postoperative radiographs were the fusion levels; cervical, thoracic, and lumbar sagittal balance; and C-2 and C-7 plumb lines. RESULTS Preoperatively, 6 (Group A) of the 22 patients included in the study had frank cervical kyphosis (mean angle 13.0°) with mean associated thoracic kyphosis of 27.2° (range 16°-37°). Postoperatively, cervical kyphosis (13.0°) remained in the patients in Group A along with mean thoracic kyphosis of 17.7° (range 4°-26°, p < 0.05). Preoperatively, the remaining 16 of 22 patients had neutral to lordotic cervical alignment (mean -13.8°) with thoracic kyphosis (mean 45°, range 30°-76°). Postoperatively, 8 (Group B) of these 16 patients demonstrated cervical sagittal decompensation (> 5° kyphosis), with 6 showing frank cervical kyphosis (10.5°, p < 0.05). In Group B, the mean postoperative thoracic kyphosis was 25.6° (range 7°-49°, p < 0.05). The other 8 patients (Group C) had mean postoperative thoracic kyphosis of 44.1° (range 32°-65°), and there was no cervical decompensation (p < 0.05). CONCLUSIONS The sagittal profile of the thoracic spine is related to that of the cervical spine. The surgical treatment of Lenke Type 1 and 2 curves by using all pedicle screw constructs has a significant hypokyphotic effect on thoracic sagittal plane alignment (19 [86%] of 22 patients). If postoperative thoracic kyphosis is excessively decreased (mean 25.6°, p < 0.05), the cervical spine may decompensate into significant kyphosis.

Diffusion tensor imaging of the pediatric spinal cord at 1.5T: preliminary results.

BACKGROUND AND PURPOSE: Recent studies suggest that pediatric subjects as old as 8-years-of-age may have difficulty with the ISNCSCI examinations. Our aim was to investigate DTI parameters of healthy spinal cord in children with noncervical IS for comparison with children with SCI and to prospectively evaluate reliability measures of DTI and to correlate the measures obtained in children with SCI with the ISNCSCI. MATERIALS AND METHODS: Five controls with thoracic and lumbar IS and 5 children with cervical SCI were imaged twice by using a single-shot echo-planar diffusion-weighted sequence. Axial imaging was performed to cover the entire cervical spinal cord in controls. For the SCI subjects, 2 vertebral bodies above and below the injury were imaged. FA and D values were obtained at different levels of the cervical spinal cord. All subjects with SCI had undergone ISNCSCI clinical examinations. Statistical analysis was performed to access differences of the DTI indices between the controls and SCI subjects, reproducibility measurements, and correlations between DTI and ISNCSCI. RESULTS: Subjects with SCI showed reduced FA and increased D values compared with controls. Test-retest reproducibility showed good ICC coefficients in all the DTI index values among controls (≥0.9), while the SCI group showed moderate ICC (≥0.77). There were statistically significant correlations between the various DTI indices and ISNCSCI scores. CONCLUSIONS: Preliminary DTI indices in children were determined and showed good reproducibility. Reduced FA and increased D values were seen in children with SCI in comparison with controls and showed good clinical correlation with ISNCSCI examinations.

Learning Curve for Placement of Thoracic Pedicle Screws in the Deformed Spine

OBJECTIVEThe placement of thoracic pedicle screws, particularly in the deformed spine, poses unique challenges, and a learning curve. We measured the in vivo accuracy of placement of thoracic pedicle screws by computed tomography in the deformed spine by a single surgeon over time. METHODSAfter obtaining institutional review board approval, we retrospectively selected the first 30 consecutive patients who had undergone a posterior spinal fusion using a pedicle screw construct for adolescent idiopathic scoliosis by a single surgeon. The average patient age was 14 years, and their preoperative thoracic Cobb angle was, on average, 62.6 degrees. Patients were divided into 3 groups: group A, patients 1 to 10; group B, patients 11 to 20; and group C, patients 21 to 30. Intraoperative evaluation of all pedicle screws included probing of the pedicle screw tract, neurophysiologic monitoring, and fluoroscopic confirmation. Postoperative computed tomographic scans were evaluated by 2 spine surgeons, and a consensus read was established, as previously described (Kim YJ, Lenke LG, Bridwell KH, Cho YS, Riew KD. Free hand pedicle screw placement in the thoracic spine: is it safe? Spine. 2004;29(3):333–342), as (1) “in,” axis of pedicle screw within the confines of the pedicle; or (2) “out,” axis of pedicle screw outside the confines of the pedicle. RESULTSA total of 553 thoracic pedicle screws were studied (group A, n = 181; group B, n = 189; group C, n = 183) with 64 graded as out (medial, 35; lateral, 29), for an overall breach rate of 11.6%. When the breach rates were stratified by the surgeons evolving experience, there was a temporal decrease in the breach rate (group A, 15.5%; group B, 10.6%; group C, 8.7%; P < .05). This decreased breach rate was reflected in fewer medial breaches over time (group A, 9.4%; group B, 5.8%; group C, 3.8%; P < .05). Similar trends were observed for the concave periapical screws, although statistical significance was not attained (group A, 21.2%; group B, 16.2%; group C, 10.5%). CONCLUSIONThe overall accuracy of placement of thoracic pedicle screws in the deformed spine was 88.4%, with no neurologic or visceral complications. One patient from group A returned to the operating room on postoperative day 2 for removal of an asymptomatic left T7 thoracic pedicle screw abutting the aorta. As surgeon experience increased, there was an overall decreased breach rate, which was mainly reflected in fewer medial breaches.

Diffusion tensor imaging in pediatric spinal cord injury: preliminary examination of reliability and clinical correlation.

Study Design. The design was a nonexperimental, repeated measures design. Objective. To examine the reliability of repeated diffusion tensor imaging (DTI) values of the pediatric cord and to compare DTI values with values obtained on the clinical examination and findings from conventional magnetic resonance imaging (MRI). Summary of Background Data. DTI quantifies the diffusion of water molecules in directions parallel and transverse to the plane of neuronal axons. The unique characteristic architecture of the spinal cord allows DTI to examine the white matter and potentially separate white matter from gray matter and assess structural damage of the cord. Methods. Ten youths with cervical spinal cord injury (SCI) were evaluated using the International Standards for Neurological Classification of SCI (ISNCSCI) and had 2 scans using a 3.0T Siemens Verio MR scanner. The imaging protocol consisted of conventional sagittal fast spin echo T1- and T2-weighted scans, axial fast spin echo T2-weighted scans, and axial DTI acquisition. Intraclass correlation coefficient (ICC) and 95% confidence interval were calculated for mean, axial, and radial diffusivity (MD, AD, RD, respectively) and fractional anisotropy (FA). Relationships among DTI, MRI, and ISNCSCI were evaluated using Spearman correlation coefficients (rs) and differences were tested using Cohens method. Results. There was moderate-to-strong reliability (ICC = 0.75–0.95) for MD, AD, and RD for all spinal levels. Reliability for FA for mid-C4 and between C5–C6 and C7–T1 was moderate (ICC = 0.75–0.80). Diffusivity values demonstrated moderate-to-good negative relationships (rs = −0.30 to −0.59), with 4 ISNCSCI values. FA values had a moderate-to-good (rs = 0.33–0.53) positive relationship, with 5 ISNCSCI values. Compared with MRI, DTI values had significantly stronger correlations (P ⩽ 0.0001) with the majority of ISNCSCI values. Conclusion. DTI values had good-to-strong reliability on repeated scans and moderate-to-good concurrent validity with clinical scores. When compared with conventional MRI, DTI values had statistically stronger correlations with the majority of values from the clinical examination.