The authors report the case of a 14-year-old male with a subependymal giant cell astrocytoma (SEGA) that occurred in the absence of tuberous sclerosis complex (TSC). The patient presented with progressive headache and the sudden onset of nausea and vomiting. Neuroimaging revealed an enhancing left ventricular mass located in the region of the foramen of Monro with significant mass effect and midline shift. The lesion had radiographic characteristics of SEGA; however, the diagnosis remained unclear given the absence of clinical features of TSC. The patient underwent gross-total resection of the tumor with resolution of his symptoms. Although tumor histology was consistent with SEGA, genetic analysis of both germline and tumor DNA revealed no TSC1/2 mutations. Similarly, a comprehensive clinical evaluation failed to reveal any clinical features characteristic of TSC. Few cases of SEGA without clinical or genetic evidence of TSC have been reported. The histogenesis, genetics, and clinical approach to this rare lesion are briefly reviewed.
Thomas L. Beaumont, Jakub Godzik, Sonika Dahiya and Matthew D. Smyth
Jakub Godzik, Vijay M. Ravindra, Wilson Z. Ray, Meic H. Schmidt, Erica F. Bisson and Andrew T. Dailey
The authors’ objectives were to compare the rate of fusion after occipitoatlantoaxial arthrodesis using structural allograft with the fusion rate from using autograft, to evaluate correction of radiographic parameters, and to describe symptom relief with each graft technique.
The authors assessed radiological fusion at 6 and 12 months after surgery and obtained radiographic measurements of C1–2 and C2–7 lordotic angles, C2–7 sagittal vertical alignments, and posterior occipitocervical angles at preoperative, postoperative, and final follow-up examinations. Demographic data, intraoperative details, adverse events, and functional outcomes were collected from hospitalization records. Radiological fusion was defined as the presence of bone trabeculation and no movement between the graft and the occiput or C-2 on routine flexion-extension cervical radiographs. Radiographic measurements were obtained from lateral standing radiographs with patients in the neutral position.
At the University of Utah, 28 adult patients underwent occipitoatlantoaxial arthrodesis between 2003 and 2010 using bicortical allograft, and 11 patients were treated using iliac crest autograft. Mean follow-up for all patients was 20 months (range 1–108 months). Of the 27 patients with a minimum of 12 months of follow-up, 18 (95%) of 19 in the allograft group and 8 (100%) of 8 in the autograft group demonstrated evidence of bony fusion shown by imaging. Patients in both groups demonstrated minimal deterioration of sagittal vertical alignment at final follow-up. Operative times were comparable, but patients undergoing occipitocervical fusion with autograft demonstrated greater blood loss (316 ml vs 195 ml). One (9%) of 11 patients suffered a significant complication related to autograft harvesting.
The use of allograft in occipitocervical fusion allows a high rate of successful arthrodesis yet avoids the potentially significant morbidity and pain associated with autograft harvesting. The safety and effectiveness profile is comparable with previously published rates for posterior C1–2 fusion using allograft.
Michael P. Kelly, Lawrence G. Lenke, Jakub Godzik, Ferran Pellise, Christopher I. Shaffrey, Justin S. Smith, Stephen J. Lewis, Christopher P. Ames, Leah Y. Carreon, Michael G. Fehlings, Frank Schwab and Adam L. Shimer
The authors conducted a study to compare neurological deficit rates associated with complex adult spinal deformity (ASD) surgery when recorded in retrospective and prospective studies. Retrospective studies may underreport neurological deficits due to selection, detection, and recall biases. Prospective studies are expensive and more difficult to perform, but they likely provide more accurate estimates of new neurological deficit rates.
New neurological deficits were recorded in a prospective study of complex ASD surgeries (pSR1) with a defined outcomes measure (decrement in American Spinal Injury Association lower-extremity motor score) for neurological deficits. Using identical inclusion criteria and a subset of participating surgeons, a retrospective study was created (rSR1) and neurological deficit rates were collected. Continuous variables were compared with the Student t-test, with correction for multiple comparisons. Neurological deficit rates were compared using the Mantel-Haenszel method for standardized risks. Statistical significance for the primary outcome measure was p < 0.05.
Overall, 272 patients were enrolled in pSR1 and 207 patients were enrolled in rSR1. Inclusion criteria, defining complex spinal deformities, and exclusion criteria were identical. Sagittal Cobb measurements were higher in pSR1, although sagittal alignment was similar. Preoperative neurological deficit rates were similar in the groups. Three-column osteotomies were more common in pSR1, particularly vertebral column resection. New neurological deficits were more common in pSR1 (pSR1 17.3% [95% CI 12.6–22.2] and rSR1 9.0% [95% CI 5.0–13.0]; p = 0.01). The majority of deficits in both studies were at the nerve root level, and the distribution of level of injury was similar.
New neurological deficit rates were nearly twice as high in the prospective study than the retrospective study with identical inclusion criteria. These findings validate concerns regarding retrospective cohort studies and confirm the need for and value of carefully designed prospective, observational cohort studies in ASD.
Jakub Godzik, Michael P. Kelly, Alireza Radmanesh, David Kim, Terrence F. Holekamp, Matthew D. Smyth, Lawrence G. Lenke, Joshua S. Shimony, Tae Sung Park, Jeffrey Leonard and David D. Limbrick
Chiari malformation Type I (CM-I) is a developmental abnormality often associated with a spinal syrinx. Patients with syringomyelia are known to have an increased risk of scoliosis, yet the influence of specific radiographically demonstrated features on the prevalence of scoliosis remains unclear. The primary objective of the present study was to investigate the relationship of maximum syrinx diameter and tonsillar descent to the presence of scoliosis in patients with CM-I–associated syringomyelia. A secondary objective was to explore the role of craniovertebral junction (CVJ) characteristics as additional risk factors for scoliosis.
The authors conducted a retrospective review of pediatric patients evaluated for CM-I with syringomyelia at a single institution in the period from 2000 to 2012. Syrinx morphology and CVJ parameters were evaluated with MRI, whereas the presence of scoliosis was determined using standard radiographic criteria. Multiple logistic regression was used to analyze radiological features that were independently associated with scoliosis.
Ninety-two patients with CM-I and syringomyelia were identified. The mean age was 10.5 ± 5 years. Thirty-five (38%) of 92 patients had spine deformity; 23 (66%) of these 35 patients were referred primarily for deformity, and 12 (34%) were diagnosed with deformity during workup for other symptoms. Multiple regression analysis revealed maximum syrinx diameter > 6 mm (OR 12.1, 95% CI 3.63–40.57, p < 0.001) and moderate (5–12 mm) rather than severe (> 12 mm) tonsillar herniation (OR 7.64, 95% CI 2.3–25.31, p = 0.001) as significant predictors of spine deformity when controlling for age, sex, and syrinx location.
The current study further elucidates the association between CM-I and spinal deformity by defining specific radiographic characteristics associated with the presence of scoliosis. Specifically, patients presenting with larger maximum syrinx diameters (> 6 mm) have an increased risk of scoliosis.