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Andrew J. Grossbach, Kelly B. Mahaney, and Arnold H. Menezes

OBJECTIVE

Meningiomas are relatively common, typically benign neoplasms in adults; however, they are relatively rare in the pediatric population. Pediatric meningiomas behave very differently from their adult counterparts, tending to have more malignant histological subtypes and recur more frequently. The authors of this paper investigate the risk factors, pathological subtypes, and recurrence rates of pediatric meningiomas.

METHODS

A retrospective chart review was conducted at the University of Iowa to identify patients 20 years old and younger with meningiomas in the period from 1948 to 2015.

RESULTS

Sixty-seven meningiomas in 39 patients were identified. Eight patients had neurofibromatosis, 2 had a family history of meningioma, and 3 had prior radiation exposure. Twelve (31%) of the 39 patients had WHO Grade II or III lesions, and 15 (38%) had recurrent lesions after resection.

CONCLUSIONS

Pediatric meningiomas should be considered for early treatment and diligent follow-up.

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Andrew J. Grossbach, Taylor J. Abel, Arnold H. Menezes, and Mathew A. Howard

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Andrew J. Grossbach, Nader S. Dahdaleh, Taylor J. Abel, Gregory D. Woods, Brian J. Dlouhy, and Patrick W. Hitchon

Object

Flexion-distraction injuries occur due to distractive forces causing disruption of the posterior and middle spinal columns. These fractures classically consist of a fracture line through the posterior bony elements; involvement of the posterior ligamentous complex is, however, common. Surgical treatment is often required for these unstable injuries to avoid neurological deterioration and posttraumatic kyphosis, and the surgery traditionally consists of an open posterior approach with instrumented fusion. Percutaneous pedicle screw fixation for these injuries, with the goal of minimal tissue disruption and preservation of normal anatomy while achieving adequate stabilization, has recently been reported in the literature, but to date, a direct comparative study comparing open and percutaneous fixation has not been reported. The authors report their experience treating these fractures with both techniques and review the available literature.

Methods

Patients with flexion-distraction injury who were treated between May 2003 and March 2013 were prospectively followed. American Spinal Injury Association scores and degree of kyphotic angulation were recorded at admission, discharge, and follow-up. Data regarding intraoperative blood loss and operative time were obtained from a chart review. Patients treated with open versus minimally invasive procedures were compared.

Results

The authors identified 39 patients who suffered flexion-distraction injuries and were treated at their institution during the specified period; one of these patients declined surgery. All had injury to the posterior ligamentous complex. Open surgical procedures with pedicle screw fixation and posterolateral fusion were performed in 27 patients, while 11 patients underwent minimally invasive pedicle screw placement. Overall, there was improvement in kyphotic angulation at the time of discharge as well as most recent follow-up in both the open surgery and minimally invasive surgery (MIS) groups. The authors found no significant difference in American Spinal Injury Association score or the degree of kyphotic angulation between the MIS and open surgery groups. There was a trend toward shorter operative time for the MIS group, and patients who underwent minimally invasive procedures had significantly less blood loss.

Conclusions

Minimally invasive percutaneous pedicle screw fixation appears to have similar efficacy in the treatment of flexion-distraction injuries and it allows for reduced blood loss and tissue damage compared with open surgical techniques. Therefore it should be considered as an option for the treatment of this type of injury.

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Taylor J. Abel, Brian D. Dalm, Andrew J. Grossbach, Adam W. Jackson, Teri Thomsen, and Jeremy D. W. Greenlee

Lesch-Nyhan disease (LND) is an X-linked hereditary disorder caused by a deficiency of hypoxanthine-guanine phosphoribosyltransferase. This syndrome is characterized by hyperuricemia, self-mutilation, cognitive impairment, and movement disorders such as spasticity and dystonia. The authors describe the case of a 15-year-old boy who underwent bilateral placement of globus pallidus internus (GPi) deep brain stimulation (DBS) electrodes for the treatment of generalized dystonia. His self-mutilating behavior gradually disappeared several weeks after the start of GPi stimulation. The dystonia and self-mutilating behavior returned on the left side only after a right lead fracture. This case is the first reported instance of LND treated with DBS in which the stimulation was interrupted and the self-mutilation returned in a lateralized fashion. The findings indicate that the neurobehavioral aspect of LND is lateralized and that contralateral GPi stimulation is responsible for lateralized improvement in self-injurious behavior.

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Justin Baum, Stephanus V. Viljoen, Connor S. Gifford, Amy J. Minnema, Ammar Shaikhouni, Andrew J. Grossbach, Shahid Nimjee, and H. Francis Farhadi

OBJECTIVE

Despite the increasing incidence of spinal epidural abscess (SEA), the baseline parameters potentially predictive of treatment failure remain poorly characterized. In this study, the authors identify the relevant baseline parameters that predict multimodal treatment failure in patients with either intravenous drug use (IVDU)–associated SEA or non-IVDU–associated SEA.

METHODS

The authors reviewed the electronic medical records of a large institutional series of consecutive patients with diagnosed SEA between January 2011 and December 2017 to characterize epidemiological trends as well as the complement of baseline measures that are predictive of failure after multimodal treatment in patients with and without concomitant IVDU. The independent impact of clinical and imaging factors in detecting treatment failure was assessed by performing stepwise binary logistic regression analysis.

RESULTS

A total of 324 consecutive patients with diagnosed SEA were identified. Overall, 226 patients (69.8%) had SEA related to other causes and 98 (30.2%) had a history of recent IVDU. While non-IVDU SEA admission rates remained constant, year-over-year admissions of patients with IVDU SEA nearly tripled. At baseline, patients with IVDU SEA were distinct in many respects including younger age, greater unemployment and disability, less frequent diabetes mellitus (DM), and more frequent methicillin-resistant Staphylococcus aureus infection. However, differences in length of stay, loss to follow-up, and treatment failure did not reach statistical significance between the groups. The authors constructed independent multivariate logistic regression models for treatment failure based on identified parameters in the two cohorts. For the non-IVDU cohort, the authors identified four variables as independent factors: DM, hepatitis B/C, osteomyelitis, and compression deformity severity. In contrast, for patients with IVDU, the authors identified three variables: albumin, endocarditis, and endplate destruction. Receiver operating characteristic and area under the curve (AUC) analyses were undertaken for the multivariate models predicting the likelihood of treatment failure in the two cohorts (AUC = 0.88 and 0.89, respectively), demonstrating that the derived models could adequately predict the risk of multimodal treatment failure. Treatment failure risk factor point scales were derived for the identified variables separately for both cohorts.

CONCLUSIONS

Patients with IVDU SEA represent a unique population with a distinct set of baseline parameters that predict treatment failure. Identification of relevant prognosticating factors will allow for the design of tailored treatment and follow-up regimens.

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Vibhu K. Viswanathan, Ranjit Ganguly, Amy J. Minnema, Nicole A. DeVries Watson, Nicole M. Grosland, Douglas C. Fredericks, Andrew J. Grossbach, Stephanus V. Viljoen, and H. Francis Farhadi

OBJECTIVE

Proximal junctional kyphosis (PJK) and failure (PJF) are potentially catastrophic complications that result from abrupt changes in stress across rigid instrumented and mobile non-fused segments of the spine (transition zone) after adult spinal deformity surgery. Recently, data have indicated that extension (widening) of the transitional zone via use of proximal junctional (PJ) semi-rigid fixation can mitigate this complication. To assess the biomechanical effectiveness of 3 semi-rigid fixation constructs (compared to pedicle screw fixation alone), the authors performed cadaveric studies that measured the extent of PJ motion and intradiscal pressure changes (ΔIDP).

METHODS

To measure flexibility and ΔIDP at the PJ segments, moments in flexion, extension, lateral bending (LB), and torsion were conducted in 13 fresh-frozen human cadaveric specimens. Five testing cycles were conducted, including intact (INT), T10–L2 pedicle screw-rod fixation alone (PSF), supplemental hybrid T9 Mersilene tape insertion (MT), hybrid T9 sublaminar band insertion (SLB1), and hybrid T8/T9 sublaminar band insertion (SLB2).

RESULTS

Compared to PSF, SLB1 significantly reduced flexibility at the level rostral to the upper-instrumented vertebral level (UIV+1) under moments in 3 directions (flexion, LB, and torsion, p ≤ 0.01). SLB2 significantly reduced motion in all directions at UIV+1 (flexion, extension, LB, torsion, p < 0.05) and at UIV+2 (LB, torsion, p ≤ 0.03). MT only reduced flexibility in extension at UIV+1 (p = 0.02). All 3 constructs revealed significant reductions in ΔIDP at UIV+1 in flexion (MT, SLB1, SLB2, p ≤ 0.02) and torsion (MT, SLB1, SLB2, p ≤ 0.05), while SLB1 and SLB2 significantly reduced ΔIDP in extension (SLB1, SLB2, p ≤ 0.02) and SLB2 reduced ΔIDP in LB (p = 0.05). At UIV+2, SLB2 similarly significantly reduced ΔIDP in extension, LB, and torsion (p ≤ 0.05).

CONCLUSIONS

Compared to MT, the SLB1 and SLB2 constructs significantly reduced flexibility and ΔIDP in various directions through the application of robust anteroposterior force vectors at UIV+1 and UIV+2. These findings indicate that semi-rigid sublaminar banding can most effectively expand the transition zone and mitigate stresses at the PJ levels of long-segment thoracolumbar constructs.