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Michael S. Turner

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Elizabeth Weinstein, Michael Turner, Benjamin B. Kuzma, and Henry Feuer

Premature return to play for the concussed pediatric athlete may result in devastating neurological injury. Identification of at-risk patients and ideal management of the concussed athlete remain challenging for the pediatrician. The authors review a case of second impact syndrome in which neuroimaging was obtained between the first and second impacts, a circumstance which to their knowledge has not been previously reported. This case offers new insights into the underlying pathophysiology of this disease process and potential risk factors for its development.

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A. Leland Albright, Michael Turner, and Jogi V. Pattisapu

In March 2004, a multidisciplinary conference, “ITB Therapy Best Practice Forum,” was held in Minneapolis, Minnesota. The goal of the conference was to develop recommendations for techniques to implant intrathecal baclofen (ITB) pump and catheter systems more effectively and with fewer complications.

The authors present the techniques for optimal pump and catheter implantation, including subfascial pump placement; insertion of the Tuohy needle in an oblique, paramedian trajectory; and positioning of the catheter tip at levels commensurate with the therapeutic indication: approximately T10–12 for spastic diplegia, C5–T2 for spastic tetraparesis, and C1–4 for generalized secondary dystonia. Techniques to minimize the incidence of cerebrospinal fluid leakage are described, including the identification of preoperative occult hydrocephalus and the use of a suture ligature around the Tuohy needle at its exit site from the fascia. Techniques to minimize surgery-related infection are also detailed; most involve the use of iodine solutions multiple times intraoperatively. Techniques to insert intrathecal catheters during spinal fusion are addressed, particularly the technique of inserting the catheter cephalad to the fusion site.

Panel members advocate the aforementioned techniques to improve the efficacy of and decrease the morbidity associated with ITB therapy.

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Michael Turner, Ha Son Nguyen, and Aaron A. Cohen-Gadol

Object

The aim of this study was to identify the benefits of intraventricular baclofen (IVB) therapy for the treatment of intractable spasticity or dystonia in a subset of patients who had experienced multiple revisions while receiving intrathecal baclofen (ITB) therapy.

Methods

The authors reviewed the charts of 22 consecutive patients with intractable spasticity or dystonia who initially underwent ITB therapy, subsequently suffered multiple revisions during ITB therapy, and ultimately received IVB therapy, all during a 12-year period from November 1998 to October 2010. The intraventricular catheters were positioned in the lateral ventricle, aided by stereonavigation.

Results

The surgical revision rate (the average number of surgical revisions per average number of follow-up years) during ITB therapy was 0.84, and was 0.50 during IVB therapy. The most frequent complication requiring surgical revision during ITB therapy was catheter occlusion, followed by pump malfunction/pump pocket issues, and infection. The most frequent complication requiring surgical revision during IVB therapy was infection, followed by catheter misplacement/migration. Four patients suffered infection that required removal of their intraventricular catheter, and currently have no baclofen system.

Conclusions

Some of these patients had a history of increasing revisions with increasing frequency during ITB therapy. Such a history puts them at risk for spinal arachnoiditis, a condition that complicates further ITB therapy. For such patients, the authors believe that IVB therapy may be a beneficial therapeutic option, given that the surgical revision rate was lower for IVB than for ITB. Intraventricular baclofen may be a cost-effective option for patients with mounting revisions during ITB therapy.

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Michael S. Turner, Ha Son Nguyen, Troy D. Payner, and Aaron A. Cohen-Gadol

Object

Posterior fossa cysts are usually divided into Dandy-Walker malformations, arachnoid cysts, and isolated and/or trapped fourth ventricles. Shunt placement is a mainstay treatment for decompression of these fluid collections when their expansion becomes symptomatic. Although several techniques to drain symptomatic posterior fossa cysts have been described, each method carries its own advantages and disadvantages. This article describes an alternative technique.

Methods

In 10 patients, the authors used an alternative technique involving stereotactic and endoscopic methods to place a catheter in symptomatic posterior fossa cysts across the tentorium. Discussion of these cases is included, along with a review of various approaches to shunt placement in this region and recommendations regarding the proposed technique.

Results

No patient suffered intracranial hemorrhage related to the procedure and catheter implantation. All 3 patients who underwent placement of a new transtentorial cystoperitoneal shunt and a new ventriculoperitoneal shunt did not suffer any postoperative complication; a decrease in the size of their posterior fossa cysts was evident on CT scans obtained during the 1st postoperative day. Follow-up CT scans demonstrated either stable findings or further interval decrease in the size of their cysts. In 1 patient, the postoperative head CT demonstrated that the transtentorial catheter terminated posterior to the right parietal occipital region without entering the retrocerebellar cyst. This patient underwent a repeat operation for proximal shunt revision, resulting in an acceptable catheter implantation. The patient in Case 8 suffered from a shunt infection and subsequently underwent hardware removal and aqueductoplasty with stent placement. The patient in Case 9 demonstrated a slight increase in fourth ventricle size and was returned to the operating room. Exploration revealed a kink in the tubing connecting the distal limb of the Y connector to the valve. The Y connector was replaced with a T connector, and 1 week later, CT scans exhibited interval decompression of the ventricles. This patient later presented with cranial wound breakdown and an exposed shunt. His shunt hardware was removed and he was treated with antibiotics. He later underwent reimplantation of a lateral ventricular and transtentorial shunt and suffered no other complications during a 3-year follow-up period.

Conclusions

The introduction of endoscopic and stereotactic techniques has expanded the available treatment possibilities for posterior fossa cysts.

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Vicko Gluncic, Michael Turner, Leonard Kranzler, and David Frim

A case of atlanto-occipital dislocation (AOD) is presented to illustrate the importance of subtle imaging findings and the occipital condyle–C1 interval (CCI) measurement in the evaluation of high cervical spine injury. Although AOD is commonly considered to be fatal, recently there have been an increasing number of reports of children surviving this injury. Prompt recognition and treatment of AOD are crucial for survival.

The authors present a case of an 8-year-old boy who sustained a destabilizing injury without bone disruption but with ligamentous tears that rendered his cervical spine unstable from the occiput to the C-1 level. On admission, imaging findings were consistent with tectorial membrane damage, perimedullary subarachnoid hemorrhage, and extraaxial blood from the clivus to the C-2 level. Most standard cervical spine radiological indices were within normal limits except the CCI. After initial management in a cervical collar, the patient was placed in halo vest, and subsequently underwent occiput to C-3 fusion. Timely recognition of the injury and subsequent craniocervical stabilization with internal fixation resulted in full neurological recovery. This report supports CCI as a valuable index for the prompt recognition of AOD. It also supports recent literature suggesting that AOD is a survivable injury with the possibility for an excellent neurological recovery.

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Experimental syringomyelia

The relationship between intraventricular and intrasyrinx pressures

Peter Hall, Michael Turner, Steven Aichinger, Phillip Bendick, and Robert Campbell

✓ The influence of ventricular pressure changes on syrinx pressure was investigated in this study of experimental canine kaolin-induced syringomyelia. The pressures of the ventricles, syrinx, and cervical subarachnoid space were measured. A complete ventriculosubarachnoid block occurred in the animals with syringomyelia. The baseline syringeal pressures exceeded those of both the ventricles and the subarachnoid space. Raising ventricular pressure elevated the syringeal pressure, but aspiration of ventricular fluid did not acutely lower the pressure. These findings suggest a ventriculosyrinx valve effect that may inflate the syrinx during transient rises of intracranial pressure.

A respiratory pressure pattern was found in the syrinx similar to that of the ventricles and subarachnoid space. This wave was reduced but not abolished by ligating the subarachnoid space distal to the syrinx. The arterial pulse was much diminished within the syrinx at rest. These findings indirectly support the possibility that transmission of thoracic pressures to the spinal subarachnoid space with compression of the syrinx is a principal force that enlarges the syrinx.

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Nicholas M. Boulis, Danielle E. Turner, Michael J. Imperiale, and Eva L. Feldman

Object. Virus-mediated central nervous system gene delivery is a promising means of treating traumatized tissue or degenerative diseases. In the present study, the authors examined gene expression and neuronal survival in the spinal cord after sciatic nerve administration of an adenovirus vector expressing a LacZ reporter gene.

Methods. The time course of adenovirus gene expression, DNA fragmentation, and neuronal density were quantified in rat lumbar spinal cord by staining for β-galactosidase (β-Gal), terminal deoxynucleotidyl transferase, and cresyl violet after microinjection of either saline or the reporter virus into rat sciatic nerve. The expression of β-Gal following remote vector delivery peaked at 7 days and declined thereafter but was not accompanied by neuronal cell death, as measured by DNA fragmentation. No significant difference in spinal motor neuron density was detected between virus-treated and control rats at any time point examined. Although the spinal cords removed from rats treated with cyclosporine prior to adenovirus injection contained substantially more neurons staining for β-Gal at 7 days (67% of total neurons), the decay in the number of stained neurons was not paralleled by a decline in motor neuron density.

Conclusions. The authors conclude that remote gene expression is suppressed by a noncytolytic process.

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Ben B. Pradhan, Alexander W. L. Turner, Michael A. Zatushevsky, G. Bryan Cornwall, Sean S. Rajaee, and Hyun W. Bae

Object

Traditional posterior pedicle screw fixation is well established as the standard for spinal stabilization following posterior or posterolateral lumbar fusion. In patients with lumbar spinal stenosis requiring segmental posterior instrumented fusion and decompression, interlaminar lumbar instrumented fusion (ILIF) is a potentially less invasive alternative with reduced morbidity and includes direct decompression assisted by an interlaminar allograft spacer stabilized by a spinous process plate. To date, there has been no biomechanical study on this technique. In the present study the biomechanical properties of the ILIF construct were evaluated using an in vitro cadaveric biomechanical analysis, and the results are presented in comparison with other posterior fixation techniques.

Methods

Eight L1–5 cadaveric specimens were subjected to nondestructive multidirectional testing. After testing the intact spine, the following conditions were evaluated at L3–4: bilateral pedicle screws, bilateral laminotomy, ILIF, partial laminectomy, partial laminectomy plus unilateral pedicle screws, and partial laminectomy plus bilateral screws. Intervertebral motions were measured at the index and adjacent levels.

Results

Bilateral pedicle screws without any destabilization provided the most rigid construct. In flexion and extension, ILIF resulted in significantly less motion than the intact spine (p < 0.05) and no significant difference from the laminectomy with bilateral pedicle screws (p = 0.76). In lateral bending, there was no statistical difference between ILIF and laminectomy with unilateral pedicle screws (p = 0.11); however, the bilateral screw constructs were more rigid (p < 0.05). Under axial rotation, ILIF was not statistically different from laminectomy with unilateral or bilateral pedicle screws or from the intact spine (p > 0.05). Intervertebral motions adjacent to ILIF were typically lower than those adjacent to laminectomy with bilateral pedicle screws.

Conclusions

Stability of the ILIF construct was not statistically different from bilateral pedicle screw fixation following laminectomy in the flexion and extension and axial rotation directions, while adjacent segment motions were decreased. The ILIF construct may allow surgeons to perform a minimally invasive, single-approach posterior decompression and instrumented fusion without the added morbidity of traditional pedicle screw fixation and posterolateral fusion.

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A. Leland Albright, Yasser Awaad, Michael Muhonen, William R. Boydston, Richard Gilmartin, Linda E. Krach, Michael Turner, Kathryn A. Zidek, Ed Wright, Dale Swift, and Karen Bloom

Object. The objectives of this multicenter study were to monitor the performance of a 10-ml pump infusing intrathecal baclofen to treat 100 children with cerebral spasticity, to monitor complications associated with the pump, and to correlate pump-related complications with body habitus.

Methods. Age at implantation of the pump ranged from 1.4 to 16.8 years (mean 8.1 years). The effects of ITB on spasticity in the upper and lower extremities were evaluated using the Ashworth Scale. Data were collected regarding implant site, infection, complication, and body mass index (BMI). Ashworth Scale scores decreased significantly in the upper and lower extremities at 6 and 12 months after pump implantation (p < 0.001). There were four serious system-related complications, all specific to catheters. There were 32 serious procedure-related complications in 21 patients: 11 complications were infections that occurred in nine patients. Four of nine pump-induced infections were treated with pump removal and antibiotic therapy; five infections were treated successfully with antibiotic therapy alone, without pump removal. In children younger than 8 years of age there was a significantly higher incidence of serious procedure-related adverse events than in older children. There was no significant correlation between BMI and the incidence of pump pocket—related complications or infections.

Conclusions. The 10-ml pump can be used therapeutically in small children, particularly those weighing less than 40 lbs, with greater ease and less wound tension, than the conventional 18-ml pump. The incidence of complications associated with the 10-ml pump in younger children appears to be similar to that previously reported with the 18-ml pump in larger-sized children.