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  • Author or Editor: Christopher Michael x
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Michael P. Steinmetz, Christopher D. Kager and Edward C. Benzel

Object. Cervical kyphotic deformation may develop after surgery involving either the ventral or dorsal approach. Regardless of the cause, the development of a cervical kyphotic deformity should be avoided, if possible, and corrected if present, when appropriate. The authors describe their experience with a technique for the ventral correction of iatrogenic (postoperative) cervical kyphosis.

Methods. A retrospective review of cases involving correction of postoperative iatrogenic cervical kyphosis via an ventral approach was performed. The authors conducted an ventral approach to kyphosis correction. The procedure required specific head positioning (in extension), convergent distraction pins, and an ventrally placed implant (axially dynamic when appropriate) with multiple points of fixation including at least one point of intermediate fixation. The pre- and postoperative sagittal angle and clinical status were evaluated.

During a nearly 14-month period, 12 patients met the inclusion criteria. Ten patients underwent a minimum of 6 months of follow up. They comprised the study population. Most patients presented with mechanical neck pain as part of their symptom profile. The mean magnitude of deformity correction (pre- to postoperative) was 20° of lordosis. The mean postoperative sagittal angle was 6° of lordosis. The mean change in the sagittal angle during the follow-up period was 2.2° of lordosis.

Conclusions. The ventral approach to correction of cervical deformity led to the achievement of lordosis in all but one patient. This posture was effectively maintained during the follow-up period. All patients exhibited improvement postoperatively; three experienced complete resolution of their preoperative symptoms. When symptoms are related to postsurgical kyphosis, deformity correction should be considered. Such a procedure may be performed effectively via an ventral approach in most circumstances.

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Christopher I. Shaffrey and Justin S. Smith

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Thomas J. Buell, Davis G. Taylor, Ching-Jen Chen, Christopher I. Shaffrey, Justin S. Smith and Shay Bess

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Alex J. Koefman, Melissa Licari, Michael Bynevelt and Christopher R. P. Lind

OBJECTIVE

An objective biomarker for pain is yet to be established. Functional MRI (fMRI) is a promising neuroimaging technique that may reveal an objective radiological biomarker. The purpose of this study was to evaluate fMRI technology in the setting of lumbosacral radiculopathy and discuss its application in revealing a biomarker for pain in the future.

METHODS

A prospective, within-participant control study was conducted. Twenty participants with painful lumbosacral radiculopathy from intervertebral disc pathology were recruited. Functional imaging of the brain was performed during a randomly generated series of nonprovocative and provocative straight leg raise maneuvers.

RESULTS

With a statistical threshold set at p < 0.000001, 3 areas showed significant blood oxygen level–dependent (BOLD) signal change: right superior frontal gyrus (x = 2, y = 13, z = 48, k = 29, Brodmann area 6 [BA6]), left supramarginal cortex (x = −37, y = −44, z = 33, k = 1084, BA40), and left parietal cortex (x = −19, y = −41, z = 63, k = 354, BA5). With a statistical threshold set at p < 0.0002, 2 structures showed significant BOLD signal change: right putamen (x = 29, y = −11, z = 6, k = 72) and bilateral thalami (right: x = 23, y = −11, z = 21, k = 29; x = 8, y = −11, z = 9, k = 274; and left: x = −28, y = −32, z = 6, k = 21).

CONCLUSIONS

The results in this study compare with those in previous studies and suggest that fMRI technology can provide an objective assessment of the pain experience.

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William B. Feldman, Aaron J. Clark, Michael Safaee, Christopher P. Ames and Andrew T. Parsa

Object

Myxopapillary ependymomas (MPEs) are rare WHO Grade I tumors found in the conus medullaris, cauda equina, and filum terminale. Treatment generally consists of resection with or without adjuvant radiotherapy. Evidence-based guidelines for surgical management are lacking due to the rarity of this tumor.

Methods

An English-language PubMed search was performed using the key words “myxopapillary” and “ependymoma.” Reports describing fewer than 3 patients or those lacking data on the extent of resection or radiotherapy were excluded. A total of 28 articles describing 475 patients met the authors' inclusion criteria. Patients were grouped by extent of resection and whether or not they underwent adjuvant radiotherapy. Differences in recurrence rates were assessed by chi-square test.

Results

The overall recurrence rate was 15.5% in patients treated by gross-total resection (GTR) and 32.6% in patients treated by subtotal resection (STR), irrespective of whether they underwent adjuvant therapy (p < 0.001). Regardless of the extent of resection, adjuvant radiotherapy was not associated with a decrease in recurrence rates. The overall recurrence rate was 15.6% in patients who underwent GTR and radiotherapy compared with 15.9% in patients who underwent GTR alone (p = 0.58), and it was 29.3% in patients who underwent STR and radiotherapy compared with 35.1% in those who underwent STR alone (p = 0.53). The difference between recurrence rates for patients who underwent GTR alone versus STR and radiotherapy was statistically significant (p = 0.02). Subgroup analysis demonstrated significantly higher recurrence rates in pediatric patients compared with adults (40.5% vs 23.4%, respectively; p = 0.02). Even in the setting of GTR alone, recurrence rates were higher in pediatric patients (65% vs 7.6%; p < 0.001).

Conclusions

Gross-total resection alone is associated with decreased recurrence rates compared with STR with or without radiotherapy. The authors' results suggest that treatment goals should include attempted GTR whenever possible. The observation that children benefitted from radiation therapy to a greater extent than did adults suggests that biological differences between tumors in these patient populations warrants more rigorous scientific studies.

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Cecilia L. Dalle Ore, Darryl Lau, Jessica L. Davis, Michael M. Safaee and Christopher P. Ames

Juvenile ossifying fibroma (JOF) is a rare benign bone tumor that occurs most frequently in the craniofacial bones of children and young adults. There are few case reports that describe its involvement outside the craniofacial skeleton, especially within the spinal column. While JOF is classified as a benign lesion, it may be locally aggressive and demonstrate a high propensity for recurrence, even after resection. Definitive surgical management may be challenging in naive cases, but it is particularly challenging in recurrent cases and when extensive spinal reconstruction is warranted. In this report, the authors describe the diagnosis and surgical management of a 29-year-old man who presented with a large recurrent sacral trabecular-subtype JOF. A review of literature regarding JOFs, management of recurrent primary spinal tumors, and sacral reconstruction are discussed.

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G. Edward Vates, Kevin C. Wang, David Bonovich, Christopher F. Dowd and Michael T. Lawton

✓ Bow hunter stroke, which is characterized by transient vertebrobasilar ischemia brought on by head turning, is an unusual condition usually caused by structural abnormalities at the craniocervical junction. The authors present a case in which compression of the left vertebral artery (VA) at the C4–5 level was caused by a laterally herniated intervertebral disc. A 56-year-old man presented with a 6-month history of dizziness and syncope when he turned his head 45° or more to the left. Transcranial Doppler (TCD) ultrasonography demonstrated decreased blood flow through the left VA, and angiography revealed an occlusion of the left VA at the C4–5 level, both when the patient turned his head to the left. Via an anterior cervical approach, the VA canal was unroofed through the transverse foramina to decompress the left VA at C4–5; intraoperatively, the left VA was found to be compressed by a laterally herniated cervical disc fragment. To the best of the authors' knowledge this is the first report of a laterally herniated cervical disc causing bow hunter stroke. The use of TCD may be of value in the diagnosis and management of the disorder, and herniated cervical disc must be included in the roster of potential causes for this rare disease.

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Devon Hoover, Aruna Ganju, Christopher I. Shaffrey, Henry Bartkowski and Michael J. Rauzzino

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Time is spine: a review of translational advances in spinal cord injury

JNSPG 75th Anniversary Invited Review Article

Jetan H. Badhiwala, Christopher S. Ahuja and Michael G. Fehlings

Acute traumatic spinal cord injury (SCI) is a devastating event with far-reaching physical, emotional, and economic consequences for patients, families, and society at large. Timely delivery of specialized care has reduced mortality; however, long-term neurological recovery continues to be limited. In recent years, a number of exciting neuroprotective and regenerative strategies have emerged and have come under active investigation in clinical trials, and several more are coming down the translational pipeline. Among ongoing trials are RISCIS (riluzole), INSPIRE (Neuro-Spinal Scaffold), MASC (minocycline), and SPRING (VX-210). Microstructural MRI techniques have improved our ability to image the injured spinal cord at high resolution. This innovation, combined with serum and cerebrospinal fluid (CSF) analysis, holds the promise of providing a quantitative biomarker readout of spinal cord neural tissue injury, which may improve prognostication and facilitate stratification of patients for enrollment into clinical trials. Given evidence of the effectiveness of early surgical decompression and growing recognition of the concept that “time is spine,” infrastructural changes at a systems level are being implemented in many regions around the world to provide a streamlined process for transfer of patients with acute SCI to a specialized unit. With the continued aging of the population, central cord syndrome is soon expected to become the most common form of acute traumatic SCI; characterization of the pathophysiology, natural history, and optimal treatment of these injuries is hence a key public health priority. Collaborative international efforts have led to the development of clinical practice guidelines for traumatic SCI based on robust evaluation of current evidence. The current article provides an in-depth review of progress in SCI, covering the above areas.

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David E. Gwinn, Christopher A. Iannotti, Edward C. Benzel and Michael P. Steinmetz

Object

Analysis of cervical sagittal deformity in patients with cervical spondylotic myelopathy (CSM) requires a thorough clinical and radiographic evaluation to select the most appropriate surgical approach. Angular radiographic measurements, which are commonly used to define sagittal deformity, may not be the most appropriate to use for surgical planning. The authors present a simple straight-line method to measure effective spinal canal lordosis and analyze its reliability. Furthermore, comparisons of this measurement to traditional angular measurements of sagittal cervical alignment are made in regards to surgical planning in patients with CSM.

Methods

Twenty preoperative lateral cervical digital radiographs of patients with CSM were analyzed by 3 independent observers on 3 separate occasions using a software measurement program. Sagittal measurements included C2–7 angles utilizing the Cobb and posterior tangent methods, as well as a straight-line method to measure effective spinal canal lordosis from the dorsal-caudal aspect of the C2–7 vertebral bodies. Analysis of variance for repeated measures or Cohen 3-way (kappa) correlation coefficient analysis was performed as appropriate to calculate the intra- and interobserver reliability for each parameter. Discrepancies in angular and effective lordosis measurements were analyzed.

Results

Intra- and interobserver reliability was excellent (intraclass coefficient > 0.75, kappa > 0.90) utilizing all 3 techniques. Four discrepancies between angular and effective lordotic measurements occurred in which images with a lordotic angular measurement did not have lordosis within the ventral spinal canal. These discrepancies were caused by either spondylolisthesis or dorsally projecting osteophytes in all cases.

Conclusions

Although they are reliable, traditional methods used to make angular measurements of sagittal cervical spine alignment do not take into account ventral obstructions to the spinal cord. The effective lordosis measurement method provides a simple and reliable means of determining clinically significant lordosis because it accounts for both overall alignment of the cervical spine as well as impinging structures ventral to the spinal cord. This method should be considered for use in the treatment of patients with CSM.