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  • Journal of Neurosurgery: Spine x
  • By Author: Johnson, J. Patrick x
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Naresh P. Patel, Neill M. Wright, William W. Choi, Duncan Q. McBride and J. Patrick Johnson

Object. Forestier Disease (FD) is a progressive skeletal disorder affecting predominantly older men. It is also known as diffuse idiopathic skeletal hyperostosis (DISH) and is characterized by massive anterior longitudinal ligament calcification that forms a bridge on the anterior border of the thoracic and subaxial cervical spine. To the authors' knowledge, retroodontoid masses associated with FD have not been described.

Methods. Five patients with FD and multilevel subaxial cervical fusion were treated for retroodontoid masses and cervicomedullary junction (CMJ) compression. There were four men and one woman (mean age 73 years, range 54–86 years). All patients suffered progressive neurological symptoms resulting from anterior compression of the CMJ.

Four patients underwent combined transoral resection of the ligamentous mass followed by an occipitocervical fusion procedure. One patient with circumferential CMJ compression underwent a posterior decompression and occipitocervical fusion. Histopathological examination of the mass showed hypertrophic degenerative fibrocartilage. Early postoperative neurological improvement was noted in all patients. The follow-up period ranged from 4 to 19 months. At the end of the follow-up period, four patients experienced neurological improvement. One patient died 3 weeks postsurgery of pulmonary complications.

Conclusions. The osseous elements of the occipitoatlantoaxial complex are not directly affected by FD. The ligamentous structures of the odontoid process, however, are exposed to significantly altered biomechanics resulting from fusion of the subaxial cervical spine associated with FD. Stress-induced compensatory ligamentous hypertrophic changes at the craniovertebral junction cause CMJ compression and subsequent neurological deterioration. This previously undescribed entity should be considered in patients with FD or DISH who present with progressive quadriparesis. Transoral decompression and posterior fusion are often needed in patients with large masses and severe progressive neurological deficits. Selected patients with smaller masses and milder neurological symptoms may be treated with posterior fusion alone.

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Rod J. Oskouian Jr. and J. Patrick Johnson

Object. Anterior approaches in thoracic and lumbar spinal surgery have potentially serious vascular injury—related complications. In this study the authors evaluate the incidence of vascular complications in anterior approaches to the thoracic and lumbar spine in cases requiring reconstructive surgery.

Methods. The authors retrospectively reviewed the medical records of 207 patients who underwent anterior thoracic and lumbar spinal reconstructive surgery during the period from 1992 through 1999 to determine the incidence, causes, and management of vascular complications.

Overall, the incidence of vascular complications following reconstructive spinal surgery was 5.8% (12 patients) and the mortality rate was 1% (two patient deaths). In seven patients (3.4%), direct vascular injuries developed as a result of surgical techniques or error; one patient died as a result. Five patients (2.4%) developed deep venous thromboses, and one patient in this subgroup died of pulmonary embolism.

Conclusions. Vascular injury to the great vessels is a known and potentially serious complication associated with anterior spinal reconstructive procedures. The authors found, however, that the incidence is relatively low in cases in which venous injuries occurred acutely and arterial injuries presented in a delayed fashion.

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Langston T. Holly, Orin Bloch, Chinyere Obasi and J. Patrick Johnson

Object. Intraoperative image guidance provides real-time three-dimensional visualization and has been successfully applied in many posterior spinal procedures. The feasibility of applying these techniques to anterior spinal surgery has not been studied systematically because the anterior spine, in contrast to the posterior spine, lacks distinct anatomical landmarks for registration. The authors sought to evaluate the practicality of performing stereotaxy in the anterior spine in a cadaveric model.

Methods. Unilateral C4—L4 pedicle screws were placed posteriorly in three cadaveric specimens to serve as unknown markers within each vertebral body. The specimens then underwent computerized tomography (CT) scanning, and the CT data were transferred to an optical tracking system. The anterior surface of the spine was registered for use with the stereotactic system by using a paired point—matching technique. Attached to a surgical drill, K-wires were placed under stereotactic guidance in a tip-to-tip orientation with the posterior pedicle screws. A second postoperative CT scan was obtained, and accuracy was determined by measuring the distance between the tips of the K-wire and pedicle screw.

The K-wires were placed tip to tip with pedicle screw markers in 57 vertebral levels. The mean registration error was 1.47 ± 0.04 mm, and when combined with the universal instrument registration error of 0.7 mm yielded an overall registration error of 2.17 ± 0.04 mm. The mean tip-to-tip distance for all K-wires placed was 2.46 ± 0.23 mm. The difference between the mean tip-to-tip distance and overall registration error was not statistically significant (p > 0.05), indicating that the K-wires were placed within the expected range of error.

Conclusions. The results of this study confirmed the feasibility of performing anterior stereotactic procedures throughout the spine. The accuracy of the findings in this study indicates that anterior stereotaxy should be applicable in clinical practice.

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Orin Bloch, Langston T. Holly, Jongsoo Park, Chinyere Obasi, Kee Kim and J. Patrick Johnson

Object. In recent studies some authors have indicated that 20% of patients have at least one ectatic vertebral artery (VA) that, based on previous criteria in which preoperative computerized tomography (CT) and standard intraoperative fluoroscopic techniques were used, may prevent the safe placement of C1–2 transarticular screws. The authors conducted this study to determine whether frameless stereotaxy would improve the accuracy of C1–2 transarticular screw placement in healthy patients, particularly those whom previous criteria would have excluded.

Methods. The authors assessed the accuracy of frameless stereotaxy for C1–2 transarticular screw placement in 17 cadaveric cervical spines. Preoperatively obtained CT scans of the C-2 vertebra were registered on a stereotactic workstation. The dimensions of the C-2 pars articularis were measured on the workstation, and a 3.5-mm screw was stereotactically placed if the height and width of the pars interarticularis was greater than 4 mm. The specimens were evaluated with postoperative CT scanning and visual inspection. Screw placement was considered acceptable if the screw was contained within the C-2 pars interarticularis, traversed the C1–2 joint, and the screw tip was shown to be within the anterior cortex of the C-1 lateral mass.

Transarticular screws were accurately placed in 16 cadaveric specimens, and only one specimen (5.9%) was excluded because of anomalous VA anatomy. In contrast, a total of four specimens (23.5%) showed significant narrowing of the C-2 pars interarticularis due to vascular anatomy that would have precluded atlantoaxial transarticular screw placement had previous nonimage-guided criteria been used.

Conclusions. Frameless stereotaxy provides precise image guidance that improves the safety of C1–2 transarticular screw placement and potentially allows this procedure to be performed in patients previously excluded because of the inaccuracy of nonimage-guided techniques.

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J. Patrick Johnson, Chinyere Obasi, Michael S. Hahn and Paul Glatleider

Object. Thoracic sympathectomy has evolved as a treatment option for patients with hyperhidrosis and pain disorders. In the past, surgical procedures were highly invasive and caused significant morbidity, but the minimally invasive thoracoscopic procedure provides detailed visualization of the sympathetic ganglia and is associated with minimal postoperative morbidity.

Methods. The authors performed 112 thoracoscopic sympathectomy procedures in 65 patients, and the outcomes were equivalent to those previously established for open surgical techniques; however, the rate of surgery-related morbidity, length of hospital stay, and time until return to normal activity were substantially reduced. Complications and recurrence of symptoms were comparable with those demonstrated in previous reports. Overall patient satisfaction and willingness to undergo a repeated operative procedure ranged from 66 to 99%. Postoperatively, higher satisfaction rates were observed in patients with hyperhidrosis whereas in those with pain syndromes, satisfaction rates were lower.

Conclusions. Minimally invasive thoracoscopic sympathectomy procedures are useful in treating sympathetically mediated disorders, and the results indicate that the procedure is associated with reduced morbidity and similar outcome when compared with results obtained after open surgery. Hyperhidrosis is well treated, but patients with pain syndromes have significantly poorer outcomes.

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Chronic renal failure causing brown tumors and myelopathy

Case report and review of pathophysiology and treatment

Igor Fineman, J. Patrick Johnson, Pier-Luigi Di-Patre and Harvinder Sandhu

✓ Brown tumors (osteoclastomas) are histologically benign lesions that are caused by primary or secondary hyperparathyroidism. Secondary hyperparathyroidism is a frequent complication of chronic renal failure. Skeletal brown tumors are relatively uncommon, and brown tumors that involve the spine are considered very rare. The authors present the case of a 37-year-old woman with systemic lupus erythematosus and hemodialysis-dependent anuric renal failure, in whom spinal cord compression developed due to a brown tumor and pathological fracture at T-9. The patient underwent transthoracic decompressive surgery and spinal reconstruction in which cadaveric femoral allograft and instrumentation were used. Brown tumors of the vertebral column require surgical treatment if medical therapy and parathyroidectomy fail to halt their progression or if acute neurological deterioration occurs. In patients with renal failure bone healing is delayed and there is an increased risk that healing will fail because the metabolic derangements can result in severe osteoporosis. Surgical reconstruction of the spine may require the use of augmentation with instrumentation and aggressive treatment of hyperparathyroidism to achieve successful outcomes.