Michael Y. Wang and Paul Khoueir
Daniel J. Hoh, Paul Khoueir, and Michael Y. Wang
✓ Ankylosing spondylitis can lead to severe cervical kyphosis, causing problems with forward vision, swallowing, hygiene, patient functionality, and social outlook. Evaluation of patients with cervical flexion deformity includes assessment of global sagittal balance and chin–brow angle. The primary treatment in extreme disabling cases is surgical correction involving a posterior cervical extension osteotomy, which is a technically demanding procedure with considerable risk of neurological injury. To address the potential complications with extension osteotomy, the authors of several reports have described modifications to the surgical technique. These developments incorporate recent advances in anesthesia, neuromonitoring, and spinal instrumentation. Complications associated with the procedure include subluxation at the osteotomy level, spinal cord injury, radiculopathy, dysphagia, and pseudarthrosis. Although the risks of spinal correction are considerable, extension osteotomy remains an effective treatment modality for patients with disabling cervical flexion deformity.
Alexander A. Khalessi, Bryan C. Oh, and Michael Y. Wang
✓ In the following literature review the authors consider the available evidence for the medical management of patients with ankylosing spondylitis (AS), and they critically assess current treatment guidelines. Medical therapy for axial disease in AS emphasizes improvement in patients' pain and overall function. First-line treatments include individualized physical therapy and nonsteroidal antiinflammatory drugs (NSAIDs) in conjunction with gastroprotective therapy. After an adequate trial of therapy with two NSAIDs exceeding 3 months or limited by medication toxicity, the patient may undergo tumor necrosis factor–α blockade therapy. Response should occur within 6–12 weeks, and patients must undergo tuberculosis screening. Evidence does not currently support the use of disease modifying antirheumatic drugs, corticosteroids, or radiotherapy in AS.
Adam S. Kanter, Michael Y. Wang, and Praveen V. Mummaneni
Patients with ankylosing spondylitis (AS) who present with cervical spine fractures represent a unique challenge to spine surgeons. These injuries often result in neurological deficits that necessitate early and aggressive surgical management with posterior and/or anterior fixation. The authors introduce a clinical problem-solving algorithm to assist in the surgical management of instability and deformity in this exigent patient population.
Thirteen patients with AS and fractures of the cervical spine were radiographically evaluated to determine if spinal realignment was obtainable with cervical manipulation or traction. Seven patients had flexible deformities that were stabilized with either anterior or posterior fixation only, and 6 patients had fixed deformities and required circumferential anterior–posterior instrumentation. All patients were observed for neurological outcome, radiographic evidence of bone fusion, and complications.
With the use of the authors' treatment algorithm, all patients were able to achieve satisfactory spinal realignment and bone fusion; 92% of patients achieved postoperative stability or improvement in Nurick and modified Japanese Orthopaedic Association scale scores. One patient experienced neurological deterioration following surgery, and 1 patient died at an acute rehabilitative facility following discharge.
Patients with AS are highly susceptible to extensive neurological injury and spinal deformity after sustaining cervical fractures from even minor traumatic forces. These injuries are uniquely complex in nature and require considerable scrutiny and aggressive surgical management to optimize spinal stability and functional outcomes. The authors' clinical problem-solving algorithm will assist spine surgeons in providing optimal care in this difficult population.
Paul Khoueir, K. Anthony Kim, and Michael Y. Wang
✓Numerous new posterior dynamic stabilization (PDS) devices have been developed for the treatment of disorders of the lumbar spine. In this report the authors provide a classification scheme for these devices and describe several clinical situations in which the instrumentation may be expected to play a role. By using this classification, the PDSs that are now available and those developed in the future can be uniformly categorized.
K. Anthony Kim, Matthew McDonald, Justin H. T. Pik, Paul Khoueir, and Michael Y. Wang
To assess the safety and efficacy of the DIAM implant, the authors compared the mean 12-month outcomes in patients who underwent lumbar surgery with DIAM placement and in those who underwent lumbar surgery only.
Of 62 patients who underwent simple lumbar surgery (laminectomy and/or microdiscectomy) in a 24-month period, 31 underwent concomitant surgical placement of a DIAM interspinous process spacer (33 devices total). Radiographic imaging, pain scores, and clinical assessments were obtained postoperatively to a mean of 12 months (range 8–25 months). Patients who did not undergo implantation of an interspinous process spacer (Group C) were compared with and stratified against patients who underwent placement of a DIAM implant (Group D).
In Group D, no statistically significant differences were noted in anterior or posterior disc height when comparing patients pre- and postoperatively. Compared with Group C, a relative kyphosis of less than 2° was noted on postoperative images obtained in Group D. No statistically significant differences in visual analog scale (VAS) pain scores or MacNab outcomes were noted between Groups C and D at a mean of 12 months of follow up. Complications in Group D included three intraoperative spinous process fractures and one infection.
After simple lumbar surgery, the placement of a DIAM interspinous process spacer did not alter disc height or sagittal alignment at the mean 12-month follow-up interval. No adverse local or systemic reaction to the DIAM was noted. No difference in VAS or MacNab outcome scores was noted between the groups treated with or without the DIAM implants, particularly when the DIAM was used to alleviate low-back pain.
Matthew McDonald, Robert Cooper, and Michael Y. Wang
✓Facet disease is believed to play a major role in axial low-back pain and may prove in the future to be an important indication for posterior dynamic stabilization. However, the lack of good diagnostic tests and imaging methods for identifying this condition have made this entity obscure. Although single-photon emission computed tomography (SPECT) imaging is a highly sensitive and specific test, the images frequently lack adequate resolution, whereas computed tomography (CT) provides excellent resolution but lacks specificity.
Thirty-seven patients with back pain clinically attributable to facet disease underwent CT–SPECT fusion imaging of the lumbar spine. The SPECT images were obtained using a dual-head gamma camera equipped with VXGP high-resolution collimators using a 20% energy window centered at 140 keV and a 360° rotation totaling 128 projections at 16 seconds each. Transaxial CT images were transferred in the Digital Imaging and Communications in Medicine format to provide proper image overlay in the axial, sagittal, and coronal planes. Scanning for both modalities was performed using standard patient positioning. Patients with concordant images and symptoms then underwent joint injection and/or rhizotomy, which was performed by an independent physician.
Image fusion was successfully performed in all patients, and the image quality allowed definitive localization of the “hot” lesion in all cases, in contrast to conventional high-resolution SPECT scanning, which often led to problems differentiating L4/5 and L5/S1. In patients with solitary lesions, injection led to definitive pain resolution, even if temporary, in all cases with anesthetic blockade.
The CT–SPECT scanning modality combines the virtues of functional and anatomical imaging, aiding the clinician in making the diagnosis of painful facet arthropathy. This modality may prove useful for the selection of patients who are candidates for posterior dynamic stabilization.
Yvette D. Marquez, Michael Y. Wang, and Charles Y. Liu
Over the course of the past few decades, it has become apparent that in contrast to previously held beliefs, the adult central nervous system (CNS) may have the capability of regeneration and repair. This greatly expands the possibilities for the future treatment of CNS disorders, with the potential strategies of treatment targeting the entire scope of neurological diseases. Indeed, there is now ample evidence that stem cells exist in the CNS throughout life, and the progeny of these stem cells may have the ability to assume the functional role of neural cells that have been lost. The existence of stem cells is no longer in dispute. In addition, once transplanted, stem cells have been shown to survive, migrate, and differentiate. Nevertheless, the clinical utility of stem cell therapy for neurorestoration remains elusive. Without question, the control of the behavior of stem cells for therapeutic advantage poses considerable challenges. In this paper, the authors discuss the cellular signaling processes that influence the behavior of stem cells. These signaling processes take place in the microenvironment of the stem cell known as the niche. Also considered are the implications attending the replication and manipulation of elements of the stem cell niche to restore function in the CNS by using stem cell therapy.
Max C. Lee, Michael Y. Wang, Richard G. Fessler, Jason Liauw, and Daniel H. Kim
Placement of instrumentation in the setting of a spinal infection has always been controversial. Although the use of allograft and autograft bone has been accepted as safe, demonstrations of the effectiveness of titanium have been speculative, based on several retrospective reviews. The authors' goal in this study was to demonstrate the effectiveness of instrumentation in the setting of a spinal infection by retrospectively reviewing their cases over the last 4 years and searching the literature regarding instrumentation in patients with pyogenic spinal infections.
The authors conducted a retrospective review of their cumulative data on spinal infections. Diagnosis was based on subjective and objective clinical findings, along with radiographic and laboratory evaluation of infection and mechanical stability. Patients with medically managed disease and those who did not receive instrumentation were eliminated from this review.
Of 105 patients with spinal infections who were admitted to the neurosurgical service between January 2000 and June 2004, 30 underwent surgical debridement necessitating spinal instrumentation. There were 17 women and 13 men in this group ranging from 28 to 86 years of age. Follow-up duration ranged from 3 to 54 months. There was one death, which occurred 3 months postsurgery. In three patients a deep wound infection developed, necessitating intervention, and two patients experienced a graft expulsion. Twenty-nine patients went on to demonstrate adequate fusion based on follow-up neuroimaging studies.
The goal of neurosurgical intervention in the setting of spinal infection is to obtain an organism culture and the debridement of infection while maintaining neurological and mechanical stability. The authors demonstrate the effectiveness of radical debridement of infected bone and placement of instrumentation in patients with spinal infections.
Michael Y. Wang and Barth A. Green
Cervical stenotic myelopathy can be treated via anterior or posterior approaches. In anterior cervical decompression and fusion (ACDF), because the risks and likelihood of pseudarthrosis increase with the number of treated segments, attempts are typically made to limit the number of treated levels. Thus, postoperative recurrence of myelopathy following ACDF may occur because stenotic levels were not treated or because adjacent segments have degenerated. Revision decompressive surgery via an anterior approach is one solution; however, if the stenosis involves multiple levels a posterior decompressive laminoplasty can be performed as an alternative.
Twenty-four cases treated over an 8-year period were identified and data were retrospectively reviewed. In 15 cases posterior decompressive surgery was necessary because of progressive spinal degeneration and stenosis (five cases following initial treatment for radiculopathy, seven after initial treatment for spondylotic myelopathy, and three due to spreading of an ossified posterior longitudinal ligament). In nine cases revision surgery was undertaken because the initial decompression was inadequate.
The mean follow-up period after the second surgery was 16 months. Improvements in myelopathy were seen in 83% of patients (mean improvement of 1.25 points on the Nurick Scale). Preoperative severe gait disorders were associated with poor recovery. Complications included two cases of transient C-5 nerve root palsy and two cases of new persistent axial neck pain.
Laminoplasty is a straightforward and effective treatment for failed ACDF due to inadequate decompression or progressive degeneration of the spinal column, avoiding reentry through scar tissue. In terms of myeolpathic pain, the recovery rate is comparable with that related to revision ACDF.