The management of cervical spondylosis has evolved over the past several decades. Surgical decompressive and stabilization techniques have become more widely accepted for use in patients with intractable pain or neurological deficits. Advances in neuroimaging, surgical technique, and surgery-related technology including the operating microscope and anterior fixation devices have all contributed to the expanding role of surgery for the treatment of this condition. In this paper the author will focus on the role of corpectomy as a surgical option for managing cervical spondylosis.
Iain H. Kalfas
Iain H. Kalfas
Our contemporary understanding of bone healing has evolved due to knowledge gleaned from a continuous interaction between basic laboratory investigations and clinical observations following procedures to augment healing of fractures, osseous defects, and unstable joints. The stages of bone healing parallel the early stages of bone development. The bone healing process is greatly influenced by a variety of systemic and local factors. A thorough understanding of the basic science of bone healing as well as the many factors that can affect it is critical to the management of a variety of musculoskeletal disorders. In particular, the evolving management of spinal disorders can greatly benefit from the advancement of our understanding of the principles of bone healing.
Iain H. Kalfas
Stenosis of the thoracic spinal canal is a relatively rare disorder with numerous causes. Clinical manifestations include signs and or symptoms consistent with focal thoracic radiculopathy and/or myelopathy. Several surgical approaches for the decompression of the stenotic thoracic canal have been described. Laminectomy is typically reserved for only those cases in which dorsal compression of the neural elements is demonstrated; it is contraindicated when the epidural compression is primarily ventral in location.
Iain H. Kalfas
Image-guided spinal navigation is an adjuvant surgical technology that has evolved over the past decade. It has been used as a replacement for conventional intraoperative imaging techniques to improve the spine surgeon's spatial orientation to nonvisualized anatomy. The author will review the principles of image-guided technology in spinal surgery and focus on its application to the management of spinal metastatic disease.
Kene T. Ugokwe, Iain H. Kalfas, Thomas E. Mroz, and Michael P. Steinmetz
Pseudarthrosis and construct failure following single-level anterior cervical discectomy, fusion, and plate placement (ACDFP) rarely occur. Routine postoperative anteroposterior and lateral radiographs may be an inconvenience to patients and expose them to additional and potentially unnecessary radiation. No standard exists to define when patients should obtain radiographs following an ACDFP. The authors hypothesize that routinely obtaining static anteroposterior and lateral radiographs in patients who recently underwent a single-level ACDFP without new axial neck pain or other neurological complaints or symptoms is unwarranted and does not alter the long-term treatment of the patient.
The authors retrospectively reviewed the charts and radiographs of patients who underwent a single-level ACDFP between January 1, 2000, and December 31, 2005. All patients underwent a single-level ACDFP and had routine cervical radiographs obtained at various intervals after surgery.
Twenty-one patients underwent ACDFP at C5–6, 14 patients underwent surgery at C6–7, 11 patients at C4–5, and 7 patients at C3–4. None of the intraoperative radiographs demonstrated malposition of the graft or instrumentation. Based on subjective reporting by the patients, the vast majority (49 of 53) showed improvement in neck and arm pain, and/or neurological dysfunction following surgery. Overall, 5 patients (9%) demonstrated abnormalities on their postoperative radiographs. No patients were returned to the operating room as a result of postoperative radiographic findings. The sensitivity of plain radiographs in this patient series or the percentage of patients with new symptoms that had an abnormality related to the construct on plain radiography was 50%. The specificity of plain radiographs or the percentage of patients who were asymptomatic and had normal radiographs was 94%. The positive predictive value was 25%; that is, there was a 25% chance that patients with symptoms would have a construct abnormality on postoperative radiographs. The negative predictive value was 98%; that is, 98% of patients without symptoms will have normal radiographs.
Pseudarthrosis and construct failure following single-level ACDFP occur rarely, and patients with new symptoms following surgery are as likely to have normal radiographic findings as they are to have abnormalities identified on their postoperative plain radiographs. Routinely obtaining postoperative radiographs at regular intervals in asymptomatic patients following single-level ACDFP does not appear to be warranted.
Iain H. Kalfas, Donald W. Kormos, Michael A. Murphy, Rick L. McKenzie, Gene H. Barnett, Gordon R. Bell, Charles P. Steiner, Mary Beth Trimble, and Joseph P. Weisenberger
✓ Interactive frameless stereotaxy has been successfully applied to intracranial surgery. It has contributed to the improved localization of deep-seated brain lesions and has demonstrated a potential for reducing both operative time and morbidity. However, it has not been as effectively applied to spinal surgery.
The authors describe the application of frameless stereotactic techniques to spinal surgery, specifically pedicle screw fixation of the lumbosacral spine. Preoperative axial computerized tomography (CT) images of the appropriate spinal segments are obtained and loaded onto a high-speed graphics supercomputer workstation. Intraoperatively, these images can be linked to the appropriate spinal anatomy by a sonic localization digitizer device that is interfaced with the computer workstation. This permits the surgeon to place a pointing device (sonic wand) on any exposed spinal bone landmark in the operative field and obtain multiplanar reconstructed CT images projected in near-real time on the workstation screen. The images can be manipulated to assist the surgeon in determining the proper entry point for a pedicle screw as well as defining the appropriate trajectory in the axial and sagittal planes. It can also define the correct screw length and diameter for each pedicle to be instrumented.
The authors applied this device to the insertion of 150 screws into the lumbosacral spines of 30 patients. One hundred forty-nine screws were assessed to be satisfactorily placed by postoperative CT and plain film radiography. In this report the authors discuss their use of this device in the clinical setting and review their preliminary results of frameless stereotaxy applied to spinal surgery. On the basis of their findings, the authors conclude that frameless stereotactic technology can be successfully applied to spinal surgery.
Presented at the 2018 AANS/CNS Joint Section on Disorders of the Spine and Peripheral Nerves
Bryan S. Lee, Kevin M. Walsh, Daniel Lubelski, Konrad D. Knusel, Michael P. Steinmetz, Thomas E. Mroz, Richard P. Schlenk, Iain H. Kalfas, and Edward C. Benzel
Complete radiographic and clinical evaluations are essential in the surgical treatment of cervical spondylotic myelopathy (CSM). Prior studies have correlated cervical sagittal imbalance and kyphosis with disability and worse health-related quality of life. However, little is known about C2–3 disc angle and its correlation with postoperative outcomes. The present study is the first to consider C2–3 disc angle as an additional radiographic predictor of postoperative adverse events.
A retrospective chart review was performed to identify patients with CSM who underwent surgeries from 2010 to 2014. Data collected included demographics, baseline presenting factors, and postoperative outcomes. Cervical sagittal alignment variables were measured using the preoperative and postoperative radiographs. Univariable logistic regression analyses were used to explore the association between dependent and independent variables, and a multivariable logistic regression model was created using stepwise variable selection.
The authors identified 171 patients who had complete preoperative and postoperative radiographic and outcomes data. The overall rate of postoperative adverse events was 33% (57/171), and postoperative C2–3 disc angle, C2–7 sagittal vertical axis, and C2–7 Cobb angle were found to be significantly associated with adverse events. Inclusion of postoperative C2–3 disc angle in the analysis led to the best prediction of adverse events. The mean postoperative C2–3 disc angle for patients with any postoperative adverse event was 32.3° ± 17.2°, and the mean for those without any adverse event was 22.4° ± 11.1° (p < 0.0001).
In the present retrospective analysis of postoperative adverse events in patients with CSM, the authors found a significant association between C2–3 disc angle and postoperative adverse events. They propose that C2–3 disc angle be used as an additional parameter of cervical spinal sagittal alignment and predictor for operative outcomes.
Samuel T. Chao, Taisei Kobayashi, Edward Benzel, Chandana A. Reddy, Glen H. J. Stevens, Richard A. Prayson, Iain Kalfas, Richard Schlenk, Ajit Krishnaney, Michael P. Steinmetz, William Bingaman, Joseph Hahn, and John H. Suh
The goal in this study was to determine the role of radiation therapy (RT) in the treatment of spinal myxopapillary ependymomas (MPEs).
Thirty-seven patients with histologically verified spinal MPEs were reviewed. Kaplan-Meier analyses and Cox proportional hazard regression were used to determine what patient and treatment factors influenced overall survival (OS) and recurrence.
At the time of initial diagnosis, the median age was 33 years and the Karnofsky Performance Scale score was 80. In 86.5% of cases, the most common presenting symptom was pain. All patients received surgery as their initial treatment. Nine patients also received RT along with surgery, with a median total dose of 50.2 Gy. The mean survival time was 12.2 years; however, only 4 of 37 patients had died at the time of this study. None of the patient or treatment parameters significantly correlated with OS. Sixteen patients (43.2%) were found to have a recurrence, with a median time to recurrence of 7.7 years. None of the patient or treatment parameters correlated with recurrence-free survival for an initial recurrence. The median time to the second recurrence (recurrence following therapy for initial recurrence) was 1.6 years. Use of RT as salvage therapy after initial recurrence significantly correlated with longer times to a second recurrence. The median recurrence-free survival time before the second recurrence was 9.6 years for those who received RT versus 1.1 years for those who did not receive RT (p = 0.0093). None of the other parameters significantly correlated with a second recurrence.
Radiation therapy may have a role as salvage therapy in delaying recurrences of spinal MPEs.
Rupesh Kotecha, Martin C. Tom, Mihir Naik, Lilyana Angelov, Edward C. Benzel, Chandana A. Reddy, Richard A. Prayson, Iain Kalfas, Richard Schlenk, Ajit Krishnaney, Michael P. Steinmetz, William Bingaman, John H. Suh, and Samuel T. Chao
The authors sought to describe the long-term recurrence patterns, prognostic factors, and effect of adjuvant or salvage radiotherapy (RT) on treatment outcomes for patients with spinal myxopapillary ependymoma (MPE).
The authors reviewed a tertiary institution IRB-approved database and collected data regarding patient, tumor, and treatment characteristics for all patients treated consecutively from 1974 to 2015 for histologically confirmed spinal MPE. Key outcomes included relapse-free survival (RFS), postrecurrence RFS, failure patterns, and influence of timing of RT on recurrence patterns. Cox proportional hazards regression and Kaplan-Meier analyses were utilized.
Of the 59 patients included in the study, the median age at initial surgery was 34 years (range 12–74 years), 30 patients (51%) were female, and the most common presenting symptom was pain (n = 52, 88%). Extent of resection at diagnosis was gross-total resection (GTR) in 39 patients (66%), subtotal resection (STR) in 15 (25%), and unknown in 5 patients (9%). After surgery, 10 patients (17%) underwent adjuvant RT (5/39 GTR [13%] and 5/15 STR [33%] patients). Median follow-up was 6.2 years (range 0.1–35.3 years). Overall, 20 patients (34%) experienced recurrence (local, n = 15; distant, n = 5). The median RFS was 11.2 years (95% CI 77 to not reached), and the 5- and 10-year RFS rates were 72.3% (95% CI 59.4–86.3) and 54.0% (95% CI, 36.4–71.6), respectively.
STR was associated with a higher risk of recurrence (HR 6.45, 95% CI 2.15–19.23, p < 0.001) than GTR, and the median RFS after GTR was 17.2 years versus 5.5 years after STR. Adjuvant RT was not associated with improved RFS, regardless of whether it was delivered after GTR or STR. Of the 20 patients with recurrence, 12 (60%) underwent salvage treatment with surgery alone (GTR, n = 6), 4 (20%) with RT alone, and 4 (20%) with surgery and RT. Compared to salvage surgery alone, salvage RT, with or without surgery, was associated with a significantly longer postrecurrence RFS (median 9.5 years vs 1.6 years; log-rank, p = 0.006).
At initial diagnosis of spinal MPE, GTR is key to long-term RFS, with no benefit to immediate adjuvant RT observed in this series. RT at the time of recurrence, however, is associated with a significantly longer time to second disease recurrence. Surveillance imaging of the entire neuraxis remains crucial, as distant failure is not uncommon in this patient population.