Christopher I. Shaffrey and Justin S. Smith
Alex J. Koefman, Melissa Licari, Michael Bynevelt and Christopher R. P. Lind
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.
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.
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).
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.
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.
Gregory D. Schroeder, Nik Hjelm, Alexander R. Vaccaro, Michael S. Weinstein and Christopher K. Kepler
The aim of this paper was to compare the severity of the initial neurological injury as well as the early changes in the American Spinal Injury Association (ASIA) motor score (AMS) between central cord syndrome (CCS) patients with and without an increased T2 signal intensity in their spinal cord.
Patients with CCS were identified and stratified based on the presence of increased T2 signal intensity in their spinal cord. The severity of the initial neurological injury and the progression of the neurological injury over the 1st week were measured according to the patient's AMS. The effect of age, sex, congenital stenosis, surgery within 24 hours, and surgery in the initial hospitalization on the change in AMS was determined using an analysis of variance.
Patients with increased signal intensity had a more severe initial neurological injury (AMS 57.6 vs 75.3, respectively, p = 0.01). However, the change in AMS over the 1st week was less severe in patients with an increase in T2 signal intensity (−0.85 vs −4.3, p = 0.07). Analysis of variance did not find that age, sex, Injury Severity Score, congenital stenosis, surgery within 24 hours, or surgery during the initial hospitalization affected the change in AMS.
The neurological injury is different between patients with and without an increased T2 signal intensity. Patients with an increased T2 signal intensity are likely to have a more severe initial neurological deficit but will have relatively minimal early neurological deterioration. Comparatively, patients without an increase in the T2 signal intensity will likely have a less severe initial injury but can expect to have a slight decline in neurological function in the 1st week.
Daniel J. Blizzard, Michael A. Gallizzi, Robert E. Isaacs and Christopher R. Brown
Lateral interbody fusion (LIF) via the retroperitoneal transpsoas approach is an increasingly popular, minimally invasive technique for interbody fusion in the thoracolumbar spine that avoids many of the complications of traditional anterior and transforaminal approaches. Renal vascular injury has been cited as a potential risk in LIF, but little has been documented in the literature regarding the etiology of this injury. The authors discuss a case of an intraoperative complication of renal artery injury during LIF. A 42-year-old woman underwent staged T12–L5 LIF in the left lateral decubitus position, and L5–S1 anterior lumbar interbody fusion, followed 3 days later by T12–S1 posterior instrumentation for idiopathic scoliosis with radiculopathy refractory to conservative management. After placement of the T12–L1 cage, the retractor was released and significant bleeding was encountered during its removal. Immediate consultation with the vascular team was obtained, and hemostasis was achieved with vascular clips. The patient was stabilized, and the remainder of the procedure was performed without complication. On postoperative CT imaging, the patient was found to have a supernumerary left renal artery with complete occlusion of the superior left renal artery, causing infarction of approximately 75% of the kidney. There was no increase in creatinine level immediately postoperatively or at the 3-month follow-up. Renal visceral and vascular injuries are known risks with LIF, with potentially devastating consequences. The retroperitoneal transpsoas approach for LIF in the superior lumbar spine requires a thorough knowledge of renal visceral and vascular anatomy. Supernumerary renal arteries occur in 25%–40% of the population and occur most frequently on the left and superior to the usual renal artery trunk. These arteries can vary in number, position, and course from the aorta and position relative to the usual renal artery trunk. Understanding of renal anatomy and the potential variability of the renal vasculature is essential to prevent iatrogenic injury.
Michael P. Kelly, Lawrence G. Lenke, Jakub Godzik, Ferran Pellise, Christopher I. Shaffrey, Justin S. Smith, Stephen J. Lewis, Christopher P. Ames, Leah Y. Carreon, Michael G. Fehlings, Frank Schwab and Adam L. Shimer
The authors conducted a study to compare neurological deficit rates associated with complex adult spinal deformity (ASD) surgery when recorded in retrospective and prospective studies. Retrospective studies may underreport neurological deficits due to selection, detection, and recall biases. Prospective studies are expensive and more difficult to perform, but they likely provide more accurate estimates of new neurological deficit rates.
New neurological deficits were recorded in a prospective study of complex ASD surgeries (pSR1) with a defined outcomes measure (decrement in American Spinal Injury Association lower-extremity motor score) for neurological deficits. Using identical inclusion criteria and a subset of participating surgeons, a retrospective study was created (rSR1) and neurological deficit rates were collected. Continuous variables were compared with the Student t-test, with correction for multiple comparisons. Neurological deficit rates were compared using the Mantel-Haenszel method for standardized risks. Statistical significance for the primary outcome measure was p < 0.05.
Overall, 272 patients were enrolled in pSR1 and 207 patients were enrolled in rSR1. Inclusion criteria, defining complex spinal deformities, and exclusion criteria were identical. Sagittal Cobb measurements were higher in pSR1, although sagittal alignment was similar. Preoperative neurological deficit rates were similar in the groups. Three-column osteotomies were more common in pSR1, particularly vertebral column resection. New neurological deficits were more common in pSR1 (pSR1 17.3% [95% CI 12.6–22.2] and rSR1 9.0% [95% CI 5.0–13.0]; p = 0.01). The majority of deficits in both studies were at the nerve root level, and the distribution of level of injury was similar.
New neurological deficit rates were nearly twice as high in the prospective study than the retrospective study with identical inclusion criteria. These findings validate concerns regarding retrospective cohort studies and confirm the need for and value of carefully designed prospective, observational cohort studies in ASD.
Aaron J. Clark, Roxanna M. Garcia, Malla K. Keefe, Tyler R. Koski, Michael K. Rosner, Justin S. Smith, Joseph S. Cheng, Christopher I. Shaffrey, Paul C. McCormick and Christopher P. Ames
Adult spinal deformity (ASD) surgery is increasing in the spinal neurosurgeon's practice.
A survey of neurosurgeon AANS membership assessed the deformity knowledge base and impact of current training, education, and practice experience to identify opportunities for improved education. Eleven questions developed and agreed upon by experienced spinal deformity surgeons tested ASD knowledge and were subgrouped into 5 categories: 1) radiology/spinopelvic alignment, 2) health-related quality of life, 3) surgical indications, 4) operative technique, and 5) clinical evaluation. Chi-square analysis was used to compare differences based on participant demographic characteristics (years of practice, spinal surgery fellowship training, percentage of practice comprising spinal surgery).
Responses were received from 1456 neurosurgeons. Of these respondents, 57% had practiced less than 10 years, 20% had completed a spine fellowship, and 32% devoted more than 75% of their practice to spine. The overall correct answer percentage was 42%. Radiology/spinal pelvic alignment questions had the lowest percentage of correct answers (38%), while clinical evaluation and surgical indications questions had the highest percentage (44%). More than 10 years in practice, completion of a spine fellowship, and more than 75% spine practice were associated with greater overall percentage correct (p < 0.001). More than 10 years in practice was significantly associated with increased percentage of correct answers in 4 of 5 categories. Spine fellowship and more than 75% spine practice were significantly associated with increased percentage correct in all categories. Interestingly, the highest error was seen in risk for postoperative coronal imbalance, with a very low rate of correct responses (15%) and not significantly improved with fellowship (18%, p = 0.08).
The results of this survey suggest that ASD knowledge could be improved in neurosurgery. Knowledge may be augmented with neurosurgical experience, spinal surgery fellowships, and spinal specialization. Neurosurgical education should particularly focus on radiology/spinal pelvic alignment, especially pelvic obliquity and coronal imbalance and operative techniques for ASD.
Shian Liu, Renaud Lafage, Justin S. Smith, Themistocles S. Protopsaltis, Virginie C. Lafage, Vincent Challier, Christopher I. Shaffrey, Kris Radcliff, Paul M. Arnold, Jens R. Chapman, Frank J. Schwab, Eric M. Massicotte, S. Tim Yoon, Michael G. Fehlings and Christopher P. Ames
Cervical stenosis is a defining feature of cervical spondylotic myelopathy (CSM). Matsunaga et al. proposed that elements of stenosis are both static and dynamic, where the dynamic elements magnify the canal deformation of the static state. For the current study, the authors hypothesized that dynamic changes may be associated with myelopathy severity and neck disability. This goal of this study was to present novel methods of dynamic motion analysis in CSM.
A post hoc analysis was performed of a prospective, multicenter database of patients with CSM from the AOSpine North American study. One hundred ten patients (34%) met inclusion criteria, which were symptomatic CSM, age over 18 years, baseline flexion/extension radiographs, and health-related quality of life (HRQOL) questionnaires (modified Japanese Orthopaedic Association [mJOA] score, Neck Disability Index [NDI], the 36-Item Short Form Health Survey Physical Component Score [SF-36 PCS], and Nurick grade). The mean age was 56.9 ± 12 years, and 42% of patients were women (n = 46). Correlations with HRQOL measures were analyzed for regional (cervical lordosis and cervical sagittal vertical axis) and focal parameters (kyphosis and spondylolisthesis between adjacent vertebrae) in flexion and extension. Baseline dynamic parameters (flexion/extension cone relative to a fixed C-7, center of rotation [COR], and range of motion arc relative to the COR) were also analyzed for correlations with HRQOL measures.
At baseline, the mean HRQOL measures demonstrated disability and the mean radiographic parameters demonstrated sagittal malalignment. Among regional parameters, there was a significant correlation between decreased neck flexion (increased C2–7 angle in flexion) and worse Nurick grade (R = 0.189, p = 0.048), with no significant correlations in extension. Focal parameters, including increased C-7 sagittal translation overT-1 (slip), were significantly correlated with greater myelopathy severity (mJOA score, Flexion R = −0.377, p = 0.003; mJOA score, Extension R = −0.261, p = 0.027). Sagittal slip at C-2 and C-4 also correlated with worse HRQOL measures. Reduced flexion/extension motion cones, a more posterior COR, and smaller range of motion correlated with worse general health SF-36 PCS and Nurick grade.
Dynamic motion analysis may play an important role in understanding CSM. Focal parameters demonstrated a significant correlation with worse HRQOL measures, especially increased C-7 sagittal slip in flexion and extension. Novel methods of motion analysis demonstrating reduced motion cones correlated with worse myelopathy grades. More posterior COR and smaller range of motion were both correlated with worse general health scores (SF-36 PCS and Nurick grade). To our knowledge, this is the first study to demonstrate correlation of dynamic motion and listhesis with disability and myelopathy in CSM.
Justin K. Scheer, Jessica A. Tang, Justin S. Smith, Eric Klineberg, Robert A. Hart, Gregory M. Mundis Jr., Douglas C. Burton, Richard Hostin, Michael F. O'Brien, Shay Bess, Khaled M. Kebaish, Vedat Deviren, Virginie Lafage, Frank Schwab, Christopher I. Shaffrey, Christopher P. Ames and the International Spine Study Group
Complications and reoperation for surgery to correct adult spinal deformity are not infrequent, and many studies have analyzed the rates and factors that influence the likelihood of reoperation. However, there is a need for more comprehensive analyses of reoperation in adult spinal deformity surgery from a global standpoint, particularly focusing on the 1st year following operation and considering radiographic parameters and the effects of reoperation on health-related quality of life (HRQOL). This study attempts to determine the prevalence of reoperation following surgery for adult spinal deformity, assess the indications for these reoperations, evaluate for a relation between specific radiographic parameters and the need for reoperation, and determine the potential impact of reoperation on HRQOL measures.
A retrospective review was conducted of a prospective, multicenter, adult spinal deformity database collected through the International Spine Study Group. Data collected included age, body mass index, sex, date of surgery, information regarding complications, reoperation dates, length of stay, and operation time. The radiographic parameters assessed were total number of levels instrumented, total number of interbody fusions, C-7 sagittal vertical axis, uppermost instrumented vertebra (UIV) location, and presence of 3-column osteotomies. The HRQOL assessment included Oswestry Disability Index (ODI), 36-Item Short Form Health Survey physical component and mental component summary, and SRS-22 scores. Smoking history, Charlson Comorbidity Index scores, and American Society of Anesthesiologists Physical Status classification grades were also collected and assessed for correlation with risk of early reoperation. Various statistical tests were performed for evaluation of specific factors listed above, and the level of significance was set at p < 0.05.
Fifty-nine (17%) of a total of 352 patients required reoperation. Forty-four (12.5%) of the reoperations occurred within 1 year after the initial surgery, including 17 reoperations (5%) within 30 days.
Two hundred sixty-eight patients had a minimum of 1 year of follow-up. Fifty-three (20%) of these patients had a 3-column osteotomy, and 10 (19%) of these 53 required reoperation within 1 year of the initial procedure. However, 3-column osteotomy was not predictive of reoperation within 1 year, p = 0.5476). There were no significant differences between groups with regard to the distribution of UIV, and UIV did not have a significant effect on reoperation rates. Patients needing reoperation within 1 year had worse ODI and SRS-22 scores measured at 1-year follow-up than patients not requiring operation.
Analysis of data from a large multicenter adult spinal deformity database shows an overall 17% reoperation rate, with a 19% reoperation rate for patients treated with 3-column osteotomy and a 16% reoperation rate for patients not treated with 3-column osteotomy. The most common indications for reoperation included instrumentation complications and radiographic failure. Reoperation significantly affected HRQOL outcomes at 1-year follow-up. The need for reoperation may be minimized by carefully considering spinal alignment, termination of fixation, and type of surgical procedure (presence of osteotomy). Precautions should be taken to avoid malposition or instrumentation (rod) failure.