Conor Dunn

Incidence of Neuraxial Abnormalities Is Approximately 8% Among Patients With Adolescent Idiopathic Scoliosis: A Meta-analysis

Background Several studies have sought to address the role of routine preoperative MRI in patients with adolescent idiopathic scoliosis (AIS) undergoing deformity correction. Despite similar results regarding the prevalence of neuraxial anomalies detected on MRI, published conclusions conflict and give opposing recommendations. Lack of consensus has led to important variations in use of MRI before spinal surgery for patients with AIS. Questions/purposes This systematic review and meta-analysis of studies about patients with AIS evaluated (1) the overall proportion of neuraxial abnormalities; (2) the patient factors and curve characteristics that may be associated with abnormalities; and (3) the proportion of patients who underwent neurosurgical intervention before scoliosis surgery and the kinds of neuraxial lesions that were identified. Methods We performed a search of four electronic databases (PubMed, EMBASE, CINAHL Plus, and SCOPUS) utilizing search terms related to routine MRI and AIS, yielding 206 articles. Studies included had at least 20 participants, patients with ages 11 to 21 years, and a Methodological Index for Non-Randomized Studies (MINORS) study quality score of 8 and 16 points for noncomparative and comparative studies, respectively. Non-English manuscripts, animal studies, and those that did not include patients with AIS solely were excluded. Eighteen articles with 4746 patients were included for analysis of the overall proportion of neuraxial abnormalities, 12 articles with 3028 patients for analysis by sex, eight articles with 1603 patients for right main thoracic curve, eight articles with 665 patients for a left main thoracic curve, and 13 articles with 3063 patients and 230 (7.5%) abnormalities for number of neurosurgical interventions before scoliosis correction. The mean MINORS score for studies included was 14 (range, 10-20). Each study was analyzed for the proportion of patients identified with neuraxial abnormalities and associations with specific demographics. We determined the proportion of patients who underwent surgical interventions before scoliosis surgery as well as the types of neuraxial lesions identified. The articles were assessed for heterogeneity and publication bias. Because all groups were determined to be heterogeneous, a random-effects model was used for each group in this meta-analysis; with this analysis, an overlap of 95% confidence intervals suggests no difference at the p < 0.05 level, but this analytic approach does not provide p values. Results The pooled proportion of neuraxial abnormalities detected on MRI was 8% (95% confidence interval [CI], 6%-12%). With the numbers available, we found no difference in the proportion of male and female patients with neuraxial abnormalities (18% [95% CI, 11%-29%] versus 9% [95% CI, 6%-12%], respectively). Likewise, there was no difference in the proportion of pooled neuraxial abnormalities in right and left curves (9% [95% CI, 6%-14%] versus 15% [95% CI, 5%-35%], respectively). In the subset of abnormalities analyzed for number of neurosurgical interventions before scoliosis correction, the pooled proportion showed that 33% (95% CI, 24%-43%) underwent neurosurgical intervention before deformity correction. The most common abnormalities of the 367 found on MRI were syringomyelia in 127 patients (35%), Arnold-Chiari Type 1 malformation with syrinx in 103 patients (28%), and isolated Arnold-Chiari Type 1 malformation in 91 patients (25%). Conclusions The proportion of patients with AIS who have neuraxial abnormalities is high (8%) and a large number undergo surgical intervention before scoliosis reconstruction. We did not find any particular demographic variables that indicated an increased risk of abnormality. Clinicians should consider advanced imaging before surgical intervention in the treatment of a patient with an idiopathic diagnosis. Preventable variables need to be identified by future studies to establish a better working treatment protocol for these patients. Level of Evidence Level III, diagnostic study.

Low energy chronic traumatic spondylolisthesis of the axis

ObjectiveThe aim of this study is to present a unique case of a patient who presented to our Emergency Department with evidence of a chronic traumatic spondylolisthesis of the axis with severe displacement treated with anterior cervical discectomy and fusion (ACDF) of C2–C3 as well as and posterior cervical fusion (PCF) of C1–C3.MethodsOne patient with an untreated traumatic spondylolisthesis of the axis with Levine type II injury pattern and 1.2 cm of anterior subluxation underwent ACDF C2–C3 and PCF C1–C3.ResultsThe patient recovered well, radiographs demonstrated reduction of the anterior subluxation, and the patient reported a neck disability index (NDI) score of 20 at 6-month follow-up with full neurologic function intact. The patient was then lost to follow-up.ConclusionIn this report, we present an alcoholic patient with a history of many falls who presented with a Levine type II traumatic spondylolisthesis of the axis with signs of chronicity seen on magnetic resonance imaging (MRI). We were able to partially reduce the anterior displacement with traction, but needed both anterior and posterior cervical approaches to achieve adequate reduction and stabilization of the injury.

Minimally invasive posterior cervical foraminotomy with tubes to prevent undesired fusion: a long-term follow-up study

OBJECTIVE The objective of this study was to compare anterior cervical discectomy and fusion (ACDF) and minimally invasive posterior cervical foraminotomy (MI-PCF) with tubes for the treatment of cervical radiculopathy in terms of the 1) overall revision proportion, 2) index and adjacent level revision rates, and 3) functional outcome scores. METHODS The authors retrospectively reviewed the records of consecutive patients who had undergone ACDF or MI-PCF at a single institution between 2009 and 2014. Patients treated for cervical radiculopathy without myelopathy and with a minimum 2-year follow-up were compared according to the procedure performed for their pathology. Primary outcome measures included the overall rate of revision with fusion and overall revision proportion as well as the rate of index and adjacent level revisions per year. Secondarily, self-reported outcome measures-Neck Disability Index (NDI) and visual analog scale (VAS) for arm (VASa) and neck (VASn) pain-at the preoperative and postoperative evaluations were analyzed. Standard binomial and categorical comparative analyses were performed. RESULTS Forty-nine consecutive patients were treated with MI-PCF, and 210 consecutive patients were treated with ACDF. The mean follow-up for the MI-PCF cohort was 42.9 ± 6.6 months (mean ± SD) and for the ACDF cohort was 44.9 ± 10.3 months. There was no difference in the overall revision proportion between the two cohorts (4 [8.2%] of 49 MI-PCF vs. 12 [5.7%] of 210 ACDF, p = 0.5137). There was no difference in the revision rate per level per year (3.1 vs. 1.7, respectively, p = 0.464). Moreover, there was no difference in the revision rate per level per year at the index level (1.8 vs. 0.7, respectively, p = 0.4657) or at an adjacent level (1.3 vs. 1.1, p = 0.9056). Neither was there a difference between the cohorts as regards the change from preoperative to final postoperative functional outcome scores (NDI, VASa, VASn). CONCLUSIONS Minimally invasive PCF for the treatment of cervical radiculopathy demonstrates rates of revision at the index and adjacent levels similar to those following ACDF. In order to confirm the positive efficacy and cost analysis findings in this study, future studies need to extend the follow-up and show that the rate of revision with fusion does not increase substantially over time.

Risk Factors for Pseudarthrosis in Minimally-Invasive Transforaminal Lumbar Interbody Fusion

Study Design Retrospective cohort study (level of evidence: 4). Purpose To describe the potential comorbid, operative, and radiographic risk factors for the development of clinically-relevant pseudarthrosis following minimally-invasive transforaminal lumbar interbody fusion (MIS-TLIF). Overview of Literature MIS-TLIF has shown long-term clinical outcomes with decreased perioperative morbidity and earlier return to work, similar to those of open TLIF. However, unsuccessful fusion still remains a concern. The impacts of various patient, operative, and radiographic risk factors have not been evaluated for their potential association with pseudarthrosis related to MIS-TLIF. Methods Between 2012 and 2015, 204 consecutive patients underwent one or two-level MIS-TLIF at St. Josephs University Medical Center, Paterson, NJ, USA; they had a minimum of 1 year of follow-up. The patients were divided into two cohorts: those who developed clinically-relevant pseudarthrosis and those who did not. Clinically-relevant pseudarthrosis was determined by both evidence on computed tomography and presence of continued clinical symptoms at 1-year follow-up. Results Revision surgery was the only identified non-radiographic factor associated with pseudarthrosis. Disc angle had the highest (R2=0.8), followed by anterior disc height (R2=0.79). Although posterior disc height and the ratio of anterior to posterior disc height showed a marked relationship with the outcome, the R2-values were <0.3, thus indicating a less-strong correlation. The overall pseudarthrosis rate was 8%. No statistically significant differences were identified between the two cohorts with respect to mean age, sex, medical comorbidities, smoking status, or number of levels fused. Conclusions Clinically-relevant pseudarthrosis is not uncommon following MIS-TLIF. In the current study, undergoing revision surgery, disc angle, and anterior disc height were observed to be associated with clinically-relevant pseudarthrosis. This study demonstrated that the patient population may benefit from an alternate approach.

Accuracy and Safety of Percutaneous Lumbosacral Pedicle Screw Placement Using Dual-Planar Intraoperative Fluoroscopy

Study Design Retrospective case series with prospective arm. Purpose To assess the safety and accuracy of percutaneous lumbosacral pedicle screw placement (PLPSP) in the lumbosacral spine using intraoperative dual-planar fluoroscopy (DPF). Overview of Literature There are several techniques available for achieving consistent, safe, and accurate results with PLPSP. There is a paucity of literature describing the beneficial operative, economic, and clinical outcomes of DPF, the most readily accessible image guidance system. Methods From 2004 to 2014, 451 consecutive patients underwent PLPSP using DPF, for a total of 2,345 screw placement. The results of prospectively obtained postoperative computed tomography (CT) examinations of an additional 41 consecutive patients were compared with the results of 104 CT examinations obtained postoperatively due to clinical symptomatology; these results were interpreted by three reviewers. The rates of revision indicated by misplaced screws with consistent clinical symptomatology were compared between groups. Pedicle screw placement was graded according to 2-mm increments in medial pedicle wall breach and measurement of screw axis placement. Results Seven of the 2,345 pedicle screws placed percutaneously with the use of the dual-planar fluoroscopic technique required revision because of a symptomatic misplaced screw, for a screw revision rate of 0.3%. There were no statistically significant demographic differences between patients who had screws revised and those who did not. All screws registered greater than 10 mA on electromyographic stimulation. In the 41 prospectively obtained CT examinations, one out of 141 screws (0.7%) was revised due to pedicle wall breach; whereas among the 104 patients with 352 screws, three screws were revised (0.9%). Conclusions DPF is an extremely accurate, safe, and reproducible technique for placement of percutaneous pedicle screws and is a readily available and cost-effective alternative to CT-guided pedicle screw placement techniques. Postoperative CT evaluation is not necessary with PLPSP unless the patient is symptomatic. Acceptable electromyographic thresholds may need to be reevaluated.