Geometric analysis of pedicle subtraction osteotomy (PSO) for Kyphosis correction: anterior lengthening may occur at the osteotomized body as well as at the discs above and below.

OBJECTIVE: To validate the authors kyphosis correction formula for pedicle subtraction osteotomy (PSO) cases. Additionally, to use the formula to evaluate the safety of PSO by determining if there is anterior lengthening. METHODS: Twenty-two patients with primarily kyphosis corrected by PSO and with clear landmarks on preoperative and postoperative x-rays were selected. Several anatomical lines and angle measurements were utilized as depicted previously in the Vertebral Column Resection formula (see below). Two approximations were calculated: the geometric approximation (G) = (tanG°*2 + 1)*15° and the rough approximation (R) which is about the same amount of actual shortening (x), if parallel length (y) ≥ 40; twice of x, if y < 40. For each patient, the change of segmental kyphosis angle (K°) was measured and compared with G° and R°, and the correlation between each value was analyzed. RESULTS: The absolute Mean ± SE for K - G and K - R was 2.33° ± 0.34 and 6.09° ± 0.58, respectively. K - G is < 3° (p = 0.03). K - R is < 8° (p = 0.001). In other words, K was close to G and R and thus can be predicted by these approximations. Average posterior shortening, anterior shortening, and kyphosis correction at each level were 20.8 ± 2.0 mm, - 3.64 ± 1.5 mm (which equates to anterior lengthening), and 31.05° ± 2.0, respectively. Anterior lengthening occurred in 13 cases (in 4 cases, both at the body as well as at the disc above and below.) The correlation between posterior and anterior shortening was 0.03 (p = 0.88). There were 3 cage insertion cases: 1 had anterior lengthening, while 2 had anterior shortening even with the cage. CONCLUSION: This study validated the geometric and rough approximations originally used in PVCR patients, for PSO patients. Additionally, this study found that anterior lengthening may occur in PSOs usually at the discs, but occasionally at the osteotomized body.

Pharyngoesophageal Damage from Hardware Extrusion at an Average of 7.5 Years After Anterior Cervical Diskectomy and Fusion: A Case Series, Discussion of Risk Factors, and Guide for Management.

OBJECTIVE: We present a single-institution case series of patients who experienced pharyngoesophageal damage, specifically from extruded hardware occurring at an average of 7.5 years after anterior cervical diskectomy and fusion (ACDF). METHODS: A retrospective chart review was conducted of patients who had undergone ACDF with subsequent delayed pharyngoesophageal perforation or erosion from extruded hardware ≥1 year after surgery. A discussion of the literature surrounding this complication, including risk factors and management, is also presented. RESULTS: Nine patients were identified (average age 58 years, 66.7% male) among a total of 4122 ACDF patients (incidence: 0.22%). Average time to injury was 7.5 years. Indications for initial ACDF were degenerative cervical disease (n = 7), ankylosing spondylitis (n = 1), and cervical fracture (n = 1). Eight patients had prior multilevel ACDF spanning 2 (n = 4), 3 (n = 1), or 4 levels (n = 2). Fusion levels for prior ACDF included C5-C7 (n = 3), C3-C7 (n = 2), C4-C7 (n = 1), C4-C6 (n = 1), C2-C5 (n = 1), and C6-C7 (n = 1). Pharyngoesophageal injuries included esophageal perforation (n = 3), pharyngeal perforation (n = 2), esophageal erosion (n = 3), and pharyngoesophageal erosion (n = 1). In most (n = 6) cases, the cause of pharyngoesophageal damage was due to ≥1 extruded screws. Dysphagia (n = 8) was the most common presenting symptom. For perforations (n = 5), 2 repairs used a rotational flap to reinforce a primary closure; the other 3 cases were repaired via primary closure. CONCLUSIONS: Pharyngoesophageal damage caused by extruded hardware may occur several years after ACDF. These delayed complications are difficult to predict. Proper screw placement may be the most important factor for minimizing the chances of this potentially devastating complication, particularly with multilevel constructs.

Decompression of Lumbar Central Spinal Canal Stenosis Following Minimally Invasive Transforaminal Lumbar Interbody Fusion.

STUDY DESIGN: This was a retrospective clinical series. OBJECTIVE: The objective of this study was to evaluate radiologic changes in central spinal canal dimensions following minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) with placement of a static or an expandable interbody device. SUMMARY OF BACKGROUND DATA: MIS-TLIF is used to treat lumbar degenerative diseases and low-grade spondylolisthesis. MIS-TLIF enables direct and indirect decompression of lumbar spinal stenosis, with patients experiencing relief from radiculopathy and neurogenic claudication. However, the effects of MIS-TLIF on the central spinal canal are not well-characterized. MATERIALS AND METHODS: We identified patients who underwent MIS-TLIF for degenerative lumbar spondylolisthesis and concurrent moderate to severe spinal stenosis. We selected patients who had both preoperative and postoperative magnetic resonance imaging (MRI) and upright lateral radiographs of the lumbar spine. Measurements on axial T2-weighted MRI scans include anteroposterior and transverse dimensions of the dural sac and osseous spinal canal. Measurements on radiographs include disk height, neural foraminal height, segmental lordosis, and spondylolisthesis. We made pairwise comparisons between each of the central canal dimensions and lumbar sagittal segmental radiologic outcome measures relative to their corresponding preoperative values. Correlation coefficients were used to quantify the association between changes in lumbar sagittal segmental parameters relative to changes in radiologic outcomes of central canal dimensions. Statistical analysis was performed for "all patients" and further stratified by interbody device subgroups (static and expandable). RESULTS: Fifty-one patients (age 60.4 y, 68.6% female) who underwent MIS-TLIF at 55 levels (65.5% at L4-L5) were included in the analysis. Expandable interbody devices were used in 45/55 (81.8%) levels. Mean duration from surgery to postoperative MRI scan was 16.5 months (SD 11.9). MIS-TLIF was associated with significant improvements in dural sac dimensions (anteroposterior +0.31 cm, transverse +0.38 cm) and osseous spinal canal dimensions (anteroposterior +0.16 cm, transverse +0.32 cm). Sagittal lumbar segmental parameters of disk height (+0.56 cm), neural foraminal height (+0.35 cm), segmental lordosis (+4.26 degrees), and spondylolisthesis (-7.5%) were also improved following MIS-TLIF. We did not find meaningful associations between the changes in central canal dimensions relative to the corresponding changes in any of the sagittal lumbar segmental parameters. Stratified analysis by interbody device type (static and expandable) revealed similar within-group changes as in the overall cohort and minimal between-group differences. CONCLUSIONS: MIS-TLIF is associated with radiologic decompression of neural foraminal and central spinal canal stenosis. The mechanism for neural foraminal and central canal decompression is likely driven by a combination of direct and indirect corrective techniques.

Population-based approaches to treatment and readmission after spinal cord injury.

BACKGROUND: Recent studies in surgical and non-surgical specialties have suggested that patients admitted on the weekend may have worse outcomes. In particular, patients with stroke and acute cardiovascular events have shown worse outcomes with weekend treatment. It is unclear whether this extends to patients with spinal cord injury (SCI). This study was designed to evaluate factors for readmission after index hospitalization for spinal cord injury. METHODS: This cohort was constructed from the State Inpatient Databases of California, New York, and Florida. For this study 14,396 patients with SCI were identified. The primary outcome measure evaluated was 30-day readmission. Secondary measures include in-hospital complications. Univariate and multivariate analysis were utilized to evaluate covariates. c2, Fisher's exact, and linear, logistic, and modified Poisson regression methods were utilized for statistical analysis. Propensity score methods were used with matched pairs analysis performed by the McNemar's Test. RESULTS: Weekend admission was not associated with increased 30- day readmission rates in multivariate analysis. Race and discharge to a facility (RR 1.60 [1.43-1.79]) or home with home care (RR 1.23 [1.07-1.42]), were statistically significant risk factors for readmission. Payor status did not affect rates of readmission. In propensity score matched pairs analysis, weekend admission was not associated with increased odds of 30-day readmission (OR 1.04 [0.89-1.21]). Patients admitted to high volume centers had significantly lower risk of readmission when compared with patients admitted to low volume centers. CONCLUSIONS: Our results suggest that the weekend effect, described previously in other patient populations, may not play as important a role in patients with SCI.

Fractional anisotropy to quantify cervical spondylotic myelopathy severity.

BACKGROUND: A number of clinical tools exist for measuring the severity of cervical spondylotic myelopathy (CSM). Several studies have recently described the use of non-invasive imaging biomarkers to assess severity of disease. These imaging markers may provide an additional tool to measure disease progression and represent a surrogate marker of response to therapy. Correlating these imaging biomarkers with clinical quantitative measures is critical for accurate therapeutic stratification and quantification of axonal injury. METHODS: Fourteen patients and seven healthy control subjects were enrolled. Patients were classified as mildly (7) or moderately (7) impaired based on Modified Japanese Orthopedic Association Scale. All patients underwent diffusion tensor imaging (DTI) and diffusion basis spectrum imaging (DBSI) analyses. In addition to standard neurological examination, all participants underwent 30-m Walking Test, 9-hole Peg Test (9HPT), grip strength, key pinch, and vibration sensation thresholds in the index finger and great toe. Differences in assessment scores between controls, mild and moderate CSM patients were correlated with DTI and DBSI derived fractional anisotropy (FA). RESULTS: Clinically, 30-meter walking times were significantly longer in the moderately impaired group than in the control group. Maximum 9HPT times were significantly longer in both the mildly and moderately impaired groups as compared to normal controls. Scores on great toe vibration sensation thresholds were lower in the mildly impaired and moderately impaired groups as compared to controls. We found no clear evidence for any differences in minimum grip strength, minimum key pinch, or index finger vibration sensation thresholds. There were moderately strong associations between DTI and DBSI FA values and 30-meter walking times and 9HPT. CONCLUSIONS: The 30-m Walking Test and 9HPT were both moderately to strongly associated with DTI/DBSI FA values. FA may represent an additional measure to help differentiate and stratify patients with mild or moderate CSM.

Spinal Fusion for Pediatric Spondylolisthesis: National Trends, Complications, and Short-Term Outcomes.

BACKGROUND: Current surgical management guidelines for pediatric spondylolisthesis (PS) are reliant on data from single-center cohorts. OBJECTIVE: To analyze national trends and predictors of short-term outcomes in spinal fusion surgery for PS by performing a retrospective cross-sectional analysis of the Kids' Inpatient Database (KID). METHODS: The KID (sampled every 3 yr) was queried from 2003 to 2012 to identify all cases (age 5-17) of spinal fusion for PS (n = 2646). We analyzed trends in patient characteristics, surgical management, and short-term outcomes. Both univariate and multivariable analyses were utilized. RESULTS: The 2646 spinal fusions for PS included posterior-only fusions (86.8%, PSF), anterior lumbar interbody fusions (4.8%, ALIF), and combined anterior and posterior fusions (8.4%, APLF) procedures. The utilization of APLF decreased over time (9.9%-6.4%, P = .023), whereas the number of total spinal fusions and the proportion of PSF and ALIF procedures have not changed significantly. Uptrends in Medicaid insured individuals (1.2%-18.9%), recombinant human bone morphogenetic protein-2 insertion (8.8%-16.6%), decompression (34.7%-42.8%), and mean inflation-adjusted hospital costs ($21 855-$32 085) were identified (all P < .001). In multivariable analysis, Medicaid status (odds ratio [OR] = 1.93, P = .004), teaching hospitals (OR = 1.94, P = .01), decompression (OR = 1.78, P = .004), and the APLF procedure (OR = 2.47, P = .001) increased the likelihood of complication occurrence (all P < .001). CONCLUSION: The addition of decompression during fusion and the APLF procedure were associated with more in-hospital complications, though this may have been indicative of greater surgical complexity. The utilization of the APLF procedure has decreased significantly, while costs associated with the treatment of PS have increased over time.

Immunogenomics of Hypermutated Glioblastoma: A Patient with Germline POLE Deficiency Treated with Checkpoint Blockade Immunotherapy.

We present the case of a patient with a left frontal glioblastoma with primitive neuroectodermal tumor features and hypermutated genotype in the setting of a POLE germline alteration. During standard-of-care chemoradiation, the patient developed a cervical spine metastasis and was subsequently treated with pembrolizumab. Shortly thereafter, the patient developed an additional metastatic spinal lesion. Using whole-exome DNA sequencing and clonal analysis, we report changes in the subclonal architecture throughout treatment. Furthermore, a persistently high neoantigen load was observed within all tumors. Interestingly, following initiation of pembrolizumab, brisk lymphocyte infiltration was observed in the subsequently resected metastatic spinal lesion and an objective radiographic response was noted in a progressive intracranial lesion, suggestive of active central nervous system (CNS) immunosurveillance following checkpoint blockade therapy. SIGNIFICANCE: It is unclear whether hypermutated glioblastomas are susceptible to checkpoint blockade in adults. Herein, we provide proof of principle that glioblastomas with DNA-repair defects treated with checkpoint blockade may result in CNS immune activation, leading to clinically and immunologically significant responses. These patients may represent a genomically stratified group for whom immunotherapy could be considered. Cancer Discov; 6(11); 1230-6. ©2016 AACR.See related commentary by Snyder and Wolchok, p. 1210This article is highlighted in the In This Issue feature, p. 1197.

Posterior Cervical Fusion With Recombinant Human Bone Morphogenetic Protein-2: Complications and Fusion Rate at Minimum 2-Year Follow-Up.

STUDY DESIGN: Retrospective case series. OBJECTIVE: The purpose of this study was to determine the fusion rate and evaluate the complications associated with the application of recombinant human bone morphogenetic protein-2 (rhBMP-2) in posterior cervical fusion. SUMMARY OF BACKGROUND DATA: The rates of fusion and complications associated with the use of rhBMP-2 in posterior cervical fusion is unclear, though recent work has shown up to a 100% fusion rate. METHODS: We independently reviewed consecutive series of patients who underwent posterior cervical, occipitocervical, or cervicothoracic instrumented fusion augmented with rhBMP-2. Two surgeons at a tertiary-referral, academic medical center performed all operations, and each patient had a minimum of 2-year follow-up. Fusion status was determined by bony bridging on computed tomography scans, absence of radiolucency around instrumentation, and absence of motion on lateral flexion/extension radiographs. RESULTS: Fifty-seven patients with a mean age of 56.7±13.2 years and mean follow-up of 37.7±20.6 months were analyzed. Forty-eight patients (84.2%) had undergone previous cervical surgery, and 42.1% had a preexisting nonunion. Constructs spanned 5.6±2.6 levels; 19.3% involved the occiput, whereas 61.4% crossed the cervicothoracic junction. The mean rhBMP-2 dose was 21.1±8.7 mg per operation. Iliac crest autograft was used for 29.8% of patients. Six patients (10.5%) experienced nonunion; only 2 required revision. In each case of nonunion, instrumentation crossed the occipitocervical or cervicothoracic junction. However, none of the analyzed variables was statistically associated with nonunion. Fourteen patients (24.6%) suffered complications, with 7 requiring additional surgery. CONCLUSIONS: The observed fusion rate of rhBMP-2-augmented posterior cervical, occipitocervical, and cervicothoracic fusions was 89.5%. This reflects the complicated nature of the patients included in the current study and demonstrates that rhBMP-2 cannot always overcome the biomechanical challenges entailed in spanning the occipitocervical or cervicothoracic junction.

Spinal fusion for pediatric neuromuscular scoliosis: national trends, complications, and in-hospital outcomes.

OBJECTIVE The objective of this study was to determine if the recent changes in technology, surgical techniques, and surgical literature have influenced practice trends in spinal fusion surgery for pediatric neuromuscular scoliosis (NMS). In this study the authors analyzed recent trends in the surgical management of NMS and investigated the effect of various patient and surgical factors on in-hospital complications, outcomes, and costs, using the Nationwide Inpatient Sample (NIS) database. METHODS The NIS was queried from 2002 to 2011 using International Classification of Diseases, Ninth Edition, Clinical Modification codes to identify pediatric cases (age < 18 years) of spinal fusion for NMS. Several patient, surgical, and short-term outcome factors were included in the analyses. Trend analyses of these factors were conducted. Both univariate and multivariable analyses were used to determine the effect of the various patient and surgical factors on short-term outcomes. RESULTS Between 2002 and 2011, a total of 2154 NMS fusion cases were identified, and the volume of spinal fusion procedures increased 93% from 148 in 2002 to 286 in 2011 (p < 0.0001). The mean patient age was 12.8 ± 3.10 years, and 45.6% of the study population was female. The overall complication rate was 40.1% and the respiratory complication rate was 28.2%. From 2002 to 2011, upward trends (p < 0.0001) were demonstrated in Medicaid insurance status (36.5% to 52.8%), presence of ≥ 1 comorbidity (40.2% to 52.1%), and blood transfusions (25.2% to 57.3%). Utilization of posterior-only fusions (PSFs) increased from 66.2% to 90.2% (p < 0.0001) while combined anterior release/fusions and PSF (AR/PSF) decreased from 33.8% to 9.8% (< 0.0001). Intraoperative neurophysiological monitoring (IONM) underwent increasing utilization from 2009 to 2011 (15.5% to 20.3%, p < 0.0001). The use/harvest of autograft underwent a significant upward trend between 2002 and 2011 (31.3% to 59.8%, p < 0.0001). In univariate analysis, IONM use was associated with decreased complications (40.7% to 33.1%, p = 0.049) and length of stay (LOS; 9.21 to 6.70 days, p <0.0001). Inflation-adjusted mean hospital costs increased nearly 75% from 2002 to 2011 ($36,805 to $65,244, p < 0.0001). In the multivariable analysis, nonwhite race, highest quartile of median household income, greater preexisting comorbidity, long-segment fusions, and use of blood transfusions were found to increase the likelihood of complication occurrence (all p < 0.05). In further multivariable analysis, independent predictors of prolonged LOS included older age, increased preexisting comorbidity, the AR/PSF approach, and long-segment fusions (all p < 0.05). Lastly, the likelihood of increased hospital costs (at or above the 90th percentile for LOS, 14 days) was increased by older age, female sex, Medicaid insurance status, highest quartile of median household income, AR/PSF approach, long-segment fusion, and blood transfusion (all p < 0.05). In multivariable analysis, the use of autograft was associated with a lower likelihood of complication occurrence and prolonged LOS (both p < 0.05). CONCLUSIONS Increasing use of IONM and posterior-only approaches may combat the high complication rates in NMS. The trends of increasing comorbidities, blood transfusions, and total costs in spinal fusion surgery for pediatric NMS may indicate an increasingly aggressive approach to these cases.

Interpedicular height as a predictor of radicular pain in adult degenerative scoliosis.

BACKGROUND CONTEXT: Spine surgeons must correlate clinical presentation with radiographic findings in a patient-tailored approach. Despite the prevalence of adult degenerative scoliosis (ADS), there are few radiographic markers to predict the presence of radiculopathy. Emerging data suggest that spondylolisthesis, obliquity, foraminal stenosis, and curve concavity may be associated with radiculopathy in ADS. PURPOSE: The purpose of this study was to determine if radicular pain in ADS is associated with reduced interpedicular heights (IPHs) as measured on routine radiographs. STUDY DESIGN/SETTING: This is a retrospective case-controlled study. PATIENT SAMPLE: The authors carried out a retrospective chart review at a tertiary care referral center that included ADS patients referred to scoliosis surgeons between 2012 and 2014. Inclusion criteria included patients with ADS and no prior thoracolumbar surgery. Data were collected from initial spine surgeon clinic notes and radiographs. OUTCOME MEASURES: Clinical outcome data included presence, side(s), and level(s) of radicular pain; presence of motor deficits; and presence of sensory deficits. METHODS: Variables included age, gender, Scoliosis Research Society-30 (SRS-30) and Oswestry Disability Index (ODI) questionnaire data, and radiographic measurements. Radiographic measurements included Cobb angles and L1 to S1 IPHs on upright and supine radiographs. Associations between variables and outcome measures were assessed with univariate and multivariate statistical analyses. Authors have no conflicts of interests relevant to this study. RESULTS: A total of 200 patients with an average age of 51 years met the inclusion criteria. Sixty of the 200 patients presented with radicular pain. Older age was associated with radicular pain, weakness, and sensory deficits. Patients who were 55 years or older were approximately eight times more likely to have radicular pain (odds ratio [OR]=7.96, 95% confidence interval [CI]: 3.73, 17.0; p<.001), five times more likely to have motor deficit (OR=5, 95% CI: 2.55, 9.79; p<.001), and five times more likely to have sensory deficit (OR=5.2, 95% CI: 2.65, 10.2; p<.001) than those younger than 55. More caudally located nerve roots are more likely to develop radicular pain (p<.001). Motor deficits were associated with worse SRS-30 functional (p=.02) and ODI scores (p=.005), but radicular pain and sensory deficits were not associated with lower SRS-30 or ODI scores. Ipsilateral and same-level radicular pain were associated with reduced IPH on supine radiographs (p=.002 and p=.0002, respectively). Finally, reduced IPH on upright radiographs was associated with side- and level-specific radicular pain (p=.04). CONCLUSIONS: Radicular pain in ADS patients is associated with reduced IPHs and older age. Measuring IPHs on routine radiographs may be helpful in associating clinical radiculopathy with radiographic measures to guide patient management and surgical planning.

Magnetic Resonance Imaging Biomarker of Axon Loss Reflects Cervical Spondylotic Myelopathy Severity.

STUDY DESIGN: A prospective cohort study. OBJECTIVE: In this study, we employed diffusion basis spectrum imaging (DBSI) to quantitatively assess axon/myelin injury, cellular inflammation, and axonal loss of cervical spondylotic myelopathy (CSM) spinal cords. SUMMARY OF BACKGROUND DATA: A major shortcoming in the management of CSM is the lack of an effective diagnostic approach to stratify treatments and to predict outcomes. No current clinical diagnostic imaging approach is capable of accurately reflecting underlying spinal cord pathologies. METHODS: Seven patients with mild (mJOA ≥15), five patients with moderate (14≥mJOA ≥11), and two patients with severe (mJOA <11) CSM were prospectively enrolled. Given the low number of severe patients, moderate and severe patients were combined for comparison with seven age-matched controls and statistical analysis. We employed the newly developed DBSI to quantitatively measure axon and myelin injury, cellular inflammation, and axonal loss. RESULTS: Median DBSI-inflammation volume is similar in control (266 µL) and mild CSM (171 µL) subjects, with a significant overlap of the middle 50% of observations (quartile 3 - quartile 1). This was in contrast to moderate CSM subjects that had higher DBSI-inflammation volumes (382 µL; P = 0.033). DBSI-axon volume shows a strong correlation with clinical measures (r = 0.79 and 0.87, P = 1.9 x 10-5 and 2 x 10-4 for mJOA and MDI, respectively). In addition to axon and myelin injury, our findings suggest that both inflammation and axon loss contribute to neurological impairment. Most strikingly, DBSI-derived axon volume declines as severity of impairment increases. CONCLUSION: DBSI-quantified axonal loss may be an imaging biomarker to predict functional recovery following decompression in CSM. Our results demonstrate an increase of about 60% in the odds of impairment relative to the control for each decrease of 100 µL in axon volume. LEVEL OF EVIDENCE: 3.

Intervertebral Micro Access Surgery for Transforaminal Lumbar Interbody Fusion.

BACKGROUND: Minimally invasive spine surgery (MIS) has undergone tremendous progress in the past 2 decades. The intervertebral micro access surgery (iMAS) technique represents a hybrid of both open and minimally invasive techniques. OBJECTIVE: To describe the surgical technique and operative nuances of the iMAS technique. METHODS: We describe a novel operative approach for the standard transforaminal lumbar interbody fusion with pedicle screw fixation. Described are the preoperative planning, incision and approach, pedicle screw insertion, facetectomy and discectomy, transforaminal interbody placement, and direct decompression. RESULTS: Early experience suggests that iMAS is well suited for the same degenerative conditions currently treated with open or MIS transforaminal lumbar interbody fusion, including grade I spondylolisthesis, unilateral synovial cysts with instability, unilateral disc herniations with instability, and recurrent disc herniations. CONCLUSION: The novel integration of both open and MIS techniques makes iMAS an attractive approach for select degenerative lumbar disease processes. Similar to other MIS procedures, minimal tissue disruption may allow for more rapid patient recovery, reduced blood loss, and reduced length of hospital stay.

Utility of Screening for Cerebral Vasospasm Using Digital Subtraction Angiography.

BACKGROUND AND PURPOSE: Cerebral arterial vasospasm (CVS) is a common complication of aneurysmal subarachnoid hemorrhage strongly associated with neurological deterioration and delayed cerebral ischemia (DCI). The utility of screening for CVS as a surrogate for early detection of DCI, especially in patients without clinical signs of DCI, remains uncertain. METHODS: We performed a retrospective analysis of 116 aneurysmal subarachnoid hemorrhage patients who underwent screening digital subtraction angiography to determine the association of significant CVS and subsequent development of DCI. Patients were stratified into 3 groups: (1) no symptoms of DCI before screening, (2) ≥1 episodes of suspected DCI symptoms before screening, and (3) unable to detect symptoms because of poor examination. RESULTS: Patients asymptomatic before screening had significantly lower rates of CVS (18%) compared with those with transient symptoms of DCI (60%; P<0.0001). None of the 79 asymptomatic patients developed DCI after screening, regardless of digital subtraction angiography findings, compared with 56% of those with symptoms (P<0.0001). Presence of CVS was significantly associated with DCI in those with transient symptoms and in those whose examinations did not permit clear assessment (odds ratio 16.0, 95% confidence interval 2.2-118.3, P=0.003). CONCLUSIONS: Patients asymptomatic before screening have low rates of CVS and seem to be at negligible risk of developing DCI. Routine screening of asymptomatic patients seems to have little utility. Screening may still be considered in patients with possible symptoms of DCI or those with examinations too poor to clinically detect symptoms because finding CVS may be useful for risk stratification and guiding management.

Predicting Kyphosis Correction During Posterior-Only Vertebral Column Resection by the Amount of Spinal Column Shortening.

STUDY DESIGN: Retrospective. OBJECTIVE: To investigate the relationship between the amount of correction achieved (K°) and extent of vertebral column shortening (mm) with posterior vertebral column resection (PVCR). SUMMARY OF BACKGROUND DATA: There is no scientific reference to the correlation between K° and column shortening (mm) with PVCR. METHODS: Based on simple geometry, we tested the hypothesis that we could predict the amount of actual kyphosis correction (K°) by calculation on 26 kyphotic PVCR patients. Using multiple linear measurements (mm), two angular approximations (°) were calculated: the geometric approximation (G°) using the geometric calculation (G-cal), and the rough approximation (R°) by more simplistic calculation (R-cal). Both G° and R° were compared against K° as measured on the pre- and postoperative radiographs. If calculated G° and R° is close to measured K°, we can use the calculations (G-cal and R-cal) in the clinical situation. RESULTS: The mean correction of K° was 38°. K°-G° and K°-R° were not significantly greater than 3° and 6°, respectively. As K° was very close to G° and R°, K° can replace G° and R°. Therefore, we can use G-cal and R-cal in the clinical setting and we can determine how much posterior shortening and what cage size is required to obtain a certain amount of K°. CONCLUSIONS: With two calculations (G-cal & R-cal), we can determine how much vertebral column shortening (mm) we need during PVCR to obtain the amount of kyphosis correction desired (K°). In order to obtain K°, using the formula deduced from G-cal and R-cal, we can determine the shortening between the upper and lower pedicle screws and cage size.

Idiopathic scoliosis and the vestibular system.

PURPOSE: Despite its high prevalence, the etiology underlying idiopathic scoliosis remains unclear. Although initial scrutiny has focused on genetic, biochemical, biomechanical, nutritional and congenital causes, there is growing evidence that aberrations in the vestibular system may play a role in the etiology of scoliosis. In this article, we discuss putative mechanisms for adolescent idiopathic scoliosis and review the current evidence supporting a role for the vestibular system in adolescent idiopathic scoliosis. METHODS: A comprehensive search of the English literature was performed using PubMed ( http://www.ncbi.nlm.nih.gov/pubmed ). Research articles studying interactions between adolescent idiopathic scoliosis and the vestibular system were selected and evaluated for inclusion in a literature review. RESULTS: Eighteen manuscripts of level 3-4 clinical evidence to support an association between adolescent idiopathic scoliosis (AIS) and dysfunction of the vestibular system were identified. These studies include data from physiologic and morphologic studies in humans. Clinical data are supported by animal model studies to suggest a causative link between the vestibular system and AIS. CONCLUSIONS: Clinical data and a limited number of animal model studies suggest a causative role of the vestibular system in AIS, although this association has not been reproduced in all studies.

The prevalence of abnormal preoperative neurological examination in Scheuermann kyphosis: correlation with X-ray, magnetic resonance imaging, and surgical outcome.

STUDY DESIGN: Retrospective. OBJECTIVE: The purpose of this study was to report the prevalence of abnormal neurological findings detected by physical examination in Scheuermann kyphosis and to correlate it to radiographs, magnetic resonance imaging (MRI) findings, and results of operative treatment. SUMMARY OF BACKGROUND DATA: There have been sporadic reports about abnormal neurological findings in patients with Scheuermann kyphosis. METHODS: Among 82 patients with Scheuermann kyphosis who underwent corrective surgery, 69 primary cases were selected. Patients' charts were reviewed retrospectively in terms of pre and postoperative neurological examinations. Sensory or motor change was defined as an abnormal neurological examination. Their duration, associated problems, and various parameters on preoperative radiographs and MRI examinations were also measured to search for any atypical findings associated with an abnormal neurological examination. RESULTS: There were 6 cases (9%) (group AbN), with an abnormal neurological examination ranging from severe myelopathy to a subtle change (e.g., sensory paresthesias on trunk). Five patients recovered to a normal neurological examination after corrective surgery. The remaining 1 patient with severe myelopathy also showed marked improvement and was ambulatory unassisted by 2-year follow-up. In patients with a normal neurological examination (group N, n = 63), only 1 patient had neurological sequelae because of anterior spinal artery syndrome after combined anterior-posterior correction. No preoperative radiographical parameters were significantly different between groups. Average age was 21.3 (AbN) and 18.6 (N) years (P = 0.55). Average preoperative T5-12 kyphosis was 69.0° (AbN) and 72.5° (N) (P = 0.61). Forty-two magnetic resonance images were obtained and all showed typical findings of Scheuermann kyphosis. Five patients in the AbN group (1 patient underwent computed tomography/myelography) and 37 patients in the N group underwent an MRI. CONCLUSION: The prevalence of abnormal neurological findings in Scheuermann kyphosis was 9%, emphasizing the importance of performing a detailed preoperative neurological examination. If congenital stenosis or a herniated thoracic disc is present, myelopathy can occur. No radiographical findings correlated with the abnormal preoperative neurological examinations. A normal MRI can exist in the face of an abnormal neurological examination, and conversely, a normal neurological examination can be seen with an abnormal MRI. Surgery was successful in alleviating abnormal neurological issues. LEVEL OF EVIDENCE: 4.

Radiographical and Clinical Outcomes of Posterior Column Osteotomies in Spinal Deformity Correction.

STUDY DESIGN: Prospectively enrolled, retrospectively analyzed case series. OBJECTIVE: To evaluate a large series of pediatric patients/patients with adult spinal deformity undergoing surgery with posterior column osteotomies (PCOs). SUMMARY OF BACKGROUND DATA: Osteotomies of the posterior column (Smith-Petersen or Ponté) are used to reduce kyphosis, increase lordosis, or increase spinal flexibility. However, little focused evidence exists regarding the efficacy and safety of this technique. METHODS: A total of 128 consecutive patients underwent posterior spinal fusion with PCOs with minimum 2-year follow-up. Seventy-five were primary surgical procedures; 53 were revisions. Data were collected from hospital charts, clinic notes, radiographs, and standardized questionnaires (Scoliosis Research Society-30 and Oswestry Disability Index). RESULTS: A total of 128 patients aged 37.6 ± 21 years underwent 518 PCOs (mean, 4.0 ± 2.2 yr) with 14.4 ± 3 mean instrumentation levels, with 3-year (range, 2-6.8 yr) average follow-up. PCOs were used for kyphosis correction in 49%, scoliosis correction at the apex of a curve in 13%, and both in 38%. One hundred six patients had complete radiographical data available for evaluation. Mean kyphosis correction per PCO was 8.8° ± 7.2°, varying with patient age (10.2° for those younger than 21 yr vs. 7.7° for those 21 yr or older, P < 0.0001) and region of the spine: thoracolumbar (T10-L2) 11.6°, lumbar (L2-S1) 9.4°, midthoracic (T6-T10) 7.2° and proximal thoracic (T1-T6) 3.6°. With PCOs at the apex of a curve, the maximum coronal Cobb decreased from 66° ± 21° to 31° ± 14° (P < 0.0001). Average estimated blood loss was 1419 ± 887 mL, correlating with greater age (P < 0.0001) and more instrumented levels (P < 0.0001), but not with the number of PCOs (P = 0.32). Complications occurred in 31 (24.2%) patients, including 4 radiculopathies (none attributable to PCOs). Complications did not correlate with the number of PCOs (P = 0.5). Six (4.7%) patients had loss of spinal cord monitoring or a failed wake-up test that could be attributed to overcorrection with PCOs, but none had postoperative deficits. Oswestry Disability Index scores improved (34.4 ± 17 to 23.6 ± 18, P < 0.0001), as did normalized Scoliosis Research Society-30 scores (63.7 ± 13 to 76.4 ± 15, P < 0.0001). CONCLUSION: Patients in this series undergoing posterior spinal fusion with PCOs achieved overall favorable outcomes for spinal deformity correction. The number of PCOs did not correlate with increased estimated blood loss or complications. The main technical concern was overcorrection, but neurological consequences associated with overcorrection were identified by intraoperative spinal cord monitoring and wake-up tests, and no patients experienced permanent neurological deficits related to PCOs. LEVEL OF EVIDENCE: 4.

Comparison of TLIF with rhBMP-2 versus no TLIF and higher posterolateral rhBMP-2 dose at L5-S1 for long fusions to the sacrum with sacropelvic fixation in patients with primary adult deformity.

STUDY DESIGN: Comparvative case series. Data was prospectively entered and retrospectively analyzed. OBJECTIVE: To evaluate the need for distal lumbar interbody fusion when sufficient recombinant human bone morphogenetic protein-2 (rhBMP-2) is used posterolaterally at L5-S1 in long spinal constructs for adult deformity via costs and radiographical and patient-reported outcome comparisons. SUMMARY OF BACKGROUND DATA: Many authors and investigators have suggested that an interbody fusion is mandatory at L5-S1 with long fusion to the sacrum with sacropelvic fixation. Past studies have shown competitive fusion rates using rhBMP-2 versus iliac crest bone graft for long fusions. There are various advocates for anterior lumbar interbody fusion versus posterior lumbar interbody fusion versus transforaminal lumbar interbody fusion (TLIF). The optimal strategy remains elusive. METHODS: Fifty-seven patients were studied at one institution. Thirty-one patients had no interbody fusion (NI group) with 20 mg of rhBMP-2 posterolaterally on 10 mL of carrier and 26 patients had TLIF at L5-S1 (TLIF group) with 6 mg of rhBMP-2 in the interbody space along with local bone graft and 6 mg of rhBMP-2 on carrier posterolaterally at L5-S1. Patients were followed for 24 to 87 months (mean follow-up, 3.92 yr). Demographics of the 2 groups were similar. RESULTS: There were no detected nonunions at L5-S1 in either group. By our limited cost analysis, the expense of performing a TLIF at L5-S1 is higher than that of using extra rhBMP-2 posterolaterally at that segment. Improvement in outcomes scores, namely Scoliosis Research Society-22 and Oswestry Disability Index, were the same statistically in both groups. Blood loss was greater in the TLIF group than the NI group. There were no identified rhBMP-2 adverse events in either group. CONCLUSION: Utilization of 20 mg of rhBMP-2 at L5-S1 has the potential to be less expensive than an interbody fusion in most patients having a primary long fusion for adult spinal deformity. The apparent fusion rates at L5-S1 were identical in both groups. Both strategies were successful in regard to improving patient outcomes and achieving apparent solid arthrodesis at the lumbosacral junction, which was the focus of this study. LEVEL OF EVIDENCE: 2.

Transforaminal versus anterior lumbar interbody fusion in long deformity constructs: a matched cohort analysis.

STUDY DESIGN: Prospectively enrolled, retrospectively analyzed matched cohort analysis. OBJECTIVE: Evaluate the relative merits of transforaminal lumbar interbody fusion (TLIF) and anterior lumbar interbody fusion (ALIF) when performed in long deformity constructs. SUMMARY OF BACKGROUND DATA: Interbody fusion is frequently used at the caudal levels of long-segment spinal deformity instrumentation constructs to protect the sacral implants and enhance fusion rates. However, there is a paucity of literature regarding which technique is more efficacious. METHODS: Forty-two patients who underwent TLIF and 42 patients who underwent ALIF were matched with respect to age, sex, comorbidities, curve magnitude, fusion length, and ALIF/TLIF level. Radiographs and clinical outcomes were compared at minimum 2-year follow-up. RESULTS: Age averaged 54.0 years and instrumented vertebrae averaged 13.6. TLIFs had less operative time (481 vs. 595 min, P = 0.0007), but greater blood loss (2011 vs. 1281 mL, P = 0.0002). Overall complications (TLIF, 12/42 vs. ALIF, 15/42) and neurological complications (TLIF, 4/42 vs. ALIF, 3/42) did not differ. One pseudarthrosis occurred at an ALIF level, with none at TLIF levels. Patients who underwent ALIF began with lower SRS scores but showed more improvement (44.4 to 70.7 vs. 58.6 to 70.6, P = 0.0043). ODI scores in both groups improved similarly. Regionally, ALIFs engendered more lordosis than TLIFs at L3-S1 (gain of 6.9° vs. -2.6°, P < 0.0001) but not T12-S1 (gain of 11.5° vs. 7.9°, P = 0.29). Locally, ALIFs created more lordosis at L4-L5 (gain of 5.6° vs. -1.7°, P < 0.0001) and L5-S1 (gain of 2.5° vs. -1.4°, P = 0.022), but not at L3-L4 (gain of 5.3° vs. 4.0°, P = 0.65). Patients who underwent TLIF obtained greater correction of anteroposterior Cobb angles in lumbar (reduction of 22.4° vs. 9.9°, P < 0.0001) and lumbosacral curves (reduction of 10.3° vs. 3.4°, P < 0.0001). CONCLUSION: Spinal deformity surgery used TLIFs rather than ALIFs resulted in shorter operative time with no difference in complication rates. ALIFs provided more segmental lordosis, whereas TLIFs afforded better correction of scoliotic curves.