Faculty Bibliography

Occipital neuralgia typically arises in the setting of nerve compression by fibrosis, surrounding anatomic structures, or osseous pathology, such as bone spurs or hypertrophic atlanto-epistropic ligament. It generally presents as paroxysmal bouts of sharp pain in the sensory distribution of the first three occipital nerves. Due to the long course of the greater occipital nerve (GON), and its peculiar anatomy, and location in a mobile region of the neck, it is unsurprising that the GON is at high risk for compression. Little is known how to diagnose or treat this neuropathic pain syndrome. The objective of this paper is to isolate the etiology involved, and treat this condition promptly. After all nonoperative efforts are exhausted, surgical transection of the nerve is the treatment of choice in these cases. An isolated C2 neurectomy or ganglionectomy is performed for an optimal pain relief. C1-2 instrumented fusion can be considered if, extensive facet arthropathy with instability is identified. Authors review the spectrum of treatment options for this debilitating condition, and discuss the case example of a patient who required conversion to a C1-C2 instrumented fusion following C2 ganglionectomy due to an underlying extensive degenerative disease and intraoperative findings suggestive of atlantoaxial instability.

STUDY DESIGN/METHODS:Single-center retrospective study. OBJECTIVE:Investigate how differing degrees of PI modulate the recruitment of pelvic tilt (PT) in response to similar amounts of sagittal malalignment as measured by T1-Pelvic Angle (TPA). SUMMARY OF BACKGROUND DATA/BACKGROUND:Past research has shown that some patients do not recruit PT in response to sagittal malalignment. Given the anatomic relationship between PI and PT, we sought to determine whether differing PI is associated with variable recruitment of PT. METHODS:Single-center retrospective study of 2077 patients undergoing full body radiographs and TPA>10°. Five groups of patients (Very Low, Low, Average, High, and Very High PI) were defined utilizing PI ranges on a gaussian distribution. Linear regression (LR) evaluated correlation of TPA to PT within each PI group. Multivariate LR evaluated whether correlation between TPA and PT differed between each PI group. RESULTS:Mean PT increased with increasing levels of PI (p < 0.05). Within the full cohort, PT correlated with TPA (r = 0.80, p < 0.001). Multivariate LR revealed significant differences between slopes and intercepts of the linear relationship between PT and TPA within the PI groups. Compared to patients with an average PI, patients with Very Low PI had 3.4° lower PT while holding TPA constant (p < 0.001). Further, patients with Very High PI displayed a PT of 1.9° higher than patients with an Average PI while holding TPA constant (p = 0.01). A similar difference of -1.8°, and 1.2° with respect to the Average PI group was observed in the Low and High PI groups, respectively (p < 0.001). Means and standard deviations of PT at varying levels of TPA were defined for PI groups. CONCLUSIONS:This is the first study which demonstrated that PI is associated with varied recruitment of PT while maintaining constant sagittal malalignment. The results reported herein are intended to allow surgeons to assess a patient's magnitude of compensatory PT for an individual patient's PI. LEVEL OF EVIDENCE/METHODS:3.

BACKGROUND:Surgical site infections (SSIs) affect 1% to 9% of all spine surgeries. Though previous work has found diabetes mellitus type 2 (DM2) to increase the risk for wound infection, the influence of perioperative hyperglycemia is poorly described. OBJECTIVE:To investigate perioperative hyperglycemia as an independent risk factor for surgical site infection. METHODS:We retrospectively identified patients undergoing operative management of SSIs occurring after spinal surgery for degenerative pathologies. These patients were individually matched to controls based upon age, surgical invasiveness, ICD-10CM, race, and sex. Cases and controls were compared regarding medical comorbidities (including diabetes), postoperative hyperglycemia, and operative time. RESULTS:Patients in the infection group were found to have a higher BMI (33.7 vs 28.8), higher prevalence of DM2 (48.5% vs 14.7%), and longer inpatient stay (8.8 vs 4.3 d). They also had higher average (136.6 vs 119.6 mg/dL) and peak glucose levels (191.9 vs 153.1 mg/dL), as well as greater variability in glucose levels (92.1 vs 58.1 mg/dL). Multivariable logistic regression identified BMI (odds ratio [OR] = 1.13), diabetes mellitus (OR = 2.12), average glucose on the first postoperative day (OR = 1.24), peak postoperative glucose (OR = 1.31), and maximal daily glucose variation (OR = 1.32) as being significant independent predictors of postoperative surgical site infection. CONCLUSION/CONCLUSIONS:Postoperative hyperglycemia and poor postoperative glucose control are independent risk factors for surgical site infection following surgery for degenerative spine disease. These data suggest that, particularly among high-risk diabetic patients, strict perioperative glucose control may decrease the risk of SSI.

STUDY DESIGN/METHODS:Retrospective review. OBJECTIVE:The aim of this study was to develop a novel surgical invasiveness index for cervical deformity (CD) surgery that incorporates CD-specific parameters. SUMMARY OF BACKGROUND DATA/BACKGROUND:There has been a surgical invasiveness index for general spine surgery and adult spinal deformity, but a CD index has not been developed. METHODS:CD was defined as at least one of the following: C2-C7 Cobb > 10°, cervical lordosis (CL) > 10°, cervical sagittal vertical axis (cSVA) > 4 cm, chin brow vertical angle (CBVA) > 25°. Consensus from experienced spine and neurosurgeons selected weightings for each variable that went into the invasiveness index. Binary logistic regression predicted high operative time (>338 minutes), estimated blood loss (EBL) (>600 cc), or length of stay (LOS; > 5 days) based on the median values of operative time, EBL and LOS. Multivariable regression modeling was utilized to construct a final model incorporating the strongest combination of factors to predict operative time, LOS, and EBL. RESULTS:85 CD patients were included (61yrs, 66%F). The variables in the newly developed CD invasiveness index with their corresponding weightings were: history of prior cervical surgery (3), anterior cervical discectomy and fusion (ACDF) (2/level), corpectomy (4/level), levels fused (1/level), implants (1/level), posterior decompression (2/level), Smith-Peterson osteotomy (2/level), three column osteotomy (8/level), fusion to upper cervical spine (2), absolute change in T1 slope minus cervical lordosis (TS-CL), cSVA, T4-T12 thoracic kyphosis and sagittal vertical axis (SVA) from baseline to 1-year. The newly developed CD-specific invasiveness index strongly predicted long LOS (R = 0.310, p < 0.001), high EBL (R = 0.170, p = 0.011), and extended operative time (R = 0.207, p = 0.031). A second analysis used multivariable regression modeling to determine which combination of factors in the newly developed index were the strongest determinants of operative time, LOS, and EBL. The final predictive model included: number of corpectomies, levels fused, decompression, combined approach, and absolute changes in SVA, cSVA and TK. This model predicted EBL (R = 0.26), operative time (R = 0.12), and LOS (R = 0.13). CONCLUSIONS:Extended length of stay, operative time, and high blood loss were strongly predicted by the newly developed CD invasiveness index, incorporating surgical factors and radiographic parameters clinically relevant for patients undergoing cervical deformity corrective surgery. LEVELS OF EVIDENCE/METHODS:4.

BACKGROUND CONTEXT/BACKGROUND:Laboratory values have been found to be useful predictive measures of survival following surgery. The utility of laboratory values for prognosticating outcomes among patients with spinal metastases has not been studied. PURPOSE/OBJECTIVE:To determine the prognostic capacity of laboratory values at presentation including white blood cell count, serum albumin and platelet-lymphocyte ratio (PLR) in patients with spinal metastases. STUDY DESIGN/METHODS:Retrospective review of records from two tertiary care centers (2005-2017). PATIENT SAMPLE/METHODS:Patients, aged 40 to 80, who received operative or nonoperative management for spinal metastases. OUTCOME MEASURES/METHODS:Survival, complications, or hospital readmissions within 90 days of treatment and a composite measure for treatment failure accounting for changes in ambulatory function and mortality at 6 months following presentation. METHODS:Multivariable Cox proportional hazard regression analysis was used to analyze the relationship between laboratory values and length of survival, adjusting for confounders. Multivariable logistic regression was used in analyses related to 6-month and 1-year mortality, complications, readmissions, and treatment failure. A scoring rubric was developed based on the performance of laboratory values in the multivariable tests. Internal validation was performed using a bootstrap simulation that consisted of sampling with replacement and 1,000 replications. RESULTS:We included 1,216 patients. Thirty-seven percent of patients received a surgical intervention and 63% were treated nonoperatively. Median survival for the cohort as a whole was 255 days (interquartile range 93-642 days). The PLR (hazard ratio [HR] 1.53; 95% confidence interval [CI] 1.29, 1.80; p<.001) and albumin (HR 0.54; 95% CI 0.45, 0.64; p<.001) were significantly associated with survival, whereas WBC count (HR 1.08; 95% CI 0.86, 1.36; p=.50) was not associated with this outcome. Similar findings were encountered for 6-month and 1-year mortality as well as the composite measure for treatment failure. The PLR and albumin performed well in our scoring rubric and findings were preserved in the bootstrapping validation. CONCLUSIONS:Individuals with low serum albumin and elevated PLR should be advised regarding the impact of these laboratory markers on outcomes including survival, irrespective of treatments received. An effort should also be made to optimize nutrition and PLR, if practicable, before treatment to minimize the potential for development of adverse events.

BACKGROUND:Proximal junctional kyphosis (PJK) is a common radiographic complication of adult spinal deformity (ASD) corrective surgery. Although previous literature has reported a 5 to 61% incidence of PJK, these studies are limited by small sample sizes and short-term follow-up. OBJECTIVE:To assess the incidence of PJK utilizing a high-powered ASD database. METHODS:Retrospective review of a prospective multicenter ASD database. Operative ASD patients > 18 yr old from 2009 to 2017 were included. PJK was defined as ≥ 10° for the sagittal Cobb angle between the inferior upper instrumented vertebra (UIV) endplate and the superior endplate of the UIV + 2. Chi-square analysis and post hoc testing assessed annual and overall incidence of acute (6-wk follow-up [f/u]), progressive (increase in degree of PJK from 6 wk to 1 yr), and delayed (1-yr, 2-yr, and 3-yr f/u) PJK development. RESULTS:A total of 1005 patients were included (age: 59.3; 73.5% F; body mass index: 27.99). Overall PJK incidence was 69.4%. Overall incidence of acute PJK was 48.0%. Annual incidence of acute PJK has decreased from 53.7% in 2012 to 31.6% in 2017 (P = .038). Overall incidence of progressive PJK was 35.0%, with stable rates observed from 2009 to 2016 (P = .297). Overall incidence of 1-yr-delayed PJK was 9.3%. Annual incidence of 1-yr-delayed PJK has decreased from 9.2% in 2009 to 3.2% in 2016 (P < .001). Overall incidence of 2-yr-delayed PJK development was 4.3%. Annual incidence of 2-yr-delayed PJK has decreased from 7.3% in 2009 to 0.9% in 2015 (P < .05). Overall incidence of 3-yr-delayed PJK was 1.8%, with stable rates observed from 2009 to 2014 (P = .594). CONCLUSION/CONCLUSIONS:Although progressive PJK has remained a challenge for physicians over time, significantly lower incidences of acute and delayed PJK in recent years may indicate improving operative decision-making and management strategies.

Cervical alignment has become increasingly important in the planning of spine surgery. A relationship between the slope of T1 (T1S), the cervical lordosis (CL), and the overall cervical sagittal vertical axis (cSVA) has previously been demonstrated, but the exact nature of this relationship is poorly understood. In this study, we derive theoretical and empirical equations to better understand how T1S and CL affect cSVA. The first equation was developed on a theoretical basis using inherent trigonometric relationships of the cervical spine. By treating the cervical spine as the arc of a circumference, and by taking into account the cervical height (CH), the geometric relationship between theT1S, CL, and cSVA was described via a trigonometric identity utilizing a novel angle δ subtended by the CH and cSVA (δ = T1S-CL/2). The second equation was developed on an empiric basis by performing a multiple linear regression on data obtained from a retrospective review of a large multicenter deformity database. The theoretical equation determined that the value of cSVA could be expressed as: $cSVA\ = \ CH*{\rm{tan}}( {\pi /180*( {T1S - CL/2} )} )$. The empirical equation determined that value of cSVA could be expressed as: $cSVA=({1.1*T1} )\ - ( {0.43*CL} ) + 6.69$. In both, the sagittal alignment of the head over the shoulders is directly proportional to the T1S and inversely proportional to CL/2. These 2 equations may allow surgeons to better understand how the CL compensates for the T1S, to accurately predict the postoperative cSVA, and to customize cervical interbody grafts by taking into consideration each individual patient's specific cervical spine parameters.

STUDY DESIGN:Retrospective review from a single institution. OBJECTIVE:To investigate the effect of hip osteoarthritis (OA) on spinopelvic compensatory mechanisms as a result of reduced hip range of motion (ROM) between sitting and standing. SUMMARY OF BACKGROUND DATA:Hip OA results in reduced hip ROM and contracture, causing pain during postural changes. Hip flexion contracture is known to reduce the ability to compensate for spinal deformity while standing; however, the effects of postural spinal alignment change between sitting and standing is not well understood. METHODS:Sit-stand radiographs of patients without prior spinal fusion or hip prosthesis were evaluated. Hip OA was graded by Kellgren-Lawrence grades and divided into low-grade (LOA; grade 0-2) and severe (SOA; grade 3 or 4) groups. Radiographic parameters evaluated were pelvic incidence (PI), pelvic tilt (PT), lumbar lordosis (LL), PI-LL, thoracic kyphosis (TK), SVA, T1-pelvic angle (TPA), T10-L2, proximal femoral shaft angle (PFSA), and hip flexion (PT change-PFSA change). Changes in sit-stand parameters were compared between LOA and SOA groups. RESULTS:548 patients were included (LOA = 311; SOA = 237). After propensity score matching for age, body mass index, and PI, 183 LOA and 183 SOA patients were analyzed. Standing analysis demonstrated that SOA had higher SVA (31.1 vs. 21.7), lower TK (-36.2 vs. -41.1), and larger PFSA (9.1 vs. 7.4) (all p < .05). Sitting analysis demonstrated that SOA had higher PT (29.7 vs. 23.3), higher PI-LL (21.6 vs. 12.4), less LL (31.7 vs. 41.6), less TK (-33.2 vs. -38.6), and greater TPA (27.9 vs. 22.5) (all p < .05). SOA had less hip ROM from standing to sitting versus LOA (71.5 vs. 81.6) (p < .05). Therefore, SOA had more change in PT (15.2 vs. 7.3), PI-LL (20.6 vs. 13.7), LL (-21.4 vs. -13.1), and T10-L2 (-4.9 vs. -1.1) (all p < .001), allowing the femurs to change position despite reduced hip ROM. SOA had greater TPA reduction (15.1 vs. 9.6) and less PFSA change (86.7 vs. 88.8) compared with LOA (both p < .001). CONCLUSIONS:Spinopelvic compensatory mechanisms are adapted for reduced hip joint motion associated with hip OA in standing and sitting. LEVEL OF EVIDENCE:Level III.

Study Design:Retrospective cohort study. Purpose:The aim of this study was to identify features associated with increased mortality risk in traumatic C2 fractures in the elderly, including measures of comorbidity and frailty. Overview of Literature:C2 fractures in the elderly are of increasing relevance in the setting of an aging global population and have a high mortality rate. Previous analyzes of risk factors for mortality have not included the measures of comorbidity and/or frailty, and no local data have been reported to date. Methods:This study comprises a retrospective review of 70 patients of age >65 years at Waikato Hospital, New Zealand with traumatic C2 fractures identified on computed tomography between 2010 and 2016. Demographic details, medical history, laboratory results on admission, mechanism of injury, and neurological status on presentation were recorded. Medical comorbidities were also detailed allowing calculation of the Charlson Comorbidity Index (CCI) and the modified Frailty Index (mFI). Results:The most common mechanism of injury was a fall from standing height (n=52, 74.3%). Mortality rates were 14.3% (n=10) at day 30, and 35.7% (n=25) at 1 year. Bivariate analysis showed that both CCI and mFI correlated with 1-year mortality rates. Reduced albumin and hemoglobin levels were also associated with 30-day and 1-year mortality rates. Forward stepwise logistic regression models determined CCI and low hemoglobin as predictors of mortality within 30 days, whereas CCI, low albumin, increased age, and female gender predicted mortality at 1 year. Conclusions:The CCI was a useful tool for predicting mortality at 1 year in the patient cohort. Other variables, including common laboratory markers, can also be used for risk stratification, to initiate timely multidisciplinary management, and prognostic counseling for patients and family members.

Background/UNASSIGNED:Klippel-Feil syndrome (KFS) includes craniocervical anomalies, low posterior hairline, and brevicollis, with limited cervical range of motion; however, there remains no consensus on inheritance pattern. This study defines incidence, characterizes concurrent diagnoses, and examines trends in the presentation and management of KFS. Methods/UNASSIGNED:This was a retrospective review of the Kid's Inpatient Database (KID) for KFSpatients aged 0-20 years from 2003 to 2012. Incidence was established using KID-supplied year and hospital-trend weights. Demographics and secondary diagnoses associated with KFS were evaluated. Comorbidities, anomalies, and procedure type trends from 2003 to 2012 were assessed for likelihood to increase among the years studied using ANOVA tests. Results/UNASSIGNED:Eight hundred and fifty-eight KFS diagnoses (age: 9.49 years; 51.1% females) and 475 patients with congenital fusion (CF) (age: 8.33 years; 50.3% females) were analyzed. We identified an incidence rate of 1/21,587 discharges. Only 6.36% of KFS patients were diagnosed with Sprengel's deformity; 1.44% with congenital fusion. About 19.1% of KFS patients presented with another spinal abnormality and 34.0% presented with another neuromuscular anomaly. About 36.51% of KFS patients were diagnosed with a nonspinal or nonmusculoskeletal anomaly, with the most prevalent anomalies being of cardiac origin (12.95%). About 7.34% of KFS patients underwent anterior fusions, whereas 6.64% of KFS patients underwent posterior fusions. The average number of levels operated on was 4.99 with 8.28% receiving decompressions. Interbody devices were used in 2.45% of cases. The rate of fusions with <3 levels (7.46%) was comparable to that of 3 levels or greater (7.81%). Conclusions/UNASSIGNED:KFS patients were more likely to have other spinal abnormalities (19.1%) and nonnervous system abnormalities (13.63%). Compared to congenital fusions, KFS patients were more likely to have congenital abnormalities such as Sprengel's deformity. KFS patients are increasingly being treated with spinal fusion. Level of Evidence/UNASSIGNED:III.