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James Xie and Maxwell Boakye

Electrophysiological measures can provide information that complements clinical assessments such as the American Spinal Injury Association sensory and motor scores in the evaluation of outcomes after spinal cord injury (SCI). The authors review and summarize the literature regarding tests that are most relevant to the study of SCI recovery—in particular, motor evoked potentials and somatosensory evoked potentials (SSEPs). In addition, they discuss the role of other tests, including F-wave nerve conductance tests and electromyography, sympathetic skin response, and the Hoffman reflex (H-reflex) test as well as the promise of dermatomal SSEPs and the electrical perceptual threshold test, newer quantitative tests of sensory function.

It has been shown that motor evoked potential amplitudes improve with SCI recovery but latencies do not. Somatosensory evoked potentials are predictive of ambulatory capacity and hand function. Hoffman reflexes are present during spinal shock despite the loss of tendon reflexes, but their amplitudes increase with time after injury. Further, H-reflex modulation is reflective of changes in spinal excitability. While these tests have produced data that is congruent with clinical evaluations, they have yet to surpass clinical evaluations in predicting outcomes. Continuing research using these methodologies should yield a better understanding of the mechanisms behind SCI recovery and thus provide potentially greater predictive and evaluative power.

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Mayur Sharma, Beatrice Ugiliweneza, Zaid Aljuboori and Maxwell Boakye

OBJECTIVE

Opioid abuse is highly prevalent in patients with back pain. The aim of this study was to identify health care utilization and overall costs associated with opioid dependence in patients undergoing surgery for degenerative spondylolisthesis (DS).

METHODS

The authors queried the MarketScan database using ICD-9 and CPT-4 codes from 2000 to 2012. Opioid dependency was defined as having a diagnosis of opioid use disorder, having a prescription for opioid use disorder, or having 10 or more opioid prescriptions. Opioid dependency was evaluated in 12-month period leading to surgery and in the period 3–15 months following the procedure. Patients were segregated into 4 groups based on opioid dependence before and after surgery: group NDND (prior nondependent who remain nondependent), group NDD (prior nondependent who become dependent), group DND (prior dependent who become nondependent), and group DD (prior dependent who remain dependent). The outcomes of interest were discharge disposition, hospital length of stay (LOS), complications, and health care resource costs. The 4 groups were compared using the Kruskal-Wallis test and linear contrasts built from generalized regression models.

RESULTS

A total of 10,708 patients were identified, with 81.57%, 3.58%, 8.54%, and 6.32% of patients in groups NDND, NDD, DND, and DD, respectively. In group DD, 96.31% of patients had decompression with fusion, compared with 93.59% in group NDND. Patients in group NDD, DND, and DD had longer hospital LOS compared with those in group NDND. Patients in group DD were less likely to be discharged home compared with those in group NDND (odds ratio 0.639, 95% confidence interval 0.52–0.785). At 3–15 months postdischarge, patients in group DD incurred 21% higher hospital readmission costs compared with those in group NDND. However, patients in groups NDD and DD were likely to incur 2.8 times the overall costs compared with patients in group NDND (p < 0.001) at 3–15 months after surgery (median overall payments: group NDD $20,033 and group DD $19,654, vs group NDND $7994).

CONCLUSIONS

Patients who continued to be opioid dependent or became opioid dependent following surgery for DS incurred significantly higher health care utilization and costs within 3 months and in the period 3–15 months after discharge from surgery.

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Mayur Sharma, Beatrice Ugiliweneza, Zaid Aljuboori, Miriam A. Nuño, Doniel Drazin and Maxwell Boakye

OBJECTIVE

The opioid crisis is identified as a national emergency and epidemic in the United States. The aim of this study was to identify risk factors associated with opioid dependence in patients undergoing surgery for degenerative spondylolisthesis (DS).

METHODS

The authors queried MarketScan databases to investigate the factors affecting postsurgery opioid use in patients with DS between 2000 and 2012. The outcome of interest was opioid dependence, which was defined as continued opioid use, > 10 opioid prescriptions, or diagnosis of or prescription for opioid dependence disorder in the period of 1 year before or 3–15 months after the procedure. Comparisons of outcomes were performed using nonparametric 2-group tests and generalized regression models.

RESULTS

A cohort of 10,708 patients was identified from the database. The median patient age was 61 years (interquartile range 54–69 years), and 65.1% were female (n = 6975). A majority of patients had decompression with fusion (n = 10,068; 94%) and underwent multilevel procedures (n = 8123; 75.9%). Of 10,708 patients, 14.85% (n = 1591) were identified as having opioid dependence within 12 months prior to the index surgical procedure and 9.90% (n = 1060) were identified as having opioid dependence within 3–15 months after the procedure. Of all the variables, prior opioid dependence (OR 16.29, 95% CI 14.10–18.81, p < 0.001) and younger age (1-year increase in age: OR 0.972, 95% CI 0.963–0.980, p < 0.001) were independent predictors of opioid dependence following surgery for DS. The use of fusion was not associated with opioid dependence following the procedure (p = 0.8396). Following surgery for DS, patients were more likely to become opioid independent than they were to become opioid dependent (8.54% vs 3.58%, p < 0.001).

CONCLUSIONS

The majority of patients underwent fusion for DS. Surgical decompression with fusion was not associated with increased risk of postsurgery opioid dependence in patients with DS. Overall, opioid dependence was reduced by 4.96% after surgery for DS. Prior opioid dependence is associated with increased risk and increasing age is associated with decreased risk of opioid dependence following surgery for DS.

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Yi-Ren Chen, Beatrice Ugiliweneza, Eric Burton, Shiao Y. Woo, Maxwell Boakye and Stephen Skirboll

OBJECTIVE

Glioblastoma is a primary glial neoplasm with a median survival of approximately 1 year. There are anecdotal reports that postoperative infection may confer a survival advantage in patients with glioblastoma. However, only a few case reports in the literature, along with 2 retrospective cohort studies, show some potential link between infection and prolonged survival in patients with glioblastoma. The objective of this study was to evaluate the effect of postoperative infection in patients with glioblastoma using a large national database.

METHODS

The linked Surveillance, Epidemiology, and End Results (SEER)–Medicare database was searched to identify patients 66 years of age and older with glioblastoma, with and without infection, from 1997 to 2010. The primary outcome was survival after diagnosis. The statistical analysis was performed with a graphical representation using Kaplan-Meier curves, univariate analysis with the log-rank test, and multivariate analysis with proportional hazards modeling.

RESULTS

A total of 3784 patients with glioblastoma were identified from the database, and from these, 369 (9.8%) had postoperative infection within 1 month of surgery. In patients with glioblastoma who had an infection within 1 month of surgery, there was no significant difference in survival (median 5 months) compared with patients with no infection (median 6 months; p = 0.17). The study also showed that older age, increased Gagne comorbidity score, and having diabetes may be negatively associated with survival.

CONCLUSIONS

Infection after craniotomy within 1 month was not associated with a survival benefit in patients with glioblastoma.

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Shivanand P. Lad, Justin G. Santarelli, Chirag G. Patil, Gary K. Steinberg and Maxwell Boakye

Object

Spinal arteriovenous malformations (AVMs) are rare and understudied vascular lesions that cause neurological insult by mass effect, venous obstruction, and vascular steal. These lesions are challenging entities to treat because of their complicated anatomy and physiology. Current management options include open microsurgery, endovascular embolization, and stereotactic radiosurgery.

Methods

Our study used the National Inpatient Sample database to analyze outcome data for spinal AVMs treated nationwide over an 11-year period from 1995 through 2006. Trends in procedural management, hospital course, and epidemiology of spinal AVMs are investigated.

Results

Annually, an average of 300 patients presented with spinal AVMs requiring hospital treatment. The average length of hospital stay for this treatment has declined from more than 9 days in 1995 to 6 days in 2006. However, the average cost of a hospital stay has increased from < $30,000 to nearly $70,000. Whereas one-half of spinal AVMs were treated operatively in 1995, one-third were managed operatively in 2006.

Conclusions

Spinal AVMs are being increasingly treated by endovascular, radiosurgical, or combined means. A discussion of modern strategies to treat these disorders is presented.

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Mark H. Bilsky, Maxwell Boakye, Frederic Collignon, Dennis Kraus and Patrick Boland

Object. The authors describe the preoperative assessment, intraoperative strategies, and long-term outcomes in 41 consecutive patients who underwent spinal reconstruction after resection of subaxial cervical neoplasms.

Methods. Thirty-three tumors were metastatic and eight were primary. Preoperative studies included direct laryngoscopy and vertebral artery (VA) balloon occlusion tests in selected patients. Based on the tumor location, approaches included 12 anterior, 13 posterior, and 16 combined. All patients underwent aggressive intralesional resection and spinal reconstruction. In 12 patients, the VA was dissected from the periphery of the tumor, two cases of which required ligation. Fibula allograft and an anterior rigid plate fixation were most commonly used for anterior reconstruction. Posterior reconstruction was initially performed using lateral mass plates (LMPs) in 13 patients and screw/rod systems in the remaining patients.

At follow up, pain level improved to mild or was absent in 39 patients (95%) who had presented with moderate or severe pain. The American Spinal Injury Association (ASIA) Scale scores were stable in 25 patients who presented with ASIA Score E and improved in 14 patients (88%) who presented with ASIA Score B, C, or D. Functional radiculopathy significantly improved in 16 (94%) of 17 patients.

Complications occurred in 10 patients (24%) and included three fixation failures requiring revision. Two fixation failures involved cervical LMP screw pullout. The overall mean survival duration was 8.6 months for patients with metastatic tumors and 33.4 months for primary tumors.

Conclusions. Surgery for the treatment of subaxial spine neoplasms is effective for relieving pain, encouraging functional nerve root recovery, and preserving spinal cord function with acceptable complication rates.

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Maxwell Boakye, Sean C. Huckins, Nikolaus M. Szeverenyi, Bobby I. Taskey and Charles J. Hodge Jr.

Object. Functional magnetic resonance (fMR) imaging was used to determine patterns of cerebral blood flow changes in the somatosensory cortex that result from median nerve stimulation (MNS).

Methods. Ten healthy volunteers underwent stimulation of the right median nerve at frequencies of 5.1 Hz (five volunteers) and 50 Hz (five volunteers). The left median nerve was stimulated at frequencies of 5.1 Hz (two volunteers) and 50 Hz (five volunteers). Tactile stimulation (with a soft brush) of the right index finger was also applied (three volunteers). Functional MR imaging data were transformed into Talairach space coordinates and averaged by group. Results showed significant activation (p < 0.001) in the following regions: primary sensorimotor cortex (SMI), secondary somatosensory cortex (SII), parietal operculum, insula, frontal cortex, supplementary motor area, and posterior parietal cortices (Brodmann's Areas 7 and 40). Further analysis revealed no statistically significant difference (p > 0.05) between volumes of cortical activation in the SMI or SII resulting from electrical stimuli at 5.1 Hz and 50 Hz. There existed no significant differences (p > 0.05) in cortical activity in either the SMI or SII resulting from either left- or right-sided MNS. With the exception of the frontal cortex, areas of cortical activity in response to tactile stimulation were anatomically identical to those regions activated by electrical stimulation. In the SMI and SII, activation resulting from tactile stimulation was not significantly different (p > 0.05) from that resulting from electrical stimulation.

Conclusions. Electrical stimulation of the median nerve is a reproducible and effective means of activating multiple somatosensory cortical areas, and fMR imaging can be used to investigate the complex network that exists between these areas.

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Shivanand P. Lad, Chirag G. Patil, Eleonora Maries Lad and Maxwell Boakye

Object

Pathological vertebral fractures (PVFs) are an increasingly important cause of disability and have many clinical and economic implications. The authors examined trends in epidemiology and surgical management of pathological vertebral fractures in the US between 1993 and 2004.

Methods

The Nationwide Inpatient Sample database was used to analyze data collected from 1993 through 2004 to determine general trends in PVFs. Patients with PVFs were identified using the appropriate International Classification of Diseases, 9th Revision (ICD-9) diagnostic code (ICD-9 733.13). Trends in vertebral augmentation procedures and spinal fusions as well as comparison with incidences of other major pathological fractures, such as hip and upper limb, were also examined.

Results

In 2004, there were more than 55,000 inpatient admissions for PVFs. The majority of patients admitted were women (78%) in the 65 to 84 year–age group (60%). Medicare accounted for greater than 80% of insurance, and nearly 50% of all patients were admitted from the emergency department. The mean duration of hospitalization has continued to decrease, from 8.1 days in 1993 to 5.4 days in 2004. The mortality rate has remained relatively constant at approximately 1.5%. The discharge disposition has continued to change with an increasing number of patients being discharged to other institutions such as nursing homes and rehabilitation facilities. There was a staggering increase in the number of vertebral augmentation procedures performed between 1993 and 2004. The “national bill” for inpatient hospitalizations for PVFs totaled $1.3 billion in 2004.

Conclusions

With the continued aging of the population, PVFs represent an important cause of disability and a significant source of healthcare resource utilization.

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Maxwell Boakye, Praveen V. Mummaneni, Mark Garrett, Gerald Rodts and Regis Haid

Object. The authors reviewed clinical and radiographic outcomes in patients who had undergone anterior cervical discectomy and fusion (ACDF) involving the placement of polyetheretherketone (PEEK) spacers filled with recombinant human bone morphogenetic protein (rhBMP)—2.

Methods. Data obtained in 24 cases were retrospectively evaluated. The follow-up period ranged from 12 to 16 months (mean 13 months). Fifteen patients presented with radiculopathy, eight with myeloradiculopathy, and one with quadriparesis. Single-level ACDF was performed in 12 patients, two-level ACDF in nine, and three-level ACDF in three. Clinical outcomes were assessed using Odom criteria, and fusion was assessed by examining flexion—extension radiographs and computerized tomography scans in cases in which arthrodesis was questionable. Follow-up data were available for 23 patients. One patient died of medical complications unrelated to surgery 4 weeks after ACDF. Clinical outcomes were rated as good/excellent in 22 patients (95%) and fair in one (5%). Solid radiographically documented fusion, with evidence of solid bridging bone and no instability on flexion—extension x-ray films, was present in all cases. Complications included transient recurrent laryngeal nerve injury in one case, transient C-5 paresis in one, cerebrospinal fluid leakage in one, and transient dysphagia in two.

Conclusions. Analysis of the results indicated that ACDF involving an rhBMP-2—filled PEEK spacer leads to good clinical outcomes (by Odum criteria) and solid fusion (even in multilevel cases) while avoiding the complications associated with harvesting iliac crest bone grafts.

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Paul Kalanithi, Ryan D. Schubert, Shivanand P. Lad, Odette A. Harris and Maxwell Boakye

Object

This study provides the first US national data regarding frequency, cost, and mortality rate of traumatic subdural hematoma (SDH), and identifies demographic factors affecting morbidity and death in patients with traumatic SDH undergoing surgical drainage.

Methods

A retrospective analysis was conducted by querying the Nationwide Inpatient Sample, the largest all-payer database of nonfederal community hospitals. All cases of traumatic SDH were identified using ICD-9 codes. The study consisted of 2 parts: 1) trends data, which were abstracted from the years 1993–2006, and 2) univariate analysis and multivariate logistic regression of demographic variables on inhospital complications and deaths for the years 1993–2002.

Results

Admissions for traumatic SDH increased 154% from 17,328 in 1993 to 43,996 in 2006. Inhospital deaths decreased from 16.4% to 11.6% for traumatic SDH. Average costs increased 67% to $47,315 per admission. For the multivariate regression analysis, between 1993 and 2002, 67,864 patients with traumatic SDH underwent operative treatment. The inhospital mortality rate was 14.9% for traumatic SDH drainage, with an 18% inhospital complication rate. Factors affecting inhospital deaths included presence of coma (OR = 2.45) and more than 2 comorbidities (OR = 1.60). Increased age did not worsen the inhospital mortality rate.

Conclusions

Nationally, frequency and cost of traumatic SDH cases are increasing rapidly.