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  • Author or Editor: Maxwell Boakye x
  • Journal of Neurosurgery: Spine x
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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, 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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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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Jefferson R. Wilson and Michael G. Fehlings

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Diana S. L. Chow, Yang Teng, Elizabeth G. Toups, Bizhan Aarabi, James S. Harrop, Christopher I. Shaffrey, Michele M. Johnson, Maxwell Boakye, Ralph F. Frankowski, Michael G. Fehlings and Robert G. Grossman

Object

The aim of this paper was to characterize individual and population pharmacokinetics of enterally administered riluzole in a Phase 1 clinical trial of riluzole as a neuroprotective agent in adults 18–70 years old with acute spinal cord injury (SCI).

Methods

Thirty-five individuals with acute SCI, American Spinal Injury Association Impairment Scale Grades A–C, neurological levels from C-4 to T-12, who were enrolled in the Phase 1 clinical trial sponsored by the North American Clinical Trials Network for Treatment of Spinal Cord Injury, received 50 mg riluzole twice daily for 28 doses. The first dose was administered at a mean of 8.7 ± 2.2 hours postinjury. Trough plasma samples were collected within 1 hour predose, and peak plasma samples were collected 2 hours postdose on Days 3 and 14 of treatment. Riluzole concentrations were quantified by high-performance liquid chromatography assay. The data were analyzed for individual and population pharmacokinetics using basic structural and covariate models. The pharmacokinetic measures studied were the peak concentration (Cmax), trough concentration (Cmin), systemic exposure (AUC0–12), clearance (CL/F), and volume of distribution (V_F) normalized by the bioavailability (F).

Results

The Cmax and AUC0–12 achieved in SCI patients were lower than those in ALS patients on the same dose basis, due to a higher CL and larger V. The pharmacokinetics of riluzole (Cmax, Cmin, AUC0–12, CL, and V) changed during the acute and subacute phases of SCI during the 14 days of therapy. It was consistently observed in patients at all clinical sites that Cmax, Cmin, and AUC0–12 (128.9 ng/ml, 45.6 ng/ml, and 982.0 ng × hr/ml, respectively) were significantly higher on Day 3 than on Day 14 (76.5 ng/ml, 19.1 ng/ml, and 521.0 ng × hr/ml, respectively). These changes resulted from lower CL (49.5 vs 106.2 L/hour) and smaller V (557.1 vs 1297.9/L) on Day 3. No fluid imbalance or cytochrome P 1A2 induction due to concomitant medications was identified during the treatment course to account for such increases in V and CL, respectively. Possible mechanisms underlying these changes are discussed.

Conclusions

This is the first report of clinical pharmacokinetics of riluzole in patients with SCI. The Cmax and AUC0–12 achieved in SCI patients were lower than those in ALS patients on the same dose basis, due to a higher clearance and larger volume of distribution in SCI patients. The finding in SCI patients of an increase in the clearance and distribution of riluzole between the 3rd and 14th days after SCI, with a lower plasma concentration of riluzole on the 14th day, stresses the importance of monitoring changes in drug metabolism after SCI in interpreting the safety and efficacy of therapeutic drugs that are used in clinical trials in SCI. Clinical trial registration no.: NCT00876889.

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Maxwell Boakye, Barbara C. Leigh and Andrea C. Skelly

Object

The aim of this study was to identify the quality of life (QOL) measures commonly used to assess patients with spinal cord injury (SCI) and to summarize studies using common QOL measures that have been validated in SCI populations to compare scores in persons with SCI with those in a control population.

Methods

A systematic search of PubMed was conducted to identify studies using common QOL measures in persons with SCI and those comparing scores for QOL measures in an SCI population with scores in other populations. The authors sought comparative studies utilizing QOL measures for which validity and reliability analyses had been done.

Results

Of 28 QOL measures found, validity and reliability studies had been conducted in patients with SCI for 5 measures. Twelve comparative studies compared QOL in SCI patients with QOL in healthy controls or in patients with other disabilities, or with normative data. The 36-Item Short Form Health Survey (SF-36) and the short version of the WHOQOL (WHOQOL-BREF) were the most widely used QOL instruments. Patients with SCI had a decreased QOL as compared with that in healthy controls or normative data, with the most pronounced deficits in the domains of physical functioning and physical role limitations. In 3 studies, patients with tetraplegia had a lower physical domain QOL than did those with paraplegia. Overall, however, the impact of injury level and injury completeness on QOL after SCI remains unclear due to a lack of longitudinal studies.

Conclusions

The SF-36 and WHOQOL-BREF are validated instruments that should be considered for use in SCI QOL studies. Future analysis of deficits in QOL among patients with SCI would benefit from the development of a QOL instrument specifically targeted to SCI. Longitudinal studies to assess the impact of injury level and injury completeness on SCI QOL are also needed.

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Kun Li, Darryn Atkinson, Maxwell Boakye, Carie Z. Tolfo, Sevda Aslan, Matthew Green, Barry McKay, Alex Ovechkin and Susan J. Harkema

Object

This study was designed to develop an objective and sensitive spinal cord injury (SCI) characterization protocol based on surface electromyography (EMG) activity.

Methods

Twenty-four patients at both acute and chronic time points post-SCI, as well as 4 noninjured volunteers, were assessed using neurophysiological and clinical measures of volitional motor function. The EMG amplitude was recorded from 15 representative muscles bilaterally during standardized maneuvers as a neurophysiological assessment of voluntary motor function. International Standards for the Neurological Classification of Spinal Cord Injury (ISNCSCI) examinations were performed as a clinical assessment of lesion severity.

Results

Sixty-six functional neurophysiological assessments were performed in 24 patients with SCI and in 4 neurologically intact individuals. The collected EMG data were organized by quantitative parameters and statistically analyzed. The correlation between root mean square (RMS) of the EMG signals and ISNCSCI motor score was confirmed by Kendall correlation analysis. The Kendall correlation value between overall muscles/levels, motor scores, and the RMS of the EMG data is 0.85, with the 95% CI falling into the range of 0.76–0.95. Significant correlations were also observed for the soleus (0.51 [0.28–0.74]), tibialis anterior (TA) (0.53 [0.33–0.73]), tricep (0.52, [0.34–0.70]), and extensor carpi radialis (ECR) (0.80 [0.42–1.00]) muscles. Comparisons of RMS EMG values in groups defined by ISNCSCI motor score further confirmed these results. At the bicep and ECR, patients with motor scores of 5 had nearly significantly higher RMS EMG values than patients with motor scores of 0 (p = 0.059 and 0.052, respectively). At the soleus and TA, the RMS of the EMG value was significantly higher (p < 0.01) for patients with American Spinal Injury Association Impairment Scale motor scores of 5 than for those with ISNCSCI motor scores of 0. Those with C-7 ISNCSCI motor scores of 5 had significantly higher RMS EMG values at the tricep than those with motor scores of 4 (p = 0.008) and 0 (p = 0.02). Results also show that surface EMG signals recorded from trunk muscles allowed the examiner to pick up subclinical changes, even though no ISNCSCI scores were given.

Conclusions

Surface EMG signal is suitable for objective neurological SCI characterization protocol design. The quantifiable features of surface EMG may increase SCI characterization resolution by adding subclinical details to the clinical picture of lesion severity and distribution.

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Maxwell Boakye, Susan Harkema, Peter H. Ellaway and Andrea C. Skelly

Object

The objective of this study was to identify commonly used physiological outcome measures and summarize evidence on the reliability and predictive validity of quantitative measures used in monitoring persons with spinal cord injury (SCI).

Methods

A systematic search of PubMed through January 5, 2012, was conducted to identify publications using common outcome measures in persons with SCI and for studies that were specifically designed to evaluate the reliability and predictive validity of selected quantitative measures. Quantitative measures were defined as tests that quantify sensory and motor function, such as amount of force or torque, as well as thresholds, amplitudes, and latencies of evoked potentials that might be useful in studies and monitoring of patients with SCI. Reliability studies reporting interclass correlation coefficients (ICCs) or weighted κ coefficients were considered for inclusion. Studies explicitly evaluating correlation between measures and specific functional outcomes were considered for predictive validity.

Results

From a total of 121 potentially relevant citations, 6 studies of reliability and 4 studies of predictive validity for quantitative tests met the inclusion criteria. In persons with incomplete SCI, ICCs for both interrater and intrarater reliability of electrical perceptual threshold (EPT) were ≥ 0.7 above the sensory level of SCI but were less reliable below the sensory level. Interclass correlation coefficients for interrater and intrarater reliability of the Graded Redefined Assessment of Strength, Sensibility, and Prehension (GRASSP) components ranged from 0.84 to 0.98. For electromyography, the ICC was consistently high for within-day tests. The overall quality of reliability of the majority of studies was poor, due to the potential for selection bias and small sample sizes. No classic validation studies were found for the selected measures, and evidence regarding the predictive validity of the measures was limited. Somatosensory evoked potentials (SSEPs) may be correlated with ambulatory capacity, as well as the Barthel Index and motor index scores, but this correlation was limited for evaluation of bladder function recovery in 3 studies that assessed the correlation between baseline or initial SSEPs and a specific clinical outcome at a later follow-up time. All studies used convenience samples and the overall sample quality was low.

Conclusions

Evidence on the reliability and validity of the quantitative measures selected for this review is limited, and the overall quality of existing studies is poor. There is some evidence for the reliability of the EPT, dermatomal SSEPs, and the GRASSP to suggest that they may be useful in longitudinal studies of patients with SCI. There is a need for high quality studies of reliability, responsiveness, and validity for quantitative measures to monitor the level and degree of SCI.

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Ranjith Babu, Steven Thomas, Matthew A. Hazzard, Yuliya V. Lokhnygina, Allan H. Friedman, Oren N. Gottfried, Robert E. Isaacs, Maxwell Boakye, Chirag G. Patil, Carlos A. Bagley, Michael M. Haglund and Shivanand P. Lad

Object

The Accreditation Council for Graduate Medical Education (ACGME) implemented resident duty-hour restrictions on July 1, 2003, in concern for patient and resident safety. Whereas studies have shown that duty-hour restrictions have increased resident quality of life, there have been mixed results with respect to patient outcomes. In this study, the authors have evaluated the effect of duty-hour restrictions on morbidity, mortality, length of stay (LOS), and charges in patients who underwent spine surgery.

Methods

The Nationwide Inpatient Sample was used to evaluate the effect of duty-hour restrictions on complications, mortality, LOS, and charges by comparing the prereform (2000–2002) and postreform (2005–2008) periods. Outcomes were compared between nonteaching and teaching hospitals using a difference-in-differences (DID) method.

Results

A total of 693,058 patients were included in the study. The overall complication rate was 8.6%, with patients in the postreform era having a significantly higher rate than those in the pre–duty-hour restriction era (8.7% vs 8.4%, p < 0.0001). Examination of hospital teaching status revealed complication rates to decrease in nonteaching hospitals (8.2% vs 7.6%, p < 0.0001) while increasing in teaching institutions (8.6% vs 9.6%, p < 0.0001) in the duty-hour reform era. The DID analysis to compare the magnitude in change between teaching and nonteaching institutions revealed that teaching institutions to had a significantly greater increase in complications during the postreform era (p = 0.0002). The overall mortality rate was 0.37%, with no significant difference between the pre– and post–duty-hour eras (0.39% vs 0.36%, p = 0.12). However, the mortality rate significantly decreased in nonteaching hospitals in the postreform era (0.30% vs 0.23%, p = 0.0008), while remaining the same in teaching institutions (0.46% vs 0.46%, p = 0.75). The DID analysis to compare the changes in mortality between groups revealed that the difference between the effects approached significance (p = 0.069). The mean LOS for all patients was 4.2 days, with hospital stay decreasing in nonteaching hospitals (3.7 vs 3.5 days, p < 0.0001) while significantly increasing in teaching institutions (4.7 vs 4.8 days, p < 0.0001). The DID analysis did not demonstrate the magnitude of change for each group to differ significantly (p = 0.26). Total patient charges were seen to rise significantly in the post–duty-hour reform era, increasing from $40,000 in the prereform era to $69,000 in the postreform era. The DID analysis did not reveal a significant difference between the changes in charges between teaching and nonteaching hospitals (p = 0.55).

Conclusions

The implementation of duty-hour restrictions was associated with an increased risk of postoperative complications for patients undergoing spine surgery. Therefore, contrary to its intended purpose, duty-hour reform may have resulted in worse patient outcomes. Additional studies are needed to evaluate strategies to mitigate these effects and assist in the development of future health care policy.

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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.