Srinivas Prasad

Intraoperative Vancomycin Use in Spinal Surgery: Single Institution Experience and Microbial Trends.

Study Design. Retrospective case series. Objective. To demonstrate the microbial trends of spinal surgical site infections in patients who had previously received crystallized vancomycin in the operative bed. Summary of Background Data. Prior large, case control series demonstrate the significant decrease in surgical site infection with the administration of vancomycin in the wound bed. Methods. A single institution, electronic database search was conducted for all patients who underwent spinal surgery who had received prophylactic crystalline vancomycin powder in the wound bed. Patients with a prior history of wound infection, intrathecal pumps, or spinal stimulators were excluded. Results. A total of 981 consecutive patients (494 males, 487 females; mean age, 59.4 yr; range, 16–95 yr) were identified from January 2011 to June 2013. The average dose of vancomycin powder was 1.13 g (range, 1–6 g). Sixty-six patients (6.71%) were diagnosed with a surgical site infection, of which 51 patients had positive wound cultures (5.2%). Of the 51 positive cultures, the most common organism was Staphylococcus aureus. The average dose of vancomycin was 1.3 g in the 38 cases where a gram-positive organism was cultured. A number of gram-negative infections were encountered such as Serratia marcescens, Enterobacter aerogenes, Bacteroides fragilis, Enterobacter cloacae, Citrobacter koseri, and Pseudomonas aeruginosa. The average dose of vancomycin was 1.2 g in 23 cases where a gram-negative infection was cultured. Fifteen of the 51 positive cultures (29.4%) were polymicrobial. Eight (53%) of these 15 polymicrobial cultures contained 3 or more distinct organisms. Conclusion. Prophylactic intraoperative vancomycin use in the wound bed in spinal surgery may increase the incidence of gram-negative or polymicrobial spinal infections. The use of intraoperative vancomycin may correlate with postoperative seromas, due to the high incidence of nonpositive cultures. Large, randomized, prospective trials are needed to demonstrate causation and dose-response relationship. Level of Evidence: 4

Evidence-based recommendations for spine surgery

Lumbar spinal imaging is commonly utilized in the evaluation of low back pain. The rationale for imaging, either plain radiographs, computed tomography (CT), or magnetic resonance imaging (MRI), is primarily based on identifying anatomical sources of pain. Unfortunately, the correlation between findings on imaging and clinical symptoms can be limited. A number of studies have been preformed to elucidate the value of spinal imaging in the setting of acute back pain. The definition of “value”, however, varies from study to study. Investigations have focused separately on diagnostic information, treatment interventions, patient outcomes, or patient satisfaction. Additionally, the inclusion and exclusion criteria for these studies have not been uniform. Specifically the definition of “red flags” for serious disease (fevers, weight loss, neurological deficits, etc.) are subjective and, in some instances, not defined. Nonetheless the clinical question remains: is immediate routine lumbar spine imaging more effective than usual care without imaging in patients with low back pain and no suggestion of “red flags.” Chou et al. used methods of systematic review and meta-analysis to address this question.

Nasal MRSA colonization: Impact on surgical site infection following spine surgery

BACKGROUND Prior studies published in the cardiothoracic, orthopedic and gastrointestinal surgery have identified the importance of nasal (methicillin-resistant Staphylococcus aureus) MRSA screening and subsequent decolonization to reduce MRSA surgical site infection (SSI). This is the first study to date correlating nasal MRSA colonization with postoperative spinal MRSA SSI. OBJECTIVE To assess the significance of nasal MRSA colonization in the setting of MRSA SSI. METHODS A retrospective electronic chart review of patients from year 2011 to June 2013 was conducted for patients with both nasal MRSA colonization within 30 days prior to spinal surgery. Patients who tested positive for MRSA were put on contact isolation protocol. None of these patients received topical antibiotics for decolonization of nasal MRSA. RESULTS A total of 519 patients were identified; 384 negative (74%), 110 MSSA-positive (21.2%), and 25 (4.8%) MRSA-positive. Culture positive surgical site infection (SSI) was identified in 27 (5.2%) cases and was higher in MRSA-positive group than in MRSA-negative and MSSA-positive groups (12% vs. 5.73% vs. 1.82%; p=0.01). The MRSA SSI rate was 0.96% (n=5). MRSA SSI developed in 8% of the MRSA-positive group as compared to only in 0.61% of MRSA-negative group, with a calculated odds ratio of 14.23 (p=0.02). In the presence of SSI, nasal MRSA colonization was associated with MRSA-positive wound culture (66.67 vs. 12.5%; p<0.0001). CONCLUSION Preoperative nasal MRSA colonization is associated with postoperative spinal MRSA SSI. Preoperative screening and subsequent decolonization using topical antibiotics may help in decreasing the incidence of MRSA SSI after spine surgery. Nasal MRSA+ patients undergoing spinal surgery should be informed regarding their increased risk of developing surgical site infection.

Impact of total disc arthroplasty on the surgical management of lumbar degenerative disc disease: Analysis of the Nationwide Inpatient Sample from 2000 to 2008.

Background: Spinal fusion is the most rapidly increasing type of lumbar spine surgery for various lumbar degenerative pathologies. The surgical treatment of lumbar spine degenerative disc disease may involve decompression, stabilization, or arthroplasty procedures. Lumbar disc athroplasty is a recent technological advance in the field of lumbar surgery. This study seeks to determine the clinical impact of anterior lumbar disc replacement on the surgical treatment of lumbar spine degenerative pathology. This is a retrospective assessment of the Nationwide Inpatient Sample (NIS). Methods: The NIS was searched for ICD-9 codes for lumbar and lumbosacral fusion (81.06), anterior lumbar interbody fusion (81.07), and posterolateral lumbar fusion (81.08), as well as for procedure codes for revision fusion surgery in the lumbar and lumbosacral spine (81.36, 81.37, and 81.38). To assess lumbar arthroplasty, procedure codes for the insertion or replacement of lumbar artificial discs (84.60, 84.65, and 84.68) were queried. Results were assayed from 2000 through 2008, the last year with available data. Analysis was done using the lme4 package in the R programming language for statistical computing. Results: A total of nearly 300,000 lumbar spine fusion procedures were reported in the NIS database from 2000 to 2008; assuming a representative cross-section of the US health care market, this models approximately 1.5 million procedures performed over this time period. In 2005, the first year of its widespread use, there were 911 lumbar arthroplasty procedures performed, representing 3% of posterolateral fusions performed in this year. Since introduction, the number of lumbar spine arthroplasty procedures has consistently declined, to 653 total procedures recorded in the NIS in 2008. From 2005 to 2008, lumbar arthroplasties comprised approximately 2% of lumbar posterolateral fusions. Arthroplasty patients were younger than posterior lumbar fusion patients (42.8 ± 11.5 vs. 55.9 ± 15.1 years, P < 0.0000001). The distribution of arthroplasty procedures was even between academic and private urban facilities (48.5% and 48.9%, respectively). While rates of posterolateral lumbar spine fusion steadily grew during the period (OR 1.06, 95% CI: 1.05-1.06, P < 0.0000001), rates of revision surgery and anterior spinal fusion remained static. Conclusions: The impact of lumbar arthroplasty procedures has been minimal. Measured as a percentage of more common lumbar posterior arthrodesis procedures, lumbar arthroplasty comprises only approximately 2% of lumbar spine surgeries performed in the United States. Over the first 4 years following the Food and Drug Administration (FDA) approval, the frequency of lumbar disc arthroplasty has decreased while the number of all lumbar spinal fusions has increased.

Timing in the surgical evacuation of spinal epidural abscesses.

OBJECT One often overlooked aspect of spinal epidural abscesses (SEAs) is the timing of surgical management. Limited evidence is available correlating earlier intervention with outcomes. Spinal epidural abscesses, once a rare diagnosis carrying a poor prognosis, are steadily becoming more common, with one recent inpatient meta-analysis citing an approximate incidence of 1 in 10,000 admissions with a mortality approaching 16%. One key issue of contention is the benefit of rapid surgical management of SEA to maximize outcomes. Timing of surgical management is definitely one overlooked aspect of care in spinal infections. Therefore, the authors performed a retrospective analysis in which they evaluated patients who underwent early (evacuation within 24 hours) versus delayed surgical intervention (> 24 hours) from the point of diagnosis, in an attempt to test the hypothesis that earlier surgery results in improved outcomes. METHODS A retrospective review of a prospectively maintained adult neurosurgical database from 2009 to 2011 was conducted for patients with the diagnostic heading: epidural abscess, infection, osteomyelitis, osteodiscitis, spondylodiscitis, and abscess. The primary end point for each patient was neurological grade, measured as an American Spinal Injury Association Impairment Scale grade using hospital inpatient records on admission and discharge. Patients were divided into early surgical (< 24 hours) and delayed surgical cohorts. RESULTS Eighty-seven consecutive patients were identified (25 females; mean age 55.5 years, age range 18-87 years). Fifty-four patients received surgery within 24 hours of admission (mean time from admission to incision, 11.2 hours), and 33 underwent surgery longer than 24 hours (mean 59 hours) after admission. Of the 54 patients undergoing early surgery 45 (85%) had a neurological deficit, whereas in the delayed surgical group 21 (64%) of 33 patients presented with a neurological deficit (p = 0.09). Patients in the delayed surgery cohort were significantly older by 10 years (59.6 vs 51.8 years, p = 0.01). With regard to history of prior revision, body mass index, intravenous drug abuse, tobacco use, prior radiation therapy, diabetes, chronic systemic infection, and prior osteomyelitis, there were no significant differences. There was no significant difference between early and delayed surgery groups in neurological grade on presentation, discharge, or location of epidural abscess. The most common organism isolated was Staphylococcus aureus (n = 51, 59.3%). The incidence of methicillin-resistant S. aureus was 21% (18 of 87). CONCLUSIONS Evacuation within 24 hours appeared to have a relative advantage over delayed surgery with regard to discharge neurological grade. However, due to a limited, variable sample size, a significant benefit could not be shown. Further subgroup analyses with larger populations are required.

Impact of Elevated Body Mass Index and Obesity on Long-term Surgical Outcomes for Patients With Degenerative Cervical Myelopathy: Analysis of a Combined Prospective Dataset.

Study Design. Analysis of a combined prospective dataset. Objective. To evaluate the impact of preoperative body mass index (BMI) on surgical outcomes in degenerative cervical myelopathy (DCM). Summary of Background Data. Although elevated BMI has been shown to have a deleterious impact on outcomes after lumbar spine surgery, limited evidence is available regarding its impact in DCM. Methods. Analyses were completed using a combined North American/International prospective surgical DCM dataset from 26 participating centers. Outcome measures included Neck Disability Index (NDI), modified Japanese Orthopedic Association (mJOA) score, and Short Form- 36 (SF-36) scores at 1 year postoperatively. Bivariate and multivariable statistics were used to model the relationship between preoperative BMI, as both a continuous and categorical variable with these outcomes. Results. Of 757 patients, mean BMI was 27.3 (±5.7) with 17 patients (3.5%) underweight, 271 patients (35.8%) normal weight, 275 patients (36.3%) overweight, and 194 patients (25.7%) obese. Controlling for preoperative mJOA, NDI, smoking status, age, and sex, elevated BMI was associated with increased neck disability at 1 year (P < 0.01). On average, NDI scores were 4.5 points higher (95% confidence interval, CI: 1.6–7.6) for overweight patients and 5.7 points higher (95% CI: 2.6–8.9) for obese patients compared with individuals of normal weight. Obese patients had 0.5 times odds (odds ratio, OR = 0.5, 95% CI: 0.3–0.8, P < 0.01) of showing improvement equal to the minimal clinically important difference of NDI compared with their normal weight counterparts. Although there were strong trends towards reduced SF-36 mental component scores and physical component scores with elevated BMI, no association was found between BMI and 1-year mJOA. Conclusion. Increased BMI, particularly obesity, was associated with increased postoperative disability. This represents a potentially modifiable risk factor which clinicians can target to optimize postoperative outcomes. Level of Evidence: 2

Efficacy of intraoperative vancomycin powder use in intrathecal baclofen pump implantation procedures: single institutional series in a high risk population.

We aimed to assess the efficacy of intraoperative vancomycin powder in intrathecal baclofen pump placement patients, a high risk population. A retrospective review was conducted using prospectively collected data at an academic tertiary care unit. The neurosurgical adult patient population was queried for all intrathecal baclofen pump implantation procedures. Patients were then reviewed for the use of intraoperative crystalline vancomycin powder. Those with a history of prior surgical site infection, chronic systemic infections or osteomyelitis were excluded. Anhydrous, crystalline vancomycin was utilized in the wound bed after completion of implantation, distributed evenly in the case of multiple incisions. Patients received 500 mg or 1,000 mg of crystallized vancomycin, evenly distributed through the wound layers based on a 70 kg weight cutoff. Intraoperative institutional standards of infection prophylaxis were unchanged throughout the study period. Infection rate of baclofen pump placement prior to the use of vancomycin powder from 2001-2009 at the same institution was monitored. Wound infection rate was tracked for a 12 month postoperative period. Six patients out of 26 baclofen pump implantations (23%) in this cohort were identified to have seven infections despite vancomycin powder placement in the lumbar and catheter wounds. Prior infection rates have been investigated for intrathecal drug delivery systems from 2001 to 2009 at the same institution with an overall infection rate of 3% (8/274). The use of vancomycin powder in patients with implants in this series did not reduce infection rates compared to published historical controls, and was elevated compared to institutional controls. Further prospective study of this high risk patient population is warranted.

Longitudinal incidence and concurrence rates for traumatic brain injury and spine injury – A twenty year analysis

BACKGROUND The reported incidence of concurrent traumatic brain (TBI) and spine or spinal cord injuries (SCI) is poorly defined, with widely variable literature rates from 16 to 74%. OBJECTIVES To define the incidence of concurrent TBI and SCI, and compare the incidence over a twenty-year time period. METHODS To define the longitudinal incidence and concurrent rate of TBI and SCI via a retrospective review of the Nationwide Inpatient Sample (NIS) database over a twenty year period. RESULTS Over the study period, the incidence of TBI declined from 143 patients/100k admissions to 95 patients/100k. However, there was a concurrent increase in SCI from 61 patients/100k admissions to 75 patients/100k admissions (P<0.0001). Regional variations in SCI trends were noted, with specific regions demonstrating an increasing trend. Cervical fractures had the greatest increase by nearly a three-fold rise (1988: 4562-2008: 12,418). There was an increase in the incidence of TBI among SCI admission from 3.7% (1988) to 12.5% (2008) (OR=1.067 per year; 95% CI=1.065-1.069 per year; P<0.0001). Concurrently, SCI patients had an increase in TBI (9.1% (1988)-15.9% (2008) (OR=1.038 per year (95% CI 1.036-1.040; P<0.001))). CONCLUSION A retrospective review of the NIS demonstrates a rising trend in the incidence of concurrent TBI and SCI. More investigative work is necessary to examine causative factors for this trend.

Thoracic myelopathy due to an intramedullary herniated nucleus pulposus: first case report and review of the literature.

BACKGROUND AND IMPORTANCE Herniation of intervertebral discs is relatively common. Migration usually occurs in the ventral epidural space; very rarely discs migrate in the subdural space. No cases of intradural intramedullary disc have been reported in humans. CLINICAL PRESENTATION A case of a herniated intervertebral disc directly into the spinal cord parenchyma is presented. The patient presented with 2 weeks of progressive bilateral lower extremity numbness and weakness, saddle hypoesthesia, urinary dysfunction and gait disturbance. Spine magnetic resonance imaging (MRI) with gadolinium revealed a solitary well-defined intramedullary lesion (T7-T8 level) with ring enhancement and focal cord expansion with significant surrounding edema. Metastatic workup and neural axis imaging was negative. A thoracic laminectomy and myelotomy was performed; the lesion was pearlescent and well circumscribed. It was densely adherent to the ventral pia and gross totally removed. Pathology was consistent with nucleus pulposus. CONCLUSION Intradural intramedullary migration of a herniated intervertebral disc is extremely rare but should be considered in the differential. It may present in a variety of clinical scenarios, including thoracic myelopathy, and mimic intramedullary spinal cord tumor.

Correlation of Posterior Occipitocervical Angle and Surgical Outcomes for Occipitocervical Fusion

Study Type Retrospective cohort study. Introduction Craniocervical instability is a surgical disease, most commonly due to rheumatoid arthritis, trauma, erosive pathologies such as tumors and infection, and advanced degeneration. Treatment involves stabilization of the craniovertebral junction by occipitocervical instrumentation and fusion. However, the impact of the fixed occipitocervical angle on surgical outcomes, in particular the need for revision surgery and the incidence of dysphagia, remains unknown. Occipitocervical fusions (OCFs) at a single institution were reviewed to evaluate the relationships between postoperative neck alignment, the need for revision surgery, and dysphagia. Objective The objective of this study is to determine whether an increased posterior occipital cervical angle results in an increase in the need for revision surgery, and secondary, dysphagia. Methods A retrospective review of spinal surgery patients from January 2007 to June 2013 was conducted searching for patients who underwent an occipitocervical instrumented fusion utilizing diagnostic and procedural codes. Specifically, a current procedural code of 22590 (arthrodesis, posterior technique [craniocervical]) was queried, as well those with a description of “craniocervical” or “occipitocervical” arthrodesis. Ideal neck alignment before rod placement was judged by the attending surgeon. A review of all cases for revision surgery or evidence of dysphagia was then conducted. Results From January 2007 to June 2013, 107 patients were identified (31 male, 76 female, mean age 63). Rheumatoid arthritis causing myelopathy was the most common indication for OCF, followed by trauma. Twenty of the patients were lost to follow-up and seven died within the perioperative period. Average follow-up for the remaining 80 patients was 16.4 months. The mean posterior occipitocervical angle (POCA), defined as the angle formed by the intersection of a line drawn tangential to the posterior aspect of the occipital protuberance and a line determined by the posterior aspect of the facets of the third and fourth cervical vertebrae, calculated after stabilization, was 107.1 degrees (range, 72–140 degrees). Reoperation was required in 11 patients (11/107, 10.3%). The mean POCA for the reoperation group was 109.5 degrees (range, 72–123) and was not significantly different than patients not requiring reoperation (106.5, p > 0.05). However, for all pathologies excluding infection as a cause for reoperation, the mean POCA was significantly higher, 115.14 degrees (p = 0.039) (Table 1). Seven patients (6.5%) complained of dysphagia postoperatively with a significantly higher POCA of 115 degrees (p = 0.039). Of these seven patients, six underwent posterior-only procedures. One patient underwent anterior and posterior procedures for a severe kyphotic deformity. The dysphagia resolved in six patients over a mean of 3 weeks (range, 2–4 weeks). One patient, whose surgery was posterior only, required the insertion of a gastrostomy tube. Conclusions An elevated POCA may result in need for reoperation due to increased biomechanical stress upon adjacent segments or the construct itself due to flexion in an attempt to maintain forward gaze. Further, an elevated POCA seems to also correlate with a higher incidence of dysphagia. Further investigation is necessary to determine the ideal craniocervical angle which is likely individualized to a particular patient based on global and regional spinal alignments.