Spontaneous spinal epidural abscess in pregnancy: a case series.

INTRODUCTION: Spontaneous spinal epidural abscess (SEA) is a rare diagnosis; only eight cases have been reported during pregnancy. Diagnosis of SEA can be difficult, especially when the classic triad of fever, back pain, and neurologic deficits are not present. Early diagnosis and treatment are necessary to reduce potential morbidity and mortality. CASE PRESENTATIONS: We report two separate cases of SEA in pregnancy and summarize the existing literature. Case 1: A 20-year-old G1P0 presented at 35-week gestation with low back pain and lower extremity (LE) weakness. Magnetic resonance imaging (MRI) revealed thoracic SEA. The patient underwent cesarian delivery followed by posterior thoracic laminectomy and fusion (T9-11), abscess decompression, and antibiotic therapy. Unfortunately, there was a recurrence of her infection requiring a second irrigation and debridement 1 month after index procedure. At final follow-up, the patient had complete neurologic recovery. Case 2: A 38-year-old G10P0 presented at 36-week gestation in labor with LE weakness and difficulty ambulating. After delivery, she had significant LE neurologic deficits. MRI demonstrated thoracic osteodiscitis with associated epidural abscess. She underwent thoracic laminectomy and fusion (T7-12), abscess decompression, and antibiotic therapy. Unfortunately, despite aggressive treatment, she has persistent LE neurologic deficits. DISCUSSION: Pregnancy complicates the diagnosis and treatment strategies of SEA: back pain is very commonly underestimated, especially in the absence of fever and gross neurologic deficits. Prompt diagnosis and treatment are paramount to prevent neurologic decline and facilitate recovery. It is important to perform a focused physical exam noting motor strength, sensation, and reflexes. Coordinated management between the Emergency Department, OB-GYN, and spinal surgery team is required for best possible patient outcomes. Typically, management consists of aggressive surgical decompression and antibiotic therapy.

Cost-Effectiveness of Bariatric Surgery Prior to Posterior Lumbar Decompression and Fusion in an Obese Population with Degenerative Spondylolisthesis.

STUDY DESIGN: Cost-effectiveness analysis. OBJECTIVE: To determine if bariatric surgery prior to posterior lumbar decompression and fusion (PLDF) for degenerative spondylolisthesis (DS) is a cost-effective strategy. SUMMARY OF BACKGROUND DATA: Obesity poses significant perioperative challenges for DS. Treated operatively, obese patients achieve worse outcomes relative to non-obese peers. Concomitantly, they fare better with surgery than with nonoperative measures. These competing facts create uncertainty in determining optimal treatment algorithms for obese patients with DS. The role of bariatric surgery merits investigation as a potentially cost-effective optimization strategy prior to PLDF. METHODS: We simulated a Markov model with two cohorts of obese individuals with DS. 10,000 patients with body mass index (BMI) more than or equal to 30 in both arms were candidates for both bariatric surgery and PLDF. Subjects were assigned either to (1) no weight loss intervention with immediate operative or nonoperative management ("traditional arm") or (2) bariatric surgery 2 years prior to entering the same management options ("combined protocol").Published costs, utilities, and transition probabilities from the literature were applied. A willingness to pay threshold of $100,000/QALY was used. Sensitivity analyses were run for all variables to assess the robustness of the model. RESULTS: Over a 10-year horizon, the combined protocol was dominant ($13,500 cheaper, 1.15 QALY more effective). Changes in utilities of operative and nonoperative treatments in non-obese patients, the obesity cost-multiplier, cost of bariatric surgery, and the probability of success of nonoperative treatment in obese patients led to decision changes. However, all thresholds occurred outside published bounds for these variables. CONCLUSION: The combined protocol was less costly and more effective than the traditional protocol. Results were robust with thresholds occurring outside published ranges. Bariatric surgery is a viable, cost-effective preoperative strategy in obese patients considering elective PLDF for DS.Level of Evidence: 3.

The revision rate and occurrence of adjacent segment disease after anterior cervical discectomy and fusion: a study of 672 consecutive patients.

LEVEL III: retrospective cohort study. OBJECTIVE: The aim of this study was to determine the rate of revision surgery and the occurrence of adjacent segment disease of patients undergoing ACDF for cervical radiculopathy and myelopathy using more modern-day instrumentation techniques. SUMMARY OF BACKGROUND DATA: Anterior cervical discectomy and fusion (ACDF) has long been the preferred treatment for cervical radiculopathy and myelopathy. METHODS: All patients undergoing ACDF between January of 2000 and December of 2010 were included. Age, sex, height, weight, body mass index, symptoms at presentation, number of levels fused, graft type, and smoking status were recorded. Outcomes included revision rate, reason for revision surgery, time to revision surgery, presence and grade of adjacent segment disease, distance from the instrumentation to the cranial and caudal endplate (plate-to-disc distance), and reporting of symptoms of adjacent segment disease at the final follow-up. RESULTS: A total of 672 patients were included in this study. The average duration of follow-up was 31 months. One hundred one (15%) patients underwent revision surgery. The reason for revision surgery was adjacent segment disease in 47 (47.5%), pseudarthrosis in 45 (45.5%) and a new problem at a nonadjacent level in 7 (7.1%) of those patients. The need for revision surgery was not affected by patient age, sex, body mass index, smoking status, symptoms at presentation, number of levels fused, plate-to-disc distance or graft type. CONCLUSION: The revision rate after ACDF is 15%. Most revisions were done for either adjacent segment disease or pseudarthrosis. No specific risk factors for revision surgery were identified in this study. LEVEL OF EVIDENCE: 3.

Lateral mass versus hybrid construct for cervical laminectomy and fusion.

Spine stabilization after C3-C7 laminectomy can be accomplished with many instrumentation options. A hybrid construct using lateral mass screws from C3 to C5 and pedicle screws at C7 can potentially maximize strength and solve the spatial constraints introduced by the placement of C6 lateral mass screws and C7 pedicle screws. Seven cadaveric cervical spines from C2 to T2 were potted in a custom testing apparatus. Differential variable reluctance transducers were placed on C6 and C7 to measure linear displacement. Specimens were loaded in flexion, extension, lateral bending, and axial torque at 1.5 Nm. A wide laminectomy was then performed, and specimens were randomized to first receive either the bilateral C3-C7 lateral mass screw construct or a hybrid construct with C3-C5 lateral mass screws and C7 pedicle screws. All specimens were tested with both constructs. Normalized deformation (mean±SD) for the lateral mass screw vs the hybrid pedicle screw constructs in the sagittal plane was 7.46%±5.48% vs 5.68%±3.67%, respectively (P=.237). Coronal deformation for lateral mass screw vs the hybrid pedicle screw constructs was 19.2%±10.9% vs 13.6%±9.53% (P=.237). Axial rotation deformation for lateral mass vs pedical screw constructs was 85.9%±83.3% vs 74.7%±58.1%, respectively (P=.868). Despite data reported in the literature indicating a higher pullout strength of pedicle screws and improved strength of hybrid pedicle screw constructs compared with lateral mass screw constructs, a hybrid construct taking spatial constraints and increased danger of pedicle screw placement above C7 into account showed no improvement in motion compared with a lateral mass screw construct.

The effect of methylprednisolone intravenous infusion on the expression of ciliary neurotrophic factor in a rat spinal cord injury model.

BACKGROUND CONTEXT: Methylprednisolone (MP) infusion after acute spinal cord injury (SCI) remains controversial despite large randomized studies, including the National Acute Spinal Cord Injury Studies (NASCIS). PURPOSE: To determine the effect of NASCIS protocol MP infusion on the expression of ciliary neurotrophic factor (CNTF), a neuroprotective cytokine, in a rat model after SCI. STUDY DESIGN: Animal laboratory study. METHODS: Thirty rats were randomized into an MP infusion group (intravenous [IV]-MP) versus normal saline (NS) control group (IV-NS) after a standardized SCI. Ciliary neurotrophic factor expression was measured by reverse transcription-polymerase chain reaction at 6, 12, 24, 48, and 72 hours post-SCI. RESULTS: Mean CNTF expression was diminished in the MP group at 12 (p=.006) and 24 (p=.008) hours postinjury compared with the control group. Expression of CNTF was not significantly different between the groups at 6, 48, and 72 hours post-SCI. CONCLUSIONS: Standardized MP infusion post-SCI reduces CNTF activation in a rat SCI model. Further study is needed to determine if this effect is seen in human SCIs.

Positional effects of the knee and ankle on the ends of acute Achilles tendon ruptures.

Conservative management of acute Achilles tendon ruptures in a plantarflexed short leg cast or functional brace is a viable alternative to surgery. The ideal plantarflexion angle to allow the free ends of the tendon to oppose one another has not been clearly defined. The purpose of this cadaveric study was to define a plantarflexion angle where the free Achilles tendon ends reliably oppose one another. Ten cadaveric legs amputated at the distal femur were obtained. A laceration of the Achilles tendon was made 4 cm above the calcaneal insertion. A joint-spanning external fixator was placed across the knee. With differing degrees of knee flexion (0, 45, and 90 degrees), the diastasis between the free ends of the Achilles tendon was measured as the ankle was moved from 20 degrees of dorsiflexion to 30 degrees of plantarflexion (-20, -10, neutral, 10, 20, and 30 degrees). Regardless of knee flexion angle, the ankle plantarflexion angle where the free ends of the Achilles tendon opposed one another was 28.0 (95% confidence interval: 25.0-33.6) degrees. The ideal ankle angle in which to immobilize patients appears tightly clustered around 28 degrees of plantarflexion.

Manipulation of carrier proteins in antibiotic biosynthesis.

Engineering biosynthetic pathways into suitable host organisms has become an attractive venue for the design, evaluation, and production of small molecule therapeutics. Polyketide (PK) and nonribosomal peptide (NRP) synthases have been of particular interest due to their modular structure, yet routine cloning and expression of these enzymes remains challenging. Here we describe a method to covalently label carrier proteins from PK and NRP synthases using the enzymatic transfer of a modified coenzyme A analog by a 4'-phosphopantetheinyltransferase. Using this method, carrier proteins can be loaded with single fluorescent or affinity reporters, providing novel entry for protein visualization, Western blot identification, and affinity purification. Application of these methods provides an ideal tool to track and quantify metabolically engineered pathways. Such techniques are valuable to measure protein expression, solubility, activity, and native posttranslational modification events in heterologous systems.