The effect of fatty infiltration, revision surgery, and sex on lumbar multifidus passive mechanical properties.

Purpose: Previous research has demonstrated increased stiffness in the multifidus muscle compared to other paraspinal muscles at the fiber bundle level. We aimed to compare single fiber and fiber bundle passive mechanical properties of multifidus muscle: (1) in 40 patients undergoing primary versus revision surgery and (2) in muscle with mild versus severe fatty infiltration. Methods: The degree of muscle fatty infiltration was graded using the patients' spine magnetic resonance images. Average single fiber and fiber bundle passive mechanical properties across three tests were compared between primary (N = 30) and revision (N = 10) surgery status, between mild and severe fatty infiltration levels, between sexes, and with age from passive stress-strain tests of excised multifidus muscle intraoperative biopsies. Results: At the single fiber level, elastic modulus was unaffected by degree of fatty infiltration or surgery status. Female sex (p = 0.001) and younger age (p = 0.04) were associated with lower multifidus fiber elastic modulus. At the fiber bundle level, which includes connective tissue around fibers, severe fatty infiltration (p = 0.01) and younger age (p = 0.06) were associated with lower elastic modulus. Primary surgery also demonstrated a moderate, but non-significant effect for lower elastic modulus (p = 0.10). Conclusions: Our results demonstrate that female sex is the primary driver for reduced single fiber elastic modulus of the multifidus, while severity of fatty infiltration is the primary driver for reduced elastic modulus at the level of the fiber bundle in individuals with lumbar spine pathology.

Immediate Effects of a Continuous Peripheral Nerve Block on Postamputation Phantom and Residual Limb Pain: Secondary Outcomes From a Multicenter Randomized Controlled Clinical Trial.

BACKGROUND: We recently reported that a 6-day continuous peripheral nerve block reduced established postamputation phantom pain 3 weeks after treatment ended. However, the immediate effects of perineural infusion (secondary outcomes) have yet to be reported. METHODS: Participants from 5 enrolling academic centers with an upper or lower limb amputation and established phantom pain received a single-injection ropivacaine peripheral nerve block(s) and perineural catheter insertion(s). They were subsequently randomized to receive a 6-day ambulatory perineural infusion of either ropivacaine 0.5% or normal saline in a double-masked fashion. Participants were contacted by telephone 1, 7, 14, 21, and 28 days after the infusion started, with pain measured using the Numeric Rating Scale. Treatment effects were assessed using the Wilcoxon rank-sum test at each time point. Adjusting for 4 time points (days 1, 7, 14, and 21), P < .0125 was deemed statistically significant. Significance at 28 days was reported using methods from the original, previously published article. RESULTS: Pretreatment average phantom and residual pain scores were balanced between the groups. The day after infusion initiation (day 1), average phantom, and residual limb pain intensity was lower in patients receiving local anesthetic (n = 71) versus placebo (n = 73): median [quartiles] of 0 [0-2.5] vs 3.3 [0-5.0], median difference (98.75% confidence interval [CI]) of -1.0 (-3.0 to 0) for phantom pain (P = .001) and 0 [0-0] vs 0 [0-4.3], and median difference 0.0 (-2.0 to 0.0) for residual limb pain (P < .001). Pain's interference with physical and emotional functioning as measured with the interference domain of the Brief Pain Inventory improved during the infusion on day 1 for patients receiving local anesthetic versus placebo: 0 [0-10] vs 10 [0-40], median difference (98.75% CI) of 0.0 (-16.0 to 0.0), P = .002. Following infusion discontinuation (day 6), a few differences were found between the active and placebo treatment groups between days 7 and 21. In general, sample medians for average phantom and residual limb pain scores gradually increased after catheter removal for both treatments, but to a greater degree in the control group until day 28, at which time the differences between the groups returned to statistical significance. CONCLUSIONS: This secondary analysis suggests that a continuous peripheral nerve block decreases phantom and residual limb pain during the infusion, although few improvements were again detected until day 28, 3 weeks following catheter removal.

Ambulatory continuous peripheral nerve blocks to treat postamputation phantom limb pain: a multicenter, randomized, quadruple-masked, placebo-controlled clinical trial.

Phantom limb pain is thought to be sustained by reentrant neural pathways, which provoke dysfunctional reorganization in the somatosensory cortex. We hypothesized that disrupting reentrant pathways with a 6-day-long continuous peripheral nerve block reduces phantom pain 4 weeks after treatment. We enrolled patients who had an upper- or lower-limb amputation and established phantom pain. Each was randomized to receive a 6-day perineural infusion of either ropivacaine or normal saline. The primary outcome was the average phantom pain severity as measured with a Numeric Rating Scale (0-10) at 4 weeks, after which an optional crossover treatment was offered within the following 0 to 12 weeks. Pretreatment pain scores were similar in both groups, with a median (interquartile range) of 5.0 (4.0, 7.0) for each. After 4 weeks, average phantom limb pain intensity was a mean (SD) of 3.0 (2.9) in patients given local anesthetic vs 4.5 (2.6) in those given placebo (difference [95% confidence interval] 1.3 [0.4, 2.2], P = 0.003). Patients given local anesthetic had improved global impression of change and less pain-induced physical and emotional dysfunction, but did not differ on depression scores. For subjects who received only the first infusion (no self-selected crossover), the median decrease in phantom limb pain at 6 months for treated subjects was 3.0 (0, 5.0) vs 1.5 (0, 5.0) for the placebo group; there seemed to be little residual benefit at 12 months. We conclude that a 6-day continuous peripheral nerve block reduces phantom limb pain as well as physical and emotional dysfunction for at least 1 month.

Acquired Thoracic Fistulas.

Fistulas are abnormal connections between 2 epithelial-lined structures. Thoracic fistulas may result from nonanatomic communications between spaces within the thorax, such as the lung, tracheobronchial tree, pleural space, and mediastinal structures, or between thoracic spaces and extrathoracic structures, such as the gastrointestinal tract. Furthermore, thoracic fistulas may result in communication between thoracic spaces and the spine or vascular structures. Potential causes include trauma, infection, neoplasm, surgical intervention, or medical syndromes. In this article, we discuss various acquired thoracic fistulas and their potential causes, key multimodality imaging manifestations, and clinical significance.

Continuous Popliteal-Sciatic Blocks for Postoperative Analgesia: Traditional Proximal Catheter Insertion Superficial to the Paraneural Sheath Versus a New Distal Insertion Site Deep to the Paraneural Sheath.

We tested the hypothesis that during a continuous popliteal-sciatic nerve block, postoperative analgesia is improved with the catheter insertion point "deep" to the paraneural sheath immediately distal to the bifurcation between the tibial and common peroneal branches, compared with the traditional approach "superficial" to the paraneural sheath proximal to the bifurcation. The needle tip location was determined to be accurately located with a fluid bolus visualized with ultrasound; however, catheters were subsequently inserted without a similar fluid injection and visualization protocol (visualized air injection was permitted and usually implemented, but not required per protocol). The average pain (0-10 scale) the morning after surgery for subjects with a catheter inserted at the proximal subparaneural location (n = 31) was a median (interquartile) of 1.5 (0.0-3.5) vs 1.5 (0.0-4.0) for subjects with a catheter inserted at the distal supraparaneural location (n = 32; P = .927). Secondary outcomes were similarly negative.

The association of neuraxial versus general anesthesia with inpatient admission following arthroscopic knee surgery.

STUDY OBJECTIVE: Arthroscopic knee procedures are increasingly being performed in an outpatient setting. Appropriate intraoperative anesthesia is vital to prevent complications such as unanticipated hospital admission. We examined differences in complications between general (GA) vs neuraxial anesthesia (NA) as the primary anesthetic for patients undergoing arthroscopic knee procedures. DESIGN: This was a retrospective cohort study. We queried the National Surgical Quality Improvement Program for arthroscopic knee procedures performed between 2007 and 2016. We compared postoperative complication rates between propensity-matched cohorts (NA vs GA). The anesthesia groups were matched based on age, race, BMI, gender, diabetes, smoking history, COPD, CHF, functional status, HTN, ASA class, steroid use, bleeding disorder history, and readmission status. Univariable and multivariable logistic regression were used to compare factors associated with inpatient admission - defined as hospital length of stay >1 day. PATIENTS: A total of 57,494 patients were included - 55,257 GA and 2237 NA patients. MAIN RESULTS: Among the matched cohorts, NA patients were significantly more likely to be admitted to the hospital postoperatively (p < 0.001). Neuraxial anesthesia (OR 5.93, 95% CI 4.90-7.21) use was also significant in the final multivariable regression model for inpatient admission. Additional significant predictors for inpatient admission included history of bleeding disorder (OR 5.44, 95% CI 2.14-12.76), Asian race (OR 6.47, 95% CI 4.90-8.56), COPD (OR 3.10, 95% CI 1.94-4.82), diabetes (OR 1.90, 95% CI 1.43-2.49), and increased operation time (OR 3.01, 95% CI 2.69-3.37). CONCLUSIONS: NA was significantly associated with inpatient admission following knee arthroscopy. Further research should focus on examining the reason for this association and methods to reduce inpatient admission for patients undergoing arthroscopic knee procedures using neuraxial anesthesia.

Postoperative outcomes with neuraxial versus general anesthesia in bilateral total hip arthroplasty.

STUDY OBJECTIVE: Current evidence remains limited on the postoperative outcomes of neuraxial (NA) versus general anesthesia (GA) as primary anesthesia type in patients receiving simultaneous bilateral total hip arthroplasty (BTHA). We aimed to evaluate the rates of postoperative outcomes among patients receiving NA versus GA for BTHA. DESIGN: Retrospective cohort study. SETTING: Multi-institutional. PATIENTS: A total of 798 patients undergoing BTHA with 519 and 279 who received GA and NA, respectively. We used the American College of Surgeons - National Surgical Quality Improvement Program database for years 2007 to 2016. INTERVENTIONS: Patients undergoing BTHA. MEASUREMENTS: We propensity-score matched on demographic factors and comorbid conditions to compare rates of postoperative outcomes among cohorts (NA versus GA). We performed Pearson chi-square and Wilcoxon rank sum test to compare NA versus GA cohorts. MAIN RESULTS: The final analysis included 798 BTHA patients, of which 35% received NA as the primary anesthetic. The median age was 58 years old and 50.8% were female. The rate of perioperative transfusion in the NA and GA group were 20.1% and 29.0%, respectively (p = 0.02). There were no significant differences in the rate of postoperative outcomes between patients receiving NA versus GA as their primary anesthesia type (Bonferroni corrected p < 0.006 was considered statistically significant). CONCLUSION: Our study showed no significant differences in postoperative outcomes between NA versus GA following BTHA. Further studies are needed to investigate outcomes among this surgical population.

Proximal Versus Distal Continuous Adductor Canal Blocks: Does Varying Perineural Catheter Location Influence Analgesia? A Randomized, Subject-Masked, Controlled Clinical Trial.

BACKGROUND: A continuous adductor canal block provides analgesia after surgical procedures of the knee. Recent neuroanatomic descriptions of the thigh and knee led us to speculate that local anesthetic deposited in the distal thigh close to the adductor hiatus would provide superior analgesia compared to a more proximal catheter location. We therefore tested the hypothesis that during a continuous adductor canal nerve block, postoperative analgesia would be improved by placing the perineural catheter tip 2-3 cm cephalad to where the femoral artery descends posteriorly to the adductor hiatus (distal location) compared to a more proximal location at the midpoint between the anterior superior iliac spine and the superior border of the patella (proximal location). METHODS: Preoperatively, subjects undergoing total knee arthroplasty received an ultrasound-guided perineural catheter inserted either in the proximal or distal location within the adductor canal in a randomized, subject-masked fashion. Subjects received a single injection of lidocaine 2% via the catheter preoperatively, followed by an infusion of ropivacaine 0.2% (8 mL/h basal, 4 mL bolus, 30 minutes lockout) for the study duration. After joint closure, the surgeon infiltrated the entire joint using 30 mL of ropivacaine (0.5%), ketorolac (30 mg), epinephrine (5 µg/mL), and tranexamic acid (2 g). The primary end point was the median level of pain as measured on a numeric rating scale (NRS) during the time period of 8:00 AM to 12:00 PM the day after surgery. RESULTS: For the primary end point, the NRS of subjects with a catheter inserted at the proximal location (n = 24) was a median (10th, 25th-75th, 90th quartiles) of 0.5 (0.0, 0.0-3.2, 5.0) vs 3.0 (0.0, 2.0-5.4, 7.8) for subjects with a catheter inserted in the distal location (n = 26; P = .011). Median and maximum NRSs were lower in the proximal group at all other time points, but these differences did not reach statistical significance. There were no clinically relevant or statistically significant differences between the treatment groups for any other secondary end point, including opioid consumption and ambulation distance. CONCLUSIONS: For continuous adductor canal blocks accompanied by intraoperative periarticular local anesthetic infiltration, analgesia the day after knee arthroplasty is improved with a catheter inserted at the level of the midpoint between the anterior superior iliac spine and the superior border of the patella compared with a more distal insertion closer to the adductor hiatus.

Treatment of Post-Latissimus Dorsi Flap Breast Reconstruction Pain With Continuous Paravertebral Nerve Blocks: A Retrospective Review.

OBJECTIVES: The addition of a perioperative continuous paravertebral nerve block (cPVB) to a single-injection thoracic paravertebral nerve block (tPVB) has demonstrated improved analgesia in breast surgery. However, its use following isolated post-mastectomy reconstruction using a latissimus dorsi flap (LDF) has not previously been examined. METHODS: We performed a retrospective review of patients who underwent salvage breast reconstruction with a unilateral LDF by a single surgeon. Preoperatively, all patients received a single-injection tPVB with 0.5% ropivacaine. Additionally, patients had the option for catheter placement to receive a continuous 0.2% ropivacaine infusion with intermittent boluses. Infusions commenced in the recovery room and the catheters were removed on the morning of discharge. The primary endpoint was the mean pain numeric rating scale (NRS) scores for the 24-hour period beginning at 7:00 on post-operative day 1. RESULTS: A total of 22 patients were included in this study (11-cPVB and 11-tPVB). The mean NRS pain score of cPVB patients (3.5 (standard deviation (SD) 1.8) was lower than that of the single-injection tPVB patients (4.4 (SD 2.1), however this difference was not statistically significant (P = 0.31). The length of hospital stay and opioid use was not statistically different between groups. CONCLUSIONS: Patients receiving a cPVB in addition to tPVB after LDF reconstruction experienced similar pain to those receiving tPVB alone. A larger, randomized clinical trial is warranted to fully determine the benefits of using cPVB in addition to tPVB for this procedure.

Superior Efficacy of Gross Total Resection in Anaplastic Astrocytoma Patients Relative to Glioblastoma Patients.

INTRODUCTION: Because of their relative rarity, anaplastic astrocytomas (AAs) often are grouped with glioblastomas in clinical treatment paradigms. There are reasons, however, to expect that the therapeutic response of AAs may differ from those of glioblastoma. Here, we examined the clinical benefit of gross total resection (GTR) in AA relative to glioblastoma patients. METHODS: Using the Surveillance, Epidemiology and End Results database, we identified 2755 patients with AA and patients with 21,962 glioblastoma between 1999 and 2010. Surgical resection was defined as GTR, subtotal resection (STR), biopsy only, or no resection. Kaplan-Meier curves and multivariate Cox regression were used to assess the association between GTR and survival. RESULTS: The hazard of dying from the AA was reduced in GTR patients by 40% relative to STR patients. This reduction is 59% greater than that observed in glioblastoma where GTR was associated only with a 24% reduction relative to STR (P < 0.0001). The median survival for patients with AA who underwent GTR and subtotal resection were 64 and 24 months, respectively. For glioblastoma patients, the corresponding numbers for median survival were 13 and 9 months, respectively. The survival benefit of GTR in patients with AA was particularly notable in patient age < 50, where the median survival was not reached during the study period. CONCLUSIONS: The Surveillance, Epidemiology and End Results data suggest that survival benefit associated with GTR was greater for patients with AA relative to glioblastoma patients, particularly for patients < age 50.