Outpatient outcomes of patients with femoral nerve neurapraxia after prone lateral lumbar interbody fusion at L4-5.

OBJECTIVE: Single-position prone lateral lumbar interbody fusion (LLIF) improves the efficiency of staged minimally invasive lumbar spine surgery. However, laterally approaching the lumbar spine, especially L4-5 with the patient in the prone position, could increase the risk of complications and presents unique challenges, including difficult ergonomics, psoas migration, and management of the nearby lumbar plexus. The authors sought to identify postoperative femoral neurapraxia after single-position prone LLIF at L4-5 to better understand how symptoms evolve over time. METHODS: This retrospective analysis examined a prospectively maintained database of LLIF patients who were treated by two surgeons (J.S.U. and J.D.T.). Patients who underwent single-position prone LLIF at L4-5 and percutaneous pedicle screw fixation for lumbar stenosis or spondylolisthesis were included if they had at least 6 weeks of follow-up. Outpatient postoperative neurological symptoms were analyzed at 6-week, 3-month, and 6-month follow-up evaluations. RESULTS: Twenty-nine patients (16 women [55%]; overall mean ± SD age 62 ± 11 years) met the inclusion criteria. Five patients (17%) experienced complications, including 1 (3%) who had a femoral nerve injury with resultant motor weakness. The mean ± SD transpsoas retractor time was 14.6 ± 6.1 minutes, the directional anterior electromyography (EMG) threshold before retractor placement was 20.1 ± 10.2 mA, and the directional posterior EMG threshold was 10.4 ± 9.1 mA. All patients had 6-week clinical follow-up evaluations. Ten patients (34%) reported thigh pain or weakness at their 6-week follow-up appointment, compared with 3/27 (11%) at 3 months and 1/20 (5%) at 6 months. No association was found between directional EMG threshold and neurapraxia, but longer transpsoas retractor time at L4-5 was significantly associated with femoral neurapraxia at 6-week follow-up (p = 0.02). The only case of femoral nerve injury with motor weakness developed in a patient with a retractor time that was nearly twice as long as the mean time (27.0 vs 14.6 minutes); however, this patient fully recovered by the 3-month follow-up evaluation. CONCLUSIONS: To our knowledge, this is the largest study with the longest follow-up duration to date after single-position prone LLIF at L4-5 with percutaneous pedicle screw fixation. Although 34% of patients reported ipsilateral sensory symptoms in the thigh at the 6-week follow-up evaluation, only 1 patient sustained a nerve injury; this resulted in temporary weakness that resolved by the 3-month follow-up evaluation. Thus, longer transpsoas retractor time at L4-5 during prone LLIF is associated with increased ipsilateral thigh symptoms at 6-week follow-up that may resolve over time.

Should Somatosensory and Motor Evoked Potential Monitoring Be Used Routinely in All Posterior Cervical Operations for Degenerative Conditions of the Cervical Spine?

OBJECTIVE: Intraoperative neuromonitoring (IONM) is useful during spinal cord operations, but whether IONM is necessary for posterior cervical surgeries for degenerative conditions is unknown. We evaluated the utility of somatosensory evoked potential (SSEP) and motor evoked potential (MEP) monitoring as a tool for predicting new postoperative neurologic deficits during posterior decompression and fusion for degenerative cervical spine conditions. METHODS: We retrospectively reviewed posterior cervical operations performed at our institute over a 4-year period. Patients with postoperative neurologic deficits were identified, and a detailed analysis performed to ascertain whether SSEP or MEP monitoring accurately predicted the onset of new postoperative deficits. RESULTS: Overall, 498 patients were included in the analysis (median age 66 years; range: 22-93 years). SSEP monitoring was performed in all patients, and both SSEP and MEP monitoring were performed in 121 patients (24%). Twenty-one patients (4.2%) had new postoperative neurologic deficits. SSEP had significantly higher specificity (90%) but lower sensitivity (33%) than MEP (74% specificity [P = 0.008], 50% sensitivity [P = 0.01]) for detecting neurologic compromise intraoperatively. For SSEP, the positive predictive value (PPV) and negative predictive value (NPV) in detecting intraoperative changes that translated to new postoperative neurological deficits were 12% and 97%, respectively, whereas for MEP, the PPV and NPV were 6% (P = 0.009) and 98% (P = 0.20), respectively. CONCLUSIONS: IONM during posterior cervical operations for degenerative conditions of the spine is not reliable at predicting new postoperative neurologic deficits in patients treated for degenerative conditions, but may provide peace of mind to the surgeon intraoperatively when no abnormalities are detected.

When Indirect Decompression Fails: A Review of 220 Consecutive Direct Lateral Interbody Fusions and Unplanned Secondary Decompression.

STUDY DESIGN: A consecutive series of patients who underwent minimally invasive spinal surgery by a single surgeon at a high-volume academic medical center were studied. OBJECTIVE: The objective of this study was to identify the prevalence, radiographic features, and clinical characteristics of patients who require unplanned secondary decompressive laminectomy or foraminotomy after lateral lumbar interbody fusion (LLIF). SUMMARY OF BACKGROUND DATA: LLIF indirectly decompresses the spinal canal, lateral recess, and neural foramen when properly performed. However, indirect decompression relies on endplate integrity, reasonable bone quality, and sufficient contralateral release so that ligament distraction can occur. Some patients have insufficient decompression, resulting in persistent axial low back pain or radiculopathy. METHODS: Patients undergoing LLIF for radiculopathy or refractory low back pain were enrolled in a prospective registry. Preoperative and postoperative imaging, clinical presentation, and operative reports were reviewed from this registry. RESULTS: During registry collection, 122 patients were enrolled (220 lumbar levels treated), with nearly even representation between men (64/122, 52.5%) and women (58/122, 47.5%). Overall, right-sided lumbar spinal approaches (74/122, 60.7%) were more common. Ultimately, 4.1% (five of 122) of patients required unplanned direct decompressive laminectomy or foraminotomy because of refractory radiculopathy and persistent radiographic evidence of compression at the index LLIF level. All patients for whom indirect decompression failed were men who underwent stand-alone LLIF and had radiculopathy contralateral to the side of the LLIF approach. Most patients (59.8%, 73/122) had evidence of graft subsidence (grade 0 or 1) or osteoporosis. CONCLUSION: We report a 4.1% rate of return to the operating room for failed indirect decompression after LLIF for refractory radiculopathy. Graft subsidence and osteoporosis were common in these patients. All five patients who required secondary decompressive laminectomy or foraminotomy underwent stand-alone primary LLIF, and the persistent radiculopathy was consistently contralateral to the initial side of the LLIF approach.Level of Evidence: 4.

Adverse Effects of Perioperative Blood Transfusion in Spine Surgery.

BACKGROUND: Perioperative blood transfusion is often necessary during spine surgery because of blood loss from the surgical field during and after surgery. However, blood transfusions are associated with a small but significant risk of causing several adverse events including hemolytic transfusion reactions and transfusion-associated circulatory overload. Moreover, many prior publications have noted increased rates of perioperative morbidity and worsened outcomes in spine surgery patients who received blood transfusions. We performed a systematic review of the literature to better characterize the effects of blood transfusion on spine surgery outcomes. METHODS: The PubMed/MEDLINE database was queried using the composite key word "transfus∗ AND 'spine surgery.'" A title and abstract review were performed to identify articles for final inclusion. RESULTS: A title and abstract review of the resulting 372 English-language articles yielded 13 relevant publications, which were subsequently incorporated into this systematic review. All included studies were retrospective, nonrandomized analyses. CONCLUSIONS: Overall, prior literature indicates a relationship between perioperative blood transfusion and worsened outcomes after spine surgery. However, the available data represent level IV evidence at best. In the future, prospective, randomized, controlled studies may help define the effects of perioperative blood transfusion on spine surgery outcomes.

Minimally Invasive Anterior Longitudinal Ligament Release for Anterior Column Realignment.

STUDY DESIGN: Review of the literature. OBJECTIVES: Anterior column realignment (ACR) is a powerful but relatively new minimally invasive technique for deformity correction. The purpose of this study is to provide a literature review of the ACR surgical technique, reported outcomes, and future directions. METHODS: A review of the literature was performed regarding the ACR technique. A review of patients at our single center who underwent ACR was performed, with illustrative cases selected to demonstrate basic and nuanced aspects of the technique. RESULTS: Clinical and cadaveric studies report increases in segmental lordosis in the lumbar spine by 73%, approximately 10° to 33°, depending on the degree of posterior osteotomy and lordosis of the hyperlordosis interbody spacer. These corrections have been found to be associated with a similar risk profile compared with traditional surgical options, including a 30% to 43% risk of proximal junctional kyphosis in early studies. CONCLUSIONS: ACR represents a powerful technique in the minimally invasive spinal surgeon's toolbox for treatment of complex adult spinal deformity. The technique is capable of significant sagittal plane correction; however, future research is necessary to ascertain the safety profile and long-term durability of ACR.

Single position spinal surgery for the treatment of grade II spondylolisthesis: A technical note.

BACKGROUND AND IMPORTANCE: Minimally invasive transpsoas approach to treat lumbar spondylolisthesis is associated with increased clinical benefits. CLINICAL PRESENTATION: Robotic and navigation aided deformity correction for grade II spondylolisthesis was performed using transpsoas approach with pedicle screw placement in lateral decubitus position. CONCLUSION: Keeping the patient in the lateral decubitus position, we supplemented interbody cage placement with screws. Single position lateral transpsoas approach provides grade II spondylolisthesis improvement.

Analysis of Cost and 30-Day Outcomes in Single-Level Transforaminal Lumbar Interbody Fusion and Less Invasive, Stand-Alone Lateral Transpsoas Interbody Fusion.

BACKGROUND: A comparative evaluation of operative costs between single-level transforaminal interbody fusion (TLIF) and stand-alone lateral transpsoas interbody fusion (LIF) has not yet been done. We analyzed the costs, operative parameters, and early outcomes of single-level stand-alone LIF versus single-level TLIF. METHODS: Ten patients who underwent single-level TLIF and 10 patients who underwent single-level stand-alone LIF were included in the analysis. Total, variable, and fixed costs from perioperative data were available from a single institution. In addition, patient demographics, length of hospital stay, and 30-day outcomes and readmission rates were reviewed. RESULTS: Total cost, variable cost, and fixed costs were significantly lower in the LIF group, and there was no difference in outcomes. CONCLUSIONS: Single-level stand-alone LIF may prove to be more cost-effective and provide cost savings with analogous 30-day outcomes compared with single-level TLIF procedures.

Early surgical intervention among patients with acute central cord syndrome is not associated with higher mortality and morbidity.

BACKGROUND: Conflicting reports exist regarding mortality and morbidity of early surgical decompression in the setting of acute central cord syndrome (ACS) in multisystem trauma despite evidence of improved neurological outcomes. Consequently, optimal decompression timing in ACS in multisystem trauma patients remains controversial. This study aims to determine the association between early surgery for acute traumatic central cord and all-cause mortality among multisystem trauma patients in the National Trauma Data Bank (NTDB) using propensity score matching. METHODS: We used the NTDB (years 2011-2014) to perform a retrospective cohort study, which included patients >18 years, with ACS (identified using ICD-9 coding). Collected patient data included demographics, surgery timing (≤24 hours, >24 hours), injury mechanism, Charlson comorbidity index (CCI), injury severity score (ISS), serious adverse events (SAE). Logistic regression and propensity matching were used to investigate the relationship between surgery timing and subsequent inpatient mortality. RESULTS: We identified 2,379 traumatic ACS patients. This group was 79.3% male with an average age of 56.3±15.2. They had an average ISS of 19.5±9.0 and mortality rate of 3.0% (n=72). A total of 731 (30.7%) patients underwent surgery for ACS within 24 hours. Univariate analysis did not show a significantly higher mortality rate in the early versus late surgery groups (3.8% vs. 2.7%, P=0.127). In unadjusted models, early surgery was not predictive of death or SAE + death in full (P=0.129, P=0.140) or matched samples (P=0.137, P=0.280). In models adjusted for age, ISS, and CCI, early surgery was predictive of death and SAE + death using the full sample (P=0.013, P=0.027), but not when using the propensity matched sample (P=0.107, P=0.255). CONCLUSIONS: Early surgical intervention does not appear to be associated with increased mortality among ACS patients unlike previously suggested. We theorize that survival noted within the NTDB is confounded by factors including existing comorbidities and multisystem trauma, rather than surgical timing. Delaying definitive surgical care may predispose patients to worsened greater neurological morbidity.

Effects of feeding monensin to bred heifers fed in a drylot on nutrient and energy balance.

The objective of this study was to determine if feeding monensin would improve diet digestion, energy and nitrogen balance in bred heifers receiving a limit-fed corn stalk-based diet. Sixteen pregnant Meat Animal Research Center (MARC) III composite heifers were used in a 161-d completely randomized design. Heifers were randomly assigned to one of two treatments, no monensin (CON) or 150 mg/d monensin (MON), with eight heifers in each treatment group. Heifers were limit-fed a corn stalk-based diet at 100% of MEm requirements. Effects of monensin on energy and nitrogen balance were determined via total fecal and urine collections and open-circuit respiration calorimetry. Total fecal and urine collection occurred on d 14, 42, and 161 of monensin feeding, and calorimetry measurements were made on d 0, 3, 14, 28, 42, and 161 of monensin feeding. DMI was not different (P = 0.94) for CON and MON heifers and, by design, increased (P < 0.01) from d 14 to d 161 of the trial to account for increasing fetal growth requirements. No differences (P = 0.91) in GE intake were observed between CON and MON heifers, and DE and ME intakes did not differ (P > 0.58) with monensin inclusion. DM, OM, NDF, and ADF digestion did not differ (P > 0.52) between treatments. Fecal, methane, urinary, and heat energy losses were not different (P > 0.16) for MON and CON heifers. Methane production was not different between treatments when expressed as daily liters of methane (P = 0.40); however, MON heifers produced 7% less (P = 0.03) methane per day than CON heifers when expressed as liters of methane produced on a metabolic body weight (MBW) basis. Furthermore, monensin had no effect (P = 0.36) on overall retained energy (RE). Nitrogen intake and excretion was not different (P > 0.13) between treatment groups. Results of this experiment indicate that adding monensin to limit-fed, corn stalk-based diets may not have a large effect on the energy and nitrogen balance of confined heifers.

First in Man: Sternal Reconstruction with Autologous Stem Cells.

Sternal nonunion is associated with high morbidity and treated using rigid plate and screw fixation. This is the first reported example of successful sternal reconstruction using adipose-derived stromal vascular fraction (SVF) stem cells in addition to traditional techniques. Mesenchymal stem cells, one component of the SVF, play an important role in bone healing and were therefore used to promote remedial processes in a patient with sternal nonunion. A 3D printed model of the patient's sternum was used for preoperative planning of the plating. Intraoperatively, SVF was isolated using ultrasonic cavitation and previously planned sternal plating was completed. A total of 300 million cells were delivered via both local injection and intravenously before chest closure. The patient's pain dramatically decreased, commensurate with healed areas of nonunion by 3 months and maintained at 6 months postoperatively, supported by three-dimensional computed tomography imaging. Utilizing autologous stem cells from the SVF in conjunction with existing plating techniques may provide an optimal platform to stabilize the sternum and promote bone healing, although additional study is recommended.

Rapid porcine lung decellularization using a novel organ regenerative control acquisition bioreactor.

To regenerate discarded lungs that would not normally be used for transplant, ex vivo reseeding after decellularization may produce organs suitable for clinical transplantation and therefore close the donor gap. Organ regenerative control acquisition (Harvard Biosciences, Holliston, MA), a novel bioreactor system that simulates physiological conditions, was used to evaluate a method of rapid decellularization. Although most current decellularization methods are 24-72 hours, we hypothesized that perfusing porcine lungs with detergents at higher pressures for less time would yield comparable bioscaffolds suitable for future experimentation. Methods involved perfusion of 1% Triton X-100 (Triton) and 0.1% sodium dodecyl sulfate at varied physiological flow rates. Architecture of native and decellularized lungs was analyzed with hematoxylin and eosin (H&E) staining, transmission electron microscopy (TEM), and scanning electron microscopy (SEM). Dry gas and liquid ventilation techniques were introduced. Our 7 hour decellularization procedure removes nuclear material while maintaining architecture. Bioscaffolds have the microarchitecture for reseeding of stem cells. Hematoxylin and eosin staining suggested removal of nuclear material, whereas SEM and TEM imaging demonstrated total removal of cells with structural architecture preserved. This process can lead to clinical implementation, thereby increasing the availability of human lungs for transplantation.

A physical sciences network characterization of non-tumorigenic and metastatic cells.

To investigate the transition from non-cancerous to metastatic from a physical sciences perspective, the Physical Sciences-Oncology Centers (PS-OC) Network performed molecular and biophysical comparative studies of the non-tumorigenic MCF-10A and metastatic MDA-MB-231 breast epithelial cell lines, commonly used as models of cancer metastasis. Experiments were performed in 20 laboratories from 12 PS-OCs. Each laboratory was supplied with identical aliquots and common reagents and culture protocols. Analyses of these measurements revealed dramatic differences in their mechanics, migration, adhesion, oxygen response, and proteomic profiles. Model-based multi-omics approaches identified key differences between these cells' regulatory networks involved in morphology and survival. These results provide a multifaceted description of cellular parameters of two widely used cell lines and demonstrate the value of the PS-OC Network approach for integration of diverse experimental observations to elucidate the phenotypes associated with cancer metastasis.

An improved one-tube RT-PCR protocol for analyzing single-cell gene expression in individual mammalian cells.

It is well known that gene expression is regulated at the level of individual cells, and more evidence is now emerging that heterogeneity of cell regulation is orders of magnitude greater than previously thought. In order to detect meaningful variations in transcription levels, it is necessary to measure gene expression at single cell levels rather than in bulk cells, where individual differences or heterogeneity could be lost. In this work, we report an improved reverse-transcriptase polymerase chain reaction (RT-PCR) protocol which allows the direct measurement of gene expression in one tube (5-25 microl of total PCR mixture) at the single mammalian cell level. The protocol employs a new cell lysis buffer, and involves no RNA isolation or nested PCR steps, significantly reducing the possibility of contamination and errors. We successfully applied this protocol in qRT-PCR and linear-after-the-exponential (LATE)-PCR to analyze selected genes of various expression levels from three cell lines. Although further characterization of RNA stability is important, the preliminary results showed that gene expression heterogeneity could be common among members of genetically identical cell populations. The protocol illustrated can be utilized for a wide array of applications without much modification, such as cancer cell analysis and preimplantation genetic diagnostics. In addition, the protocol is based on intercalator-based (SYBR Green PCR) chemistry, which is less expensive and suitable for high-throughput platforms.