Human spinal cord tissue is an underutilised resource in degenerative cervical myelopathy: findings from a systematic review of human autopsies.

STUDY DESIGN: Systematic review. BACKGROUND: Although degenerative cervical myelopathy (DCM) is the most prevalent spinal cord condition worldwide, the pathophysiology remains poorly understood. Our objective was to evaluate existing histological findings of DCM on cadaveric human spinal cord tissue and explore their consistency with animal models. METHODS: MEDLINE and Embase were systematically searched (CRD42021281462) for primary research reporting on histological findings of DCM in human cadaveric spinal cord tissue. Data was extracted using a piloted proforma. Risk of bias was assessed using Joanna Briggs Institute critical appraisal tools. Findings were compared to a systematic review of animal models (Ahkter et al. 2020 Front Neurosci 14). RESULTS: The search yielded 4127 unique records. After abstract and full-text screening, 19 were included in the final analysis, reporting on 150 autopsies (71% male) with an average age at death of 67.3 years. All findings were based on haematoxylin and eosin (H&E) staining. The most commonly reported grey matter findings included neuronal loss and cavity formation. The most commonly reported white matter finding was demyelination. Axon loss, gliosis, necrosis and Schwann cell proliferation were also reported. Findings were consistent amongst cervical spondylotic myelopathy and ossification of the posterior longitudinal ligament. Cavitation was notably more prevalent in human autopsies compared to animal models. CONCLUSION: Few human spinal cord tissue studies have been performed. Neuronal loss, demyelination and cavitation were common findings. Investigating the biological basis of DCM is a critical research priority. Human spinal cord specimen may be an underutilised but complimentary approach.

Vastus lateralis versus rectus femoris muscle flaps for recalcitrant hip joint infection: An anatomical study comparing the effectiveness of acetabular dead space control.

Eliminating recalcitrant prosthetic hip joint infections remains one of the greatest challenges in orthopedic surgery. In such cases, the salvage procedure of femoral head excision (the Girdlestone procedure) is often performed. There has been emerging surgical interest in filling the resulting acetabular dead space with a pedicled muscle flap, to enable antibiotic delivery. Both vastus lateralis (VL) and rectus femoris (RF) muscle flaps have been described for this purpose with good success. This study is the first anatomical investigation comparing VL and RF as candidates for interposition myoplasty following hip joint excision. Following standard surgical technique, the Girdlestone procedure and interposition myoplasty of both RF and VL were performed on 10 cadavers. The primary aim was to determine which muscle flap eliminated a greater volume of acetabular dead space. Secondary aims were to characterize the blood supply to RF and assess additional metrics indicative of the likelihood of flap success. The VL flap eliminated more dead space than RF. However, the use of the RF flap was feasible in all cases and has several benefits, including ease of harvest, mobility, and aesthetics. The location of the inferior vascular pedicle into RF was relatively consistent and the most effective predictor of flap success. Both VL and RF are effective in reducing acetabular dead space. While VL can fill a greater volume, the RF flap has technical advantages, related to the predictability of the blood supply.

The sputum microbiome and clinical outcomes in patients with bronchiectasis: a prospective observational study.

BACKGROUND: Infection is a key component of bronchiectasis pathophysiology. Characterisation of the microbiome offers a higher degree of sensitivity and resolution than does traditional culture methods. We aimed to evaluate the role of the microbiome in determining the risk of exacerbation and long-term outcomes, including all-cause mortality, in bronchiectasis. METHODS: We did a prospective observational cohort study of patients with bronchiectasis from eastern Scotland. Patients were enrolled from Sept 11, 2012, to Dec 21, 2015, and followed until Jan 8, 2019, for long-term outcomes. Patients were included if they were aged 18 years or older, and had a high-resolution CT-confirmed diagnosis of bronchiectasis and clinical symptoms consistent with the disease. Sputum samples were obtained when patients were clinically stable. Repeat sputum samples were taken at stable and exacerbation visits during follow-up. The V3-V4 region of the bacterial 16S rRNA gene was sequenced using the Illumina MiSeq platform. The dominant bacterial genus in each sample was assigned on the basis of a previously published method. Microbiome characteristics were analysed for their association with measures of clinical disease severity and long-term outcomes using PERMANOVA, random forest, and survival analyses. FINDINGS: Sequencing data were obtained from the sputum samples of 281 patients with bronchiectasis who were included in the stable baseline cohort. 49 (17%) of 281 patients provided more than one sample when clinically stable and were included in the longitudinal analysis. 64 (23%) patients provided both stable and exacerbation samples. In both stable bronchiectasis and during exacerbations, a sputum microbiome dominated by Proteobacteria and Firmicutes was observed. Individual patients' microbiome profiles were relatively stable over time, during exacerbations and at disease stability. Lower microbiome diversity, measured using the Shannon-Wiener diversity index, was associated with more severe bronchiectasis defined by the bronchiectasis severity index, lower FEV1, and more severe symptoms. Random forest analysis of baseline samples identified Pseudomonas, Enterobacteriaceae, and Stenotrophomonas as being associated with severe bronchiectasis (bronchiectasis severity index ≥9) and greater lung inflammation and Pseudomonas and Enterobacteriaceae with more frequent exacerbations. Patients in whom Pseudomonas was dominant (n=35) were at increased risk of all-cause mortality (hazard ratio 3·12, 95% CI 1·33-7·36; p=0·0091) and had more frequent exacerbations (incident rate ratio 1·69, 95% CI 1·07-2·67; p=0·024) during follow-up compared with patients with other dominant genera (n=246). INTERPRETATION: A reduction in microbiome diversity, particularly one associated with dominance of Pseudomonas, is associated with greater disease severity, higher frequency and severity of exacerbations, and higher risk of mortality. The microbiome might therefore identify subgroups of patients at increased risk of poor outcomes who could benefit from precision treatment strategies. Further research is required to identify the mechanisms of reduced microbiome diversity and to establish whether the microbiome can be therapeutically targeted. FUNDING: British Lung Foundation and European Respiratory Society EMBARC2 consortium.