MR Neurography and Quantitative Muscle MRI of Parsonage Turner Syndrome Involving the Long Thoracic Nerve.

BACKGROUND: Parsonage-Turner syndrome (PTS) is characterized by severe, acute upper extremity pain and subsequent paresis and most commonly involves the long thoracic nerve (LTN). While MR neurography (MRN) can detect LTN hourglass-like constrictions (HGCs), quantitative muscle MRI (qMRI) can quantify serratus anterior muscle (SAM) neurogenic changes. PURPOSE/HYPOTHESIS: 1) To characterize qMRI findings in LTN-involved PTS. 2) To investigate associations between qMRI and clinical assessments of HGCs/electromyography (EMG). STUDY TYPE: Prospective. POPULATION: 30 PTS subjects (25 M/5 F, mean/range age = 39/15-67 years) with LTN involvement who underwent bilateral chest wall qMRI and unilateral brachial plexus MRN. FIELD STRENGTH/SEQUENCES: 3.0 Tesla/multiecho spin-echo T2-mapping, diffusion-weighted echo-planar-imaging, multiecho gradient echo. ASSESSMENT: qMRI was performed to obtain T2, muscle diameter fat fraction (FF), and cross-sectional area of the SAM. Clinical reports of MRN and EMG were obtained; from MRN, the number of HGCs; from EMG, SAM measurements of motor unit recruitment levels, fibrillations, and positive sharp waves. qMRI/MRN were performed within 90 days of EMG. EMG was performed on average 185 days from symptom onset (all ≥2 weeks from symptom onset) and 5 days preceding MRI. STATISTICAL TESTS: Paired t-tests were used to compare qMRI measures in the affected SAM versus the contralateral, unaffected side (P < 0.05 deemed statistically significant). Kendall's tau was used to determine associations between qMRI against HGCs and EMG. RESULTS: Relative to the unaffected SAM, the affected SAM had increased T2 (50.42 ± 6.62 vs. 39.09 ± 4.23 msec) and FF (8.45 ± 9.69 vs. 4.03% ± 1.97%), and decreased muscle diameter (74.26 ± 21.54 vs. 88.73 ± 17.61 µm) and cross-sectional area (9.21 ± 3.75 vs. 16.77 ± 6.40 mm2 ). There were weak to negligible associations (tau = -0.229 to <0.001, P = 0.054-1.00) between individual qMRI biomarkers and clinical assessments of HGCs and EMG. DATA CONCLUSION: qMRI changes in the SAM were observed in subjects with PTS involving the LTN. LEVEL OF EVIDENCE: 2 TECHNICAL EFFICACY: Stage 1.

Hourglass-like constrictions on MRI are common in electromyography-confirmed cases of neuralgic amyotrophy (Parsonage-Turner syndrome): A tertiary referral center experience.

INTRODUCTION/AIMS: Hourglass-like constrictions (HGCs) of involved nerves in neuralgic amyotrophy (NA) (Parsonage-Turner syndrome) have been increasingly recognized with magnetic resonance neurography (MRN). This study sought to determine the sensitivity of HGCs, detected by MRN, among electromyography (EMG)-confirmed NA cases. METHODS: This study retrospectively reviewed records of patients with the clinical diagnosis of NA, and with EMG confirmation, who underwent 3-Tesla MRN within 90 days of EMG at a single tertiary referral center between 2011 and 2021. "Severe NA" positive cases were defined by a clinical diagnosis and specific EMG criteria: fibrillation potentials or positive sharp waves, along with motor unit recruitment (MUR) grades of "discrete" or "none." On MRN, one or more HGCs, defined as focally decreased nerve caliber or diffusely beaded appearance, was considered "imaging-positive." Post hoc inter-rater reliability for HGCs was measured by comparing the original MRN report against subsequent blinded interpretation by a second radiologist. RESULTS: A total of 123 NA patients with 3-Tesla MRN performed within 90 days of EMG were identified. HGCs were observed in 90.2% of all NA patients. In "severe NA" cases, based on the above EMG criteria, HGC detection resulted in a sensitivity of 91.9%. Nerve-by-nerve analysis (183 nerve-muscle pairs, nerves assessed by MRN, muscles assessed by EMG) showed a sensitivity of 91.0%. The second radiologist largely agreed with the original HGC evaluation, (94.3% by subjects, 91.8% by nerves), with no significant difference between evaluations (subjects: χ2 = 2.27, P = .132, nerves: χ2 = 0.98, P = .323). DISCUSSION: MRN detection of HGCs is common in NA.

Quantitative MRI Differentiates Electromyography Severity Grades of Denervated Muscle in Neuropathy of the Brachial Plexus.

BACKGROUND: Quantitative MRI (qMRI) metrics reflect microstructural skeletal muscle changes secondary to denervation and may correspond to conventional electromyography (EMG) assessments of motor unit recruitment (MUR) and denervation. HYPOTHESIS: Differences in quantitative T2 , diffusion-based apparent fiber diameter (AFD), and fat fraction (FF) exist between EMG grades, in patients with clinically suspected neuropathy of the brachial plexus. STUDY TYPE: Prospective. POPULATION: A total of 30 subjects (age = 37.5 ± 17.5, 21M/9F) with suspected brachial plexopathy. FIELD STRENGTH/SEQUENCE: 3-Tesla; qMRI using fast spin echo (T2 -mapping), multi-b-valued diffusion-weighted echo planar imaging (for AFD), and dual-echo Dixon gradient echo (FF-mapping) sequences. ASSESSMENT: qMRI values were compared against EMG grades (MUR and denervation). qMRI values (T2 , AFD, and FF) were obtained for five regional shoulder muscles. A 4-point scale was used for MUR/denervation severity. STATISTICAL TESTS: Linear mixed models and least-squares pairwise comparisons were used to evaluate qMRI differences between EMG grades. Predictive accuracy of EMG grades from qMRI was quantified by 10-fold cross-validated logistic models. A P value < 0.05 was considered statistically significant. RESULTS: Mean (95% confidence interval) qMRI for "full" MUR were T2  = 39.40 msec (35.72-43.08 msec), AFD = 78.35 µm (72.52-84.19 µm), and FF = 4.54% (2.11-6.97%). Significant T2 increases (+8.36 to +14.67 msec) and significant AFD decreases (-11.04 to -21.58 µm) were observed with all abnormal MUR grades as compared to "full" MUR. Significant changes in both T2 and AFD were observed with increased denervation (+9.59 to +15.04 msec, -16.25 to -18.66 µm). There were significant differences in FF between some MUR grades (-1.45 to +2.96%), but no significant changes were observed with denervation (P = 0.089-0.662). qMRI prediction of abnormal MUR or denervation was strong (mean accuracy = 0.841 and 0.810, respectively) but moderate at predicting individual grades (accuracy = 0.492 and 0.508, respectively). DATA CONCLUSION: Quantitative T2 and AFD differences were observed between EMG grades in assessing muscle denervation. LEVEL OF EVIDENCE: 2 TECHNICAL EFFICACY: Stage 1.

Advanced Concepts in Hip Morphology, Associated Pathologies, and Specific Rehabilitation for Athletic Hip Injuries.

Hip and groin injuries comprise up to 17% of athletic injuries and can pose rehabilitation challenges for many athletes. Injuries involving abnormal femoral acetabular morphology, reduced range of motion, and decreased lumbopelvic strength and endurance also may increase the risk of injury to lower extremities and delay return to play if proper rehabilitation does not take place. The rehabilitation of athletic hip injuries requires a multifaceted interdisciplinary approach that manages the interplay of multiple factors to restore preinjury function and facilitate return to play. Emphasis should be placed on activity modification, preservation of the arcs of range of motion, functional strengthening of the lumbopelvic core, and optimization of proprioceptive and neuromechanical strategies. Communication between providers and the injured athlete also is crucial to ensure that proper therapeutic approaches are being applied.

The novel polysaccharide deacetylase homologue Pdi contributes to virulence of the aquatic pathogen Streptococcus iniae.

The aquatic zoonotic pathogen Streptococcus iniae represents a threat to the worldwide aquaculture industry and poses a risk to humans who handle raw fish. Because little is known about the mechanisms of S. iniae pathogenesis or virulence factors, we established a high-throughput system combining whole-genome pyrosequencing and transposon mutagenesis that allowed us to identify virulence proteins, including Pdi, the polysaccharide deacetylase of S. iniae, that we describe here. Using bioinformatics tools, we identified a highly conserved signature motif in Pdi that is also conserved in the peptidoglycan deacetylase PgdA protein family. A Deltapdi mutant was attenuated for virulence in the hybrid striped bass model and for survival in whole fish blood. Moreover, Pdi was found to promote bacterial resistance to lysozyme killing and the ability to adhere to and invade epithelial cells. On the other hand, there was no difference in the autolytic potential, resistance to oxidative killing or resistance to cationic antimicrobial peptides between S. iniae wild-type and Deltapdi. In conclusion, we have demonstrated that pdi is involved in S. iniae adherence and invasion, lysozyme resistance and survival in fish blood, and have shown that pdi plays a role in the pathogenesis of S. iniae. Identification of Pdi and other S. iniae virulence proteins is a necessary initial step towards the development of appropriate preventive and therapeutic measures against diseases and economic losses caused by this pathogen.

Associations of Race and Ethnicity With Patient-Reported Outcomes and Health Care Utilization Among Older Adults Initiating a New Episode of Care for Back Pain.

STUDY DESIGN: Secondary analysis of the Back Pain Outcomes using Longitudinal Data (BOLD) cohort study. OBJECTIVE: To characterize associations of self-reported race/ethnicity with back pain (BP) patient-reported outcomes (PROs) and health care utilization among older adults with a new episode of care for BP. SUMMARY OF BACKGROUND DATA: No prior longitudinal studies have characterized associations between multiple race/ethnicity groups, and BP-related PROs and health care utilization in the United States. METHODS: This study included 5117 participants ≥65 years from three US health care systems. The primary BP-related PROs were BP intensity and back-related functional limitations over 24 months. Health care utilization measures included common diagnostic tests and treatments related to BP (spine imaging, spine-related relative value units [RVUs], and total RVUs) over 24 months. Analyses were adjusted for multiple potential confounders including sociodemographics, clinical characteristics, and study site. RESULTS: Baseline BP ratings were significantly higher for blacks vs. whites (5.8 vs. 5.0; P < 0.001). Participants in all race/ethnicity groups showed statistically significant, but modest improvements in BP over 24 months. Blacks and Hispanics did not have statistically significant improvement in BP-related functional limitations over time, unlike whites, Asians, and non-Hispanics; however, the magnitude of differences in improvement between groups was small. Blacks had less spine-related health care utilization over 24 months than whites (spine-related RVU ratio of means 0.66, 95% confidence interval [CI] 0.51-0.86). Hispanics had less spine-related health care utilization than non-Hispanics (spine-related RVU ratio of means 0.60; 95% CI 0.40-0.90). CONCLUSION: Blacks and Hispanics had slightly less improvement in BP-related functional limitations over time, and less spine-related health care utilization, as compared to whites and non-Hispanics, respectively. Residual confounding may explain some of the association between race/ethnicity and health outcomes. Further studies are needed to understand the factors underlying these differences and which differences reflect disparities. LEVEL OF EVIDENCE: 3.

Running Injuries During Adolescence and Childhood.

The popularity of running among young athletes has significantly increased over the past few decades. As the number of children who participate in running increases, so do the potential number of injuries to this group. Proper care of these athletes includes a thorough understanding of the unique physiology of the skeletally immature athlete and common injuries in this age group. Treatment should focus on athlete education, modification of training schedule, and correction of biomechanical deficits contributing to injury. Early identification and correction of these factors will allow a safe return to running sports.

Renal nitric oxide synthase and antioxidant preservation in Cyp1a1-Ren-2 transgenic rats with inducible malignant hypertension.

BACKGROUND: Dietary administration of 0.30% indole-3-carbinol (I3C) to Cyp1a1-Ren2 transgenic rats (TGRs) generates angiotensin II (ANG II)-dependent malignant hypertension (HTN) and increased renal vascular resistance. However, TGRs with HTN maintain a normal or slightly reduced glomerular filtration rate. We tested the hypothesis that maintenance of renal function in hypertensive Cyp1a1-Ren2 TGRs is due to preservation of the intrarenal nitric oxide (NO) and antioxidant systems. METHODS: Kidney cortex, kidney medulla, aortic endothelial (e) and neuronal (n) nitric oxide synthase (NOS), superoxide dismutases (SODs), and p22phox (nicotinamide adenine dinucleotide phosphate-oxidase subunit) protein abundances were measured along with kidney cortex total antioxidant capacity (TAC) and NOx. TGRs were fed a normal diet that contained 0.3% I3C or 0.3% I3C + candesartan (AT1 receptor antagonist; 25mg/L in drinking water) (n = 5-6 per group) for 10 days. RESULTS: Blood pressure increased and body weight decreased in I3C-induced TGRs, while candesartan blunted these responses. Abundances of NOS, SOD, and p22phox as well as TAC were maintained in the kidney cortex of I3C-induced TGRs with and without candesartan, while kidney cortex NOx production increased in both groups. Kidney medulla eNOS and extracellular (EC) SOD decreased and nNOS were unchanged in both groups of I3C-induced TGRs. In addition, a compensatory increase occurred in kidney medulla Mn SOD in I3C-induced TGRs + candesartan. Aortic eNOS and nNOS∝ fell and p22phox and Mn SOD increased in hypertensive I3C-induced TGRs; all changes were reversed with candesartan. CONCLUSIONS: The preservation of renal cortical NO and antioxidant capacity is associated with preserved renal function in Cyp1a1-Ren2 TGRs with ANG II-dependent malignant HTN.

Enhanced urinary angiotensinogen excretion in Cyp1a1-Ren2 transgenic rats with inducible ANG II-dependent malignant hypertension.

INTRODUCTION: Previous studies have demonstrated that the urinary excretion of angiotensinogen is significantly increased in ANG II-infused hypertensive rats, which is associated with an augmentation of intrarenal ANG II levels. These findings suggest that urinary angiotensinogen excretion rates provide an index of intrarenal ANG II levels in ANG II-dependent hypertensive states. However, little information is available regarding the urinary excretion of angiotensinogen in ANG II-dependent malignant hypertension. METHODS: This study was performed to determine if urinary angiotensinogen excretion is increased in Cyp1a1-Ren2 transgenic rats [strain name: TGR(Cyp1aRen2)] with inducible ANG II-dependent malignant hypertension. Adult male Cyp1a1-Ren2 rats (n = 6) were fed a normal diet containing 0.3% indole-3-carbinol (I3C) for 10 days to induce ANG II-dependent malignant hypertension. RESULTS: Rats induced with I3C exhibited pronounced increases in systolic blood pressure (208 ± 7 versus 127 ± 3 mm Hg; P < 0.001), marked proteinuria (29.4 ± 3.6 versus 5.9 ± 0.3 mg/d; P < 0.001) and augmented urinary angiotensinogen excretion (996 ± 186 versus 241 ± 31 ng/d; P < 0.01). Chronic administration of the AT1 receptor antagonist, candesartan (25 mg/L in drinking water, n = 6), prevented the I3C-induced increases in systolic blood pressure (125 ± 5 mm Hg; P < 0.001), proteinuria (7.3 ± 1.0 mg/d; P < 0.001) and urinary angiotensinogen excretion (488 ± 51 ng/d, P < 0.01). CONCLUSIONS: These data demonstrate that the urinary excretion of angiotensinogen is markedly augmented in ANG II-dependent malignant hypertension. Such increased urinary angiotensinogen excretion may contribute to augmented intrarenal ANG II levels and, thereby, to the increased blood pressure in Cyp1a1-Ren2 transgenic rats with inducible ANG II-dependent malignant hypertension.