Brain-derived neurotrophic factor contributes to activity-induced muscle pain in male but not female mice.

Activity-induced muscle pain increases interleukin-1ß (IL-1ß) release from muscle macrophages and the development of hyperalgesia is prevented by blockade of IL-1ß in muscle. Brain derived neurotrophic factor (BDNF) is released from sensory neurons in response to IL-1ß and mediates both inflammatory and neuropathic pain. Thus, we hypothesize that in activity-induced pain, fatigue metabolites combined with IL-1ß activate sensory neurons to increase BDNF release, peripherally in muscle and centrally in the spinal dorsal horn, to produce hyperalgesia. We tested the effect of intrathecal or intramuscular injection of BDNF-Tropomyosin receptor kinase B (TrkB) inhibitors, ANA-12 or TrkB-Fc, on development of activity-induced pain. Both inhibitors prevented the hyperalgesia when given before or 24hr after induction of the model in male but not female mice. BDNF messenger ribonucleic acid (mRNA) and protein were significantly increased in dorsal root ganglion (DRG) 24hr after induction of the model in both male and female mice. Blockade of IL-1ß in muscle had no effect on the increased BNDF mRNA observed in the activity-induced pain model, while IL-1ß applied to cultured DRG significantly induced BDNF expression, suggesting IL-1ß is sufficient but not necessary to induce BNDF. Thus, fatigue metabolites, combined with IL-1ß, upregulate BDNF in primary DRG neurons in both male and female mice, but contribute to activity-induced pain only in males.

Structural changes and contractility in muscle assessed by magnetic resonance imaging in individuals with ryanodine receptor 1-related rhabdomyolysis or myalgia.

INTRODUCTION/AIMS: Ryanodine receptor 1 (RYR1)-related myopathies associated with variants in the RYR1 gene present with a wide range of symptoms and severity. Two of the milder phenotypes associated with dominant pathogenic variants in RYR1 are rhabdomyolysis and myalgia. Only a few studies have investigated the muscle function and structure of individuals with RYR1-related rhabdomyolysis/myalgia objectively, showing inconsistent results. This study aimed to describe structural changes and contractility of muscles in individuals with RYR1-related rhabdomyolysis/myalgia. METHODS: We investigated 15 individuals with dominant variants in the RYR1-gene and compared them with 15 age-, sex-, and body mass index (BMI)-matched controls using MRI, stationary isokinetic dynamometry, and comprehensive clinical evaluation. RESULTS: No significant differences were found between individuals with RYR1-related rhabdomyolysis/myalgia and healthy controls in peak torque, fat fraction, cross-sectional area, contractile cross-sectional area, or contractility (p > .05) in muscles of the lower back (MRI data only), thigh, or calf. On clinical examination, three individuals exhibited weakness in hip or back extension on the Medical Research Council (MRC) test and eight had muscle hypertrophy. Individuals with weakness were not hypertrophic. DISCUSSION: Most individuals with RYR1-related rhabdomyolysis/myalgia have close to normal strength, and normal fat fraction and contractility of muscles, and therefore constitute a mild phenotype of RYR1-related myopathies.

Patient-reported muscle symptoms and their characterization in a hypertensive population eligible for statin therapy: An exploratory study.

BACKGROUND AND AIMS: Statin-associated muscle symptoms (SAMS) are claimed to be frequent in clinical practice. We evaluated the prevalence and characteristics of patient-reported muscle symptoms (PRMS) attributed to drugs/nutraceuticals in hypertensive patients, focusing the attention on statin treatment. METHODS AND RESULTS: Observational study on 390 consecutive outpatients. All patients were asked the following question: "Have you ever taken a drug/nutraceutical that you think gave you muscle symptoms?". Patients who answered "yes" were evaluated with a modified version of the SAMS-clinical index (SAMS-CI). Mean age: 60.5 ± 13.5 years (males 53.8%.). Patients who have ever taken a statin: 250. Patients who have never taken a statin: 140. Prevalence of PRMS (48.5% of the entire study population) did not differ between groups (p = 0.217). Only age, followed by number of drugs taken, was significantly associated with PRMS at multivariate analysis. A high prevalence of low scores to all the questions of "modified" SAMS-CI was found in both groups. Localization and pattern of PRMS did not differ between groups (p = 0.170). Timing of PRMS onset after starting the drug (p = 0.036) and timing of improvement after withdrawal (p = 0.002) were associated with statin therapy. CONCLUSION: PRMS are highly prevalent among the hypertensive population and are believed to be drug-related, especially with aging and regardless of whether the drug taken is a statin or not. These findings are in line with the growing evidence that subjective muscle symptoms are often misattributed to statins, while they may more likely be related to the nocebo/drucebo effect or to other common undiagnosed conditions.

Beyond the acute: pain in long COVID survivors at 1.5 years.

OBJECTIVE: Long COVID, characterized by persistent symptoms post-acute COVID-19, remains a subject of intense investigation. This study focuses on pain, a common and notable symptom reported by long COVID patients. METHOD: A cohort of 191 individuals, initially diagnosed with mild-to-moderate COVID-19, was followed up 1.5 years later to assess the frequency, clinical characteristics, and factors associated with pain persistence. RESULTS: Our study revealed that 31.9% of participants experienced at least one persistent pain symptom after 1.5 years. Headache emerged as the most prevalent symptom (29.8%), followed by myalgia (5.8%) and neuropathic pain (4.2%). Factors such as female gender and the presence of neuropathic pain symptom were identified as predictors of long-term headaches. Myalgia, showed associations with headache, arthralgia, and low ferritin levels. Persistent neuropathic pain symptom (4.2%) was linked to older age, female gender, sore throat, and headache. CONCLUSION: This study provides insights into the evolution of pain symptoms over time after COVID-19 infection, emphasizing the interconnection between different pain syndromes. This research contributes to understanding the diverse and evolving nature of pain in long COVID survivors, offering valuable insights for targeted interventions and further investigations into the underlying mechanisms of persistent pain.

Toxicology and safety study of L-tryptophan and its impurities for use in broiler feed.

L-tryptophan has been utilized as a feed additive in animal nutrition to improve growth performance, as well as a dietary supplement to alleviate various emotional symptoms in humans. Despite its benefits, concerns regarding its safety arose following the outbreak of eosinophilia-myalgia syndrome (EMS) among individuals who consumed L-tryptophan. The causative material of EMS was determined to be not L-tryptophan itself, but rather L-tryptophan impurities resulting from a specific manufacturing process. To investigate the effect of L-tryptophan and its impurities on humans who consume meat products derived from animals that were fed L-tryptophan and its impurities, an animal study involving broiler chickens was conducted. The animals in test groups were fed diet containing 0.065%-0.073% of L-tryptophan for 27 days. This study aimed to observe the occurrence of toxicological or EMS-related symptoms and analyze the residues of L-tryptophan impurities in meat products. The results indicated that there was no evidence of adverse effects associated with the test substance in the investigated parameters. Furthermore, most of the consumed EMS-causing L-tryptophan impurities did not remain in the meat of broiler chickens. Thus, this study demonstrated the safety of L-tryptophan and some of its impurities as a feed additive.

Toxicology and safety study of L-tryptophan and its impurities for use in swine.

L-tryptophan, an essential amino acid for physiological processes, metabolism, development, and growth of organisms, is widely utilized in animal nutrition and human health as a feed additive and nutritional supplement, respectively. Despite its known benefits, safety concerns have arisen due to an eosinophilia-myalgia syndrome (EMS) outbreak linked to L-tryptophan consumed by humans. Extensive research has established that the EMS outbreak was caused by an L-tryptophan product that contained certain impurities. Therefore, safety validations are imperative to endorse the use of L-tryptophan as a supplement or a feed additive. This study was conducted in tertiary hybrid [(Landrace × Yorkshire) × Duroc] pigs to assess general toxicity and potential risks for EMS-related symptoms associated with L-tryptophan used as a feed additive. Our investigation elucidated the relationship between L-tryptophan and EMS in swine. No mortalities or clinical signs were observed in any animals during the administration period, and the test substance did not induce toxic effects. Hematological analysis and histopathological examination revealed no changes in EMS-related parameters, such as eosinophil counts, lung lesions, skin lesions, or muscle atrophy. Furthermore, no test substance-related changes occurred in other general toxicological parameters. Through analyzing the tissues and organs of swine, most of the L-tryptophan impurities that may cause EMS were not retained. Based on these findings, we concluded that incorporating L-tryptophan and its impurities into the diet does not induce EMS in swine. Consequently, L-tryptophan may be used as a feed additive throughout all growth stages of swine without safety concerns.

Assessing the effectiveness of gabapentin in paclitaxel-induced arthralgia, myalgia, and neuropathic pain: An observational, cohort study.

BACKGROUND AND OBJECTIVES: Arthralgia, myalgia, and neuropathic pain are the most common side effects observed due to paclitaxel chemotherapy. The aim of this study was to investigate the prophylactic role, maintenance, remission, and re-occurrence of arthralgia, myalgia, and neuropathic pain post-gabapentin therapy. METHODOLOGY: This study was conducted in the Department of Oncology, Dhiraj Hospital, Vadodara with a sample of 51 patients. Newly detected cancer patients who observed arthralgia, myalgia, and neuropathic pain due to paclitaxel were taken and a baseline pain assessment was done using the Common Terminology Criteria for Adverse Events (CTCAE) and painDETECT questionnaire. Gabapentin was given in the first cycle after symptoms appeared and prophylactic treatment was given in the subsequent three cycles and evaluation of pain was done post-gabapentin therapy to assess the symptomatic as well as prophylactic effect. RESULTS: At baseline, neuropathic pain score was 22.7 ± 3.6 which reduced to 0.01 ± 0.14 on subsequent follow-ups. Grade 2 arthralgia, myalgia, and neuropathic pain were more observed at baseline which reduces to Grade 0 in the third cycle. The difference in baseline and post-gabapentin therapy was statistically analyzed by conducting t-test which showed p-value <0.00001 and t-value was less than -2 which indicated a statistically significant result. CONCLUSION: This study shows that gabapentin reduces neuropathic pain. Prophylactic usage of gabapentin was highly effective at bringing about quick pain relief when compared to symptomatic treatment. In further follow-ups, it was noted that gabapentin maintained the impact throughout the cycles.

Effect of clinical experience and training with visual feedback on standardized palpation outcomes-Potential implications for assessment of jaw muscle sensitivity.

BACKGROUND: The evaluation of muscle pain and sensitivity by manual palpation is an important part of the clinical examination in patients with myalgia. However, the effects of clinical experience and visual feedback on palpation of the masticatory muscles with or without a palpometer are not known. OBJECTIVE: To estimate the effects of clinical experience and visual feedback on the accuracy of palpation in standardized settings. METHODS: Thirty-two dentists (age 35 ± 11 years) classified as either specialists (n = 16) or generalists (n = 16) participated in this experiment. All dentists were instructed to target force levels of 500- or 1000-gf, as determined on an electronic scale using either standardized palpometers or manual palpation (MP). All dentists participated in four different tests: MP, MP with visual feedback (MPVF), palpometer (PAL) and PAL with visual feedback (PALVF). Actual force values for each type of palpation from 0 to 2, 2 to 5 and 0 to 5 s were analysed by calculating target force level. RESULTS: The relative differences during 2-5 and 0-5 s with 1000 gf were significantly lower for generalists than for specialists (p < .05). In generalists and specialists, the coefficients of variation and the relative differences during 2-5 s were significantly lower for PAL and PALVF than for MP (p < .05). CONCLUSIONS: These findings suggest that the use of a palpometer, but not clinical experience with palpation of masticatory muscles, increases the accuracy of palpation, and ≥2 s of palpation with a palpometer is optimal for masticatory muscles.

Debilitating lower back pain during menses unexpectedly resolved after treatment of subclinical temporomandibular disorder: a case report.

This case report describes a patient in whom debilitating lower back pain that always occurred during menses resolved when she received treatment for subclinical temporomandibular disorder (TMD). The patient was diagnosed with subclinical TMD and facial myalgia based on the results of clinical and radiographic examinations. She was treated with maxillary (nighttime) and mandibular (daytime) dental orthotics to provide stabilization and decompression of the temporomandibular joints. After 12 weeks of appliance therapy, which resulted in resolution of the TMD symptoms, the patient reported that the debilitating lower back pain she experienced during menses had ceased. Her back pain did not return after the use of the mandibular appliance was discontinued. The authors discuss how neurologic, postural, inflammatory, and qi flow changes attributed to the patient's TMD treatment may have contributed to the cessation of the patient's menses-related lower back pain.

Acute effects of exercise-induced muscle damage on sprint and change of direction performance: A systematic review and meta-analysis.

The aim of this study is to determine the acute effects of resistance and plyometric training on sprint and change of direction (COD) performance in healthy adults and adolescents. A systematic literature search was conducted via Medline, Cinahl, Scopus and SportDiscus databases for studies that investigated: 1) healthy male, female adults, or adolescents; and 2) measured sprint or change of direction performance following resistance and plyometric exercises. Studies were excluded if: 1) resistance or plyometric exercises was not used to induce muscle damage; 2) conducted in animals, infants, elderly; 3) sprint performance and/or agility performance was not measured 24 h post muscle damaging protocol. Study appraisal was completed using the Kmet Quality Scoring for Quantitative Study tool. Forest plots were generated to quantitatively analyse data and report study statistics for statistical significance and heterogeneity. The included studies (n = 20) revealed sprint and COD performance was significantly impaired up to 72 hr following resistance and plyometric exercises; both protocols significantly increased creatine kinase (CK), delayed-onset muscle soreness (DOMS) and decreased countermovement jump (CMJ) up to 72 hr. The systematic review of 20 studies indicated that resistance and plyometric training significantly impaired sprint and COD performance up to 72 hours post-exercise. Both training protocols elevated exercise-induced muscle damage (EIMD) markers (CK, DOMS) and decreased CMJ performance within the same timeframe.

Variants in DTNA cause a mild, dominantly inherited muscular dystrophy.

DTNA encodes α-dystrobrevin, a component of the macromolecular dystrophin-glycoprotein complex (DGC) that binds to dystrophin/utrophin and α-syntrophin. Mice lacking α-dystrobrevin have a muscular dystrophy phenotype, but variants in DTNA have not previously been associated with human skeletal muscle disease. We present 12 individuals from four unrelated families with two different monoallelic DTNA variants affecting the coiled-coil domain of α-dystrobrevin. The five affected individuals from family A harbor a c.1585G > A; p.Glu529Lys variant, while the recurrent c.1567_1587del; p.Gln523_Glu529del DTNA variant was identified in the other three families (family B: four affected individuals, family C: one affected individual, and family D: two affected individuals). Myalgia and exercise intolerance, with variable ages of onset, were reported in 10 of 12 affected individuals. Proximal lower limb weakness with onset in the first decade of life was noted in three individuals. Persistent elevations of serum creatine kinase (CK) levels were detected in 11 of 12 affected individuals, 1 of whom had an episode of rhabdomyolysis at 20 years of age. Autism spectrum disorder or learning disabilities were reported in four individuals with the c.1567_1587 deletion. Muscle biopsies in eight affected individuals showed mixed myopathic and dystrophic findings, characterized by fiber size variability, internalized nuclei, and slightly increased extracellular connective tissue and inflammation. Immunofluorescence analysis of biopsies from five affected individuals showed reduced α-dystrobrevin immunoreactivity and variably reduced immunoreactivity of other DGC proteins: dystrophin, α, ß, δ and γ-sarcoglycans, and α and ß-dystroglycans. The DTNA deletion disrupted an interaction between α-dystrobrevin and syntrophin. Specific variants in the coiled-coil domain of DTNA cause skeletal muscle disease with variable penetrance. Affected individuals show a spectrum of clinical manifestations, with severity ranging from hyperCKemia, myalgias, and exercise intolerance to childhood-onset proximal muscle weakness. Our findings expand the molecular etiologies of both muscular dystrophy and paucisymptomatic hyperCKemia, to now include monoallelic DTNA variants as a novel cause of skeletal muscle disease in humans.

Simultaneous determination of L-tryptophan impurities in meat products.

L-tryptophan has been used as a feed additive for swine and poultry and as a nutrient supplement for humans. However, some impurities in L-tryptophan have been reported as causative components of eosinophilia-myalgia syndrome. Therefore, from a safety perspective, it is important to analyze meat samples for these impurities. This study aims to develop an analytical method for the simultaneous detection of L-tryptophan impurities in meat products using LC-MS/MS. Among the various impurities, detection methods for (S)-2-amino-3-(5-hydroxy-1H-indol-3-yl)propanoic acid (5-hydroxytryptophan) (HTP), 1-methyl-1,2,3,4-tetrahydro-ß-carboline-3-carboxylic acid (MTCA), 3a-hydroxy-1,2,3,3a,8,8a-hexahydropyrrolo-[2,3-b]-indole-2-carboxylic acid (PIC), and 1,1'-ethylidenebistryptophan (EBT) and 2-(3-indoylmethyl)-L-tryptophan (IMT) were developed. The developed method allowed simultaneous determination of these four impurities in 5 min. No interferences from the matrix were observed, and the method showed good sensitivity to each analyte. The method detection limit and limit of quantification in meat matrices were below 11.2 and 35.7 µg/kg, respectively.

Persistent post-COVID-19 neuromuscular symptoms.

Neuromuscular symptoms may develop or persist after resolution of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Besides residual sensorimotor symptoms associated with acute neuromuscular complications of coronavirus disease-2019 (COVID-19), such as Guillain-Barré syndrome, critical illness neuromyopathy, and rhabdomyolysis, patients may report persistent autonomic symptoms, sensory symptoms, and muscle symptoms in the absence of these acute complications, including palpitations, orthostatic dizziness and intolerance, paresthesia, myalgia, and fatigue. These symptoms may be associated with long COVID, also known as post-COVID-19 conditions or postacute sequelae of SARS-CoV-2 infection, which may significantly impact quality of life. Managing these symptoms represents a challenge for health-care providers. Recent advances have identified small-fiber neuropathy as a potential etiology that may underlie autonomic dysfunction and paresthesia in some long COVID patients. The pathogenic mechanisms underlying myalgia and fatigue remain elusive and need to be investigated. Herein we review the current state of knowledge regarding the evaluation and management of patients with persistent post-COVID-19 neuromuscular symptoms.

Quantitative muscle magnetic resonance imaging depicts microstructural abnormalities but no signs of inflammation or dystrophy in post-COVID-19 condition.

BACKGROUND AND PURPOSE: Post-COVID-19 condition (PCC) has high impact on quality of life, with myalgia and fatigue affecting at least 25% of PCC patients. This case-control study aims to noninvasively assess muscular alterations via quantitative muscle magnetic resonance imaging (MRI) as possible mechanisms for ongoing musculoskeletal complaints and premature exhaustion in PCC. METHODS: Quantitative muscle MRI was performed on a 3 Tesla MRI scanner of the whole legs in PCC patients compared to age- and sex-matched healthy controls, including a Dixon sequence to determine muscle fat fraction (FF), a multi-echo spin-echo sequence for quantitative water mapping reflecting putative edema, and a diffusion-weighted spin-echo echo-planar imaging sequence to assess microstructural alterations. Clinical examination, nerve conduction studies, and serum creatine kinase were performed in all patients. Quantitative muscle MRI results were correlated to the results of the 6-min walk test and standardized questionnaires assessing quality of life, fatigue, and depression. RESULTS: Twenty PCC patients (female: n = 15, age = 48.8 ± 10.1 years, symptoms duration = 13.4 ± 4.2 months, body mass index [BMI] = 28.8 ± 4.7 kg/m2 ) were compared to 20 healthy controls (female: n = 15, age = 48.1 ± 11.1 years, BMI = 22.9 ± 2.2 kg/m2 ). Neither FF nor T2 revealed signs of muscle degeneration or inflammation in either study groups. Diffusion tensor imaging (DTI) revealed reduced mean, axial, and radial diffusivity in the PCC group. CONCLUSIONS: Quantitative muscle MRI did not depict any signs of ongoing inflammation or dystrophic process in the skeletal muscles in PCC patients. However, differences observed in muscle DTI depict microstructural abnormalities, which may reflect potentially reversible fiber hypotrophy due to deconditioning. Further longitudinal and interventional studies should prove this hypothesis.

Immune-mediated necrotizing myopathy (NAM) related to SARS-Cov-2 infection: a case report.

BACKGROUND: There is a growing body of evidence that severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) or COVID-19 infection is associated with the development of autoimmune diseases. A recent systematic review reported that the new-onset autoimmune disorders during or after COVID-19 infection included inflammatory myopathies such as immune-mediated necrotizing myopathies. CASE PRESENTATION: We described a 60-year-old man diagnosed with COVID-19 infection and later presented with a two-week history of myalgia, progressive limb weakness, and dysphagia. He had a Creatinine Kinase (CK) level of more than 10,000 U/L, was strongly positive for anti-signal recognition particle (SRP) and anti-Ro52 antibody, and a muscle biopsy revealed a paucity-inflammation necrotizing myopathy with randomly distributed necrotic fibers, which was consistent with necrotizing autoimmune myositis (NAM). He responded well clinically and biochemically to intravenous immunoglobulin, steroids and immunosuppressant and he was able to resume to his baseline. CONCLUSION: SARS-CoV-2 may be associated with late-onset necrotizing myositis, mimicking autoimmune inflammatory myositis.

Pelvic mapping to explore patterns of chronic pelvic pain.

PURPOSE: Chronic pelvic pain syndromes (CPPS) are commonly encountered by urologists and urogynecologists and pose diagnostic and therapeutic challenges. Body maps have been helpful adjuncts to verbal descriptions of pain and may serve a role in phenotyping what is known to be a heterogeneous patient population. The aim of this study was to assess whether patterns of pain as marked on a body map of the pelvis exist among common CPPS diagnoses. The secondary aim was to investigate the association between the total number of pain locations marked on the map and clinical indices in patients with 1 to 3 CPPS diagnoses. MATERIALS AND METHODS: Data was collected on patients who visited the Northwell Health Pelvic Pain Treatment Center (PPTC) from January to May 2022 and were diagnosed with at least one of four major CPPS diagnoses: interstitial cystitis/bladder pain syndrome (IC/BPS), pelvic floor myalgia (PFM), chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS), and vulvodynia. Demographic data as well as survey data from pelvic pain maps, Genitourinary Pain Index (GUPI) forms, and the short form-6 of the Pain Catastrophizing Scale (PCS-6) were recorded. Descriptive statistics among CPPS groups and Pearson correlations among the number of CPPS diagnoses were computed. RESULTS: One hundred seventy females and 125 males with CPPS were included in the study. Significant cross-over in mapping patterns was notable between IC/BPS and PFM groups, both most commonly marking "abdomen" and "genital" regions. The most distinct pattern of pain was seen in patients with CP/CPPS and in patients with vulvodynia. Among the total sample, as the mean number of pain locations marked within the pelvis increased, GUPI and PCS scores increased (p < 0.05). As the number of CPPS diagnoses increased, the strength of the relationship independently increased. CONCLUSIONS: Pelvic body mapping demonstrated that different forms of CPPS displayed different distributions of pain, but mapping was not predictive of any diagnostic group. Nevertheless, the pelvic body map proved useful in identifying precise locations of pain and may help uncover regions of pain that cannot be easily communicated. The total number of pain sites marked appeared to correlate with worse clinical features.

Bi-allelic loss-of-function OBSCN variants predispose individuals to severe recurrent rhabdomyolysis.

Rhabdomyolysis is the acute breakdown of skeletal myofibres in response to an initiating factor, most commonly toxins and over exertion. A variety of genetic disorders predispose to rhabdomyolysis through different pathogenic mechanisms, particularly in patients with recurrent episodes. However, most cases remain without a genetic diagnosis. Here we present six patients who presented with severe and recurrent rhabdomyolysis, usually with onset in the teenage years; other features included a history of myalgia and muscle cramps. We identified 10 bi-allelic loss-of-function variants in the gene encoding obscurin (OBSCN) predisposing individuals to recurrent rhabdomyolysis. We show reduced expression of OBSCN and loss of obscurin protein in patient muscle. Obscurin is proposed to be involved in sarcoplasmic reticulum function and Ca2+ handling. Patient cultured myoblasts appear more susceptible to starvation as evidenced by a greater decreased in sarcoplasmic reticulum Ca2+ content compared to control myoblasts. This likely reflects a lower efficiency when pumping Ca2+ back into the sarcoplasmic reticulum and/or a decrease in Ca2+ sarcoplasmic reticulum storage ability when metabolism is diminished. OSBCN variants have previously been associated with cardiomyopathies. None of the patients presented with a cardiomyopathy and cardiac examinations were normal in all cases in which cardiac function was assessed. There was also no history of cardiomyopathy in first degree relatives, in particular in any of the carrier parents. This cohort is relatively young, thus follow-up studies and the identification of additional cases with bi-allelic null OBSCN variants will further delineate OBSCN-related disease and the clinical course of disease.

Dexamethasone dose-dependently prevents taxane-associated acute pain syndrome in breast cancer treatment.

PURPOSE: Taxane-associated acute pain syndrome (T-APS) is one of the most bothersome adverse effects caused by taxanes. We have previously reported the attenuating effect of dexamethasone (DEX) on T-APS and its risk factors under DEX prophylaxis. However, the appropriate DEX dosage administration remains unclear. Therefore, this study aimed to investigate whether DEX dose-dependently prevents T-APS in breast cancer patients. METHODS: We retrospectively evaluated patients with breast cancer who received docetaxel (75 mg/m2)-containing chemotherapy without pegfilgrastim and regular non-steroidal anti-inflammatory drugs. The patients were divided into 4 mg/day and 8 mg/day DEX groups, with each DEX dosage on days 2-4 (n = 68 for each group). Primary endpoint was the comparison of all-grade T-APS incidence between the groups. Propensity score-matching was performed to adjust the baseline factors between the groups, and outcomes in the matched-population were also assessed. RESULTS: The incidence of all-grade T-APS was 72.1% in 4 mg/day group and 48.5% in 8 mg/day group, which was significantly lowered by higher DEX dosage (P = 0.008). The severity of T-APS was also significantly reduced in 8 mg/day group (P = 0.02). These results were confirmed in the propensity score matching. Multivariate logistic analysis showed that higher DEX dosage was an independent T-APS preventive factor, whereas age < 55 years was a risk factor. Moreover, DEX-dosage-associated adverse effects similarly appeared in both groups. CONCLUSION: Our study suggested that DEX dose-dependently prevents T-APS in breast cancer treatment. As understanding of the nature of T-APS and its appropriate management can significantly contribute to less onerous chemotherapy provision, further studies are required.

Benign acute children myositis: 5 years experience in a tertiary care pediatric hospital.

Benign acute childhood myositis (BACM) is a self-limited childhood illness, and viral infections mainly cause it. Clinical and laboratory alterations usually normalize rapidly; generally, the only medical intervention required is supportive (hydration and analgesic medication). The low awareness about BACM often led to delayed diagnosis and unneeded ancillary investigations. This study aims to better characterize the clinical and laboratory features of BACM to improve the diagnostic process and inpatient and outpatient management. We conducted a retrospective study selecting all children admitted to Meyer's Children's Hospital-IRCCS (Florence, Italy) with a diagnosis of BACM over the last 5 years, both those visited at Emergency Department (ED) and those admitted to the Pediatric Unit. Clinical, laboratory, and instrumental data were collected from electronic clinical records and analyzed. Overall, sixty-five patients were enrolled; 49 children were visited and discharged directly from ED, whereas 16 were admitted in the Pediatric or Neurologic Wards. The median age was 6.56 years (IQR 4.9-9.1). Male gender (66.1%) and Caucasian ethnicity (70%) were prevalent. Most patients were admitted during winter, and a second peak was found in autumn. All patients had bilateral calf pain, most of them (87.7%) associated with asthenia and refuse to walk (93.8%). Prodromal symptoms were fever (75.3%), cough (32.3%), coryza (26.1%), sore throat (26.1%), and vomiting (15.3%). The median value of CPK was 1827 U/L (IQR 915.5-2462) at peak. CPK median time to normalization was 7 days (IQR 7-8.5) from the nadir. Influenza B was the virus most frequently BACM associated, followed by Influenza A; a novel association with Sars-CoV-2 has been detected. Two patients had pathogenic variants at the Next Generation Sequencing myopathies panel.    Conclusion: School-aged children admitted to the hospital with walking difficulty and myalgia, generally after an upper respiratory tract infection with a moderate CPK elevation, should remind at first of BACM. Rapid complaint resolution and biochemical markers normalization will prevent unnecessary tests and inappropriate therapies. What is Known: • BACM is a self-limited syndrome associated with acute infections. Influenza A and B viruses are the main etiological agents, but BACM may be related to many other microorganisms like Parainfluenza virus, Epstein-Barr virus, Cytomegalovirus, Human herpesvirus 6, Respiratory syncytial virus, Coxsackieviruses, Mycoplasma pneumoniae, Streptococcus pyogenes, Legionella, and Salmonella spp. • Clinical and laboratory alterations usually normalize rapidly; generally, the only medical intervention required is supportive (hydration, analgesic medication). Evolution in rhabdomyolysis and kidney damage is possible but rarely reported. What is New: • Sars-CoV-2 could be an emerging possible cause of BACM. During and after the Sars-CoV-2 outbreak, virus infection seasonality has changed, and so has BACM seasonality. • Screening tests for muscular and metabolic disorders are recommended in recurrent myositis and/or cases with marked CPK elevation (≥ 5000 U/L).

Statin Intolerance: A Review and Update.

OBJECTIVE: To review the evidence of existing literature on the management of statin intolerance. METHODS: We searched for literature pertaining to statin intolerance and treatments in PubMed. We reviewed articles published between 2005 and 2022. RESULTS: Statin-associated myalgia is the most common adverse effect of statin therapy and the most common reason for statin discontinuation. The risk factors for statin intolerance include unexplained muscle pain with other lipid-lowering therapy, unexplained cramps, a history of increased creatine kinase levels, a family history of muscle symptoms, and a family history of muscle symptoms with lipid therapy. Vitamin D repletion and coenzyme Q supplementation may help alleviate the musculoskeletal effects of statins. Trials of different types of statins and different dosing regimens are recommended to improve tolerability. The use of statins in individuals who perform regular exercise requires closer attention to muscular symptoms and creatine kinase levels; however, it does not preclude the use of statins. CONCLUSION: Management of the adverse effects of statin therapy and improving statin tolerability are key to achieving optimum cardiovascular benefits. Identifying statin-associated adverse effects and managing them appropriately can reduce unnecessary statin discontinuation and subsequently provide longer cardiovascular protection.