Background Progressive pseudorheumatoid dysplasia (PPD) is a rare autosomal recessive skeletal dysplasia frequently misdiagnosed as juvenile idiopathic arthritis because of overlapping clinical features.  Case presentation We report a 21-year-old man who presented with bilateral leg pain and acute progressive lower-limb weakness associated with gait disturbance. Clinical examination revealed asymmetric motor weakness, absent knee and ankle reflexes, and preserved bowel and bladder function. Radiographs demonstrated generalized platyspondyly, scoliosis, and epiphyseal enlargement of long bones. Magnetic resonance imaging revealed a right paracentral L1-L2 disc extrusion causing severe central canal stenosis with compression and displacement of cauda equina nerve roots. Laboratory investigations were negative for inflammatory markers. Whole-exome sequencing identified a homozygous missense variant c.1010G  A (p.Cys337Tyr) in the CCN6 gene, confirming the diagnosis of PPD. The patient underwent posterior decompressive laminectomy with stabilization, resulting in complete neurological recovery at six weeks. Conclusion This case highlights the rarity of acute cauda equina syndrome in PPD and emphasizes the importance of early recognition and appropriate surgical management.

Adult skeletal muscle can regenerate. After muscle injury, muscle stem cells (satellite cells) can generate new muscle fibers. Under normal conditions, satellite cells are mitotically quiescent and located beneath the basal lamina of muscle fibers. In response to regenerative stimuli, satellite cells activate and proliferate as myogenic precursor cells. After several rounds of cell division, these precursor cells differentiate and fuse to form new muscle fibers. A subset of proliferating myogenic precursor cells returns to a quiescent state to replenish the satellite cell pool through self-renewal. Intensive care unit-acquired weakness (ICU-AW) affects many critically ill patients partly due to acute muscle loss. It is a major physical component of post-intensive care syndrome. Current explanations of ICU-AW focus on rapid protein breakdown and impaired energy metabolism during the early catabolic phase, but these mechanisms do not fully explain why some survivors fail to rebuild muscle once the initial catabolic stress has subsided. In this review, we argue that persistent weakness may also reflect defective muscle regeneration, with satellite cell dysfunction and niche abnormalities as plausible contributors. Recent serial-biopsy studies suggest that dysfunction can occur without stem-cell depletion: satellite cell number can be preserved even when differentiation or later proliferative capacity is impaired in culture. We first review the normal satellite cell niche, including the parent fiber, microvasculature and perivascular cells, extracellular matrix, resident immune and interstitial cells, and systemic signals, with separate consideration of the diaphragm. We then examine how critical illness affects these compartments and how cell-intrinsic defects may additionally impair regeneration. We use this evidence to develop three working hypotheses (niche-detached activation, abortive myogenesis, and niche locking) and treat them as testable models rather than recognized mechanisms. Finally, we consider how future studies might measure, target, and test these processes.

Subgroup selection in clinical trials is essential for identifying patient groups that react differently to a treatment, thereby enabling personalized medicine. In particular, subgroup selection can identify patient groups that respond particularly well to a treatment or that encounter adverse events more often. However, this is a post-selection inference problem, which may pose challenges for traditional techniques used for subgroup analysis, such as increased Type I error rates and potential biases from data-driven subgroup identification. In this paper, we discuss two recently developed methods for subgroup selection in regression problems: one based on generalized linear modeling and another on isotonic regression. We demonstrate how these methods can be used for data-driven subgroup identification in the analysis of clinical trials, focusing on two distinct tasks: identifying patient groups that are safe from manifesting adverse events and identifying patient groups with high treatment effect, while controlling for Type I error in both cases. A thorough simulation study is conducted to evaluate the strengths and weaknesses of each method, providing detailed insight into the sensitivity of the Type I error rate control to modeling assumptions.

A core outcome set(COS) refers to the minimum set of outcomes that should be measured and reported in all clinical studies within a specific field. With the development of the COS for traditional Chinese medicine(COS-TCM), there has been a rapid increase in related publications, highlighting the need for a periodic secondary review. This study systematically reviewed and evaluated the quality of published COS-TCM research by comprehensively searching Chinese and English literature databases as well as specialized databases, using qualitative analysis and quality assessment methods. The objective is to synthesize the current state of research, identify common issues and methodological weaknesses, thereby supporting the high-quality advancement of the COS-TCM field. A total of 39 COS-TCM studies were included. It was found that existing studies generally employ sound methodologies. However, methodological improvements are needed in areas such as patient involvement, the development and publication of study protocols, the generation of a preliminary list of outcomes, and managing attrition in Delphi surveys. While the structural presentation is largely complete, reporting remains insufficient regarding the roles played by different stakeholder groups, detailed content of the consensus process, and the presentation of core outcomes. To improve future development, researchers could focus on both methodological application and reporting quality, and also address aspects such as research topic selection, stakeholder engagement, and the development of TCM-specific outcome and measurement instruments to better reflect the therapeutic characteristics and comparative advantages of TCM.