HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is a chronic, progressive neurological disorder and shares many radiological and clinical features with other more prevalent myelopathies. Here, we quantified spinal cord and brain volumes in adults with HAM/TSP in comparison with healthy volunteers (HVs) and individuals diagnosed with relapsing–remitting or progressive multiple sclerosis (RRMS or P-MS). Clinical disability and MRI were assessed in 24 HVs, 43 HAM/TSP subjects, and 46 MS subjects. Spinal cord cross-sectional area (SCCSA) and brain tissue volumes were measured and compared. HAM/TSP subjects had significantly lower SCCSA corresponding to cervical levels 2 and 3 (C2–3) (54.0 ± 8 mm²), cervical levels 4 and 5 (C4–5) (57.8 ± 8 mm²), and thoracic levels 4 to 9 (T4–9) (22.7 ± 4 mm²) and significantly elevated brain white matter hyperintensity (WMH) fraction (0.004 ± 0.008) compared to the HVs (C2–3: 69.4 ± 8 mm², C4–5: 75.1 ± 9 mm², T4–9: 34.1 ± 4 mm²; all p < 0.0001; and WMH: 0.0005 ± 0.0007; p < 0.001). In the HAM/TSP subjects, SCCSA at all levels but not WMH showed a significant correlation with clinical disability scores. WMH in HAM/TSP subjects, therefore, may not be related to clinical disability. SCCSA in our limited RRMS cohort was higher than the HAM/TSP cohort (C2–3: 67.6 ± 8 mm², C4–5: 72.7 ± 9 mm², T4–9: 33.4 ± 5 mm²; all p < 0.0001) and WMH was lower than in P-MS subjects (p = 0.0067). Principal component analysis suggested that SCCSA and WMH may be used to differentiate HAM/TSP from MS. Understanding these differences msay help establish early diagnostic criteria for HAM/TSP patients.

HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is a chronic progressive neurological disorder and shares many radiological and clinical features with other more prevalent myelopathies. Here, we quantified spinal cord and brain volumes in adults with HAM/TSP in comparison with healthy volunteers (HVs) and participants diagnosed with multiple sclerosis (MS). Clinical disability and MRI were assessed in 24 HVs, 43 HAM/TSP, and 46 MS participants. Spinal cord cross-sectional area (SCCSA) and brain tissue volumes were measured and compared. HAM/TSP participants had significantly lower SCCSA at C2-3 (54.0±8 mm2), C4-5 (57.8±8 mm2), and T4-9 (22.7±4 mm2) and significantly elevated brain white matter hyperintensity (WMH) fraction (0.004±0.008) was compared to HVs (C2-3: 69.4±8 mm2, C4-5: 75.1±9 mm2, T4-9: 34.1±4 mm2; all p < 0.0001; and WMH: 0.0004±0.0007; p < 0.001). In HAM/TSP, SCCSA at all levels but not WMH showed the significant correlation with clinical disability scores. Brain white matter hyperintensities in HAM/TSP, therefore, may not be related to clinical disability. SCCSA and WMH in our limited MS cohort were higher than the HAM/TSP cohort (67.6±8 mm2, 72.7±9 mm2, 33.4±5 mm2; p < 0.0001). Principal component analysis suggested that SCCSA and WMH may be used to differentiated HAM/TSP from MS. Understanding these differences may help establish early diagnostic criteria for HAM/TSP patients.

Epstein–Barr virus (EBV) infection is nearly ubiquitous and strongly linked to multiple sclerosis (MS), but how EBV-infected B cells communicate with distal tissues remains unclear. We performed an integrated multiomic characterization of small extracellular vesicles (sEVs) released from spontaneous lymphoblastoid cell lines (SLCLs) derived from healthy donors and patients with MS, transformed ex vivo by endogenous wild-type EBV. Proteomics identified over 6,000 shared proteins enriched in nucleic acid–binding and chromatin-associated factors. EV-associated DNA resolved into two structurally distinct compartments: DNase-sensitive, high–molecular weight DNA associated with the vesicle corona and DNase-resistant, nucleosome-sized (∼130–150 bp) DNA. Both compartments were overwhelmingly host-derived and broadly genomically distributed, whereas EBV DNA was minimal. In contrast, viral RNA cargo was dominated by the EBV noncoding RNA EBER1, which was strikingly enriched across all lines and confirmed within individual vesicles by ddPCR and super-resolution microscopy. EBER1 has previously been detected in MS brain tissue, yet its route to the CNS has remained unexplained. Our findings identify sEVs as a plausible vehicle for disseminating this immunostimulatory viral ncRNA beyond sites of latency, pointing to EV-mediated export of EBER1 as a candidate mechanism linking peripheral EBV infection to distal tissue signaling in MS and beyond.

Extracellular vesicles (EVs) are lipid spheres released from cells. Research utilizing EVs has met several hurdles owing to the small size of the majority of EVs and other nanoparticles (<150 nm) and the lack of detection technologies capable of providing high-throughput single particle measurements at this scale. The use of high-throughput single particle measurements is critical for the assessment of EV heterogeneity and abundance which are features often used to assess the development of isolation protocols or particle characterization. The Coulter principle, known in the field as resistive pulse sensing (RPS), has been used for several decades to size and count cells. More recently, this technology has evolved to accommodate nanoparticle analysis. In the last decade a platform utilizing microfluidic resistive pulse sensing (MRPS) has been demonstrated for nanoparticles, offering ergonomic characterization of nanoparticles along with utilizing open format data. To date, assessment of MRPS accuracy and reporting standards have not been assessed. With the aim of increasing data accuracy, ergonomics, and reporting transparency, we developed a microfluidic resistive pulse sensing post-acquisition analysis software (RPSPASS) application for automated cohort calibration, population gating, statistical output, QC plot generation, alternative data file outputs, and standardized reporting templates.

Background: Despite comprising 50.5% of medical students, women remain underrepresented in orthopaedic surgery. As of 2024, orthopaedics had the lowest rate of female residents among surgical specialties at 23.7%. While early exposure programs and signaling have helped promote access, some residencies still match classes without a female resident. Tracking long-term trends in female match rates may highlight opportunities to improve representation. The purpose of this study was to provide longitudinal context for the gender composition of orthopaedic residency programs most visible to applicants by tracking changes in female representation from 2005 to 2025. Methods: We used Doximity’s Residency Navigator to sort programs by perceived reputation, and the programs in the top third results were included in our analysis as these programs are most visible to residency applicants and are presumed to shape applicant perceptions and behavior. Gender composition of interns was collected from program websites and social media for each available year. Weighted linear regression assessed temporal trends; two-proportion Z-tests evaluated regional and urbanicity differences. Results: Among 69 programs, women comprised 23.2% of interns overall. Representation rarely exceeded 20% before 2017, reaching a low of 11.5% in 2006, but surpassed 30% annually since 2022. Female representation increased by 1.2% per year (p < 0.001, R ² = 0.77). Regional variation persisted, but growth was consistent across geography and program size. Significant increases occurred in metropolitan programs (+18.9%, p < 0.0001) from 2015 to 2025. Conclusion: Female representation at orthopaedic programs most visible on Doximity has risen steadily, with a marked inflection after 2017 and exceeding 30% since 2022. These gains likely reflect combined effects of diversity initiatives, preference signaling, and broader cultural movements advocating gender equity. Future research should examine the impact of signaling on gender diversity and evaluate gender diversity in all orthopaedic residency programs.

BACKGROUND: Schwannomas are CNS WHO grade 1 benign peripheral nerve sheath tumors. They can occur anywhere in the body where there are peripheral nerves, but they are most common in the vestibular system. To the authors’ knowledge, there has been only one previous report of their presentation in the filum terminale. OBSERVATIONS: The author present the case of a 36-year-old man who presented to the emergency department with acute-on-chronic right low back pain and shooting pain to his right groin with radiation to his knee. He was found to have an L1–2 intradural extramedullary lesion on MRI abutting the conus. His preoperative neurological examination was otherwise unremarkable, and he was promptly taken for L1–2 laminectomy and resection of the lesion. Final pathological diagnosis was intradural extramedullary cellular schwannoma, CNS WHO grade 1, of the filum terminale. Postoperative MRI demonstrated gross-total resection. The patient had new urinary fullness and constipation, which resolved by the 2-month follow-up, and otherwise recovered well with resolution of his back and leg pain. LESSONS: This case illustrates a rare presentation of an intradural extramedullary cellular schwannoma at the filum terminale, emphasizing the importance of a broad differential diagnosis. Resection of these neoplasms offers a definitive and safe treatment. https://thejns.org/doi/10.3171/CASE25333