Citations

ABSTRACT Background Primary lateral sclerosis (PLS) is an ultrarare upper motor neuron syndrome with a prognosis unique from classical ALS. The study of PLS is complicated by its rarity and the difficulty distinguishing PLS from ALS. We present data from a 1‐year prospective follow‐up study on PLS and efforts to distinguish it from ALS. Methods Seventy‐six PLS participants enrolled in this prospective natural history study. EMG studies, blood neurofilament light chain levels (NfLs), and demographic characteristics were obtained at baseline. At 1‐year follow‐up, repeat EMG studies were conducted to determine which participants fulfilled criteria for ALS. Baseline characteristics were then compared to determine features that predict reclassification. Results Seventy participants completed 1‐year follow‐up. Five of the 70 were reclassified to ALS (7.1%). Those reclassified had higher trends in baseline blood NfL levels (91.4 vs. 34.0 pg/mL, p = 0.13) and shorter symptom duration (39 vs. 69 months in the PLS group, p = 0.15). Reclassification was noted in both probable and definite PLS participants. All cases with a symptomatic duration of less than 2 years retained the PLS phenotype (5 of 5). NfL levels over 90 pg/mL predicted reclassification with 94% specificity and 60% sensitivity. No other features predicted reclassification to ALS. Conclusions In our population, reclassification of PLS to ALS occurred at a low frequency at 1 year follow‐up (7.1%). Baseline NfL was the strongest predictor in differentiating UMN dominant ALS from PLS at 1‐year follow‐up. Based on our data, we propose EMG and NfL criteria for enrollment in future PLS trials.

Objective The primary lateral sclerosis ( PLS ) consensus diagnostic criteria and functional rating scale ( PLSFRS ) were recently established to facilitate and optimize future PLS clinical trials. We examined the trajectory of the PLSFRS and other functional outcome measures and biomarkers in the PLS Natural History Study ( PLS NHS ) to understand their performance in this prospective cohort. Methods The PLS NHS is a prospective, longitudinal, multicenter study of people living with PLS in different diagnostic categories: early (disease duration <2 years); probable (2–4 years); and definite PLS (4–15 years). PLSFRS scores and other functional outcome measures were collected at baseline, 3‐, 6‐, 9‐, and 12‐month follow‐up visits. Baseline characteristics were compared between the groups. The slopes of the PLSFRS and other functional outcome measures over 12 months were examined in the overall cohort and subgroups using linear mixed‐effect models. The associations between baseline characteristics and the rate of PLSFRS decline were analyzed with linear regression models. Results A total of 76 participants were included: early (n = 6); probable (n = 26); and definite (n = 44) PLS . Baseline PLSFRS total scores were highest in the early PLS group, followed by the probable and definite PLS groups. In the overall cohort, the PLSFRS total score declined by 0.33 points/month (95% confidence interval [0.27–0.39], adjusted p < 0.05). The rate of decline was steepest in the early PLS group, followed by the probable and definite PLS groups. Baseline neurofilament light chain level was associated with the rate of PLSFRS decline over 1 year ( p = 0.001). Interpretation In PLS, the rate of functional decline, as measured by the PLSFRS total score, is faster during the early phase of the disease. Neurofilament light might serve as a prognostic biomarker in PLS. ANN NEUROL 2026;99:418–428

AbstractFor many years, Neuromuscular Medicine programs lacked a standardized means of handling fellowship applications and offering positions. Programs interviewed applicants and made offers as early as the first half of Post Graduate Year 3 (PGY3), a suboptimal timeline for applicants who may have had little prior exposure to neuromuscular or electrodiagnostic medicine. In 2021, the American Association of Neuromuscular & Electrodiagnostic Medicine (AANEM) developed the Neuromuscular Fellowship Portal to standardize a later timeline and establish a process for fellowship applications and offers. In its first year, the Neuromuscular Fellowship Portal used a unique one‐way match, in which the portal released serial offers to applicants based on rank order lists submitted by programs. Fifty‐two Neuromuscular Medicine programs and seven electromyography (EMG)‐focused Clinical Neurophysiology programs participated. Sixty‐eight positions were filled, a similar number to previous years. A survey of fellowship directors and applicants following this process showed overwhelming support for the standardized timeline and application portal, but all program directors and most applicants favored moving to a traditional match. To maintain the existing application timeline and minimize costs for all parties, the AANEM Neuromuscular Fellowship Portal will host a two‐way match, based on existing commercial match algorithms, in 2022. A match will afford a fair and efficient process for all involved. Both Neuromuscular Medicine and EMG‐focused Clinical Neurophysiology programs will be encouraged to participate. The process undertaken by the AANEM can stand as an example for other neurologic subspecialties who are interested in standardizing their application timeline.