ALS-OPM

In amyotrophic lateral sclerosis (ALS), heterogeneity of motor phenotypes is a fundamental hallmark of the disease. Motor phenotyping is an essential aspect of understanding the clinical heterogeneity of ALS. It is determined by the variability of three anatomical determinants: the region of onset, the spatial and temporal propagation of motor dysfunction from the site of onset to other body regions, and the relative involvement of upper motor neuron (UMN) and lower motor neuron (LMN) degeneration. Distinct ALS phenotypes were associated with varying rates of progression and survival. A broader consensus on the classification of ALS phenotypes is relevant for clinical practices and research. The OPM Classification provides a structured, three-determinant anatomical framework based on the region of onset, pattern of symptom propagation, and degree of upper and lower motor neuron dysfunction (Reference). Developed through expert consensus from Germany, Austria and Switzerland, this classification aims to standardize the description of ALS phenotypes, enhance prognostic precision, and improve patient stratification in clinical trials. By systematically describing onset sites, spread patterns, and motor neuron involvement, the OPM Classification supports both clinical decision-making and the design of more targeted ALS research.

The ALS Functional Rating Scale-Revised version (ALSFRS-R) is a disease-specific severity score that reflects motor impairment and functional deterioration in people with amyotrophic lateral sclerosis (ALS). Several variants of the scale, each differing slightly from the others, have developed over time and are currently in circulation. This lack of uniformity may hinder data interpretation and decrease item validity. The ALSFRS-R-SE (self-explanatory) is an adapted version of the widely used ALS Functional Rating Scale-Revised (ALSFRS-R). It retains the original scale’s structure while incorporating clear annotations and explanatory notes to make the tool more self-explanatory for clinicians, patients, and caregivers alike. Developed through a rigorous consensus process in Germany, the ALSFRS-R-SE improves the consistency and validity of functional assessments by addressing linguistic ambiguities and standardizing item interpretation (Reference). This enhances its use in both clinical care and research, supporting accurate monitoring of disease progression and outcome measurement.