Primary Lateral Sclerosis French National Diagnostic and Care Protocol

Primary lateral sclerosis (PLS) is a rare neurodegenerative motor neuron disease characterized by progressive and selective involvement of the central motor neuron within the bulbar and spinal regions. It is estimated to account for 1-5% of motor neuron diseases and typically presents in the fifth or sixth decade of life, with a slight male predominance. According to current consensus criteria, the diagnosis relies on the demonstration of progressive upper motor neuron dysfunction in the absence of lower motor neuron involvement, with persistence of isolated upper motor neuron signs for at least four years in order to exclude a slowly progressive upper motor neuron-predominant form of amyotrophic lateral sclerosis (ALS). The French Motor Neuron Disease Network (FILSLAN) developed a National Diagnostic and Care Protocol (PNDS) with the aim of standardizing diagnostic criteria, optimizing differential diagnosis, and providing evidence-based recommendations for therapeutic management and follow-up across the national territory. These recommendations were elaborated in accordance with the methodological framework of the French National Authority for Health for rare diseases. The protocol provides practical guidance for establishing PLS as a diagnosis of exclusion, distinguishing it from ALS and hereditary spastic paraplegias, and organizing appropriate clinical and paraclinical investigations. It also outlines indications for genetic testing in selected cases and defines a multidisciplinary management strategy centered on symptomatic treatment, early rehabilitation, respiratory and nutritional surveillance, and psychosocial support. Given the slower progression of PLS compared with ALS, biannual multidisciplinary follow-up is generally appropriate. This protocol aims to harmonize clinical practice and improve patient care while acknowledging the current absence of disease-modifying therapies.