21 May 2026

Summary

Primary lateral sclerosis (PLS) is a rare neurodegenerative motor neuron disease characterised by progressive and selective degeneration of the central motor neurons in the bulbar and spinal regions. It is estimated that this condition accounts for 1–5 per cent of all motor neurone diseases and usually presents in the fifth or sixth decade of life, with men being affected slightly more often than women. According to current consensus criteria, the diagnosis is based on the demonstration of progressive upper motor neuron dysfunction without lower motor neuron involvement, with isolated upper motor neuron symptoms persisting for at least four years, in order to rule out a slowly progressive, predominantly upper motor neuron form of amyotrophic lateral sclerosis (ALS). The French Network for Motor Neuron Diseases (FILSLAN) has developed a national diagnosis and care protocol (PNDS) with the aim of standardising diagnostic criteria, optimising differential diagnosis and providing evidence-based recommendations for therapeutic management and follow-up throughout the country.

These recommendations have been drawn up in accordance with the methodological framework of the French National Health Authority for Rare Diseases. The protocol provides practical guidelines for diagnosing PLS as a diagnosis of exclusion, distinguishing it from ALS and hereditary spastic paraplegias, and for organising appropriate clinical and paraclinical investigations. It also outlines the indications for genetic testing in selected cases and defines a multidisciplinary treatment strategy focused on symptomatic management, early rehabilitation, monitoring of respiration and nutrition, and psychosocial support. Given the slower progression of PLS compared with ALS, half-yearly multidisciplinary follow-up is generally recommended. The aim of this protocol is to harmonise clinical practice and improve patient care, whilst recognising that there are currently no therapies available that influence the course of the disease.

Translation: Ann Bracke

Source: Revue Neurologique