[Spasticity in Multiple Sclerosis: 2026 Expert Consensus]

Multiple sclerosis (MS) is a chronic neuroinflammatory disease that significantly impairs quality of life. Spasticity is one of the most frequent and highly disabling features of MS, often accompanied by cramps, pain, bladder dysfunction, sleep disturbances, fatigue, and tremor. Recently, the concept of 'spasticity-plus syndrome' (SPS) has emerged to reflect the interplay among these symptoms. This work aims to update the Spanish clinical guideline for managing MS-related spasticity (MSS) by adopting this evolving concept.

A panel of 14 Spanish neurologists assessed the available evidence using a two-level literature review strategy, combining a systematic review focused on SPS with a rapid review of MSS management. Building on the previous guideline, the panel formulated updated recommendations with the scientific endorsement of the Spanish Society of Neurology (SEN). To support a structured and transparent development process, an adapted GRADE-informed framework was used to guide the appraisal of the evidence and formulation of recommendations.

A total of nine publications addressing the SPS concept were identified. Based on the evidence and expert consensus, the panel developed 13 recommendations covering triggering and aggravating factors, the diagnosis and evaluation of spasticity, and therapeutic strategies for patient management. In addition, a comprehensive treatment algorithm was proposed to guide therapeutic decision-making according to patients' clinical profiles.

This work provides updated recommendations for the management of patients with MSS, integrating the SPS concept into clinical practice. The panel highlights the importance of a symptom-oriented approach that considers the full spectrum of clinical manifestations to individualize treatment, simplify the therapeutic approach, and minimize the risk of polypharmacy.