Comparison Between Palpatory and Ultrasound-guided Methods for Botulinum Toxin Administration in Spastic Paraplegia

Spasticity in spastic paraplegia is a major cause of chronic pain and functional limitation. Although botulinum toxin type A (BoNT-A) reduces muscle tone, studies like the SPASTOX trial have shown limited functional improvement, which may be related to injection accuracy in deep or complex muscle groups. Ultrasound guidance enhances injection precision, potentially improving clinical outcomes. This prospective, single-group, fixed-sequence crossover study ($N = 40$) aims to compare the response to BoNT-A in patients with spastic paraplegia (all etiologies included). Participants will receive treatment in two distinct phases separated by a 16-week washout period: first with conventional anatomical landmark-guided injections, followed by ultrasound-guided injections. A fixed sequence (anatomical first, ultrasound second) is used to prevent observer bias, ensuring the injector remains blinded to muscle ultrasound features (e.g., fatty infiltration or fibrosis) during the landmark-guided phase. Both the participants and the outcome assessor are blinded to the application sequence. Assessments will occur before and 4 weeks after each intervention using validated tools, including the Modified Ashworth Scale, Goal Attainment Scaling (GAS), Timed Up and Go (TUG), Visual Analog Scale (VAS) for pain, modified Barthel Index, SF-36 questionnaire, and the Heckmatt scale. The hypothesis is that ultrasound-guided injections will achieve greater spasticity reduction and functional recovery.

Inclusion Criteria * Age over 18 years * Clinical diagnosis of spastic paraplegia * Spasticity with Ashworth Scale score between 2 and 3 in at least one muscle group with indication for botulinum toxin treatment * Muscle strength ≥ 3 on the Muscle Strength Assessment Scale * Enrollment in a rehabilitation program * For women of childbearing potential, a negative beta-hCG test at the time of injection Exclusion Criteria * Concomitant neuromuscular disorders * History of hypersensitivity to botulinum toxin * Active infection at the injection site * Ashworth Scale score of 4 * Pregnancy or breastfeeding