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.
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
Concomitant neuromuscular disorders
History of hypersensitivity to botulinum toxin
Active infection at the injection site
Ashworth Scale score of 4
Single group
AbobotulinumtoxinA - Ultrasound-Guided Technique
DrugAdministration of AbobotulinumtoxinA (500U) into spastic lower limb target muscles under real-time ultrasound guidance to ensure precise muscle localization. Performed 16 weeks after the first intervention. Assessments are performed pre-injection and 4 weeks post-injection
AbobotulinumtoxinA - Conventional Technique
DrugAdministration of AbobotulinumtoxinA (500U) into spastic lower limb target muscles using standard anatomical landmarks and manual palpation. Assessments are performed at baseline and 4 weeks post-injection.
Change in spasticity after BoNT-A injection techniques
Change in spasticity measured by the Modified Ashworth Scale (MAS), comparing conventional landmark-guided versus ultrasound-guided botulinum toxin type A injections in patients with spastic paraplegia. The Modified Ashworth Scale ranges from 0 to 4, with higher scores indicating greater muscle tone/spasticity (worse outcome)
Functional improvement assessed by Goal Attainment Scaling
Functional improvement assessed by Goal Attainment Scaling (GAS) after conventional landmark-guided versus ultrasound-guided botulinum toxin type A injections. The Goal Attainment Scaling score ranges from -2 to +2, with higher scores indicating greater achievement of the predefined treatment goals (better outcome)
Functional mobility assessed by the Timed Up and Go Test
Change in functional mobility measured by the Timed Up and Go (TUG) Test, comparing conventional landmark-guided versus ultrasound-guided botulinum toxin type A injections. The Timed Up and Go Test is measured in seconds, with lower times indicating better functional mobility (better outcome)
Change in functional independence assessed by the Modified Barthel Index
Change in functional independence measured by the Modified Barthel Index, comparing conventional landmark-guided versus ultrasound-guided botulinum toxin type A injections. The Modified Barthel Index ranges from 0 to 100, with higher scores indicating greater functional independence (better outcome).
Pain intensity after BoNT-A injection techniques
Change in pain intensity measured by the Visual Analog Scale (VAS). The Visual Analog Scale ranges from 0 to 10, with higher scores indicating greater pain intensity (worse outcome)
Quality of life after BoNT-A injection techniques
Change in quality of life assessed by the 36-Item Short Form Health Survey (SF-36). The SF-36 assesses eight health domains, with scores ranging from 0 to 100 for each domain. Higher scores indicate better health status (better outcome)
Adverse events related to BoNT-A injection techniques
Incidence and severity of adverse events associated with conventional landmark-guided and ultrasound-guided botulinum toxin type A injections
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