Introduction A large number of stroke patients develop spasticity in the upper and lower extremities, which is one of the clinical signs of damage to motor neuron 1, causing abnormal postures and movement patterns due to motor neuron hyperexcitability and rheological alterations in the affected muscles. These alterations limit the use of the arm and leg, restricting their use in functional activities and affecting the quality of life and social participation of users. In recent years, the Heckmann scale has been used to evaluate spastic muscle alterations by ultrasound; however, evidence is limited regarding its benefits as an assessment tool for spastic hypertonia.

Objective To describe the morphological characteristics of spastic muscles in the lower extremities using ultrasound examination in subjects after stroke.

Method A prospective, multicenter descriptive study will be conducted. The sample will be non-probabilistic, consisting of 80 subjects who meet the eligibility criteria and provide informed consent.

Analysis of results Using the SPSS 27 program, a descriptive analysis will be performed using statistical indices of central tendency, dispersion, and distribution according to the measurement scale of each variable. The normality of the distribution of continuous variables will be investigated. In addition, a bivariate correlation analysis (ANOVA) will be performed. The significance level will be 0.05.

Expected Results It will provide updated evidence in the field of assessing the state of spastic muscles in subjects with neurological damage, a situation that will guide the therapeutic process and may improve the patient's prognosis and quality of life.

Background: Spasticity is considered a positive clinical sign of upper motor neuron damage, associated with prevalent neurological pathologies such as stroke, constituting a clinical characteristic with a high incidence in the field of neurorehabilitation.

General Objective To describe the morphological characteristics of spastic biceps brachii and triceps surae muscles, using ultrasound examination, in subjects who have suffered a stroke.

Specific Objectives

1. Identify the morphological characteristics of the biceps, using ultrasound examination, in subjects after stroke.
2. Identify the morphological characteristics of the triceps surae, using ultrasound examination, in subjects after stroke.
3. Correlate the morphological characteristics of the biceps and triceps surae with the values obtained on the Ashworth and Tardieu scales.
4. Correlate the morphological characteristics of the biceps and triceps surae with the time of evolution and type of stroke.

Procedure

The first recruitment contact will be made by a professional from each participating center, who will inform the patient about the characteristics of the study and their future participation. Subsequently, eligibility criteria will be evaluated in order to identify 10 to 15 users per participating center.

After identification and signing of the consent form, participants will be invited to each center, where a professional will complete a structured clinical interview to obtain demographic and clinical data such as: type of stroke, time of onset, location, side affected, and treatments received.

Ultrasound evaluation Each participant will undergo a non-invasive ultrasound evaluation of the upper limb on the paralyzed side (using a portable Ekipomed ultrasound machine) to determine its pathological morphology (thickness, fiber orientation, and echogenicity) using the modified Heckmatt scale. This procedure will be performed by a physiatrist who is an expert in muscle ultrasound (with extensive experience and training in sonoanatomy). The technique involves placing the person in a supine or seated position, requesting that the biceps and triceps surae muscles be left free, then applying a colorless, hypoallergenic gel and proceeding with the examination by applying a transducer head to the gel located on the muscle to be evaluated. The procedure lasts 15 minutes per person.

nalysis All information will be compiled in an Excel database and statistically analyzed using SPSS 25 statistical software. The analysis will be descriptive, using statistical indices of central tendency, dispersion, and distribution according to the measurement scale of each variable. The normality of the distribution of continuous variables will be investigated. In addition, a bivariate correlation analysis will be performed using ANOVA. In all relevant analyses, the significance level will be 0.05.

Expected results Currently, advances in technology raise new questions and challenges. Given the above, this study will provide updated evidence in the field of neurorehabilitation assessment, associated with a pathology of high prevalence at the national and global level, such as stroke. This pathology manifests itself with clinical signs, including spastic hypertonia, a disorder that causes severe disability and affects people's quality of life. The results of this study will guide the therapeutic process, specifically in relation to the management of spastic hypertonia, a condition that can improve the patient's prognosis and promote a better quality of life and social interaction.

Inclusion Criteria:

• Patients over 18 years of age with a history of stroke more than three months ago.
• Who are undergoing or have undergone some type of rehabilitation in the acute and/or subacute stage.
• Who present spastic hypertonia in the upper and lower extremities detectable by Ashworth and Tardieu assessment.
• Presence of spastic pattern according to Hefter classification.
• Who agree to participate in the study and sign the consent form.

Exclusion Criteria:

• Structural joint involvement that prevents tone assessment.
• Patients who have been injected with antispastic drugs in the last 6 months.

Adult stroke patients with spasticity.