This study aims to compare between High tone power therapy (modulated frequency current) and Transcutaneous electrical nerve stimulation (fixed frequency current) on spasticity and selected kinematic gait parameters in stroke patients.

Stroke is a neurological deficit attributed to an acute focal injury of the central nervous system (CNS) by a vascular cause . Stroke is one of the leading causes of disability and mortality in the globe, stroke occurs when blood flow to the brain is restricted due to a blocked or ruptured artery; the cerebral energy supply is interrupted, resulting in tissue destruction and widespread neuronal, cognitive impairments, and psychological morbidity .

Stroke is the second major cause of death and disability worldwide with over 13 million new cases annually . Stroke has been described as a major source of both mortality and global disability . Approximately 795,000 people experience stroke annually, and 60% (or 465,000) of them need rehabilitation .

Spasticity is a symptom of stroke, brain and spinal cord damage, multiple sclerosis, cerebral palsy, and other neurological illnesses that cause paralysis . The most common spastic pattern in the lower limbs is adduction and extension of the knee with an Equinovarus foot . This impacts gait patterns and daily functioning activities .

Treatment modalities for the management of spasticity include Stretching, splinting, Neuromuscular electrical stimulation (NMES), extracorporeal shock wave therapy, transcranial and spinal cord magnetic stimulation, Surgical treatment, neurectomy, rhizotomy, and myelotomy; also, many drugs used for treating spasticity oral drugs like Baclofen, Tizanidine, and injectable medications like Phenol/alcohol and Botulinum 2 toxin .

Transcutaneous electrical nerve stimulation (TENS) stimulates large diameter mechano-sensitive nerve fibers in the skin it's a non-invasive treatment that has been reported to affect pain control and sensory stimulation which is commonly used in the treatment of chronic and acute pain with possible mechanisms of action including segmental inhibition, the release of endogenous opioids, counter-irritation, nerve conduction block, increase muscle power and movement function .

High-tone power therapy (HTT) is a unique characteristic of electrotherapy. It uses intermediate frequency, metal-compatible alternating current whose frequency oscillates between approximately 4000 Hz and 33000 Hz, and intensity is adjusted, unlike traditional electrotherapies as transcutaneous electrical nerve stimulation (TENS). Its main effects are introducing energy into the body to activate cells, producing an oscillation or vibration in the cells and tissues to promote metabolism, scattering the mediators of pain and inflammation leading to pain relief, and normalizing cell metabolism and nerve regeneration ).

The effective management of spasticity continues to pose challenges to physiotherapy management, there appears to be a dearth of adequate information on high tone power therapy in the management of spasticity; There are several physiotherapy approaches for managing spasticity but there is a lack of evidence to show which is most effective .

Statement of the problem:

This study will answer the following question: Is there any difference between the effect of high-tone power therapy (modulated frequency current) versus transcutaneous electrical nerve stimulation (fixed frequency current) on spasticity and selected kinematic gait parameters in stroke patients?

Inclusion Criteria:

1. Duration of illness not less than six months post-stroke (Hillis A. et al., 2006).
2. Patients' age ranges from forty-five to sixty-five years (Feigin et al., 2022).
3. Body mass index from (18.5 to 24.9).
4. Patients can respond to verbal instructions (Consciousness and orientation to time, place, and person) more than 13 degrees on the Glasco coma scale (Hegazy et al., 2020).
5. Able to walk independently on an even surface without any assistive device (Fan and Yin, 2013).
6. Patients with moderate Spasticity of the ankle joint (grade 2 and 3 According to Modified Ashworth Scale) (Hegazy et al., 2020).

Exclusion Criteria:

1. Subjects with any other Co-existing Progressive neurological disorder (Hegazy et al., 2020).
2. Unstable Cardiac condition (E.g., Acute Myocardial infarction, severe Cardiac Failure) (Teslim et al., 2013).
3. Subjects with any anti-spastic Drugs (Chang et al., 2013).
4. Musculoskeletal disorders affecting gait kinematics such as severe arthritis, knee surgery, and total hip joint replacement, lower limb fractures less than 6 months or contractures of fixed deformity, leg length discrepancy.
5. Any previous Contracture or deformities (Hegazy et al., 2020).
6. Un co-operative patients (Gupta and Chatterjee, 2019).
7. Open wounds, burns, or Loss of sensation (Grevstad et al., 2016).
8. Patients with metal implants (von Lewinski et al., 2009).
9. Visual, auditory problems.