Effects of Neurodynamics on Lower Extremity Spasticity - a Study in Chronic Stroke

Post-stroke spasticity in the lower extremity affects balance and gait, leading to decreased mobility and functional independence. Therefore, effective intervention for reducing spasticity is crucial in stroke rehabilitation. Recently, neurodynamics, though originally designed for pain management in orthopedic patients, has also been applied for treating spasticity in patients with neurological disorders. However, previous studies focused mainly on treating the upper extremity spasticity, but not on lower extremity spasticity, and not on possible neurophysiological changes. The present study aims to investigate the immediate effects of neurodynamics in reducing lower limb spasticity and neurophysiological changes in people with chronic stroke.

Sample size calculation: There was no reference for the effect size of neurodymanics on reducing lower extremity spasticity, and the effect size of neurodynamics treatment for improving knee range of motion was between 0.89 to 2.55. We set the effect size of 0.6 (moderate effect size) with an alpha level of 5%, power at 80%, and a paired t-test model to calculate the sample size. Statistical analysis: Paired t-test will be used for within condition (experimental or control condition) comparisons. The change values between pre and post in each condition will be calculated and compared by paired t-test for between condition comparisons. The significance is set at p< 0.05.

Neurodynamic treatment for about 13 minutes in supine position. It will be comprised of three stages, and the tensioner technique of the tibial nerve will be used.

The patient will lie supine with the trunk and neck in neutral position. During the first stage, participants will receive passive straight leg raise of the affected side held for 20 seconds for 3 repetitions. In the second stage, hip adduction and internal rotation, ankle dorsiflexion, and ankle eversion are added in the straight leg raise position. Slow oscillations of the ankle movement for 1 minute will be applied, followed by holding the position for 20 seconds, for 3 repetitions. In the third stage, the head of the patient will be held in flexion with pillows while the same oscillation procedure as the second stage is performed. There will be a 2-minute rest between the stages.

The modified Ashworth scale (MAS) will be used, which is a 6-point scale commonly used to assess muscle spasticity in clinical settings.

The H-reflex will be recorded by placing a disposable surface electrode on the muscle belly of the gastrocnemius after a stimulation of the tibial nerve just proximal to the electrode.

Gait performance will be measured by using the GAITRite system (CIR system, Inc., Havertown, Pennsylvania). Participants will be instructed to walk along the walkway at their comfortable speed. Gait velocity, cadence, and step length of the affected and unaffected limbs, and spatial and temporal asymmetry ratios are calculated.

Motor control of the lower extremity will be assessed by the motor section of the Fugl-Meyer Assessment (FMA). Higher scores represent better motor control, with a total score of 34.

Inclusion Criteria: diagnosis of first-ever stroke with unilateral lesion for more than 6 months demonstrating calf muscle spasticity as indicated by modified Ashworth scale equal to or greater than 1 with passive ROM of ankle dorsiflexion at least to neutral position (defined as 0°) ability to walk at least 10m independently without a walking device or ankle-foot orthosis (AFO) sufficient cognition (mini-mental state examination, MMSE score of 24 or higher) Exclusion Criteria: contraindications to nerve conduction tests other orthopedic and neurological disorders interfering participating in the study

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