The purposes of the study are:

1. To measure differences in Sciatic nerve (SN) stiffness using shear-wave elastography (SWE) during two movement sequences of the lower limb neurodynamic test (LLNT) in low back pain with sciatica.
2. To measure differences in Sciatic nerve stiffness using shear-wave elastography during two movement sequences of the lower limb neurodynamic test in control group.
3. To compare difference in Sciatic nerve stiffness using shear-wave elastography during two movement sequences of the lower limb neurodynamic test between low back pain patients with sciatica and control group.

As peripheral nerves can exhibit regional variations in their anatomy and mechanical properties, investigating the response of different nerve segments to different loading patterns based on the order of joint movement will provide a better understanding of nerve biomechanics during neurodynamic testing.

This may help optimize the lower limb neurodynamic test (LLNT) application for different pathological situations and potentially increase its diagnostic capacity to detect localized alterations in a specific nerve segment such as sciatica.

Ultrasonography does not have the sensitivity required to detect all forms of peripheral nerve disorders and fails to provide information about nerve mechanical properties such as stiffness.

By using neurodynamic sequencing, clinicians may direct neural stress toward targeted areas suspected of involvement and, at the same time, perform the test with reduced load on more remote nerve segments. The ability to modify neural load distribution during the LLNT could play an interesting role in differential diagnosis, when symptoms present similar characteristics but have different regional origin.

There is a gap in the literature concerning the measurement of (SWV) of sciatic nerve during LLNT proximal (LLNT-PROX) to distal and from distal (LLNT_DIST) to proximal sequences of LLNT.

Inclusion Criteria:

• Thirty participants ranging in age from 25 to 40 years from both genders with a diagnosis of low back pain with radiating leg pain and thirty control group.
• The main symptoms are low back pain with unilateral leg pain(sciatica) for 3-12 months for group A.
• Patients with lumbar disc herniation (L4-5) with diagnostic imaging as MRI for group A.
• Positive straight leg raising are considered for inclusion in the study for group A.
• Control group must be free from any symptoms of nerve irritation or compression, with normal neurological examination findings, including reflexes, sensation, negative straight leg raising and motor strength.

Exclusion Criteria:

• Diabetes mellitus.
• Any type of polyneuropathy
• Trauma of lumbar spine
• Previous history of back surgery
• Piriformis syndrome.
• Participants with conditions that reduce image quality on US imaging (thick gluteal subcutaneous fat tissue.
• Hip joint prosthesis.
• Professional athletes (Neto et al., 2024).
• Skin infection

Sixty subjects of both genders will be participated in this study. Their age will range between 25 to 40 years. They will receive verbal and written explanations for this study. If they decide to participate in this study, they will sign the consent form. The sample will be selected from the faculty of physical therapy outpatient clinics and at El kasr Elainy.