Dynamics of the Tibial Nerve During Straight Leg Raise Test: A Study of Individuals With Lumbar Disc Herniation

This study aimed to investigate tibial nerve dynamics during the straight leg raise (SLR) test in patients with lumbar disc herniation (LDH) and the relationship between neurological symptoms and dynamics at the radiating pain-occurring (RPO) angle.

Participants with LDH were 20 adults (10 males, 10 females, average age of 58.4 years, average body mass index [BMI] of 21.9 kg/m²) who visited the orthopedic clinic between November 2019 and December 2020. The SLR test was performed at 20°, 40°, and the RPO angle for patients with LDH. In healthy participants, the test was performed at 20°, 40°, and the maximum elevation angle. The excursion and strain of the proximal and distal ends of the tibial nerve were compared using ultrasound imaging at each angle. Furthermore, the nerve dynamics at the RPO angle were compared between the LDH groups with and without neurological symptoms.

Movement at the proximal and distal ends of the tibial nerves at 20° and 40° leg elevation was smaller in the LDH group than in the healthy group. No significant difference was observed in the amounts of strain at these two angles. In LDH, nerve strain at the RPO angle was lower in the group with neurological symptoms than in the group without. During the SLR test, excursion of the tibial nerve was less in LDH than in healthy participants, suggesting that the sciatic nerve was more strained in LDH.

Our findings show an association between insufficient tibial nerve strain during SLR and neurological symptoms.