Modified straight leg raise test for sural nerve pathology
Sural nerve pathology is a rare but often neglected differential diagnosis of posterior ankle pain. Problems in the sural nerve mimic those of Achilles tendinopathy and, thus, the differentiation of these two conditions remains challenging. A modified straight leg raise test for the sural nerve (mSLRsural) is a neurodynamic test that has been proposed as means to diagnose sural nerve problems. The aim of this study was to examine whether the strain in the sural nerve and Achilles tendon increases hip flexion (last component of mSLRsural).
The measurements were done in seven cadavers. During the mSLRsural dorsiflexion-inversion of the ankle joint is performed first -challenging both the sural nerve and Achilles tendon-and it is followed by hip flexion. The results of the study showed that hip flexion and the associated load that was placed on the sciatic nerve was transmitted to the sural nerve resulting in an increase of the strain in the sural nerve but not the Achilles tendon.
The findings provide biomechanical support to the use of the mSLRsural for the differential diagnosis of posterior ankle pain when pathology of the sural nerve is suspected. Yet, the diagnostic accuracy of the mSLRsural in clinical practice needs further exploration.
> From: Coppieters et al., Man Ther (2015) (Epub ahead of print). All rights reserved to Elsevier Ltd. Click here for the Pubmed summary.
A video on the modified straight leg raise test (only the second part):