Relation between nerve fiber function and mechanosensitivity to tension in patients suffering from lumbosacral...

A link between small nerve fiber dysfunction and reduced mechanosensitivity has been reported in carpal tunnel syndrome, this relationship has not been studied in patients suffering from lumbosacral radicular pain (LRP).

This cross-sectional observational study aimed to evaluate the link between mechanosensitivity to tension and nerve fiber dysfunction in people with LRP and radiculopathy.

Participants with LRP and radiculopathy attended a single assessment session including a neurological examination investigating motor, reflex and sensory function (including small nerve fiber assessment) and neurodynamic tests assessing mechanosensitivity to tension, namely the Slump and Straight Leg Raise test (SLR).

Median symptom duration of the 31 participants (mean age 43.5 ± 13.2 years, 61 % female (n=19) included was 8 months [IQR: 6-18]. The SLR was positive in 54 % (n = 17) of participants and the Slump test in 80 % (n = 23). Small nerve fiber dysfunction was observed in 39 % (n = 12) to 61 % (n = 19) of participants, while large nerve fiber dysfunction was present in 39 % (n = 12) to 74 % (n = 24). Among those with small nerve fiber function impairment, the percentage of participants with a positive or negative neurodynamic test result (Slump test or SLR) did not differ (p-value >0.1). Similar findings were observed for large nerve fiber impairment (p-value >0.05).

These results did not detect a significant association between neurodynamic test results and small or large nerve fiber dysfunction in participants with LRP and radiculopathy. These findings differ from those of a similar study on carpal tunnel syndrome.