Low back skin sensitivity has minimal impact on active lumbar spine proprioception and stability in healthy adults

Abstract

The purpose of the current work was to (1) determine whether low back cutaneous sensitivity could be reduced through the use of a topical lidocaine-prilocaine anesthetic (EMLA(®)) to mirror reductions reported in chronic lower back pain (CLBP) patients, as well as to (2) identify whether reductions in cutaneous sensitivity resulted in decreased lumbar spine proprioception, neuromuscular control and dynamic stability. Twenty-eight healthy participants were divided equally into matched EMLA and PLACEBO treatment groups. Groups completed cutaneous minimum monofilament and two-point discrimination (TPD) threshold tests, as well as tests of sagittal and axial lumbar spine active repositioning error, seated balance and repeated lifting dynamic stability. These tests were administered both before and after the application of an EMLA or PLACEBO treatment. Results show that low back minimum monofilament and TPD thresholds were significantly increased within the EMLA group. Skin sensitivity remained unchanged in the PLACEBO group. In the EMLA group, decreases in low back cutaneous sensitivity had minimal effect on low back proprioception (active sagittal and axial repositioning) and dynamic stability (seated balance and repeated lifting). These findings demonstrate that treating the skin of the low back with an EMLA anesthetic can effectively decrease the cutaneous sensitivity of low back region. Further, these decreases in peripheral cutaneous sensitivity are similar in magnitude to those reported in CLBP patients. Within this healthy population, decreased cutaneous sensitivity of the low back region has minimal influence on active lumbar spine proprioception, neuromuscular control and dynamic stability.

Low Back Pain: The Potential Contribution of Supraspinal Motor Control and Proprioception

“…A shifted sensory representation in S1 of tactile input from the back was observed more than 20 years ago in a small group of chronic LBP patients by magnetencephalography (Flor and others 1997). As discussed above, S1 (re)organization of proprioceptive input from paraspinal muscle spindles is likely to be more important pathophysiologically for the chronification of LBP than that of tactile input (Beaudette and others 2016).…”

In the back of your mind: Cortical mapping of paraspinal afferent inputs

“…Such maps are potentially crucial to enable further exploration of potential relationships between brain changes and the development and maintenance of chronic LBP (Schmid et al, 2021). In this regard, altered proprioceptive inputs from paraspinal muscles might be more important pathophysiologically -relative, for example, to tactile sensory inputs (Beaudette et al, 2016) -for the chronification of LBP.…”

One session of motor control exercise improves joint position sense assessed by an iPhone application: a randomized controlled trial

“…The sensory inputs from the ligaments and joint capsule are thought to act as limit detector, providing sensory feedback particularly near the end or at the extreme of range of motion32, 33 ) . Low back skin receptor has also been reported to contribute to the lumbar position sense34, 35 ) . In the present study, the contribution from muscles, ligaments, joint capsules, or skin at 30° of lumbar flexion might be insufficient to enable a greater position sense even with exercise.…”