Plantar Cutaneous Sensitivity With and Without Cognitive Loading in People With Chronic Ankle Instability, Copers, and Uninjured Controls

Abstract

Study design: Controlled laboratory study.

Background: Deficits in light touch have recently been identified on the plantar surface of the foot in those with chronic ankle instability (CAI) but not in uninjured controls. It is unknown whether copers display similar deficits. Similarly, cognitive loading has been shown to impact postural control in different populations, but it is unclear how it may impact sensory perception.

Objectives: To evaluate the difference in cutaneous sensation thresholds at rest and under cognitive loading, using Semmes-Weinstein monofilaments (SWMs), among uninjured controls, copers, and those with CAI.

Methods: A total of 45 participants (mean ± SD age, 20.2 ± 2.8 years; height, 167.6 ± 9.9 cm; mass, 66.3 ± 14.7 kg) were recruited and categorized to a CAI, coper, or control group, based on Ankle Instability Instrument scores. Participants were assessed with SWMs for cutaneous thresholds using a 4-2-1 stepping algorithm at the head of the first metatarsal, base of the fifth metatarsal, calcaneus, and sinus tarsi. Each participant was then retested while generating random digits to the beat of a metronome in order to simulate cognitive loading.

Results: Participants with CAI displayed significantly higher SWM thresholds at the head of the first metatarsal, base of the fifth metatarsal, and sinus tarsi than those of the control participants, and significantly higher thresholds at the base of the fifth metatarsal and calcaneus than those of copers (all, P<.05). Copers showed higher thresholds than those of controls at the sinus tarsi only (P<.05). A main effect of cognitive loading was identified at all 4 sites (P<.05).

Conclusion: People with CAI have deficits in plantar sensation relative to controls and copers. Cognitive loading increases plantar cutaneous sensation thresholds irrespective of CAI status.

Keywords: deafferentation; dual-task interference; light touch; mechanoreceptor.