Contralateral cutaneous reflex modulation during gait in individuals with and without chronic ankle instability

Area of Science:

• Neuroscience
• Biomechanics
• Sports Medicine

Background:

• Chronic ankle instability (CAI) is a common sequela of ankle injury, presenting with sensorimotor deficits beyond the injured limb.
• Altered cutaneous reflexes, particularly following sural nerve stimulation, have been observed in individuals with CAI.
• Previous research has not investigated cutaneous reflexes in the unaffected limb of individuals with unilateral CAI.

Purpose of the Study:

• To measure and compare contralateral cutaneous reflexes during gait in individuals with unilateral CAI and healthy controls.
• To investigate potential systemic neural alterations following lateral ankle sprains (LAS).

Main Methods:

• Nineteen participants (unilateral CAI and healthy controls) underwent muscle activity measurement of 6 lower limb muscles.
• Random, non-noxious sural nerve stimulations were applied during a walking task.

Main Results:

• Cutaneous reflex patterns in the CAI group differed from controls during the gait cycle.
• Specific alterations included a lack of lateral gastrocnemius facilitation and medial gastrocnemius inhibition in the CAI group.
• Reduced facilitation in the biceps femoris (BF) during contralateral swing was also noted in the CAI group.

Conclusions:

• Reflex alterations in individuals with unilateral CAI extend to the unaffected limb, indicating spinal-level changes post-LAS.
• The observed variability in reflexes may be attributed to increased motor output variability.
• Rehabilitation for LAS should consider systemic neural pathways, not just local deficits.