Corticospinal Excitability During Standing and Its Association With Postural Control After Acute Lateral Ankle Sprain

Area of Science:

• Neuroscience
• Biomechanics
• Sports Medicine

Background:

• Acute lateral ankle sprain (ALAS) is linked to balance deficits and altered neural excitability.
• The impact of ALAS on corticospinal excitability during standing and its relationship with injury symptoms remains unclear.

Purpose of the Study:

• To investigate corticospinal excitability during single-legged standing in individuals with ALAS.
• To determine the relationship between corticospinal excitability, postural control, and acute injury symptoms after ALAS.

Main Methods:

• A case-control study involving 14 individuals with ALAS and 14 matched controls.
• Transcranial magnetic stimulation (TMS) measured normalized motor-evoked potentials (MEP) in the fibularis longus during single-legged stance.
• Postural control was assessed via center-of-pressure (COP) variables during a 10-second single-legged stance.

Main Results:

• Individuals with ALAS showed a trend toward facilitated corticospinal excitability in the fibularis longus during single-leg balance.
• A significant portion of ALAS participants exceeded control group norms for MEP at 100% active motor threshold (AMT).
• Higher normalized MEP correlated with increased total COP velocity (r = 0.543, P = .048), with severity influencing outcomes.

Conclusions:

• Corticospinal excitability of the fibularis longus may be facilitated after ALAS during single-leg stance.
• Facilitated excitability appears associated with increased postural sway, potentially indicating a compensatory supraspinal mechanism.
• Ankle sprain severity may influence both corticospinal excitability and postural control deficits.