Examination of Corticomotor Plasticity in Individuals with CAI

Chronic Ankle Instability (CAI) is a multifactorial ankle pathology arising from a combination of mechanical and sensorimotor alterations, adversely influencing movement patterns such as impaired postural control and gait dysfunction. These negative movement consequences associated with CAI are thought to contribute to diminished physical activity, lower quality of life, and increased risk of post-traumatic osteoarthritis (OA). Previously, deficits in the corticomotor excitability of selected muscles around the ankle observed in CAI patients have been directly linked to increased perceived disability. A new and novel technique that has been used to investigate specific portions of the sensorimotor system is mapping of the corticomotor output using Transcranial Magnetic Stimulation (TMS). Mapping of the corticomotor output provides additional information about the plastic changes occurring in the motor cortex. For instance, mapping of the motor cortex identifies potential shifting and expansion of the area of the motor cortex that best communicates with selected muscle. These shifts or expansions would indicate reorganization of the corticomotor output, influencing the communication efficacy within the descending motor pathway, which is likely a contributing factor to the movement alterations observed in CAI. Currently, there is no investigation that has examined the effects of ankle pathology on the plastic alterations in the motor cortex and its effect on quality of life. Therefore, we plan to (1) Compare plastic changes of the corticomotor excitability in patients with and without history of ankle sprains using corticomotor output mapping with TMS and (2) Establish the association between plastic alterations in the motor cortex and self-reported quality of life. Our central hypothesis is individuals with CAI will have a shifting and expansion in the area of the motor cortex that best communicates with selected muscles, and this reorganization will be associated with individual's quality of life.