Sensorimotor Changes In A Patient With Chronic Ankle Instability: A Case Report Study

Balance training (BT) has been proven effective in treating chronic ankle instability (CAI). However, recurrent ankle sprains are still reported in some patients with CAI after the rehabilitation, which may be associated with changes in sensorimotor functions. PURPOSE: To examine sensorimotor functions of a patient with CAI who experienced recurrent acute lateral ankle sprain (ALAS) after 2 weeks of BT program. METHODS: A female patient with CAI (age: 19 yrs, height: 165.1 cm, weight: 68.0 kg) completed a 2-week (3 sessions/wk) BT intervention, consisting of single-leg balance, single-leg deadlift, and wobble-board exercises. The patient had an inversion ankle sprain (grade I) nine days after completing the BT program. The patient presented swelling, pain, and laxity. We measured two standard sensorimotor measures, such as postural control as indicated by center of pressure (COP) area and spinal reflex excitability of soleus muscle as assessed by H-reflex in her injured side during single-leg stance. Maximum H-reflex was normalized to maximal M-response to calculate Hmax/Mmax ratio. In addition, we assessed a dynamic balance performance using Star Excursion Balance Test (SEBT). All outcome measures were assessed at baseline, post-BT, 5 days after ALAS, and 12 days after ALAS. RESULTS: COP area was decreased after BT by 35.5% (baseline: 3.4 cm2, post-BT: 2.2 cm2). COP areas gradually returned to pre-trained level after ALAS (5 days after ALAS: 2.6 cm2, 12 days after ALAS: 3.4 cm2). Similarly, Hmax/Mmax ratio of soleus muscle was decreased after BT by 42.0% (baseline: 0.50, post-BT: 0.29). Hmax/Mmax ratio of soleus returned to pre-trained value after ALAS (5 days after ALAS: 0.54, 12 days after ALAS: 0.51). There were no significant changes in the composite SEBT scores after either BT or ALAS (baseline: 67.1, post-BT: 65.2, 5 days after ALAS: 63.4, 12 days after ALAS: 65.5). CONCLUSIONS: A patient with CAI had significant gains in sensorimotor functions after the 2-week BT program. However, once a patient with CAI experienced a recurrent ALAS trauma, improved sensorimotor functions seemed no longer retained. Our findings indicate that static balance and spinal reflex excitability are adaptive in response to BT, but these two factors may not play a significant role in preventing a subsequent ALAS in a patient with CAI.