Chronic Ankle Instability and Corticomotor Excitability of the Fibularis Longus Muscle

Abstract

Context: Neuromuscular deficits are common in people with chronic ankle instability (CAI). Corticomotor pathways are very influential in the production of voluntary muscle function, yet these pathways have not been evaluated in people with CAI.Objective: To determine if corticomotor excitability of the fibularis longus (FL) differs between individuals with unilateral CAI and matched control participants without CAI.Design: Case-control study. Setting: Laboratory.Patients or Other Participants: Ten people with CAI (4 men, 6 women; age ¼ 21.2 6 1.23 years, height ¼ 175.13 6 9.7 cm, mass ¼ 77.1 6 13.58 kg) and 10 people without CAI (4 men, 6 women; age ¼ 21.2 6 2.3 years; height ¼ 172.34 6 8.86 cm, mass ¼ 73.4 6 7.15 kg) volunteered for this study.Main Outcome Measure(s): Transcranial magnetic stimulation was performed over the motor cortex on neurons corresponding with the FL. All testing was performed with the participant in a seated position with a slightly flexed knee joint and the ankle secured in 108 of plantar flexion. The resting motor threshold (RMT), which was expressed as a percentage of 2 T, was considered the lowest amount of magnetic energy that would induce an FL motor evoked potential equal to or greater than 20 lV, as measured with surface electromyography, on 7 consecutive stimuli. In addition, the Functional Ankle Disability Index (FADI) and FADI Sport were used to assess self-reported function.Results: Higher RMTs were found in the injured and uninjured FL of the CAI group (60.8% 6 8.4% and 59.1% 6 8.99%, respectively) than the healthy group (52.8% 6 8.56% and 52% 6 7.0%, respectively; F 1,18 ¼ 4.92, P ¼ .04). No leg 3 group interactions (F 1,18 ¼ 0.1, P ¼ .76) or between-legs differences (F 1,18 ¼ 0.74, P ¼ .40) were found. A moderate negative correlation was found between RMT and FADI (r ¼ À0.4, P ¼ .04) and FADI Sport (r ¼ À0.44, P ¼ .03), suggesting that higher RMT is related to lower self-reported function.Conclusions: Higher bilateral RMTs may indicate deficits in FL corticomotor excitability in people with CAI. In addition, a moderate correlation between RMT and FADI suggests that cortical excitability deficits may be influential in altering function.Key Words: motor cortex, neuromuscular activity, muscles, transcranial magnetic stimulation Key PointsBilateral fibularis longus resting motor threshold was higher in participants with chronic ankle instability (CAI) than in participants without CAI. Increased resting motor threshold might indicate deficits in fibularis longus corticomotor excitability in people with CAI. Resting motor threshold and self-reported function were moderately correlated, suggesting deficits in corticomotor excitability might influence function.A nkle sprains are the most common injury in physically active people and account for approximately 23% 1 and 15% 2 of all injuries in high school and collegiate athletics, respectively. In addition, 628 000 ankle sprains are treated annually in emergency facilities within the United States, representing approximately 20% of...

Spinal and Peripheral Dry Needling Versus Peripheral Dry Needling Alone Among Individuals With a History of Lateral Ankle Sprain: A Randomized Controlled Trial

“…6 Other investigators have reported reduced corticomotor excitability of the fibularis muscles among individuals with unilateral chronic ankle instability compared to healthy individuals. 7 Should dry needling of the fibularis muscles have any effect on their cortiomotor excitability or reaction time, this may explain an increase in performance on unilateral balance tests and are future areas of investigation. If dry needling the multifidi has any inhibitory effect on the fibularis muscles, then the effects of needling spinally may negate the facilitory effects of dry needling the fibularis muscles.…”

“…Previous investigators have shown abnormalities of the fibularis muscles in persons with CAI, including reduced reaction time, diminished postural control and corticomotor excitability, and the presence of myofascial trigger points (MTrPs). 5,6,7 MTrPs are areas of increased irritability in palpable taut bands of skeletal muscle tissue that are clinically associated with both local and referred pain, muscle dysfunction, and autonomic phenomena. [8][9][10] In addition to other intervention strategies, the use of dry needling as a treatment for MTrPs is gaining attention as investigations on its effectiveness emerge.…”

Chronic Ankle Instability and Neural Excitability of the Lower Extremity

“…Resting motor thresholds of the fibularis longus were bilaterally higher in patients with unilateral CAI than in control participants, 23 suggesting that unilateral injury may cause bilateral alterations of corticospinal excitability or that these alterations were present before injury and potentially led to the development of CAI. Bilateral deficits in quadriceps neuromuscular control have been reported after unilateral anterior cruciate ligament injury, 42 suggesting that bilateral neuromuscular alterations are common after unilateral injury at joints in addition to the ankle.…”

“…22 Similarly, corticospinal excitability of the fibularis longus in CAI patients has been shown to be diminished when compared with healthy participants assessed using transcranial magnetic stimulation (TMS). 23 Neuromuscular control adaptations in joints proximal to the ankle also have been demonstrated in patients with CAI, manifesting as deficits in force production, 17,24 changes in kinematic patterns, 10,11,14,[25][26][27] and deficits in muscle-activation patterns 12,[28][29][30][31] about the knee and hip during slow and dynamic tasks. Whereas these alterations are observed consistently, the source of these changes has not been established.…”

Current concepts on the pathophysiology and management of recurrent ankle sprains and chronic ankle instability

“…Physical disability subsequent to recurrent ankle sprains has included range of motion and strength deficits, sensorimotor alterations, balance impairments, gait alterations and post-traumatic osteoarthritis [9][10][11][12][13][14][15]. Current research in these areas has focused on improving function and lessening disability associated with this condition, as well as identifying what leads to recurrent sprains.…”