Exploration Of Muscle Motor Control To Guide Botox Injections For Runner’s Dystonia

HISTORY: The patient (female, age 44) was diagnosed with runner’s dystonia (RD) of the right lower extremity (LE) in April 2022. RLE heel whip emerged in 2016 during a race. Notable medical history includes severe traumatic brain injury at age 4 and from 2017-2021: abdominal muscle diastasis (DRAM) postpartum, PT treatment of DRAM, abdominoplasty to correct DRAM and steroid injection for mild right hip dysplasia. Botox injection to R tensor fascia lata received in July 2022 did not resolve RD symptoms, which has increased in severity and now impact walking and cycling. PHYSICAL EXAMINATION: The patient completed the following tests in June 2023 to guide future Botox interventions: Lower Extremity Functional Scale (LEFS), LE strength and coordination, upper (UMN) and lower motor neuron (LMN) screen, McGill’s torso muscular endurance test battery for endurance, and treadmill running gait analysis with bilateral surface electromyography (EMG) of the medial gastrocnemius, tibialis anterior, biceps femoris, and gluteus maximus. Neuromuscular effort was calculated as the time duration spent in, above, and below the activation measured during maximum voluntary contraction during the stance phase of running. DIFFERENTIAL DIAGNOSIS: Genetic testing ruled out Parkinson's-related diseases. MRI and EMG screening ruled out multiple sclerosis. TEST AND RESULTS: UMN/LMN screen was negative. LEFS score = 70/80. Mild gross strength deficits in right hip external rotators, hip abductors, and ankle plantarflexors as compared with left. McGills’s test confirmed low endurance of back extensors. Neuromuscular effort of tibialis anterior and gluteus maximus during running was greater in right compared with left. FINAL WORKING DIAGNOSIS: The patient meets the following RD clinical assessment criteria: task specificity, first onset of symptoms during running, inconsistent orthopedic examination, negative UMN/LMN exam, absence of pain, and excessive muscle activation observed with EMG. TREATMENT AND OUTCOMES: The patient agreed to back extensor and hip muscle strengthening exercises. Abnormal running gait mechanics may benefit from biofeedback gait retraining due to muscular imbalances resulting in poor motor control. Botox injections could be explored, but risks, benefits and patient preference must be considered.