Poster 213: Relief Through Botulinum Neurotoxin Injection for Postoperative Chronic Myofascial Pain

Abstract

Setting: Tertiary care hospital. Patient: A 29-year-old man with chronic shoulder pain. Case Description: The patient had a medical history significant for multiple shoulder repairs, now with persistent burning pain in his left trapezius, levator scapulae, and rhomboids since his last surgery. A physical therapist and active tri-athlete, the patient had been self-treating with his own therapy regimen. The patient has had 2 sets of traditional trigger point injections (TPI) with minimal relief. Assessment/Results: On examination, the patient exhibited a forward flexed c-spine and protracted shoulders with noticeable tightness and palpable painful bands in the bilateral pectoralis and upper trapezius muscles (left > right). He had restricted scapulohumeral rhythm on the left and required the use of his trapezius and scapula for arm abduction. Neurologically, the patient was normo-reflexive symmetrically. He failed several conventional modalities (stretching, deep-tissue massage, muscle energy technique, ultrasound, electric stimulation, TPI). Physical therapy was, therefore, focused on scapular stabilization exercises. After receiving 2 series of botulinum neurotoxin injections to the pectoralis muscles, he had great shoulder pain relief with improved range of motion in his glenohumeral and scapulothoracic rhythm. Discussion: The pathophysiology of myofascial pain is not well understood. Research suggests both a peripheral sensitization of the mechanosensitive affect nerves associated with dysfunctional motor endplates as well as a central sensitization of the dorsal horn neurons within the spinal cord. Recently, the use of botulinum neurotoxin has been implemented to treat myofascial pain. Treatment is targeted at the peripheral sensitization, which indirectly treats the central sensitization. Botulinum neurotoxin works at the neuromuscular junction to inhibit the release of acetylcholine and other neuropeptides responsible for sensitization. To date, the U.S. Food and Drug Administration (FDA) has approved indications for botulinum neurotoxin that include strabismus, blepharospasms, hyperhidrosis, and cervical dystonia. Conclusions: Although there is no FDA indication for use of botulinum toxin for treatment of muscular and myofascial pain, it has been shown to be of great utility.