(Kiosk 4) Droopy Shoulder Syndrome: A Case Report for Iatrogenic Shoulder Subluxation Due to Chronic Chemodenervation with Botulinum Toxin

Case Diagnosis: 31-year-old female with progressive shoulder pain from inferior shoulder subluxation as a result of chronic botulinum treatment for right upper limb dystonia.

Case Description or Program Description: This patient has right upper limb dystonia from traumatic brain injury at 2-years of age. Patient has been receiving botulinum toxin injections since childhood to address dystonia in her arm abductors, external rotators, and wrist flexors/extensors. She presented to clinic approximately 1 month after chemodenervation with complaints of acute worsening of chronic shoulder pain and decreased shoulder range of motion. Patient reports a fall without injury and has had chronic intermittent numbness and tingling in the limb that is worse.

Setting: Outpatient non-operative Orthopedic Clinic

Assessment/Results: Physical Exam found pain with internal and external rotation of the right shoulder, positive impingement testing, but preserved strength in the rotator cuff muscles. Xray of the shoulder 1-month post injection revealed inferior subluxation of the humeral head and no fracture. Etiology was suspected to be deltoid weakness due to chemodenervation, therefore, it was recommended to avoid deltoid injections. Repeat imaging at 3-month injection appointment showed improvement in subluxation. She also reported mild improvement in shoulder pain thus deltoid muscle was not injected at that appointment. Patient participated in outpatient rehabilitation to address shoulder subluxation and shoulder positioning and pain has since improved.

Discussion (relevance): Long-term chemodenervation with botulinum toxin injections can result in fatty infiltration of muscle fibers, atrophy, and decreased muscle mass. Although literature supports the evidence of temporary muscle atrophy following repeat botulinum toxin injections, longitudinal studies in spastic or dystonic patients are limited. Given that many childhood-onset neurological conditions result in spasticity or dystonia, it is imperative to recognize potential anatomical changes that can occur as this patient population transitions into adulthood.

Conclusions: This case highlights the importance of recognizing the long-term effects of repeat botulinum toxin injections and revisiting treatment plans to optimize functional outcomes.