1302 - Rare case of dystonia following biceps tenodesis treated with botulinum toxin injections

Case Diagnosis: Acquired dystonia in elbow flexors after biceps tenodesis treated with botulinum toxin injections

Case Description: 75-year-old male with surgical history of right shoulder rotator cuff repair and biceps tenodesis, who presented with intermittent muscle contractions and non-radiating pain at elbow flexors, which started over the course of a year and half following surgery. Patient completed conservative management without relief. MRI showed intact biceps tenodesis without complications, acromioclavicular joint degenerative changes and rotator cuff tendinosis. EDX revealed no evidence of a right cervical radiculopathy and was negative for focal neuropathy. Patient underwent a trial of 1.5 mL of lidocaine infiltration of the biceps and brachialis muscles via sono-guided approach, with reported relief lasting 4 to 6 weeks. Thereafter, the patient received sono-guided Incobotulinum toxin A infiltrations on two points of the biceps and one point of the brachialis muscles, 10 units each, which resulted in significant improvement up to 6 months following the procedure.

Discussions: Dystonia is characterized by intermittent muscle contractions that can cause involuntary movements, which may be acquired, idiopathic or hereditary. Acquired cases are rarely reported post-operatively, even more rare following orthopedic surgery. Complications after biceps tenodesis are very rare, including infections, hematomas, and neurovascular injuries. Biceps cramping and pain have been reported at the tenodesis site associated with orthopedic hardware, however incidence is low, and dystonia has been reported following shoulder surgery in context of complex regional pain syndrome. In this case, dystonia at elbow flexors was observed more than a year after biceps tenodesis, with alternative work-up negative, and adequate response to sono-guided botulinum toxin infiltrations was obtained with significant improvement of symptoms.

Conclusions: Dystonia following orthopedic surgery is an uncommon diagnosis with no precise incidence or prevalence. Botulinum toxin may be considered as a treatment option in patients presenting with similar symptoms, refractory to conservative management, following shoulder surgery.