516 - Botulinum toxin for post-stroke spastic hammer toes: a case report

Case Diagnosis: Left sided hammer toes in setting of prior stroke

Case Description: A 61-year-old male with a history of cerebrovascular accident (CVA) in December of 2023 with resultant left-sided hemiparesis was seen in clinic for long-standing spasticity management with botulinum toxin injections. At this patient's most recent appointment, he reported the onset of painful hammer toes of the left foot, which were limiting both his participation in therapy and overall mobility. He was evaluated by podiatry where the possibility of tendon release surgery was discussed. As a less invasive alternative, a trial of botulinum toxin was recommended. The patient then underwent injection of 40 units of botulinum toxin to the flexor digitorum brevis.

Discussions: Spasticity-related foot deformities are a well-established complication in patients with CVAs. While some literature exists supporting the treatment of claw toes with botulinum toxin injections to the flexor digitorum longus and brevis, evidence for the management of hammer toes deformities with botulinum toxin is limited. The flexor digitorum brevis originates from the calcaneus and inserts on the middle phalanges of digits two through five. In this patient, we hypothesize that spasticity to flexor digitorum brevis is contributing to hammer toe formation. Given the functional impairment and pain, we thought it was reasonable to trial a botulinum toxin injection to this muscle before considering more invasive surgical approaches.

Conclusions: This case highlights the innovative application of botulin toxin for spastic hammer toes in the post-stroke population. While existing literature supports its role in other deformities such as claw toes, our case suggests that injection of the flexor digitorum brevis may be an effective approach to managing hammer toes as well. Further study is warranted to better define optimal dosing and long-term outcomes. This approach may offer relief in patients with multiple types of spastic foot deformities before the consideration of surgical intervention.