- Background: Muscle activity contributes to the enhancement of facial aging deformity, blepharospasm, cerebral palsy spasticity, trismus, torticollis, and other conditions. Myotomy of the involved muscles in order to reduce the deformity has variable success rates due to muscle healing and regeneration of activity. Objectives: The goal of this study was to investigate whether blocking striated muscle activity with Botulinum toxin (BtxA) during the healing time after myotomy alters the healing process and reduces long-term muscle activity. Methods: Eighteen Sprague Dawley rats where divided into 3 groups: group A (n = 7) underwent myotomy of their Latisimus Dorsi muscle; group B (n = 7) underwent myotomy and injection of BtxA into their severed muscle; group C (n = 4) injection of BtxA only. Muscle strength was tested periodically using a grip test. Results: Starting at week 16 and until the termination of study at week 22, group B (Myotomy + BtxA) showed significant reduction in muscle power compared to the two control groups. Conclusions: Addition of BtxA injection into a muscle immediately after myotomy may interfere with muscle healing and contribute to a more successful long-term result.