The Movement of Botulinum Toxin Through the Lateral Gastrocnemius Muscle in Humans: An Expanded Examination

Despite the wide-spread use of botulinum toxin (BT) to treat spasticity (increased muscle tone) in central neurological disease, evidence-based guidance on dosing, dilution, and injection technique is limited. The wide-spread use of BT in spasticity management, expense of these agents, and detrimental impact from movement into non-injected muscles mandates a better understanding of BT movement within muscles. A proof-of-concept paper written by investigators at Weill Cornell Medicine introduced a non-invasive MRI approach with "voxel thresholds" that was able to detect intramuscular effects of BT at 2 and 3 months post-injection of BT. The purpose of the current set of studies is to refine this MRI technique to better visualize the movement of botulinum toxin through muscle. In addition, the investigators plan to explore, using the imaging technique, how spastic muscle and differing dilutions affect BT movement in an effort to support the development of better research techniques to study toxin movement in human muscle.