Exploring Advanced Imaging Techniques to Characterize Botulinum Toxin Diffusion in Human Muscle

• MRI [ Time Frame: Baseline (0 months), 2 months and 3 months ] [ Designated as safety issue: No ]
  Subjects will undergo non-contrast MRI's of the target leg prior to Botox injections (0 months), then again at both 2 months and 3 months following the Botox injections.
  
  

Drug: Botox (botulinum toxin)
A series of three injections will be made simultaneously to the gastroc-soleus muscles of the affected lower limb; this will be the only drug intervention/injection session throughout the study, and occurs at baseline. The top injection site, closest to the knee, consists of 25 units of Botox and 0.25 cc saline. The bottom injection site, closest to the ankle, also consists of 25 units of Botox and 0.25 cc saline. The middle injection site will be considered the placebo injection, as it will not contain any Botox (0 units Botox) and 0.25 cc saline.

Over the past decade, botulinum toxins (BT) have been extensively used to treat any number of diverse disorders, including functionally significant, focal spasticity in the arm and leg of persons with injury/disease of the central nervous system. Spasticity is an involuntary muscle stiffness that limits movement of an extremity and often leads to pain, hygiene problems, difficulty in bed or wheelchair positioning, and functional deficits in self-care and mobility.

There are three BT products on the market: MyoBloc®, Botox®, and Dysport®. FDA approval for use of Botox® in spasticity is anticipated sometime during 2010. In the Weill Cornell Division of Rehabilitation Medicine alone, nearly 50,000 units of Botox® were injected for the treatment of spasticity during the 2008-2009 academic year. (Note: The vast majority of the BT market share in the US rests with Botox®.)

There is excellent evidence supporting the effectiveness of BT in decreasing tone and modest clinical evidence supporting functional improvement. Despite the frequent use, however, there is astonishingly little evidence delineating the impact on diffusion of dosing, dilution, approach to muscle localization, or serotype of BT. To better study these relationships we will be using advanced imaging to develop a model to characterize the physical characteristics of BT diffusion in human skeletal muscle.