To assess central fractional anisotropy changes of the white matter in subjects with spasticity treated with botulin toxin.
Seven subjects with spasticity that developed 2-22 years after cerebrovascular accidents (CVA) were studied with 3T MRI of the brain including diffusion tractography (DTI) and fractional anisotropy (FA) measurements of the white matter of the corticospinal tracts (CST), corpus callosum (CC) and cerebral lobes of the affected and contralateral sides prior and after the injection of botulin toxin at the contours of peripheral nerves of the affected side.
All 7 subjects improved their preexisting spasticity after the injections of botulin toxin. 4 out of 7 showed FA changes post injection in the CST of the affected side. The latter had CVAs occurring 5-15 years prior to the development of spasticity. 3 out of 7 subjects did not show significant FA changes post-treatment. They had CVAs occurring less than 5 years and more than 15 years prior to the development of spasticity. There was regression between 'years of evolution', as a dependent variable, and the square of pre and post injection differences of FA on the contralateral CST, as well as white matter of the parietal and frontal lobes as independent variables.
Botulin toxin injections improved spasticity in all the subjects of our cohort. There also were FA changes in the white matter of the CST of the affected side in those subjects with CVAs happened between 5-15 years prior to the development of spasticity, while those with lesions of less than 5 years and more than 15 years did not show statistically significant FA changes post treatment.