Mohammed Abdulrahman Alshaikh, Presenter: Nothing to Disclose

Fabrice Michel MD, PhD, Abstract Co-Author: Nothing to Disclose

Bruno Alfred Kastler MD, PhD, Abstract Co-Author: Nothing to Disclose

Sebastien Louis Aubry MD, PhD, Abstract Co-Author: Nothing to Disclose

Botox injection is a new treatment of the piriformis muscle syndrome and the purpose of our study was to evaluate by MRI the morphological modifications of the piriformis muscle treated by Botox injection or by surgical desinsertion.

Seventeen patients presenting with a piriformis muscle syndrome treated either by Botox injection or surgery, and who benefited from an MRI were included retrospectively (mean age 43 y/o). The following parameters were assessed and compared to a normal contralateral muscle: maximal thickness and volume of piriformis muscle, and its fatty infiltration according to Goutaillier’s classification.

The affected side showed a significant reduction in thickness (p<0.001) and volume (p<0.001) of the piriformis muscle, and an increase in fatty infiltration (p<0.004) versus the normal side. Univariate analysis in treated patients revealed a significant reduction in the thickness (p<0.001) and volume (p<0.001) and an increase of fatty infiltration (p<0.001) of the piriformis muscle treated by Botox injection, whereas we found no significant difference in those parameters after surgical treatment.

To our knowledge, our study is the first that shows quantitatively the effect of infiltration therapy by Botox over the piriformis muscle: atrophy and fatty infiltration

Botox injection into the piriformis muscle in the treatment of the eponymous syndrome has morphological effects on the muscle that can be demonstrated and followed-up by MRI

Alshaikh, M, Michel, F, Kastler, B, Aubry, S, An MRI Evaluation of Piriformis Muscle Modifications Induced by Botulinum Toxin (Botox) Injections.  Radiological Society of North America 2013 Scientific Assembly and Annual Meeting, December 1 - December 6, 2013 ,Chicago IL. http://archive.rsna.org/2013/13027438.html