Influence of Physiotherapy on the Spastic Musculus Biceps Brachii Under Routine Botulinum Toxin Injection. - An Explorative MRI Study

Intramuscular application of botulinum toxin (BoNT) is used as a successful therapy of muscle spasticity. Clinical practice shows, that even with the use of special guidance techniques to increase accuracy of targeting, BoNT may spread to adjacent sites by diffusion. This causes fluctuating treatment response, unintended side effects, and decrease of effect due to production of antibodies. Hence, clinicians require increase of efficacy and safety by dose reduction, improvement of injection technique, and additional treatment strategies. Referring to this, animal model showed increased efficacy and decreased systemic side effects of BoNT in the injected muscle after active or passive manipulation of muscle. The mechanism of this effect remain unclear.

T2 and (Diffusion Tensor Imaging) DTI technique can evaluate the in-vivo distribution of fluids in human skeletal muscle. In addition, it allows to differentiate denervated muscle tissue, caused by BoNT injections, from surrounding unaffected muscle tissue.

Up to the investigators knowledge, neither a human, in vivo measurement of the influence of passive muscle activity on the area of denervation, nor the primary, in-vivo distribution of BoNT within spastic human muscle tissue, been evaluated.

The aim of this explorative study is:

• to monitor the inflow and regional distribution of the injection bolus by dynamic T2-weighted-, DTI-sequences;
• to assess the effect of passive muscle exercise on the area of denervated, caused by BoNT, measured by DTI-, T2-weighted and flair sequences.

The investigators hypothesize, that

• intramuscular denervation area, measured by DTI-, T2-weighted and Fluid Attenuated Inversion Recovery (FLAIR) sequences, 3 weeks after routine BoNT injection, is facilitated by passive muscle exercise;
• primary distribution of the injected BoNT bolus can be non-invasively monitored by dynamic T2-, DTI- and T2 weighted sequences.

Therefore, in this investigator blinded, cross-over study, 6 patients suffering from upper limb spasticity, including musculus biceps brachii, will be investigated. (Magnetic Resonance Tomography) MRI of the musculus biceps brachii will be performed at two consecutive, routine BoNT-injection days (baseline and week 16). Patients receive dosage as clinically indicated, due to routine treatment. Patients will be randomised to receive thirty minutes of physiotherapy of the affected arm, including exercise of the elbow flexors, at one of the injection days (baseline, or week 16, respectively). In addition, MRI will be repeated 3 weeks after injection.