P06-Cortical somatosensory processing after botulinum toxin therapy in post-stroke spasticity

Abstract

In movement disorders, neurophysiology and functional MRI demonstrated abnormalities of sensorimotor processing, responding to peripheral botulinum toxin A (BoNT) treatment. We used Modified Ashworth scale (MAS) to assess spasticity and median nerve somatosensory evoked potentials (SEP) to study changes in sensorimotor cortical areas after BoNT therapy of post-stroke arm spasticity. Seventeen patients (10 men, 7 women, average age 60.2 years) with post-stroke arm spasticity were treated with BoNT into the affected muscles. Clinical and electrophysiological examinations were performed before BoNT (W0), 4 (W4) and 11 (W11) weeks after BoNT. BoNT treatment was associated with statistically significant MAS decrease MAS at W4 (W0: 2.63 ± 0.40, W4: 1.65 ± 0.37, P = 0.001) and increase at W11 (2.25 ± 0.41), the reduction against W0 remained significant (P = 0.022). In the impaired limb median nerve SEP, both components of interest manifested non-significant trends of transient decrease at W4. Peak-to-peak P22/N30: W0, 1.83 ± 1.32 μV, W4, 1.33 ± 0.65 μV, W11, 1.57 ± 1.41 μV. N20/P23 at W0: 2.39 ± 2.41 μV, W4: 2.12 ± 1.74 μV, W11: 2.24 ± 2.13 μV. In conclusion, median nerve SEP responses manifested transient non-significant decreases at the time of effective BoNT treatment of post-stroke spasticity, possibly reflecting decreased cortical excitability. Larger patient group may be necessary to reach significance.