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J Rehabil Med. 2015 Nov;47(10):910-6. doi: 10.2340/16501977-2014.

Plastic changes in spinal synaptic transmission following botulinum toxin A in patients with post-stroke spasticity.

Author information

1
APHM, Hôpital de la Timone, Pôle de Médecine Physique et de Réadaptation, FR-13385, Marseille, France. E-mail : marjorie.kerzoncuf@ap-hm.fr.

Abstract

OBJECTIVE:

The therapeutic effects of intramuscular injections of botulinum toxin-type A on spasticity can largely be explained by its blocking action at the neuromuscular junction. Botulinum toxin-type A is also thought to have a central action on the functional organization of the central nervous system. This study assessed the action of botulinum toxin-type A on spinal motor networks by investigating post-activation depression of the soleus H-reflex in post-stroke patients. Post-activation depression, a presynaptic mechanism controlling the synaptic efficacy of Ia-motoneuron transmission, is involved in the pathophysiology of spasticity.

PATIENTS:

Eight patients with chronic hemiplegia post-stroke presenting with lower limb spasticity and requiring botulinum toxin-type A injection in the ankle extensor muscle.

METHODS:

Post-activation depression of soleus H-reflex assessed as frequency-related depression of H-reflex was investigated before and 3, 6 and 12 weeks after botulinum toxin-type A injections in the triceps surae. Post-activation depression was quantified as the ratio between H-reflex amplitude at 0.5 and 0.1 Hz.

RESULTS:

Post-activation depression of soleus H-reflex, which is reduced on the paretic leg, was affected 3 weeks after botulinum toxin-type A injection. Depending on the residual motor capacity of the post-stroke patients, post-activation depression was either restored in patients with preserved voluntary motor control or further reduced in patients with no residual voluntary control.

CONCLUSION:

Botulinum toxin treatment induces synaptic plasticity at the Ia-motoneuron synapse in post-stroke paretic patients, which suggests that the effectiveness of botulinum toxin-type A in post-stroke rehabilitation might be partly due to its central effects.

PMID:
26424152
DOI:
10.2340/16501977-2014
[Indexed for MEDLINE]
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