Intrafusal effects of botulinum toxin in post-stroke upper limb spasticity.

Abstract

A previous study in subjects with focal dystonia suggested that the greater and longer-lasting effect induced by botulinum toxin type A (BoNT-A) on the tonic vibration reflex (TVR) than on the maximal M-wave (M-max) might be the physiological marker of the toxin's action at the level of intrafusal muscle fibres. With this approach, we investigated the possible effect of BoNT-A on fusimotor synapses in eight patients with post-stroke spasticity (four with no residual motor capacity before treatment and four with partially spared muscle strength and residual motor capacity). TVR and M-max were recorded from the wrist and finger flexor muscles before treatment and at 1, 4 and 7 months afterwards. The TVR reduction was greater than the M-max reduction and remained fairly constant over time only in the subjects with a residual motor capacity before the treatment. This pilot study suggests that some degree of strength and active movement is necessary for the action of BoNT-A on intrafusal fibres.

• Authors: C Trompetto, M Bove, L Avanzino, G Francavilla, A Berardelli, G Abbruzzese
• Journal: European journal of neurology (Eur J Neurol) Vol. 15 Issue 4 Pg. 367-70 (Apr 2008) ISSN: 1468-1331 [Electronic] England
• PMID: 18266870 (Publication Type: Clinical Trial, Journal Article)

Chemical References

• Neuromuscular Agents
• Botulinum Toxins, Type A

Topics

• Adult
• Aged
• Analysis of Variance
• Botulinum Toxins, Type A (administration & dosage)
• Electromyography (methods)
• Female
• Humans
• Injections, Intramuscular (methods)
• Male
• Middle Aged
• Muscle Contraction (drug effects)
• Muscle Spasticity (drug therapy, etiology, pathology)
• Neuromuscular Agents (administration & dosage)
• Reflex, Stretch (drug effects)
• Stroke (complications)
• Upper Extremity