Botulinum toxin changes intrafusal feedback in dystonia: A study with the tonic vibration reflex

Carlo Trompetto, Antonio Currà, Alessandro Buccolieri, Antonello Suppa, Giovanni Abbruzzese, Alfredo Berardelli

Research output: Contribution to journalArticlepeer-review


To investigate the possible role of botulinum toxin (BT-A) injection in reducing muscle afferent feedback, we evaluated electrophysiologically 10 right-handed patients with writer's cramp before and 3 weeks after treatment. The ratio between pre- and postinjection values of maximal M-wave (M-max), maximal voluntary contraction (MVC), and tonic vibration reflex (TVR) were measured in the injected muscles (wrist flexors or extensors). In all the subjects, BT-A injection reduced the TVR more than the M-max and MVC (mean ratio ± SD: TVR, 0.24 ± 0.22; MVC, 0.59 ± 0.32; M-max, 0.68 ± 0.24; P = 0.003). Long-term evaluation of 2 patients disclosed that, after 7 months, when some clinical benefits persisted, M-max and MVC had fully recovered, whereas the TVR was still depressed. This special sensitivity of the TVR to suppression by BT-A injection could be mediated by the chemodenervation of intrafusal muscle fibers, leading to a reduction in spindle inflow to the central nervous system during vibration. The action on intrafusal fibers could alter sensorimotor integration, thus contributing to the clinical benefits of BT-A injection.

Original languageEnglish
Pages (from-to)777-782
Number of pages6
JournalMovement Disorders
Issue number6
Publication statusPublished - Jun 2006


  • Botulinum toxin
  • Focal dystonia
  • Intrafusal feedback
  • Tonic vibration reflex

ASJC Scopus subject areas

  • Clinical Neurology
  • Neuroscience(all)


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