title: Botulinum toxin modulates cortical maladaptation in post-stroke spasticity.
abstract: BACKGROUND
  Maladaptive plasticity involving the unaffected hemisphere (UH) in stroke patients may contribute to post-stroke deficits, including spasticity. We investigated the central and peripheral effects of botulinum toxin in post-stroke spasticity to determine whether there is modulation of cortical processes in the UH.
  
  
  METHODS
  Transcranial magnetic stimulation and peripheral nerve excitability studies were undertaken in 5 stroke patients with upper limb spasticity before (T1) and 6 weeks after (T2) botulinum injection.
  
  
  RESULTS
  Transcranial magnetic stimulation demonstrated inexcitable motor cortices of the affected hemisphere at T1 and T2, and short-interval intracortical inhibition (SICI) in the UH was significantly reduced at T1. At T2, SICI in the UH increased significantly compared with T1, normalizing to controls, and was found to be associated with clinical improvements in spasticity. Peripheral excitability parameters were unchanged after injection.
  
  
  CONCLUSIONS
  Cortical excitability changes were demonstrated in UH, suggesting that the clinical benefits of botulinum toxin relate to modulation of abnormal central reorganization (maladaptive plasticity) in post-stroke spasticity.
authors.affiliation: Neuroscience Research Australia and Prince of Wales Clinical School, University of New South Wales, Barker Street, Randwick, New South Wales 2031, Australia.
authors.forename: William
authors.initials: W
authors.lastname: Huynh
authors.forename: Arun V
authors.initials: AV
authors.lastname: Krishnan
authors.forename: Cindy S-Y
authors.initials: CS
authors.lastname: Lin
authors.forename: Steve
authors.initials: S
authors.lastname: Vucic
authors.forename: Pesi
authors.initials: P
authors.lastname: Katrak
authors.forename: Michael
authors.initials: M
authors.lastname: Hornberger
authors.forename: Matthew C
authors.initials: MC
authors.lastname: Kiernan
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects / Q000502:physiology; D000368:Aged; D000369:Aged, 80 and over; D019274:Botulinum Toxins, Type A / Q000494:pharmacology / Q000627:therapeutic use*; D019054:Evoked Potentials, Motor / Q000187:drug effects / Q000502:physiology; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000187:drug effects / Q000502:physiology*; D009128:Muscle Spasticity / Q000175:diagnosis / Q000188:drug therapy* / Q000503:physiopathology*; D020521:Stroke / Q000175:diagnosis / Q000188:drug therapy* / Q000503:physiopathology*; D050781:Transcranial Magnetic Stimulation / Q000187:drug effects
chemical_list: D019274:Botulinum Toxins, Type A