Unilateral injection of botulinum toxin in blepharospasm: single fiber electromyography and blink reflex study

Mov Disord. 1996 Jan;11(1):27-31. doi: 10.1002/mds.870110107.


We studied six patients affected with blepharospasm (BSP). We injected botulinum toxin (BTX) around only one eye and saline solution around the other. Clinical rating of BSP was performed. Single fiber electromyography (SFEMG), compound motor action potential (cMAP) at the orbicularis oculi muscle by stimulation of the facial nerve, blink reflex, and blink reflex recovery curve were recorded. All clinical and electrophysiological investigations were carried out before, and 1, 2, and 4 weeks after treatment. Evidence of bilateral clinical benefit was provided. Following therapy, facial cMAP decreased bilaterally and SFEMG revealed statistically significant changes on both sides while the excitability curve of blink reflex remained unmodified. The results confirm that BTX affects merely the neuromuscular junctions. The clinical and neurophysiological effects are present on both sides also for unilateral injection probably because of toxin spreading.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial

MeSH terms

  • Aged
  • Blepharospasm / drug therapy*
  • Blinking / drug effects*
  • Botulinum Toxins / administration & dosage*
  • Botulinum Toxins / adverse effects
  • Electromyography / drug effects*
  • Evoked Potentials, Motor / drug effects
  • Female
  • Functional Laterality / drug effects
  • Humans
  • Injections, Intramuscular
  • Male
  • Middle Aged
  • Neuromuscular Junction / drug effects
  • Synaptic Transmission / drug effects


  • Botulinum Toxins