title: Comparison between intramuscular and perimuscular injections of botulinum toxin type A.
abstract: BACKGROUND
  Botulinum toxin type A (BTX-A) must be injected in the intramuscular area to exert its paralytic effect. The durability of the BTX-A effect varies in different patients, and this fact can result from different locations of the drug injection, for example, the muscle peripheral area (perimuscular). This study aimed to evaluate whether a difference exists in the effect duration of the muscle paralysis between intramuscular and perimuscular injections of BTX-A.
  
  
  METHODS
  This study used 18 male New Zealand rabbits divided into two groups (A and B) based on the location of the BTX-A injection. The group A animals received 10 units of BTX-A diluted with 0.1 ml of normal saline injected perimuscularly. The group B animals received the same dosage injected in the intramuscular area of the left masseter muscle. An electroneurophysiologic study was performed 1 week before the experiment for all the animals, then repeated 1, 4, and 8 weeks after the toxin injection.
  
  
  RESULTS
  The amplitude values recorded in the masseter muscle were significantly lower in both groups throughout the study than the physiologic amplitude. The comparison between groups A and B did not show any statistically significant amplitude variations throughout the 8 weeks.
  
  
  CONCLUSIONS
  No significant difference in the neuromuscular blockade induced by botulinum toxin type A was observed between injections into the muscle peripheral area and intramuscular injections.
authors.affiliation: Fundação Bahiana para Desenvolvimento das Ciências, Técnica Operatória e Cirurgia Experimental 1, Av. Dom João VI, 274-Brotas-Salvador, Bahia, Brazil.
authors.forename: José H
authors.initials: JH
authors.lastname: Campos
authors.forename: Lise B
authors.initials: LB
authors.lastname: Oliveira
authors.forename: Taise O
authors.initials: TO
authors.lastname: Queiroz
authors.forename: Kleber P
authors.initials: KP
authors.lastname: Santos
authors.forename: Francesca M
authors.initials: FM
authors.lastname: Freitas
mesh_terms: D000818:Animals; D019274:Botulinum Toxins, Type A / Q000008:administration & dosage*; D004333:Drug Administration Routes; D004576:Electromyography / Q000295:instrumentation; D007273:Injections, Intramuscular; D008297:Male; D008406:Masseter Muscle; D009465:Neuromuscular Agents / Q000008:administration & dosage*; D011817:Rabbits
chemical_list: D009465:Neuromuscular Agents; D019274:Botulinum Toxins, Type A