title: Central effect of botulinum toxin type A in humans.
abstract: This study investigated the changes in the cortical excitability with a paired-pulse transcranial magnetic stimulation (TMS) model after a botulinum toxin type A (BTA) injection in normal humans. Ten healthy subjects were enrolled in the study, which involved applying paired TMS to the motor cortex and recording the motor evoked potentials (MEP) before and after the BTA injection. BTA (2.5 mouse units) was injected into the right extensor digitorum brevis muscle. The amplitudes of MEP during rest and the cortical silent period (CSP) for the period of the tonic muscle contraction were measured at an interstimulus interval (ISI) of 3 ms and 20 ms. One month and three months after BTA injection, the level of intracortical inhibition increased significantly at an ISI of 3 ms and the intracortical facilitation decreased at an ISI of 20 ms. The duration of CSP shortened significantly at an ISI of 3 ms 1 month after BTA injection, which was also shortened significantly at an ISI of 20 ms. These findings were maintained until 3 months after the injection. It was concluded that cortical excitability could be modified by BTA injection in normal humans.
authors.affiliation: Department of Rehabilitation Medicine Seoul National University College of Medicine Seoul National University Borame Hospital Seoul, Republic of Korea.
authors.forename: Dae-Yul
authors.initials: DY
authors.lastname: Kim
authors.forename: Byung-Mo
authors.initials: BM
authors.lastname: Oh
authors.forename: Nam-Jong
authors.initials: NJ
authors.lastname: Paik
mesh_terms: D000328:Adult; D019274:Botulinum Toxins, Type A / Q000494:pharmacology*; D002540:Cerebral Cortex / Q000187:drug effects* / Q000502:physiology / Q000528:radiation effects; D019054:Evoked Potentials, Motor / Q000187:drug effects / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D009498:Neurotoxins / Q000494:pharmacology*; D013997:Time Factors; D050781:Transcranial Magnetic Stimulation / Q000379:methods
chemical_list: D009498:Neurotoxins; D019274:Botulinum Toxins, Type A