title: Alteration of central motor excitability in a patient with hemimasticatory spasm after treatment with botulinum toxin injections.
abstract: Hemimasticatory spasm (HMS) is a condition characterized by paroxysmal involuntary contraction of masticatory muscles. We performed an electrophysiological investigation of a single patient with HMS to identify any pathophysiological changes associated with the condition. We identified a delayed M wave and jaw jerk on the affected side and an absent masseteric silent period during spasm. Botulinum toxin injections successfully treated the clinical symptoms and resulted in a significant reduction in the excitability of the blink reflex recovery cycle. These data suggest that HMS may be due to ectopic activity in the motor portion of the trigeminal nerve that is capable of inducing changes in the excitability of central reflex pathways. These changes can be altered by successful treatment with botulinum toxin.
authors.affiliation: Sobell Department of Movement Neuroscience and Movement Disorders, Institute of Neurology, Queen Square, London, United Kingdom.
authors.forename: Pablo
authors.initials: P
authors.lastname: Mir
authors.forename: Francesca
authors.initials: F
authors.lastname: Gilio
authors.forename: Mark
authors.initials: M
authors.lastname: Edwards
authors.forename: Maurizio
authors.initials: M
authors.lastname: Inghilleri
authors.forename: Kailash P
authors.initials: KP
authors.lastname: Bhatia
authors.forename: John C
authors.initials: JC
authors.lastname: Rothwell
authors.forename: Niall
authors.initials: N
authors.lastname: Quinn
mesh_terms: D001767:Blinking / Q000187:drug effects / Q000502:physiology; D019274:Botulinum Toxins, Type A / Q000009:adverse effects / Q000627:therapeutic use*; D001933:Brain Stem / Q000187:drug effects / Q000503:physiopathology; D002908:Chronic Disease; D004558:Electric Stimulation; D004576:Electromyography / Q000187:drug effects; D007839:Functional Laterality / Q000187:drug effects / Q000502:physiology; D006801:Humans; D007273:Injections, Intramuscular; D008297:Male; D008406:Masseter Muscle / Q000187:drug effects / Q000294:innervation*; D008875:Middle Aged; D009046:Motor Neurons / Q000187:drug effects / Q000502:physiology; D009415:Nerve Net / Q000187:drug effects / Q000503:physiopathology; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology; D012008:Recurrence; D012815:Signal Processing, Computer-Assisted; D013035:Spasm / Q000188:drug therapy*; D013126:Spinal Nerve Roots / Q000187:drug effects / Q000503:physiopathology; D014276:Trigeminal Nerve / Q000187:drug effects / Q000503:physiopathology
chemical_list: D019274:Botulinum Toxins, Type A