title: Auditory startle response in cervical dystonia.
abstract: The excitability of brainstem neurons is abnormally enhanced in patients with cervical dystonia (CD), but the extend of such abnormality is not known. We examined whether patients with CD showed abnormalities in the auditory startle response (ASR), a brainstem reflex elicited by an unexpected loud stimulus. Thirteen patients with CD were investigated 3 months after botulinum toxin treatment. Thirteen healthy volunteers served as controls. ASRs were elicited by binaural high-intensity auditory stimuli. Reflex electromyographic (EMG) activity was recorded simultaneously with surface electrodes bilaterally from masseter, orbicularis oculi, sternocleidomastoid, and biceps brachii muscles. We found that ASR onset latencies were similar for patients and controls. CD patients had significantly lower ASR probabilities than controls (P = 0.007). ASR area under the curve was significantly smaller in CD patients (P = 0.017). Similar to controls, patients showed a significant habituation of ASR (P < 0.001, each); however, CD patients showed a prolonged tonic or phasic EMG activity after the initial ASR that was not observed in controls. Normal latencies and recruitment pattern indicate a preserved organization of intrinsic neural pathways mediating ASR in CD. Reduced ASR probability and magnitude as well as prolonged EMG activity after the proper startle response corroborate and extend previous findings on brainstem dysfunction in CD.
authors.affiliation: Department of Neurology, University Hospital Innsbruck, Innsbruck, Austria.
authors.forename: Jörg
authors.initials: J
authors.lastname: Müller
authors.forename: Markus
authors.initials: M
authors.lastname: Kofler
authors.forename: Gregor K
authors.initials: GK
authors.lastname: Wenning
authors.forename: Klaus
authors.initials: K
authors.lastname: Seppi
authors.forename: Josep
authors.initials: J
authors.lastname: Valls-Solé
authors.forename: Werner
authors.initials: W
authors.lastname: Poewe
mesh_terms: D000328:Adult; D000368:Aged; D001307:Auditory Perception / Q000502:physiology*; D019274:Botulinum Toxins, Type A / Q000627:therapeutic use; D001933:Brain Stem / Q000503:physiopathology*; D004576:Electromyography / Q000295:instrumentation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009465:Neuromuscular Agents / Q000627:therapeutic use; D013216:Reflex, Startle / Q000502:physiology*; D014103:Torticollis / Q000188:drug therapy / Q000503:physiopathology*
chemical_list: D009465:Neuromuscular Agents; D019274:Botulinum Toxins, Type A