Auditory startle response in cervical dystonia.
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.
Müller
Jörg
J
Department of Neurology, University Hospital Innsbruck, Innsbruck, Austria.
Kofler
Markus
M
Wenning
Gregor K
GK
Seppi
Klaus
K
Valls-Solé
Josep
J
Poewe
Werner
W
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*
D009465:Neuromuscular Agents; D019274:Botulinum Toxins, Type A