Habituation of the auditory startle response in cervical dystonia and Parkinson's disease.
The auditory startle response (ASR) is a brainstem reflex elicited by an unexpected acoustic stimulus. In focal dystonia (FD), the excitability of brainstem neurons is abnormally enhanced. To identify a possible impact of this pathology on the processing of acoustic stimuli, we studied the habituation of the ASR in patients (n = 11) with FD and compared the findings to those of patients with Parkinson's disease (PD; n = 11) and controls (n = 11). Latencies in FD patients did not differ from those of controls but were delayed in PD patients compared to controls (p < 0.0001). Habituation was normal at the orbicularis oculi muscles but reduced at the sternocleidomastoid muscles in FD (p = 0.005). Habituation in PD was comparable to controls. Normal latencies and sequence activation indicate intact neural pathways mediating the ASR in FD. Impaired habituation of the ASR points towards a reduced inhibition of acoustic stimuli in FD.
Putzki
Norman
N
Department of Neurology, University of Duisburg-Essen, Essen, Germany. norman.putzki@uni-due.de
Graf
Karoline
K
Stude
Philipp
P
Diener
Hans-Christoph
HC
Maschke
Matthias
M
D000161:Acoustic Stimulation / Q000379:methods; D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D004307:Dose-Response Relationship, Radiation; D004576:Electromyography / Q000379:methods; D005260:Female; D006185:Habituation, Psychophysiologic / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000503:physiopathology*; D011930:Reaction Time / Q000502:physiology; D013216:Reflex, Startle / Q000502:physiology*; D014103:Torticollis / Q000503:physiopathology*