Diagnostic potential of acoustic startle reflex, acoustic blink reflex, and electro-oculography in progressive supranuclear palsy: a prospective study.

We carried out a prospective study to analyze the diagnostic potential of acoustic startle reflex (ASR), acoustic blink reflex (ABR) and electro-oculography (EOG) in early stages of atypical parkinsonian syndrome. The study was carried out in a consecutive series of 41 patients clinically diagnosed as atypical parkinsonism (mean time from first symptoms of 38 months and follow-up of 26 months). The three procedures were carried out immediately after the first clinical evaluation. ASR and ABR were elicited by auditory stimuli while the patient was attending to a simple reaction time task. Outcome measures were: ASR (absence/presence, latency), ABR (absence/presence, latency) and EOG (suggestive/not suggestive of progressive supranuclear palsy [PSP]). Final clinical diagnosis was carried out by two neurologists blind to the neurophysiological results. A study of diagnostic sensitivity and odds ratio (OR) calculation for the PSP diagnosis was carried out. Neurophysiological examination showed the following sensitivity/specificity (%) for the diagnosis of PSP: ASR: 100/89; ABR 85/89; EOG 100/72. OR values were: ASR: 0.011; ABR: 0.037; EOG: 0.038. The three tests taken simultaneously showed a sensitivity of 100% and a specificity of 95%. The three neurophysiological tests investigated provided sensitive and specific measures with predictor value in early stages of atypical parkinsonian syndrome.