Brain Advance Access published online on November 29, 2008
Brain, doi:10.1093/brain/awn317
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Voluntary, spontaneous and reflex blinking in patients with clinically probable progressive supranuclear palsy
1Department of Neurological Sciences and 2Neuromed Institute, Sapienza, University of Rome, Italy
Correspondence to:
Prof. Alfredo Berardelli, Department of Neurological Sciences, Sapienza, University of Rome, Viale dell’Università n° 30, 00185 Rome, Italy E-mail: alfredo.berardelli{at}uniroma1.it
Patients with progressive supranuclear palsy (PSP) often have blinking abnormalities. In this study we examined the kinematic features of voluntary, spontaneous and reflex blinking in 11 patients with PSP and healthy control subjects. Patients were asked to blink voluntarily as fast as possible; spontaneous blinking was recorded during two 60 s rest periods; reflex blinking was evoked by electrical stimulation of the supraorbital nerve. Eyelid movements were recorded with the SMART analyzer motion system. During voluntary blinking the closing and opening phases lasted longer in patients than in healthy subjects. Furthermore, the peak velocity of the closing phase of voluntary blinking was lower in patients than healthy subjects. During spontaneous blinking the blink rate was markedly lower in patients than in control subjects. Patient's recordings also showed kinematic abnormalities of spontaneous (reduced peak velocity of both closing and opening phases) and reflex (reduced peak velocity and increased duration of the opening phase) blinking. Recordings during reflex blinking disclosed an enhanced excitability of the interneuronal pool mediating the closing and opening blink phases. Finally, the pause, a neurophysiological marker of the switching processes between the closing and opening phases, was prolonged in all the three types of blinking. The abnormal kinematic variables correlated with patients’ clinical and kinematic features. Abnormal voluntary, spontaneous and reflex blinking in patients with PSP reflects the widespread cortical, subcortical and brainstem degeneration related to this disease.
Key Words: progressive supranuclear palsy; blinking; movement control
Abbreviations: ANOVA, analysis of variance; ISI, interstimulus interval; MRI, magnetic resonance imaging; NINDS-SPSP, National Institute of Neurological Disorders and Stroke-society for progressive supranuclear palsy; PSP, progressive supranuclear palsy; PSPRS, progressive supranuclear palsy rating score; ROC, receiver operating characteristic
Received July 21, 2008. Revised October 31, 2008. Accepted October 31, 2008.