Voluntary, spontaneous and reflex blinking in patients with clinically probable progressive supranuclear palsy

Abstract

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.

High-speed camera characterization of voluntary eye blinking kinematics

“…Other methods include home video camera recording [5,6] and tracking the displacement of a reflective marker taped onto a subject's upper eyelid using infrared cameras License http://creativecommons.org/licenses/by/3.0/, which permits unrestricted use, provided the original author and source are credited. [4]. In this work, a high-speed video camera was used to study the rapid eye motion of the voluntary blink.…”

“…A high-speed camera does not require such devices, and hence it can be considered to be more convenient for both participants and researchers. Furthermore, the relatively high palpebral aperture measurements [4,9] may also reflect inaccuracies in measurement techniques that involve attaching either tape or coils to the upper eyelid, which may have only approximated the lid margin position. In contrast, more accurate and reliable results could be obtained from high-speed camera images as no extra eye weight, which might affect the blink dynamics, is involved and also the apparent palpebral aperture between the upper and lower eyelids is measured on a sequential series of images, whereas the coil marker is usually attached about 1 mm above the lid margin.…”

Is increased blinking a form of blepharospasm?

“…Whether spontaneous blink generator overactivation depends on altered descending control from basal ganglia or on altered projections from mesial frontal areas to basal nuclei remains unclear. The normal blink reflex recovery cycle (a variable known to be abnormal in several basal ganglia diseases) 16,33 argues against a basal ganglia dysfunction. Consistent with the observation that in patients with movement disorders low dopamine levels determine a reduced BR and enhanced R2 recovery index, 33 the correlation between BR and R2 recovery index further supports the hypothesis that the brainstem neural circuits for the BR differ from those for the R2 recovery cycle.…”

Effects of Position and Task Demands on Endogenous Eyeblink

“…The origin of blink triggers, as well as the neurological basis for kinematics, was hypothesized to be the same in the two positions; however, the kinematic behaviors of the eyelids were observed to be strongly modifi ed by the supine position in addition to the previously reported aging eff ect (Sun, Baker, Rouholiman, Hasan, Caza, & Stava, 1997). Certain eyeblink characteristics, even when in a sitting position, suggest specifi c neurological problems such as Parkinson's disease (Agostino, Bologna, Dinapoli, Gregori, Fabbrini, Accornero, et al, 2008) or progressive supranuclear palsy (Bologna, Agostino, Gregori, Belvisi, Ottaviani, Colosimo, et al, 2009). In addition, the present study suggested that the supine position also affects the blink waveform attributes.…”