Pupillary hippus as clinical manifestation of refractory autonomic nonconvulsive status epilepticus: Pathophysiological implications

Fernández‐Torre, José L.; Paramio-Paz, Alicia; Ríos, Icíar Lorda-de los; Martín-García, María; Hernández-Hernández, Miguel A.

doi:10.1016/j.seizure.2018.11.006

Cited by 8 publications

(4 citation statements)

References 4 publications

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“…The results presented are preliminary evidence for using an alternative method to pupillary stimulation. In the short term, we propose connecting with electroencephalography tools, which allow us to know the behavior that this device induces and evokes when performing neurological examinations through the use of light patterns, such as Fernández-Torre et al [29], that identify nonconvulsive status epilepticus by the EEG and the pupillometry test captured prolonged oscillations of pupillary diameter. Likewise, different stimulation protocols will be performed to improve the detection and generalization of the detection model as well as the improvement of the device to make it more portable, without the necessity of external devices, offering diagnostic techniques with greater portability, lower equipment maintenance costs, and real-time processing.…”

Section: Discussionmentioning

confidence: 99%

Characterization of Pupillary Light Response through Low-Cost Pupillometry and Machine Learning Techniques

Gutiérrez-Hernández,

Gómez-Díaz,

Casillas-Rodríguez

et al. 2024

Eng

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This article employed pupillometry as a non-invasive technique to analyze pupillary light reflex (PLR) using LED flash stimuli. Particularly, for the experiments, only the red LED with a wavelength of 600 nm served as the light stimulation source. To stabilize the initial pupil size, a pre-stimulus (PRE) period of 3 s was implemented, followed by a 1 s stimulation period (ON) and a 4 s post-stimulus period (POST). Moreover, an experimental, low-cost pupillometer prototype was designed to capture pupillary images of 13 participants. The prototype consists of a 2-megapixel web camera and a lighting system comprising infrared and RGB LEDs for image capture in low-light conditions and stimulus induction, respectively. The study reveals several characteristic features for classifying the phenomenon, notably the mobility of Hjórth parameters, achieving classification percentages ranging from 97% to 99%, and offering novel insights into pattern recognition in pupillary activity. Moreover, the proposed device successfully captured the PLR from all the participants with zero reported incidents or health affectations.

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Section: Discussionmentioning

confidence: 99%

Characterization of Pupillary Light Response through Low-Cost Pupillometry and Machine Learning Techniques

Gutiérrez-Hernández,

Gómez-Díaz,

Casillas-Rodríguez

et al. 2024

Eng

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“…The term hippus has been used for many centuries and was already used by Hippocrates and Galen (9). Thought it has been frequently associated with pathology, like epilepsy (10,11), it is a physiological and ubiquitous phenomenon (9,12) occurring in adults and children (13). Yoss et al define hippus as follows: "an inconstant spontaneous bilateral synchronous rhythmic constriction and [dilatation] of the pupils of sufficiently large amplitude to be easily visible by the clinician" (12).…”

Section: Introductionmentioning

confidence: 99%

“…Turnbull et al (16) find, by locally (at the eyes level) and selectively inhibiting either the parasympathetic (with tropicamide) or the sympathetic (phenylephrine) branch of the ANS, that hippus is modulated only by the parasympathetic nervous system (16,17). However, there is also increasing evidence that hippus may be controlled by the rivalry of sympathetic and parasympathetic activation (10,11,13). In fact, Centeno et al (10) and Fernández-Torre et al (11) suggest hippus could be due to cyclic periods of sympathetic activation followed by a rebalancing or increase of parasympathetic tone (postictal phase).…”

Section: Introductionmentioning

confidence: 99%

“…However, there is also increasing evidence that hippus may be controlled by the rivalry of sympathetic and parasympathetic activation (10,11,13). In fact, Centeno et al (10) and Fernández-Torre et al (11) suggest hippus could be due to cyclic periods of sympathetic activation followed by a rebalancing or increase of parasympathetic tone (postictal phase). Moreover, Bufo et al (13) find a correlation between the hippus frequency and peaks of electrodermal activity which tends to support this hypothesis.…”

Section: Introductionmentioning

confidence: 99%

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Top-down and bottom-up influences on pupil hippus

Rabadan,

Bufo,

Ricou

et al. 2024

Preprint

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Pupil diameter, controlled by the autonomic nervous system (ANS), reflects numerous processes, from arousal to cognitive functions. In particular, the characteristics of the pupil at rest, its size and dynamics, reflect the tonic activity of the ANS. However, which factor can influence these pupillary characteristics at rest remains unclear. Pupil has been shown to have a physiological, rhythmic oscillatory activity called hippus which is naturally occurring in children and adults and is still poorly characterised. Our aim is to better characterise the hippus by investigating how its parameters are influenced by different bottom-up (illumination) and top-down (cognitive load) conditions. Thirty adults were included in the study (19-35 years old). In order to disentangle the influence of illumination and cognitive load, we recorded pupil size variations during 5 randomly appearing blocks. For each block, the participant had to fixate a central cross. The blocks varied according to gradients of illumination (11 lux, 19 lux and 28 lux) and cognitive load (fixation, dot counting and mental subtraction). Three main parameters were assessed: the median pupil diameter, and the frequency and amplitude of the hippus. We observed clear differences between the conditions. For bottom-up variations of illumination, pupil size and hippus amplitude decreased when illumination increased. For top-down conditions, a high cognitive load led to a greater dilation of the pupil and a greater hippus frequency. Overall, top-down and bottom-up processing influenced pupillary parameters differently, probably through shared integrative structures like the locus coeruleus and superior colliculus.

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