We will be proposing in this paper a new approach to bilateral assessment based on PLR.Īutomated infrared pupillometry (AIP) is a highly reliable objective assessment tool for monitoring the pupil. Anisocoria which is the difference of the two diameters of the pupils at rest, is another expression of asymmetry often associated to intracranial pathologies. The swinging flashlight test is a tool for measuring relative afferent pupillary defect, a condition of many retinal or optical nerve diseases. The “swinging flashlight test” for example is a well-known procedure in neuro-ophthalmology in which the examiner, by swinging a penlight back and forth between the two eyes, tries to detect a difference in the amount of the dilation between the two pupils. īilateral assessments of the pupil light reflex are in fact contemplated in several clinical conditions to verify this symmetric nature. Although the two decussations in the optic chiasm and in the superior colliculus are not perfectly symmetrical, the neuroanatomy and dynamics of the two direct PLR responses – direct because the pupil being measured is ipsilateral to the stimulated eye – are identical under normal conditions. From there, pupillary motor fibers travel with the efferent oculomotor cranial nerve (CN III) to reach the ciliary ganglia of the eye (third synapse) and finally, via short ciliary nerves, to the sphincter muscle of the pupil. Each pretectal nucleus then projects to synapse onto the two oculomotor Edinger-Westphal nuclei (EWN). Output of these ganglion cells coalesces into the optic cranial nerve (CN II), partially crosses in the optic chiasm with fibers of the contralateral optic nerve, and synapses on the ipsilateral pretectal nucleus anterior to the superior colliculus. The neural pathway of the pupil light reflex (PLR) originates in the retina where a layer of retinal ganglion cells collects light both intrinsically, due to their photosensitive nature, and extrinsically, by connecting to rods and cones. In healthy individuals, a flash of light shone into the eye will cause a brisk constriction of both pupils. The NPi differential is an important factor that clinicians should consider when managing critically ill neurological injured patients admitted to the neurocritical care units. Finally, our analysis confirmed ≥ 0.7 as the optimal cutoff value for the NPi differential (AUC = 0.71, P < .001). When patients experience both abnormalities, abnormal (NPi < 3.0) and an NPi differential, the latter has an anticipatory relationship with respect to the former ( P < .001 for z-score skewness analysis). Patients with TBI and at least 1 occurrence of an NPi differential during their NSICU stay have higher discharge modified Rankin Scale scores (4.1) compared to those without an NPi differential (2.9 P < .001). Stroke patients with at least 1 occurrence of an NPi differential during their NSICU stay have higher DC mRS scores (3.9) compared to those without an NPi differential (2.7 P < .001). and 1 Japanese hospitals and for two cohorts of brain injuries: stroke (including subarachnoid hemorrhage, intracerebral hemorrhage, acute ischemic stroke, and aneurysm, 1,200 total patients) and 185 traumatic brain injury (TBI) patients for a total of more than 54,000 pupillary measurements. We explored NPi differential by considering the modified Rankin Score at discharge (DC mRS) among patients admitted to neuroscience intensive care units (NSICU) of 4 U.S. The presence of an NPi differential (a difference ≥ 0.7 between the left and right eye) is a potential sign of neurological abnormality. AIP values demonstrate emerging value as a prognostic tool with predictive properties that could allow practitioners to anticipate neurological deterioration and recovery. NPi quantifies the PLR and ranges from 0 to 5 in healthy individuals, the NPi of both eyes is expected to be ≥ 3.0 and symmetric. Automated infrared pupillometry (AIP) and the Neurological Pupil index (NPi) provide an objective means of assessing and trending the pupillary light reflex (PLR) across a broad spectrum of neurological diseases.
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