Pupillary hippus, also known as pupillary athetosis, is spasmodic, rhythmic, but regular dilating and contracting pupillary movements between the

sphincter A sphincter is a circular muscle that normally maintains constriction of a natural body passage or orifice and which relaxes as required by normal physiological functioning. Sphincters are found in many animals. There are over 60 types in the hum ...

and

dilator Dilator or dilatator is a medical term with a number of uses, including: *A surgical instrument or medical implement used to induce dilation, that is, to expand an opening or passage such as the cervix (see cervical dilator), urethra, esophagu ...

muscles Skeletal muscles (commonly referred to as muscles) are organs of the vertebrate muscular system and typically are attached by tendons to bones of a skeleton. The muscle cells of skeletal muscles are much longer than in the other types of musc ...

.Cassin, B. and Solomon, S. ''Dictionary of Eye Terminology''. Gainesville, Florida: Triad Publishing Company, 1990. Pupillary hippus comes from the Greek ''

hippos A hippo or hippopotamus is either of two species of large African mammal which live mainly in and near water: * Hippopotamus * Pygmy hippopotamus Hippo or Hippos may also refer to: Toponymy * The ancient city of Hippo Regius (modern Annaba, Alg ...

'' meaning horse, perhaps due to the rhythm of the contractions representing a galloping horse.Beatty, J., & Lucero-Wagoner, B. (2000). The pupillary system. In J. T. Cacioppo, L. G. Tassinary & G. G. Bernston (Eds.), ''The handbook of psychophysiology'' (2nd ed.) (pp. 142-162). USA: Cambridge University Press. It is particularly noticeable when

pupil The pupil is a black hole located in the center of the iris of the eye that allows light to strike the retina.Cassin, B. and Solomon, S. (1990) ''Dictionary of Eye Terminology''. Gainesville, Florida: Triad Publishing Company. It appears black ...

function is tested with a light, but is independent of eye movements or changes in illumination. It is usually normal, however pathological hippus can occur. Pathologic hippus, the phenomenon of increased oscillation or their amplitude, is associated with aconite poisoning,Forensic and State Medicine: Reddy

altered mental status An altered level of consciousness is any measure of arousal other than normal. Level of consciousness (LOC) is a measurement of a person's arousability and responsiveness to stimuli from the environment. A mildly depressed level of consciousn ...

, trauma, cirrhosis, and

renal disease Kidney disease, or renal disease, technically referred to as nephropathy, is damage to or disease of a kidney. Nephritis is an inflammatory kidney disease and has several types according to the location of the inflammation. Inflammation ca ...

; suggesting a common pathway of

frontal lobe The frontal lobe is the largest of the four major lobes of the brain in mammals, and is located at the front of each cerebral hemisphere (in front of the parietal lobe and the temporal lobe). It is parted from the parietal lobe by a groove be ...

dysfunction. A retrospective study of 117 hospitalized patients with hippus noted an increased 30-day mortality when compared to controls and adjusted for other factors.

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References