Hippus

Hippus, also known as pupillary athetosis, is spasmodic, rhythmic, but regular dilating and contracting pupillary movements between the sphincter and dilator muscles.[1][2] Pupillary hippus comes from the Greek hippos meaning horse, perhaps due to the rhythm of the contractions representing a galloping horse.[3]

It is particularly noticeable when pupil function is tested with a light,[2] but is independent of eye movements or changes in illumination.[1] It is usually normal, however pathological hippus can occur.[2][3]

Pathologic hippus, the phenomena of increased oscillation or their amplitude, is associated with aconite poisoning,[4] altered mental status, trauma, cirrhosis, and renal disease; suggesting a common pathway of frontal lobe dysfunction.[5] A retrospective study of 117 hospitalized patients with hippus noted an increased 30-day mortality when compared to controls and adjusted for other factors (odds ratio=4.1, p<0.001).[5]

References

  1. ↑ 1.0 1.1 McLaren J. W., Erie J. C., Brubaker R. F. (1992). "Computerized analysis of pupillograms in studies of alertness". Investigative Ophthalmology and Visual Science 33: 671–6.
  2. ↑ 2.0 2.1 2.2 Cassin, B. and Solomon, S. Dictionary of Eye Terminology. Gainesville, Florida: Triad Publishing Company, 1990.
  3. ↑ 3.0 3.1 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.
  4. ↑ Forensic and State Medicine: Reddy
  5. ↑ 5.0 5.1 Denny JC, Arndt FV, Dupont WD, Neilson EG (2008). "Increased hospital mortality in patients with bedside hippus". Am J Med 121 (3): 239–45. doi:10.1016/j.amjmed.2007.09.014. PMID 18328309.