Caloric reflex test

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In medicine, the caloric reflex test is a test of the vestibulo-ocular reflex. It is used by audiologists and other trained professionals to validate a diagnosis of asymmetric function in the peripheral vestibular system. Calorics are usually a subtest of the electronystagmography (ENG) test battery.

Contents

[edit] Technique and results

It involves irrigating cold or warm water or air into the external auditory canal.

  • If the water is cool (30°C) the eyes turn toward the ipsilateral ear, with horizontal nystagmus (quick horizontal eye movements) to the contralateral ear.[1][2]
  • If the water is warm (44°C) the eyes turn toward the contralateral ear, with horizontal nystagmus to the ipsilateral ear.
  • Absent reactive eye movement suggests vestibular weakness of the horizontal semicircular canal of the side being stimulated.

[edit] Mnemonic

Mnemonics are common in the medical literature. One mnemonic used to remember the FAST direction of nystamgus is COWS.[3]

COWS: Cold water = FAST phase of nystagmus to the side Opposite from the cold water filled ear, Warm water = FAST phase of nystagmus to the Same side as the warm water filled ear.

[edit] References

  1. ^ Bardorf CM, Van Stavern GP. Nystagmus, Acquired. eMedicine.com. URL: http://www.emedicine.com/oph/topic339.htm. Accessed on: August 17, 2006.
  2. ^ Narenthiran G. Neurosurgery Quiz. Annals of Neurosurgery. URL: http://www.annals-neurosurgery.org/quiz/nsq2/#a3. Accessed on: August 17, 2006.
  3. ^ Webb C (1985). "COWS caloric test.". Ann Emerg Med 14 (9): 938. doi:10.1016/S0196-0644(85)80671-5. PMID 4026002. 

[edit] External links

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Nervous system physiology: neurophysiology - reflex
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