Caloric reflex test
| Caloric reflex test, vestibulo-ocular reflex | |
|---|---|
 Caloric test. Cold water introduced into right external meatus showing effects opposite to that produced by introduction of hot water. (Lawrence et al. 1960) | |
| ICD-9-CM | 95.44 |
| MedlinePlus | 003429 |
In
Utility
The test is commonly used by physicians, audiologists and other trained professionals to validate a diagnosis of asymmetric function in the peripheral
One novel use of this test has been to provide temporary pain relief from
Technique and results
Ice cold or warm water or air is introduced into the
- If the water is warm (44 °C or above) endolymph in the ipsilateral horizontal canal rises, causing an increased rate of firing in the vestibular afferent nerve. This situation mimics a head turn to the ipsilateral side. Both ipsilateralear.
- If the water is cold, relative to body temperature (30 °C or below), the endolymph falls within the semicircular canal, decreasing the rate of vestibular afferent firing. This situation mimics a head turn to the contralateral side. The eyes then turn toward the ipsilateral ear, with horizontal nystagmus to the contralateral ear.[5][6]
Absent reactive eye movement suggests vestibular weakness of the horizontal semicircular canal of the side being stimulated.
In comatose patients with cerebral damage, the fast phase of nystagmus will be absent as this is controlled by the cerebrum. As a result, using cold water irrigation will result in deviation of the eyes toward the ear being irrigated. If both phases are absent, this suggests the patient's brainstem reflexes are also damaged and carries a very poor prognosis.[7]
While large interindividual differences exist, females exhibit a slightly higher average caloric excitability than males.[8]
See also
References
- PMID 11513103.
- PMID 11402363.
- ISBN 978-0-86377-208-5. Retrieved 2010-06-04.
- ^ Purves D, et al. (2004). Neuroscience. Sinauer.
- ^ Nystagmus, Acquired at eMedicine
- ^ Narenthiran G. Neurosurgery Quiz. Annals of Neurosurgery. Accessed on: August 17, 2006.
- PMID 3585347.
- .