Caloric Test
Introduction
The caloric test was developed by Robert Barany in the early 1900s. He was the first to turn the caloric response into a practical tool for assessing vestibular function.[1]
Purpose
Caloric testing is a valuable clinical method used to assess and measure the function of each vestibular system separately. It works by stimulating the vestibulo-ocular reflex (VOR), which depends on a properly functioning brainstem. The VOR helps keep the eyes focused on a still object while the head moves, allowing steady vision.
In caloric testing, this reflex is triggered to evaluate the health of the lateral semicircular canals and their nerve connections. Abnormal responses may indicate vestibular problems and are often seen in people with one-sided hearing loss, making the test a helpful additional diagnostic tool.[2]
Technique
1. Patient Positioning
The patient lies on their back (supine) with the head elevated at a 30° angle.
This position brings the lateral semicircular canals into a vertical alignment for accurate stimulation.
2. Stimulation Methods
Water or air can be used for thermal stimulation.
Water is preferred for its consistency and effectiveness.
Air requires more skill due to higher variability.
3. Water Caloric Irrigation
Each ear is irrigated with:
Warm water: 44°C
Cold water: 30°C
Duration: 40 seconds
These temperatures are ±7°C from body temperature.[3]
4. Air Caloric Irrigation
Air temperatures:
Warm air: 50°C
Cold air: 24°C
Flow rate: 8 L/min
Duration: 60 seconds
Other protocols may use 45.5°C and 27.5°C for 100 seconds at 13 L/min.
5. Observation
Monitor for nystagmus (eye movements): note its onset, direction, intensity, and duration.
Use electronystagmography (ENG) or video-Frenzel goggles for accurate recording.
6. Interpretation of Results
Normal Response
Both ears produce symmetrical nystagmus.
Direction and intensity fall within expected limits.
Asymmetrical Response
Suggests unilateral or bilateral vestibular dysfunction, indicating an issue in one or both labyrinths.[3]
The video below will show about the caloric test;
Evidence
Caloric testing is a useful method for evaluating dizziness and helps distinguish between central and peripheral causes. Monothermic testing (using only warm stimulation) can be helpful when there's a low chance of a peripheral issue, but its sensitivity varies widely (54%–100%), making it less reliable when the likelihood is moderate. For patients with a high suspicion of peripheral vestibular dysfunction, bithermic testing (using both warm and cold stimuli) is recommended for more accurate results.[2]
Although warm water is commonly used, warm air is also effective, showing 87% sensitivity and a 90% negative predictive value for detecting unilateral vestibular weakness when a 25% difference between ears is the cutoff. However, cold stimulation often produces a stronger and clearer nystagmus response, making it more specific for confirming peripheral lesions. For patients where air or water stimulation is not suitable, such as those with chronic ear infections or a perforated eardrum, near-infrared radiation offers an effective alternative for caloric testing.[5][6][7]
References
- ↑ BellADEF A. What Barany’s caloric test might have overlooked: The primary factor may be the middle ear muscles. Journal of Hearing Science. 2019;9(4).
- ↑ 2.0 2.1 Murphy KA, Anilkumar AC. Caloric testing.
- ↑ 3.0 3.1 Gonçalves DU, Felipe L, Lima TM. Interpretation and use of caloric testing. Revista Brasileira de Otorrinolaringologia. 2008;74:440-6.
- ↑ Youtu.be. Available at: https://youtu.be/6F1sSfGnTXk?si=tbTOSvsY6fkI0Trj (Accessed: July 14, 2025).
- ↑ Bush, M. L., Bingcang, C. M., Chang, E. T., Fornwalt, B., Rayle, C., Gal, T. J., Jones, R. O., & Shinn, J. B. (2013). Hot or cold? Is monothermal caloric testing useful and cost-effective?. The Annals of otology, rhinology, and laryngology, 122(6), 412–416. https://doi.org/10.1177/000348941312200611
- ↑ Barros AC, Caovilla HH. From nystagmus to the air and water caloric tests. Braz J Otorhinolaryngol. 2012 Jul-Aug;78(4):120-5.
- ↑ Walther LE, Asenov DR, DI E MA. Caloric stimulation with near infrared radiation does not induce paradoxical nystagmus. Acta Otorhinolaryngologica Italica. 2011 Apr;31(2):90.