What is Bilateral Caloric Weakness?

10 mins
09 February 2022


The answer here depends on the stimulus and recording parameters, and guidelines for these may vary e.g. between different regions. For this reason it is often recommended that vestibular clinics gather their own normative data.  The British Society of Audiology guidelines indicate a value of < 8 º / sec for all 4 irrigations as indicative of bilateral weakness (BSA 2010) whereas another commonly used criteria is that the total response should be 20 °/sec or greater. Zapala et al (2008) present an extensive literature review of the ranges shown in different studies, and provide a description based on several thousand cases with caloric response data.

Please note that the law of large numbers applies when considering the interaural ratios (canal paresis and directional preponderance). The low overall numbers in a case of bilateral caloric weakness make these ratios unstable so should be ignored when this is the case.

Related course: Caloric test for beginners


References and caveats

Zapala, D.D., Olsholt, K.F., and Lundy, L.B. (2008) A comparison of water and air caloric responses and their ability to distinguish between patients with normal and impaired ears. Ear and Hearing 29 (4) pages 585-600.


Michael Maslin
After working for several years as an audiologist in the UK, Michael completed his Ph.D. in 2010 at The University of Manchester. The topic was plasticity of the human binaural auditory system. He then completed a 3-year post-doctoral research program that built directly on the underpinning work carried out during his Ph.D. In 2015, Michael joined the Interacoustics Academy, offering training and education in audiological and vestibular diagnostics worldwide. Michael now works for the University of Canterbury in Christchurch, New Zealand, exploring his research interests which include electrophysiological measurement of the central auditory system, and the development of clinical protocols and clinical techniques applied in areas such as paediatric audiology and vestibular assessment and management.

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