During caloric irrigation of the right ear with water at 44 degrees C in a patient with an intact tympanic membrane, the expected direction of the induced nystagmus fast phase is:

• A Downbeat vertical
• B Left beating
• C Upbeat vertical
• D Right beating ✓

Explanation

Warm irrigation produces convection currents that depolarise the ipsilateral horizontal semicircular canal, creating a slow phase away from the irrigated ear and a fast phase toward it. The classic mnemonic COWS (Cold Opposite, Warm Same) gives right-beating nystagmus for warm water in the right ear. Cold water would give left-beating nystagmus, which kills distractor B.

Reference: Cummings Otolaryngology: Head and Neck Surgery, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.