III. Technique
- Examine External Ear canals first to confirm no significant ear Trauma, or Tympanic Membrane Perforation
- Patient supine with head at 30 degrees elevation
- Isolates input of horizontal semicircular canals
- Instill 10-20 ml iced saline or water into auditory canal
- Use 20 cc syringe
- Use butterfly tubing with needle cut off
- Cools mastoid bone and alters endolymphatic flow
- Stimulates vestibular nuclei as if head turned rapidly to opposite side
IV. Interpretation: Findings
-
Nystagmus both eyes slow toward cold, fast to midline (away from cold)
- Not comatose
- Both eyes tonically deviate toward cold water
- No eye movement
- Brainstem injury
- Movement only of eye on side of stimulus
- Internuclear Ophthalmoplegia
- Suggests Brainstem structural lesion
V. Interpretation: By Condition
- Normal patient
- Nystagmus both eyes slow toward cold, fast to midline (away from cold)
- Deep coma (Tonic pupil response)
- Eyes will deviate toward the cold water infusion
- Rapid correction is slow or absent
-
Brainstem lesion
- Eyes will not deviate on Cold Calorics (no slow or fast component)
- Lesion at CN 3 or 6 (or the Medial Longitudinal Fasciculus)
- Results in abnormal Cold Calorics depending on the lesion location