Calorics Flashcards
What does ABB stand for?
Alternating Binaural Bitheraml
What temperatures are used in water calorics?
cool= 30 degrees celsius warm= 44 degrees celsius
What are the 2 types of water irrigation systems?
- closed loop- water circulates in a balloon, the water never actually contacts the ear
- open loop
When is fixation suppression incorporated?
at peak of the nystagmus
What is COWS?
Cold= opposite direction nystagmus Warm= Same direction nystagmus
Why is the fast phase in the opposite direction of the ear being stimulated during cold calorics?
because of hyperpolarization
Formula for Unilateral Weakness
(LC+LW) - (RC-RW)
———————– x 100
(LC+LW+RC+RW)
Should not be greater than 22% difference between ears (negative= left problem positive= right problem)
Formula for Bilateral Weakness
LC + LW + RC + RW = should be less than 20%/sec
What is Directional Preponderance? Formula?
-Calculates tendency for nystagmus to beat stronger in one direction
(LC+RW) - (RC+LW)
———————— x 100
(LC+LW+RC+RW)
What is Fixation Suppression? Formula?
-used to evaluate the integrity of the neural connections between vestibular nuclei and cerebellar structures
FI= SPV (EO)
———–
SPV (EC)
Temperatures for Air calorics. How long is the stimulus?
cool= 26 degrees Celsius
warm= 48 degrees celsius
60 seconds
When are Ice Water Calorics used?
when patient shows absent function in one or both ears, or when spontaneous nystagmus is suspected and for bedside examinations or comatose patients
Temperature of Ice Water Calorics?
24 degrees celsius
Caloric Abnormalities
- Caloric Inversion
- Caloric Perversion
- Premature Caloric Reversal
- Hyperactive Caloric Response
What is Caloric Inversion?
caloric response beating in opposite direction than expect
What is caloric perversion?
vertical or oblique nystagmus during caloric stimulation of HSCC
What is premature caloric reversal?
caloric response changes direction prior to 140 second post-irrigation
What is hyperactive caloric response?
total Slow phase velocity is great than 221 degrees/sec
Factors the confound calorics.
- ear surgeries
- ingestion of medications
- spontaneous/congenital nystagmus
- body temperature
- body position
