CALORIC TESTS Shelendra Kr. Gupta

J.R. 3

Introduction It is done to know the vestibular function of

the ear.Principle : Changes in temp. in EAC influence

the level of activity of vesti. Labyrinth.Still the main test available to the clinician to

assess the individual ear vestibular func.

Types Hallpike- Fitzgerald Bithermal Caloric Test :

most reliableKobrak methodMinimal Caloric TestLinthicum Test : 0.2 ml ice water instilled for

20 sec to observe nystagmusDundas Grant Air Caloric Test : most

convenient to exclude dead ear in presence of perforation.

Hallpike Fitzgerald TestPatient is supine , head

raised to 30 degree above horizontal (Lat SCC is made vertical)

Ear irrigated for 40 sec using 250-500 ml water at 7 degree above & below body temperature.

Patient is told to look straight & duration of nystagmus is recorded.

Nystagmus produced is of 2nd degree.

Interpretation Nystagmus is produced in a normal person

with a healthy labyrinth.Mechanism : Hot water heats the

fluid ,forming convection currents , causing fall in sp. Gravity of fluid which moves towards the ampulla = nystagmus with quick component to stimulated side.

Theories suggest that there may be direct thermal effect on the end organ.

Responses

Interpretation Cold water irrigaation induces horizontal

beating nystagmus in opp. Direction & ipsilaterally during warm irrigation

Nystagmic response is recorded by EOG & VOG.

Velocity of the slow phase component is measured & displayed as function of time

Abnormalities of responseBilateral absence – drug toxicity , post-

meningitisUnilateral paresis –uni. Vest.

Schwannoma/neuronitis.Directional preponderance-asymmetry in

VOR.Abnormal VOR suppressionPerverted nystagmus- nystagmus in other

planes ; occurs in post. Fossa disease

Modified kobrak testPatient is seated ,head tilted back 60 degrees

in vertical position.5 ml of ice water is used to irrigate EAC &

nystagmus noted.Upto 40 ml water can be used.No response indicates dead labyrinth.