Hot and cold test

The cold and heat test examines the vestibular response by temperature stimulation of the semicircular canal. After receiving cold or thermal stimulation through the external auditory canal, the temperature changes through the tympanic membrane, tympanic cavity and bone wall to the outer semicircular canal. The endolymph fluid changes its specific gravity due to thermal expansion and contraction, resulting in convection of the endolymph fluid "hot rise and fall". Phenomenon, the final top will be skewed and stimulate the nystagmus of the ampulla. Basic Information Specialist Category: Otolaryngology Examination Category: Other Inspections Applicable gender: whether men and women apply fasting: not fasting Tips: Take nerve sedation or stimulant, alcoholic beverages for 48 hours before the test. Normal value The normal nystagmus duration is about 2 minutes for the cold water test and about 1 minute and 40 seconds for the hot water. Clinical significance Abnormal result 1. The sum of the duration of the nystagmus of the semi-regulatory tube, that is, one side of the cold and hot water test, is lower than the other side, indicating that the semi-regular function is low or even disappears. The difference between the two must be more than 20% (more than 40 seconds). 2. The advantage bias is the time increase when the nystagmus is in a certain direction during the hot and cold water test, which is the dominant deviation of the nystagmus, indicating the sac sac lesion (preferred biased multi-directional contralateral side) or temporal lobe lesion (preferred biased multi-directional disease) side). The difference must be more than 20% (more than 40 seconds) to have a diagnostic value. At present, there are different views on the dominant bias, and some scholars believe that it has no diagnostic value. 3, combined type has both dominant bias and semi-regular tube palsy, common in membrane labyrinth, VIII cranial neuropathy, vestibular neuritis and other diseases. There may be lesions at the same time as the semicircular canal and the elliptical sac. Patients with vestibular dysfunction in the population need to be examined. Precautions Taboo before inspection: 1. Taboo strenuous exercise. 2, forbidden to take nerve sedation or stimulant, alcoholic beverages 48 hours before the examination. Taboo when checking: 1. Choose a quiet environment to prevent the subject from being disturbed. 2. Pay attention to adjusting the temperature of the water. 3. When the alternating hot and cold experiment is performed, the inspector looks at the front. Inspection process (1) Trace ice water method: The subject is supine, the head is inclined to one side, and the subject is tested upward. Water is injected into the external auditory canal for 0.2ML for 20 seconds, then the ice water is poured out, the head is restored to the neutral position, and the temperature is raised by 30°, so that the outer semicircular canal is in the vertical position, and the nystagmus is observed. After the reaction occurs, the rest is checked after 3 to 5 minutes. Opposite side. (2) The alternating hot and cold test is supine, the head is raised by 30°, the bucket is hung 60cm on the patient's head, and the inside is 30 °C cold water, and the barrel is connected with a leather tube and a special olive head. The inner diameter of the olive head is 4mm, and the outer shell has a back sink. The olive head is placed in the external auditory canal, and the cold water is poured into the external auditory canal for 40 seconds (the water injection amount is about 250-500ml). At the same time, the patient looks at the front and the upper part to observe the nystagmus. Direction and reaction time. The reaction time is calculated from the start of perfusion to the stop of nystagmus. Rest for 5 to 10 minutes and check the opposite side. The ears were then tested as above using hot water at 44 °C. Not suitable for the crowd Not suitable for the crowd: no.