eustachian tube physiology ppt

ETFUNCTION

GAJALAKSHMI

EMBRYOLOGY AND POSTNATALDEVELOPMENT

• The eustachian tube is derived from the first pharyngeal pouch

ET Adults and Children

PHYSIOLOGY

• pressure equalization,• mucociliary clearance and “drainage,”• protection from both the influences of the

nasopharyngeal environment and loud sounds.

• Role of surfactant• Parasympathetic tone

• hydrops ex vacuo model-Politzer• flask model-Bluestone

MUCOCILIARY CLEARANCEAND DRAINAGE

• programmed movement of the mucous blanket out of the eustachian tube

• epithelium of the tube are covered with cilia• goblet cells-floor of the tube• Aquaporins• Surfactant• Mucins

PROTECTION

• the closed orifice of the cartilaginous eustachian tube

• Lyzozyme,lactoferrin,betadefencins and colectin

• MALT• Surfactant proteins - host defense• Sound protection

EUSTACHIAN TUBE FUNCTION ASSESSMENT

• History and Physical Examination• Pneumatic Otoscopy

• Nasopharyngoscopy • Imaging of the Eustachian Tube-MRI

Valsalva’s Test

POLITZER’S TEST

EUSTACHIAN TUBE CATHETERIZATIONATTACHED TO A PRESSURE SYSTEM TO INSUFFLATE THE

MIDDLE EAR

TYMPANOMETRY

Holmquist’s method 1. A tympanogram is recorded to determine the initial middle-ear

pressure. 2. A negative pressure is created in the nasopharynx by a

pressure device connected to the nose, and the subject is asked to swallow to establish a negative pressure of about 200 mm H2O in the middle ear. 3. A second tympanogram is recorded to evaluate the exact negative middle-ear pressure achieved. 4. The patient is told to swallow repeatedly 5. A third tympanogram -the final middle- ear pressure

PATULOUS EUSTACHIAN TUBE

Bluestone’s nine-step test

Sonotubometry

• An earphone: could generate a continuous sound of 6, 7, or 8 kHz sound of 6, 7, or 8 kHz Æ inserted into inserted into the nostril of the test subject the nostril of the test subject

• Sound source: � �• A microphone embedded in a circumaural ear

muff was placed in the ear muff was placed in the ipsilateral external auditory canal external auditory

• The microphone and insert earphone The microphone and insert earphone Æ were connected to a heterodyne

• A continuous tone generated by the oscillator with filter set with filter set &the earphone inserted into the nose �

• Test sound the external auditory canal - picked up by a calibrated condenser microphone picked up connected to a preamplifier connected to a sound level recorder recorder

When TM is not intact

• Manometry• Forced response test• Clearance test• Modified inflation and deflation test

My ref

• Cummings 3rd edition• Bluestone CD, Shurin PA. Middle-ear diseases in

children: pathogenesis,diagnosis, and management. Pediatr Clin North Am 1974;21:379–400.

• Sando I, Takahashi H, Matsune S, Aoki H. Localization of function in the Eustachian tube: a hypothesis. Ann Otol Rhinol Laryngol 1994;103