Eustachian Tube

ENT
Written By Maladywise

Fact Sheet

Overview

  • Middle ear is an air-filled chamber

  • Middle ear disease may be in part due to ETD - Eustachian tube dysfunction

  • Normal ET ventilates the middle ear allowing drainage of middle ear secretions

  • ETD is a spectrum including obstruction to the opposite extreme which is patulous dysfunction

Anatomy

  • Adult ET is 36 to 38mm

  • Children ET is shorter, more horizontal and floppy with larger adenoids than adults

  • ET reaches adult length by age 8

  • ET is not static pipe, it is dynamic with a lumen, skeleton, mucosal lining and surrounding soft tissue and muscles

  • Skeleton of the tube is cartilage in its inferior and medial two thirds and bone in the superior and lateral one-third

  • Within the bone and cartillage are four muscles related to ET function

    • Tensor veli palatini (TVP)

    • Levator veli palatini (LVP)

    • Tensor tympani

    • Salpingopharyngeus

Normal Function

ET has 3 functions

  • Equalisation of pressure across TM

  • Protection of the middle ear from infection and reflux of nose contents

  • Clearance of middle ear secretions

Pathophysiology

Three processes

Pressure dysregulation / impaired ventilation

  • Functional obstruction

    • Compromise of the norma tube dilation in the absence of a fixed blocked

    • Chronic functional obstruction is most commonly due to mucosal inflammation with oedema and secretions which limit the ability of the functional valve to open

    • Less commonly failure of muscular actions limits the dilatory ability

    • True muscle weakness can occur in ALS or MG

    • In the middle ear, negative pressure is induced by the continuous absorption of middle ear gases and can be exacerbated by descent during air travel, scuba diving etc as well as habitual sniffing and thumb sucking

    • Once excessive negative pressure occurs within the middle ear, it can become a self-perpetuating cycle in which the absence of ET opening makes it increasingly difficult to dilate the tube

  • Anatomic obstruction

    • Severe inflammation with swelling, mucosa, polyps or neoplasms

    • Trauma from adenoidectomy, turbinectomy and maxillary osteotomy

    • Inflammatory diseases such as granulomatosis with polyangitis and mucosal pemphigus

Impaired protective function

  • Normal ET protects against reflux of nasopharyngeal pathogens and allergy inducing proteins, and gastric secretions into the middle ear

  • If gastric secretions reach the middle ear there may be loss of protection

  • ET also limits hearing of one’s own breathing and speaking (autophony)

  • Valve closure progresses proximally to distal creating a pumping action that further serves to prevent reflux

  • ET reflux occurs with

    • An abnormally patent ET

    • Short, floppy, ETs, typically in kids and adults with craniofacial abnormalities

    • Elevated pressure in the nasopharynx (blowing nose, crying)

Impaired Clearance

  • Loss of ciliary function can occur from bacteria and bacterial toxins, viruses, smoking, toxin exposure, allergic disease and other sources of inflammation

Etiology

  • Failure of opening (obstruction)

  • Failure of closing (patulous)

Obstructive Dysfunction

  • Impaired ability to equalise pressure between middle ear and nasopharynx

  • Often associated visible retraction of the TM

Causes

  • Any inflammation of the oropharynx

    • Infections of adenoids, nasopharynx, nose and sinuses

    • Acute or chronic rhinosinusitis

    • Seasonal or environmental allergies

    • Irritants such as tobacco smoke, electronic cigarette aerosol, wood burning stoves and air pollution

    • Laryngo-pharnygeal and gastro-oesophageal reflux

    • Hormone changes (pregnancy rhinitis)

    • Primary mucosal disease (Granulomatosis)

    • Ciliary disorders

    • Pressure dysregulation

  • Acquired anatomic abnormalities

    • Masses, cancer

    • Trauma, surgery, intubation

    • Trigeminal nerve injury

    • Chronic hypertrophied adenoids

  • Congenital abnormalities and craniofacial syndromes

  • Degenerative neurological and neuromuscular diseases

Patulous Dysfunction

  • More common than previously believed, underrecognised and often misdiagnosed

  • 6 to 7% of the population has some

Study of patulous dysfunction

  • 190 patients

  • 50% had allergic disease with patches of mucosal burnout with mucosal and submucosal atrophy

  • 38% had weight loss, as little as 2.5kg may be sufficient to productive tissue atrophy and patulous ET

  • 33% had layrngo-pharyngeal reflux inducing mucosal atrophy

  • 31% had stress and anxiety - chronic lateralisation fo the anterolateral wall in the valve due to tension in TVP or underlying pterygoid muscle has been observed. May be related to jaw clenching, bruxism and other TMJ disorders.

Other associated factors

  • Dehydration due to exercise, caffeine, or diuretics

  • Neuromuscular disorders (stroke, MS, trauma)

  • Scarring due to surgery

  • Allergic rhinitis

  • Hormonal factors such as oestrogren levels in pregnancy

  • Drugs including stimulants (topical or nasal decongestants, nicotine, cocaine, steroid sprays, antihistamines)

History

Distinguish obstructive versus patulous

  • Obstructive

    • Symptoms during baro-challenge (altitude changes whilst flying)

    • Ear pain

    • Aural fulness or pressure

    • Hearing loss

    • Tinnitus

    • Ear popping and snapping noises

    • Sometimes vertigo and dysequilibirum

  • Patulous

    • Loud perception of their own internal sounds (autophony) specifically their own voice

    • Symptoms fluctuateMay be relieved by head in a dependent position

    • Aggravated by mucosal dehydration such as exercise or prolonged speaking or singing

    • Pulsatile tinnitus is common

Other symptoms

  • Nasal itch, sneezing and rhinorrhoea = allergic

  • Discoloured nasopharyngeal discharge and sinus pressure = chronic rhinosinusitis

  • Sore throat, cough, heartburn, choking, voice changes, salivation = laryngo-pharyngeal reflux

  • Nasal obstruction might be mass lesion

  • Smoking may be a factor

  • History of head or neck radiation therapy

  • Habitual sniffing can cause chronic negative pressure

  • Forceful nose blowing or autoinsufflation can force the ET open but repetition over time may distend and weaken the ET leading to patulous tube

Examination

  • Focused head and neck exam

  • Hearing evaluation

  • Otoscopy

    • Normal TM has shiny appearance

    • Dull bluish grey or yellow colour = effusion

      • Air-Fluid Level may be seen

      • Reddish colour and engorged vessels indicates inflammation

      • Also straining

    • Movement of TM with respiration

      • Patulous TM moves with breathing

  • Frequent sniffing is suspicious for patulous with normal TM or negative pressure TM

  • Pneumatic otoscopy

  • Nasal cavity inspection for abnormalities

  • Neck exam

  • Hearing test - clinical

  • Nasal endoscopy

  • Tympanometry and audiometry

Investigations

  • Persistent unilateral symptoms and persistent middle ear effusion, consider imaging to exclude neoplasm

  • MRI with contrast has greatest sensitivity

  • Otherwise sinus or temporal bone MRI with contrast

  • CT without contrast may also be used to provide additional information about surrounding structures

Differential diagnosis

  • TMJ disorders

  • Meniere’s disease

Treatment

Obstructive dysfunction

  • Treat the obstruction

    • Rhinosinusitis (acute viral + bacterial)

      • INCS, sinus rinses, pain medication

      • Antibiotics

      • Nasal decongestants

      • Surgical management of polyps

    • Allergic and nonallergic rhinitis

      • Trigger avoidance

      • Smoking cessation

      • Medication

    • Laryngo-pharyngeal reflux

      • Lifestyle and dietary modifications (eg, avoidance of caffeine, alcohol, chocolate, mints, carbonated beverages, spicy foods; instruction to eat smaller meals and avoid eating immediately before sleep; maintaining a healthy weight; avoidance of nicotine

      • PPI

    • Mass lesions

      • Remove

  • No cause identified

    • Intermittent insufflation

    • ENT review

    • Tympanostomy tubes

    • Baloon dilation

Patulous Dysfunction

  • Stop decongestants or nasal steroid therapy

  • Adequate hydration

  • Treat the underlying cause

    • Allergies - trigger avoidance, antihistamines, INCS, nasal saline irrigation, nasal cromolyn spray

    • LPR - Treat

    • TMJ - Treat

    • Anxiety - Treat

    • Weight Loss - Treat if appropriate

  • Intranasal saline drops

    • Increases oedema, secretions and closes patulous ET lumen

    • Proper application to reach ET

      • Extend head off end of bed 15 degree extension

      • Three to four drops in ipsilateral nostril

      • Rotate head 45 degrees toward the floor

      • Should feel twinge radiate to ear

      • Repeat for 8 weeks to achieve lasting benefit

    • Can use hypertonic saline

    • Can use topical ascorbic acid but irritating

    • Surgical options

      • Tympanostomy tubes

      • Shim placement

      • Augmentation surgery

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