2. Anatomy and physiology of the middle ear. Methods of examination. Acute Otitis media. Otitis media with effusion, Mastoiditis, Facial nerve paralysis

Question 1

What are the 3 MAIN PARTS of the Middle Ear?

Answer 1

1) Tympanic Cavity = Bounded LATERALLY by Tympanic Membrane

2) Systemic of Temporal Bone Air Cells

3) Eustachian Tube

Question 2

What are the 2 Parts of the TYMPANIC MEMBRANE?

Answer 2

• Pars Tensa (Larger Part)
• Pars Flaccida (Smaller Part)

Question 3

What is the Pars Tensa (Larger)?

Answer 3

• Funnel-Shaped Area
• Stretched BTW the Malleus Handle AND Bony Ear Canal

Question 4

What is the Pars Flaccida (Smaller)?

Answer 4

• Composed of 3 Layers
• Has FIBROCARTILAGINOUS RING, anchoring the Tympanic Membrane TO the Tympanic SULCUS of Tympanic Bone

Question 5

What are the SURFACE DETAILS of the Tympanic Membrane?

Answer 5

• SHORT Process of MALLEUS
• HANDLE of MALLEUS
• UMBO
• Light Reflex

Question 6

What are the 2 FUNCTIONS of the Tympanic Membrane?

Answer 6

1) GATHERS SOUND like the MEMBRANE of MICROPHONE

2) PROVIDES Sonic Shielding of ROUND WINDOW Membranes

Question 7

Describe the TYMPANIC CAVITY

Answer 7

Contains 3 OSSICLES
- Malleus (Lateral; Attached to TM)
- Incus
- Stapes

Contains 2 MUSCLES, Chorda Tympani AND Tympanic Plexus

Question 8

Describe the EUSTACHIAN TUBE

Answer 8

Consists of:
- Bony Part, on LATERAL 1/3

• Cartilaginous Part, on MEDIAL 2/3 = A folded cartilage, helping with opening / closing of tube; opens due to MUSCLES of SOFT PALATE during swallowing, yawning + chewing
• Isthmus = NARROWEST Part of Tube; Also JUNCTION

Functions:
- Ventilates TC AND Air Cells (Pneumatised / Sclerotic Type)
- Equalised pa difference BTW TC AND atm
- Drains Middle Ear Spaces
- Creates barrier to ascending INFX

In Children:
- MORE Horizontal
- SHORTER, BROADER
- Has SOFTER Cartilage

Question 9

Describe the PHYSIOLOGY of the Middle Ear

Answer 9

• External AND Middle Ear CONVEY SOUND TO the Inner Ear
• VIA Sound Energy (SE) that’s TRANSFERRED to Nerve Action Potential

1) IMPEDANCE MATCHING
- 99% Loss Compensation
- External Ear (2 - 4KHz)
- Middle Ear (Lever Action / 1KHz)

2) PROTECTION = Muscles protect from LOUD Noises

Question 10

Explain the TRAUMATIC RUPTURE of Tympanic Membrane

Answer 10

A) INDIRECT INJURIES
- MOST Common!
- Due to an Ear Slap or Diving

B) DIRECT INJURIES
- Due to SHARP Branches / Self-Cleaning Manipulations / Welder’s Slag Burns

Symptoms = Brief Pain / Clogged Sensation / Slight Bleeding (Ear Canal) / Feel air-escape (Due to Valsalva Maneuver, nose blowing)

Diagnosis = Detected at Otoscopy / Perform Hearing Tests (Shows Mild Conductive HL)

Treatment = Myringoplasty via Covering w/ Plastic Film or Cigarette Paper; PROTECT AGAINST water, soap + shampoo

Question 11

What are the Methods of Examination?

Answer 11

1) Hearing Tests
2) Imaging Tests

Question 12

Describe the Hearing Tests

Answer 12

A) TUNING FORK TESTS = Use LOW f (250 - 1000) determining Conductive OR Sensorineural HL

• Weber’s Test
• Rinne’s Test
• Bing’s Test

B) Pure Tone Audiometry
C) Tympanometry

Question 13

Describe the Imaging Tests

Answer 13

A) SCHULLER’s X-Ray = Projection along EC to show Mastoid Air Cells

B) STENVER’s X-Ray = Angled at 45D FORWARD to show Petroid Ridge / Apex

C) CT Scan = Best Established for Temporal Bone

D) MRI

Question 14

What is ACUTE OTITIS MEDIA?

Answer 14

• Most Common Pathological process in the Middle Ear
• Followed by SEVERAL WEEKS of Middle Ear Effusion
• Most Common in Children = 80% by 3 Years Old

Question 15

What are the Etiology, Risk Factors and Symptoms of AOM?

Answer 15

Etiology = Due to INFX of Middle Ear, via the Eustachian Tube (Bacteria are Isolated)

• S. Pneumoniae / H. Influenzae / B. Cattarhalis

RFs = Craniofacial Anomalies / Previous EP of AOM / Parental Smoking

Symptoms = Severe Earache / Rubbing Affected Ear / Fever in first 24h (Children) / Aural Discharge from TM

Question 16

What are the Diagnosis (AND Differential), and Course of AOM?

Answer 16

Diagnosis = NO Swelling BUT, tender to pressure

• Otoscopy = Opaque, thick, erythematosus, Bulging TM (DIFFICULT in Children, due to Cerumen / Fussy Behaviour)
• Differential Dx = Otitis Externa / Acute Exacerbation of Chronic OM
• Course = Spontaneous Perforation of TM; Acute OM; Residual Inflammatory Effusion in TC

Question 17

What is the Treatment for Acute Otitis Media?

Answer 17

• NSAIDs / Acetaminophen = Pain Relief
• Decongestant Nose Drop / Irrigation = Nasal Obstruction (IMPROVES drainage effect of Eustachian Tube)
• Antibiotic Therapy for 7 - 10 Days

IF there’s NO Response / Symptoms WORSEN in 48h = Try Different Antibiotic / Paracentesis to obtain fluid sample of Bacteriologic Exam

Question 18

What is OTITIS MEDIA WITH EFFUSION?

Answer 18

Inflammatory Effusion BEHIND intact TM

• Acute = Up-to 3 Weeks
• Subacute = Up-to 3 Mont

Question 18

What is OTITIS MEDIA WITH EFFUSION?

Answer 18

Inflammatory Effusion BEHIND intact TM

• Acute = Up-to 3 Weeks
• Subacute = Up-to 3 Months
• Chronic = More than 3 Months

Question 19

Describe OM With Effusion IN CHILDREN?

• Symptoms, Diagnosis & Treatment

Answer 19

SYMPTOMS
- BOTH Ears are affected
- Impaired Middle Ear Ventilation
- Hearing Loss
- Speech / Language Developmental Delay
- Perceptual Impairment

DIAGNOSIS
- Otoscopy (Pale-Red-Yellow-Blue)
- Tympanogram shows TM Mobility (Flat Curve, Negative pa Peak)

TREATMENT
A) Conservative (Acute / Subacute Form)
- Improving Nasal Breathing
- Improving Eustachian Tube Function (Nasal Drops / Topical Steroid)

B) Surgical (Chronic Form)
- Paracentesis (Incision of TM) for Immediate Restoration of Normal Hearing
- Incision will close in 1 - 2 Weeks
- New Fluid Collection

Question 20

Describe OM With Effusion IN ADULTS?

• Symptoms, Diagnosis, Complications & Treatment

Answer 20

SYMPTOMS
- Clogged / Pressure Sensation in Affected ear
- Popping / Sloshing Sounds

DIAGNOSIS
- History of a Cold
- Otoscopy = Opaque TM with V.Poor Mobility
- Effusion in TC (Air Bubbles)
- Hearing Tests (Conductive HL); Rinne’s (-ve)
- Tympanogram (Flat Curve)
- Pure-Tone Audiometry (Air Bone Gap)

DDx
- Bullous Otitis Externa
- Otosclerosis
- Ossicular Chain Disruption
- Barotrauma
- CSF Leak from Lateral Skull Base
- Tumors of Temporal Bone
- Perilymphatic Fistula

• Patent Eustachian Tube Syndrome = SIMILAR Symptoms BUT, NO Conductive HL, and MOBILE TM

COMPLICATIONS = Bacterial Infx, leading to Acute OM / Serous Labrynithis VIA Round / Oval Window

TREATMENT
- Relieving Nasal Obstruction
- Treating Infection of Nose AND Paranasal Sinuses
- Px instructed to perform regular VALSALVA MANEUVERS
- Surgical Tx = Insert Myringotomy Tube

IF Disease PERSISTS for MORE than 3 Weeks = TM is THICKENED; Px undergo Surgical Tx

Question 21

What is MASTOIDITIS?

Answer 21

Inflammation of Air Cells in the Mastoid Process
- Involving its Mucous Membranes AND Bony Part of Mastoid

IF Temporal Bone is Well-Pneumatised = Inflammation of Cells in Petrous Bone / Zygomatic Arch

Question 22

What is the Etiopathogenesis of Mastoiditis?

Answer 22

DUE TO, INFECTION of Middle Ear

Depends on:
- DEGREE of Mastoid Pneumatisation
- VIRULENCE of AFFECTING Organism
- Host’s Immune Status
- Treatment GIVEN for Otitis Media

Question 23

What are the Symptoms, Diagnosis (Differential), and Treatment for Mastoiditis?

Answer 23

SYMPTOMS
- Fever
- Local Pain
- Malaise, Abdominal Pain, Anorexia (Children)

DIAGNOSIS {Clinical Triad}
a. PROMINENT Auricle with RETROAURICULAR Swelling
b. Tenderness over Mastoid
c. Otorrhoea

Otoscopy = Shows features of Acute, Subacute Otitis Media / Posterior Wall of EAC is Erythematous, Swollen

BEST ESTABLISHED by CT
Lab Tests = ELEVATED WBC, CRP, ESR

DDx
- Otitis Externa W/ Abscess Formation behind ear
- Inflamed Retro-auricular Lymph Node
- Tumours of Temporal Bone (Eosinophilic Granulomas, Sarcoma, Metastasis)

Tx
- Mastoidectomy WITH I.V. Antibiotics
- Riracentesis
- Placing Myringotomy Tube (DECOMPRESS Middle Ear)

Question 24

What is FACIAL NERVE PARALYSIS?

Answer 24

MOST COMMON Cranial Nerve Complication of Otitis Media

• Involving inflammation of the peripheral nerve, where Tympanic Segment is mostly affected!
• Otitis Media in Children can LEAD TO Facial Nerve Palsy
• Treated with Antibiotics AND Corticosteroids
• Mastoidectomy / Drainage of Middle Ear

Question 25

What is the Etiology, Diagnosis (Differential), and Treatment for Facial Nerve Paralysis?

Answer 25

ETIOLOGY
- Cholesteatoma (Adults) = Surgical Tx
- Direct Toxic Insult
- Inflammatory Epineural Oedema
- Pressure
- Osteitis

DIAGNOSIS
- Audiological Examinations
- CT Scan (Temporal Bone)

DDx
- Herpes Zoster Oticus
- Tumours of Lateral Skull Base
- Temporal Bone
- Parotid Gland

TREATMENT
- Surgical Exposure of Nerve
- Appropriate Antibiotic Therapy
- Corticosteroids (REDUCE Oedema)