2. Anatomy and physiology of the middle ear. Methods of examination. Acute Otitis media. Otitis media with effusion, Mastoiditis, Facial nerve paralysis Flashcards
What are the 3 MAIN PARTS of the Middle Ear?
1) Tympanic Cavity = Bounded LATERALLY by Tympanic Membrane
2) Systemic of Temporal Bone Air Cells
3) Eustachian Tube
What are the 2 Parts of the TYMPANIC MEMBRANE?
- Pars Tensa (Larger Part)
- Pars Flaccida (Smaller Part)
What is the Pars Tensa (Larger)?
- Funnel-Shaped Area
- Stretched BTW the Malleus Handle AND Bony Ear Canal
What is the Pars Flaccida (Smaller)?
- Composed of 3 Layers
- Has FIBROCARTILAGINOUS RING, anchoring the Tympanic Membrane TO the Tympanic SULCUS of Tympanic Bone
What are the SURFACE DETAILS of the Tympanic Membrane?
- SHORT Process of MALLEUS
- HANDLE of MALLEUS
- UMBO
- Light Reflex
What are the 2 FUNCTIONS of the Tympanic Membrane?
1) GATHERS SOUND like the MEMBRANE of MICROPHONE
2) PROVIDES Sonic Shielding of ROUND WINDOW Membranes
Describe the TYMPANIC CAVITY
Contains 3 OSSICLES
- Malleus (Lateral; Attached to TM)
- Incus
- Stapes
Contains 2 MUSCLES, Chorda Tympani AND Tympanic Plexus
Describe the EUSTACHIAN TUBE
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
Describe the PHYSIOLOGY of the Middle Ear
- 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
Explain the TRAUMATIC RUPTURE of Tympanic Membrane
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
What are the Methods of Examination?
1) Hearing Tests
2) Imaging Tests
Describe the Hearing Tests
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
Describe the Imaging Tests
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
What is ACUTE OTITIS MEDIA?
- 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
What are the Etiology, Risk Factors and Symptoms of AOM?
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
What are the Diagnosis (AND Differential), and Course of AOM?
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
What is the Treatment for Acute Otitis Media?
- 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
What is OTITIS MEDIA WITH EFFUSION?
Inflammatory Effusion BEHIND intact TM
- Acute = Up-to 3 Weeks
- Subacute = Up-to 3 Mont
What is OTITIS MEDIA WITH EFFUSION?
Inflammatory Effusion BEHIND intact TM
- Acute = Up-to 3 Weeks
- Subacute = Up-to 3 Months
- Chronic = More than 3 Months
Describe OM With Effusion IN CHILDREN?
- Symptoms, Diagnosis & Treatment
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
Describe OM With Effusion IN ADULTS?
- Symptoms, Diagnosis, Complications & Treatment
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
What is MASTOIDITIS?
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
What is the Etiopathogenesis of Mastoiditis?
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
What are the Symptoms, Diagnosis (Differential), and Treatment for Mastoiditis?
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)
What is FACIAL NERVE PARALYSIS?
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
What is the Etiology, Diagnosis (Differential), and Treatment for Facial Nerve Paralysis?
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)
