Ear examination..upto tympanic membrane and otoscopy examination
Ear examination..upto tympanic membrane and otoscopy examination with images
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Ear Examination: Up to the Tympanic Membrane and Otoscopy
1. Instruments Required
The standard instruments used for ear examination include:
- Hand-held otoscope (auriscope) - with a light source, magnifying lens, and specula of varying sizes
- Operating otoscope - lens can be moved to allow instrumentation of the canal
- Pneumatic otoscope - with insufflating bulb to assess TM mobility
- Binocular otomicroscope - for specialist examination (gives stereovision, depth perception)
- 512 Hz tuning fork - for Rinne and Weber tests
- 4 mm rigid endoscope - can substitute for speculum, allows angling into attic
2. Anatomy: The External Ear and Canal
External Auditory Canal (EAC)
- Runs in a sigmoid (S-shaped) fashion - this is why pinna traction is needed to straighten it
- Outer 1/3: cartilaginous - contains hair follicles, cerumen glands (modified apocrine), sebaceous glands
- Inner 2/3: bony (tympanic and squamous parts of temporal bone)
- Length: approximately 2.5 cm in adults
- Innervation (sensory):
- Anterior/superior wall: auriculotemporal nerve (V3 branch)
- Posterior/inferior wall: auricular branch of vagus nerve (CN X) - explains referred otalgia from throat/larynx
- Minor contribution from facial nerve (CN VII)
3. Anatomy: The Tympanic Membrane
Structure
The tympanic membrane (TM) separates the EAC from the middle ear. It is:
- Oriented obliquely - slopes medially from top to bottom and posteriorly to anteriorly; the lateral surface faces inferiorly and anteriorly
- Layers (3): skin (lateral) + fibrous connective tissue core + mucous membrane (medial/middle ear side)
- Attached to the tympanic part of the temporal bone by a fibrocartilaginous annulus (fibrous annulus)
Key Landmarks on the Tympanic Membrane
| Landmark | Location | Description |
|---|---|---|
| Pars tensa | Inferior 4/5 | Thick, taut portion; 3-layered |
| Pars flaccida (Shrapnell's membrane) | Superior, above malleolar folds | Thin, slack, only 2 layers; most common site of cholesteatoma |
| Handle (manubrium) of malleus | Runs from lateral process to umbo | Seen as a whitish streak running inferiorly |
| Umbo | Inferior end of malleus handle | Deepest point of TM concavity |
| Lateral process (short process) of malleus | Superior knob-like projection | Marks junction of pars tensa and pars flaccida |
| Anterior & posterior malleolar folds | Extending from lateral process | Separate pars tensa from pars flaccida |
| Cone of light (light reflex) | Anteroinferior, at 5 o'clock (right) or 7 o'clock (left) | Triangular bright reflection; points toward umbo at its apex |
| Notch of Rivinus | Superior bony notch | Where pars flaccida attaches |
Structures Visible Through a Translucent TM
- Round window niche
- Incudostapedial complex
- Chorda tympani nerve
- Long process of incus
4. Normal TM Appearance
A normal TM is:
- Color: pearly grey, slightly translucent
- Position: neutral (not retracted or bulging)
- Light reflex: bright, cone-shaped, anteroinferior
- Landmarks: handle of malleus and umbo clearly visible
5. Otoscopy Technique
Patient Positioning
Step-by-Step Technique
1. Preparation
- Ensure the otoscope is fully charged (low battery causes a yellow tint that mimics middle ear effusion)
- Select the largest speculum that fits comfortably in the meatus
- Warn the patient - the procedure should be painless
2. Pinna Traction
- Adults: pull the pinna superiorly and posteriorly (up and back) to straighten the sigmoid cartilaginous canal
- Children under 2: pull inferiorly and posteriorly (the canal takes a different curve)
- This is mandatory because the canal is tortuous and without traction the TM cannot be seen
3. Holding the Otoscope
- Hold the barrel like a pen, with the little finger braced against the patient's cheek or mastoid
- This ensures the instrument moves with the patient's head - preventing the speculum from impinging on the TM during sudden movement
4. Insertion
- Insert the speculum gently into the cartilaginous (outer) canal only - do not push into the bony canal
- Advance with a gentle downward/forward angling movement
5. Speculum Size Choice
- A narrow speculum limits the visible field - the examiner must mentally piece together multiple overlapping views
- A larger speculum gives a wider, more complete view with less repositioning needed
- A large speculum also allows pneumatic insufflation and passage of instruments
6. Systematic (Structured) Otoscopy
A structured approach is recommended to avoid missing pathology. Follow this sequence:
Step 1 - External canal first: Check for wax, discharge, foreign bodies, masses, skin changes, or signs of otitis externa
Step 2 - Identify the handle of malleus: This is the most consistently recognizable landmark - find it first
Step 3 - Identify the umbo and lateral process: Establish orientation
Step 4 - Examine the pars tensa: Is it intact? Is it in normal position?
- Foreshortening of the handle = TM retracted medially
- "Neoannulus" lipping around the annulus = retraction
- Check for perforations (central vs. marginal), thinning, or bulging
Step 5 - Examine the pars flaccida / attic: Look for retraction pockets (most common site for cholesteatoma)
Step 6 - Assess the cone of light: Loss of the light reflex can indicate retraction, inflammation, or scarring (less diagnostically important on its own)
Step 7 - Assess color and translucency:
- Normal: grey, slightly translucent
- Opaque white / thickened = tympanosclerosis (hyaline degeneration + calcium deposits from prior inflammation)
- Amber/yellow fluid level = middle ear effusion ("glue ear")
- Red, bulging = acute otitis media
7. Pneumatic Otoscopy
- The insufflating bulb is attached to the otoscope and an airtight seal is formed with a properly fitting speculum
- Gentle compression increases pressure, gentle release decreases pressure
- A normal TM moves briskly inward with compression and outward with release
- Reduced or absent mobility = middle ear effusion (most common cause) or tympanosclerosis
- Sensitivity: 85-93%, specificity: 71-89% (when performed by trained clinicians)
- Also used for the bedside Hennebert's (fistula) test - a perilymph fistula causes nystagmus or vertigo with pressure change
8. Describing TM Findings
When documenting findings, describe:
- Perforation location: use the clock face (e.g., central at 6 o'clock)
- Marginal vs. central: marginal (involving the annulus) carries higher risk of cholesteatoma
- Retraction pockets: describe quadrant, depth, and whether debris is present
- Attic/pars flaccida: check superiorly for keratin debris (hallmark of cholesteatoma)
9. Alternative Examination Tools
| Tool | Advantage | Limitation |
|---|---|---|
| Hand-held otoscope | Portable, widely available | Monocular, low magnification, difficult to instrument canal |
| Binocular otomicroscope | Stereovision, depth, high magnification, two-handed instrumentation | Expensive, not portable |
| Rigid endoscope (4 mm, 0°) | No speculum needed, angles into attic; photo/video documentation | Lens condensation; single-handed only |
| Pneumatic otoscope (Bruening) | Dynamic TM assessment, fistula test | Requires seal, training |
Sources
- Scott-Brown's Otorhinolaryngology Head & Neck Surgery, Vol. 2 - Chapter 73 (Structured Otoscopy)
- Cummings Otolaryngology Head and Neck Surgery - Chapter 137 (Direct Examination, Tympanic Membrane)
- Gray's Anatomy for Students - Chapter 8 (Tympanic Membrane Anatomy)
- Bailey and Love's Short Practice of Surgery, 28th Ed. - Chapter 51 (Examination of the Ear)
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