How to read Tympanogram

A tympanogram is a diagnostic test used to evaluate the function of the middle ear by measuring its response to changes in air pressure. The results are typically classified into types based on the shape of the tympanometric curve. 

During this test probe was inserted into the ear canal and measured the compliance of the tympanic membrane with different pressures. And measure the volume from the probe to the tympanic membrane. If a hole in the tympanic membrane it will measure the volume including the middle ear volume. With the perforation of the middle ear that volume will be higher than the other side. Compliance with the tympanic membrane is maximum when the pressure on each side of the tympanic membrane is equal. Usually, it is atmospheric pressure. 

Table of Contents

Types of tympanograms

These types indicate the health and functionality of the middle ear system:

Different types of tymphanograms

1. Type A (Green Curve)

• Description: Normal middle ear function.

• Peak: The curve has a sharp peak near 0 daPa (normal air pressure).

• Shape: Sharp, symmetrical peak centred around 0 data (normal atmospheric pressure).

• Meaning: Indicates normal compliance and air pressure in the middle ear. The eardrum moves as expected.

• Associated Condition: Normal hearing or conductive pathway.

2. Type As (Shallow or Stiff) (Blue Curve)

• Description: Reduced compliance or stiffness in the middle ear.

• Peak: A sharp peak with reduced height, indicating less mobility of the eardrum.

• Shape: A sharp peak similar to Type A but with reduced height (less compliance).

• Meaning: The eardrum moves less than normal due to stiffness in the middle ear system.

• Associated Conditions: Otosclerosis (abnormal bone growth) or tympani sclerosis (eardrum scarring).

3. Type Ad (Deep) (Red Curve)

• Description: Hypermobile middle ear system.

• Peak: Extremely high peak, indicating excessive eardrum mobility.

• Shape: A very high peak, often broader than Type A, showing excessive compliance.

• Meaning: The eardrum moves more than normal, indicating hypermobility.

• Associated Conditions: Ossicular chain disarticulation (disconnected middle ear bones) or a thin, overly compliant eardrum.

4. Type B (Orange Line)

• Description: Flat or no peak.

• Peak: Absent, with no distinct compliance curve.

• Shape: Flat, with no identifiable peak regardless of pressure changes.

• Meaning: Indicates little to no movement of the eardrum.

• Associated Conditions: Middle ear fluid (otitis media with effusion), perforated eardrum, or excessive earwax blocking the canal.

5. Type C (Purple Curve)

• Description: Negative middle ear pressure.

• Peak: Shifted to the negative side (below -100 daPa).

Shape: A sharp peak shifted to the negative pressure side (left of 0 daPa).

• Meaning: Negative pressure in the middle ear, often due to poor Eustachian tube function.

• Associated Conditions: Eustachian tube dysfunction, early/late stages of otitis media, or resolving middle ear infections.

FAQs

General Questions

1. What is a tympanogram, and why is it done?

A tympanogram is a diagnostic test that measures how the eardrum (tympanic membrane) responds to changes in air pressure. It helps evaluate middle ear function and detect conditions like fluid buildup, perforations, or Eustachian tube dysfunction.

2. How does a tympanogram work?

A small probe is placed in the ear canal, and air pressure is varied while sound is emitted. The device records the movement of the eardrum and plots it as a graph.

3. Is a tympanogram painful or uncomfortable?

No, the test is generally painless. Some people might feel mild pressure changes in their ears during the test, similar to changes experienced during air travel.

4. How long does it take to perform a tympanogram?

The test usually takes 2–5 minutes per ear.

5. What are the normal results of a tympanogram?

A normal tympanogram (Type A) shows a peak at 0 daPa, indicating healthy middle ear pressure and normal eardrum compliance.

Technical Questions

6. What does the graph of a tympanogram represent?

The x-axis shows air pressure in the ear canal (in daPa), and the y-axis shows the compliance or mobility of the eardrum and middle ear system.

7. What do the terms “compliance,” “pressure,” and “volume” mean in a tympanogram?

• Compliance: The mobility of the eardrum.

• Pressure: The air pressure in the middle ear, relative to the external environment.

• Volume: The size of the ear canal, which can help detect perforations or obstructions.

8. What is the difference between static compliance and gradient in tympanometry?

• Static Compliance: Measures the maximum mobility of the eardrum at peak pressure.

• Gradient: Indicates the sharpness or flatness of the tympanogram peak, helping assess middle ear conditions.

9. How is ear canal volume measured, and what does it indicate?

The ear canal volume is measured by the tympanometer at high pressure.

• High volume may indicate a perforation or open tube.

• Low volume may suggest wax blockage.

10. How does the Eustachian tube affect tympanogram results?

If the Eustachian tube is not functioning properly, it can cause negative middle ear pressure (Type C) or fluid buildup (Type B).

Interpretation Questions

11. What are the different types of tympanograms, and what do they mean?

• Type A: Normal middle ear function.

• Type As: Reduced compliance due to stiffness.

• Type Ad: Excessive compliance due to hypermobility.

• Type B: Flat curve, indicating fluid or perforation.

• Type C: Negative pressure due to Eustachian tube dysfunction.

12. How do you differentiate between a Type B tympanogram caused by fluid and one caused by a perforated eardrum?

• Fluid: Normal ear canal volume.

• Perforation: Large ear canal volume due to the probe measuring the middle ear space as well.

13. What does a Type C tympanogram indicate, and how is it treated?

It indicates negative pressure in the middle ear, often due to Eustachian tube dysfunction. Treatment may include decongestants, nasal sprays, or autoinflation techniques.

14. Can a tympanogram detect hearing loss?

Indirectly, yes. It identifies middle ear conditions that may cause conductive hearing loss, but it doesn’t measure hearing ability itself.

15. What conditions can cause abnormal tympanograms?

• Type As: Otosclerosis, tympanosclerosis.

• Type Ad: Ossicular disarticulation, flaccid eardrum.

• Type B: Otitis media with effusion, and perforation.

• Type C: Eustachian tube dysfunction.

Clinical Application Questions

16. When should a tympanogram be performed?

It’s performed when patients have symptoms like hearing loss, ear pain, fullness, or recurring ear infections.

17. Can a tympanogram diagnose an ear infection?

Yes, it can detect fluid buildup associated with middle ear infections (Type B).

18. What role does tympanometry play in diagnosing Eustachian tube dysfunction?

Tympanometry helps identify negative middle ear pressure (Type C), a common sign of Eustachian tube dysfunction.

19. How are tympanogram results used to guide treatment?

Results help determine whether to treat with medications (e.g., antibiotics, decongestants) or consider surgery (e.g., myringotomy, tympanoplasty).

20. What are the limitations of tympanometry?

It cannot directly measure hearing ability or diagnose inner ear problems like sensorineural hearing loss.

Special Population Questions

21. Is tympanometry safe for children or infants?

Yes, it is non-invasive and safe for all ages. Special probes are used for infants.

22. How do you interpret tympanograms in young children with narrow ear canals?

Pediatric probes are used to account for smaller ear canal volumes, and results are interpreted with adjusted norms.

23. Can tympanometry be performed on patients with hearing aids or cochlear implants?

Yes, but the hearing aids must be removed, and the test cannot be used to evaluate the implanted ear.

24. What adjustments are needed for patients with earwax or ear canal deformities?

The earwax may need to be removed, and care is taken to ensure a proper seal with the probe.

Follow-up Questions

25. What happens if my tympanogram is abnormal?

Further evaluation is needed, such as otoscopy, audiometry, or medical imaging, to confirm the underlying cause.

26. Do I need further testing, like audiometry or imaging, if my tympanogram is abnormal?

Yes, especially if symptoms persist or if the abnormality suggests a more serious condition.

27. Can an abnormal tympanogram resolve on its own?

In some cases, like temporary Eustachian tube dysfunction, it can resolve without treatment.

28. Will my symptoms improve after treating the issue indicated by my tympanogram?

Most middle ear conditions are treatable, and symptoms like hearing loss or pain typically improve after appropriate management.

29. How often should tympanometry be repeated for monitoring?

It depends on the condition. For chronic issues, tympanometry may be repeated every few months or as needed.