A tympanogram shows a sharp peak at -180 mm H2O. What does this value indicate?

A tympanogram shows a sharp peak at -180 mm H2O. What does this value indicate?

• A. A normal tympanic membrane
• B. Middle ear effusion
• C. Negative ear pressure
• D. Tympanic membrane perforation

Answer: (B)

Tympanometry measures how easily the eardrum moves as the ear canal pressure is varied; the peak of the curve shows the pressure at which the middle ear is most compliant, meaning the tympanic membrane is moving best when the pressures are equal on both sides. A peak positioned at -180 mm H2O means the middle ear pressure is about 180 mm of water negative relative to the outside atmosphere. In other words, the middle ear is under substantial negative pressure, which happens when the Eustachian tube isn’t effectively equalizing pressure. This pattern is known as a negative middle-ear pressure (Type C tympanogram). This is not a normal finding (which would have a peak near zero). It’s also not a sign of fluid in the middle ear, which typically yields a flat tracing with little or no peak because the fluid dampens membrane movement. Likewise, a perforation often disrupts the normal seal and can produce a flat or irregular tracing rather than a sharp negative peak. So, the value indicates negative ear pressure in the middle ear due to Eustachian tube dysfunction, which can precede or contribute to future effusion if it persists.

Tympanometry measures how easily the eardrum moves as the ear canal pressure is varied; the peak of the curve shows the pressure at which the middle ear is most compliant, meaning the tympanic membrane is moving best when the pressures are equal on both sides.

A peak positioned at -180 mm H2O means the middle ear pressure is about 180 mm of water negative relative to the outside atmosphere. In other words, the middle ear is under substantial negative pressure, which happens when the Eustachian tube isn’t effectively equalizing pressure. This pattern is known as a negative middle-ear pressure (Type C tympanogram).

This is not a normal finding (which would have a peak near zero). It’s also not a sign of fluid in the middle ear, which typically yields a flat tracing with little or no peak because the fluid dampens membrane movement. Likewise, a perforation often disrupts the normal seal and can produce a flat or irregular tracing rather than a sharp negative peak.

So, the value indicates negative ear pressure in the middle ear due to Eustachian tube dysfunction, which can precede or contribute to future effusion if it persists.