During tympanometry, a seal is lost intermittently when swallowing; large external canal volume; most likely cause?

During tympanometry, a seal is lost intermittently when swallowing; large external canal volume; most likely cause?

• A. Eustachian tube dysfunction
• B. Collapsed canal
• C. Otitis media
• D. Perforated tympanic membrane

Answer: (D)

During tympanometry, the measured ear canal volume reflects the air space from the probe tip to the tympanic membrane. If the tympanic membrane is perforated, the middle ear communicates directly with the ear canal, so the volume measured is abnormally large because the cavity beyond the membrane is included in the reading. That perforation also makes it easier for air to escape when you swallow, so the probe seal can fail intermittently as swallowing moves tissues and air through the hole. This combination—much larger-than-normal ear canal volume and seal instability with swallowing—best fits a perforated tympanic membrane. Eustachian tube dysfunction mainly shifts pressure readings without greatly enlarging ear canal volume, a collapsed canal would typically affect the seal without producing a large volume, and otitis media usually alters stiffness/compliance patterns rather than creating a markedly increased ear canal volume.

During tympanometry, the measured ear canal volume reflects the air space from the probe tip to the tympanic membrane. If the tympanic membrane is perforated, the middle ear communicates directly with the ear canal, so the volume measured is abnormally large because the cavity beyond the membrane is included in the reading. That perforation also makes it easier for air to escape when you swallow, so the probe seal can fail intermittently as swallowing moves tissues and air through the hole. This combination—much larger-than-normal ear canal volume and seal instability with swallowing—best fits a perforated tympanic membrane. Eustachian tube dysfunction mainly shifts pressure readings without greatly enlarging ear canal volume, a collapsed canal would typically affect the seal without producing a large volume, and otitis media usually alters stiffness/compliance patterns rather than creating a markedly increased ear canal volume.