Study on the Middle Ear Function before and after the Surgical Treatment of Laryngeal Cancer

Abstract

The author has examind the middle ear function before and after the laryngectomy and radical neck dissection of laryngeal cancer in 35 patients.
1) The retraction-grade of the tympanic membranes was measured by the use of the myringo- goniometer (Kawata-Ochiai).
The average retraction-grade of the tympanic membranes before the operation was 39 degrees in the right, and 32. 8 degrees in the left ear. The average retraction grade of the tympanic membranes after the operation was 36 degrees in the right, 29 degrees in the left ear.
After the laryngectomy the tympanic membranes were retracted inwards in 34 ears (48.5%) and were unchanged in 28 ears (40%).
2) The air-conduction threshold of 40 ears was measured by the NY-A audiometer. The hear ing acuity was unchanged in 25 ears (63%) and was impaired in 9 ears (23%) after the laryn gectomy.
3) The author modified van Dischoeck's pneumophon and attached a crystal receiver, a water manometer and a syringe to the 49-A audiometer (as shown in the photographs), that the pressure of the external auditory canal could be varried from 20cm H₂O to -20cm H₂O.
The auditory threshold for the 1024 cps tone was first measured by means of this pneumophon.
The author made the patients hear the tone, as a rule, of 30 to 40 db above the threshold and made them compare its loudness at 0cm H₂O and that at a certain auditory canal pressure.
By repeated questioning the zone of the clearest hearing (die Zone des deutlichen Hoerens, d. h. Z. D. H. nach Dischoeck) was obtained.
In the 11 of the 20 ears, Z. D. H. was unchanged befor and after the laryngectomy, and in 6 ears negative Z. D. H. increased.
4) In most patients whose hearing was unchanged after the laryngectomy, the nasal cavities were clean, and the patency of the auditory tubes and Z. D. H. were unchanged before and after the laryngectomy.
In 23% of the patients the hearing was decreased after the operation. In most of them nasal secretion and malform of the nasal cavities were found and the patency of the auditory tubes was bad.