Atonal PE segment
Atonal PE segment (hypotonic voice)
The PE segment (pharyngo-esophageal segment) is an area of the esophagus and pharynx above the voice prosthesis that starts to vibrate as air flows in, and which produces the actual sound when talking with a voice prosthesis. This PE segment consists of several layers of the involved organs. Following a simple pharyngeal reconstruction, there is a mucous layer on the inside that is encased in a muscle layer on the outside. This muscle layer must not be able to develop a circular tension, as otherwise it would block the airflow upwards towards the mouth. That is why the myotomy of the M. constrictor pharyngis is carried out in this area.
Despite the unilateral myotomy, the muscles of the PE segment can build up a certain level of tension, and the PE segment is usually closed and collapsed. The air coming up from below “bubbles” through, as shown in film A, creating a sound. The oscillation of the PE segment can be felt against the skin of the neck to cranial (above) the tracheostoma.
If the muscles in the PE segment lack any tone or if the pharynx has been reconstructed by transplant (jejunum, radialis flaps etc.), then often a non-collapsed PE segment, similar to rigid pipe, is evident. Air flows through this pipe without causing significant oscillations (a radial forearm flap does not have the oscillating mucous membrane), as shown in film B. The resulting voice is described as hypotonic. It is quiet and breathy despite the high air flow.
No good surgical solution has yet been found to this problem. However, the voice can be improved by pressing against the PE segment from the outside. Apply pressure to the skin of the neck approx. 2-5 cm above the tracheostoma, on the midline. Skilled patients combine digitally closing the tracheostoma with applying pressure to the PE segment. A rubber collar can also bring improvement.
Just how effective digital pressure against the PE segment is, is confirmed by the fact that, time and again, patients present for injections with Botulinum toxin because of a supposed pharyngeal spasm, whereas in fact these patients are applying too much pressure to the tracheostoma in the digital occlusion, completely closing the PE segment below it – which is what stops them from being able to talk!