Deterioration of Voice Prostheses Caused by Fungal Vegetations

Abstract

To the Editor.\p=m-\During the past few years, there has been a widespread use of silicone-rubber valves, which are inserted into tracheoesophageal fistulas to facilitate the voice restoration of laryngectomees. In the beginning, one of the major problems encountered in using these "voice prostheses" was the daily routine of the mandatory removal, cleaning, and replacement, a routine that proved to be difficult for many patients and that resulted in several complications.The Groningen button is one of these silicone-rubber valves\p=m-\itwas one of the first prostheses that was self-retaining and self-cleaning, resulting in a placement for a longer period; a period that varies considerably between patients. The mean device lifetime of the button is slightly more than three months, and the range varies from a few weeks to more than 30 months. A relationship was suspected between this varying, but limited lifetime and the deposits that were found on the removed buttons.Until now, no mention of these deposits was encountered in the liter¬ ature. Experience with more than 90 patients in four years established that these deposits were mostly found on the esophageal side of the prosthesis where the valve part is formed by a slit in the silicone-rubber material.The patients experienced no discom¬ fort from these deposits and com¬ plaints concerning swallowing disor¬ ders, pain, or local infection were few. Chemical analysis of the deposits showed that these did not consist of lime or other salt-deposits. Bactério¬ logie cultures of ten removed buttons showed an extremely high concentra¬ tion of Candida species in all sam¬ ples. Scanning electron microscopic ex¬ amination of the deposits on the but¬ tons demonstrated yeastbuds and hyphenated fungal vegetations, typi¬ cal of Candida species, growing into the esophageal surface and the valve surface of the prosthesis. Bulges of silicone material, filled with fungal vegetations, were also found to be situated on these surfaces. The expanding forces of the fungal vegeta¬ tions inside these bulges, will eventu¬ ally result in rupture, thus tearing the silicone-rubber material.Despite the fact that high concen¬ trations of Candida species were found on the buttons and in the tra¬ cheoesophageal fistulas, no relation¬ ship could be established between these concentrations and clinical manifestations of infection.It is our considered opinion that if the growth of Candida species on the button could be prevented, the life¬ time of the prosthesis will be pro¬ longed. The results of our study may also be of interest in matters concern¬ ing the implantation of other siliconerubber devices in the upper digestive tract. A more detailed report of this study will be presented shortly.

Candida – ‘the cancer of silastic’

“…The colonization of silastic by Candida species has been known for some time. Hans Mahieu et al reported that the expanding forces of fungal vegetations cause rupture and tearing of the silicone-rubber material of Groningen valves (Mahieu et al, 1985). Subsequently, they published a detailed study of the scanning electron microscopic appearances of the invasion of silicone material by Candida organisms and proposed this as a mechanism for the finite life of the speaking valve (Mahieu et al, 1986).…”

“…The use of silastic tracheo-oesophageal fistula valves for speech rehabilitation post-laryngectomy has improved the duration and fluency of speech over oesophageal speech. However, there have been a number of reports on the erosion of the silastic by Candida species focusing on scanning electron microscopy of silastic tracheo-oesophageal speaking-valves (Mahieu et al, 1985(Mahieu et al, , 1986 These studies illustrate the fine detail of the erosion but do not demonstrate the overall nature of the invading colony and its effect on the valve structure. The effects of this erosion are well-known by those interested in speech rehabilitation after laryngectomy; all speaking valves fail ultimately as a result.…”