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Speech prostheses, or voice prostheses, is a overall term for small, silicon one-way valves that are inserted into the tracheo-oesophageal puncture of laryngectomy patients. The prosthesis not only safely divides the oesophagus and trachea, but also allow speech when the outside of the tracheostoma, the opening on the neck to allow air in, is covered with a finger or otherwise occluded. This is greatly beneficial to patients because it allows to communicate without the need to use either an [[Electrolarynx]] or [[Speech synthesizers]].

== Main characteristics ==

Oesophageal valves are made of medical grade silicon rubber and primarily consists of four parts: One-way valve, two flanges on each side of the tube, rigid valve ring in the middle of the tube, and a safety strap that is either removed after the insertion, or left on the device depending on whether it is in-dwelling or patient-changeable. The two flanges are tracheal flange and esophageal flange respectively. They vary in rigidity and size. Both depend on the valve being patient-changeable or not, with the latter being bigger in size and rigid so as to facilitate bigger longevity. The overall size, especially the diameter of the tube depends on patient's preference and the size of the tracheo-oesophageal puncture.

Usage of a valve for voice restoration was first described by a Polish otolaryngologist prof. dr. Erwin Mozolewski in the 1970s.<ref>Mozolewski, Erwin S., et al. "Arytenoid vocal shunt in laryngectomized patients." The Laryngoscope 85.5 (1975): 853-861.</ref> First commercially available oesophageal valve was introduced in the late 1970s, which was introduced by Eric Blom and Mark Singer and was considered a major step in voice restoration. Up to the introduction of this procedure, laryngectomy patients were required to learn oesophageal speech or use an electrolarynx to be able to communicate again.<ref name="kazi07">KAZI, Rehan, et al. Surgical voice restoration following total laryngectomy. Journal of cancer research and therapeutics, 2007, 3.4: 188. Available online at: http://medind.nic.in/jat/t07/i4/jatt07i4p188.htm (Retrieved 24 February 2016)</ref> In 1985, inserting oesophageal valves has been accepted as a primary procedure in the US.<ref>HAMAKER, Ronald C., et al. Primary voice restoration at laryngectomy. Archives of Otolaryngology, 1985, 111.3: 182-186.</ref> Since then, the procedure became the de facto standard for post-laryngectomy treatment and voice restoration.<ref>HUTCHESON, Katherine A., et al. Enlarged tracheoesophageal puncture after total laryngectomy: A systematic review and meta‐analysis. Head & neck, 2011, 33.1: 20-30.</ref>

=== Purpose ===

The purpose of speech prostheses is to return the ability to speak to patients after total laryngectomy. 
 
== Important Dates ==

1873 - Austrian surgeon Theodore Billroth performs the first laryngectomy.<ref>KAZI, R. A., et al. Christian Albert Theodor Billroth: Master of surgery. Journal of postgraduate medicine, 2004, 50.1: 82. Available online at: https://tspace.library.utoronto.ca/bitstream/1807/2074/1/jp04025.pdf (Retrieved 25 February)</ref>

1972 - Polish-born otolaryngologist prof. dr. Erwin Mozolewski develops a way to give back voice abilities to laryngectomy patients with a small plastic valve connecting their larynx and oesophagus. The valve was officially unveiled on a international conference in Boston in 1979.<ref>http://www.mp.pl/kurier/51663</ref>

1980s - The technique was popularized and made commercially available by an American company Bloom-Singer.<ref>http://www.inhealth.com/v/vspfiles/pdf/brochures/Blom-Singer_Historic_Achievements_Brochure.pdf</ref>

== Enhancement/Therapy/Treatment ==

Treatment - Speech prostheses aim to restore the ability to speak and bring the patient's quality of life as close as possible to the state before the laryngectomy.

== Ethical & Health Issues ==

Ethical - "hole in the neck", accessories to cover it (turtle-necks etc.)

Health - leakage, sanitation, valves need replacement, heat & moisture (https://en.wikipedia.org/wiki/Heat_and_moisture_exchanger_after_laryngectomy), https://en.wikipedia.org/wiki/Esophageal_speech

== Public & Media Impact and Presentation ==

TODO: Cancer support groups and websites.

== Public Policy ==
<!-- Information related to any regulations (law, patents, ISOs, government recommendations and so on.) -->

== Related Technologies, Projects or Scientific Research ==

TODO: Add list and pictures of specific valves.

https://www.inhealth.com/category_s/44.htm

http://www.cancerresearchuk.org/about-cancer/type/larynx-cancer/living/stoma/starting-out-with-a-breathing-stoma

http://www.webwhispers.org/library/tepprosthesis.asp

https://en.wikipedia.org/wiki/Voice_prosthesis

http://medind.nic.in/jat/t07/i4/jatt07i4p188.htm

== References ==

[[Category:External Hardware or Software]]
[[Category:Electronic and Other Devices]]
[[Category:Speech Technologies]]