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A clinical trial was made of two types of laryngeal endoprostheses in surgery of stenosis caused by benign diseases. A total of 15 patients were operated on. In 11 patients endoprosthesis of biocompatible polymers was inserted, in 4 patients the stenosis was corrected with endoprosthesis of silicon rubber. Most of the patients had stenosis as a result of complication of thyroid surgery. The operative technique is described. In extensive defects of the anterior wall of the larynx and trachea, advanced scar stenoses a new operation is proposed-autoalloplasty using body and manubrium of the sternum.

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The combination of a narrow oesophageal lumen and a hypertonic pharyngo-oesophageal (P-E) segment following laryngectomy and secondary tracheo-oesophageal puncture (TEP) can cause obstruction of a voice prosthesis and consequently prevent phonation. The 'Allan Johnson' modification of the Bivona voice prosthesis incorporates a stainless steel slide and has been successfully used to remedy such a circumstance.

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The surgical treatment of throat cancer often requires total laryngectomy. The necessary tracheostoma attracts attention, especially during speech, when one must close it manually to force air into the esophagus. To avoid this manual control, several devices have been developed. These must be placed in or around the tracheostoma and possess a valve which closes with a large air flow value. Most devices have a major drawback; coughing calls for manual adaptation, which again attracts attention. A new hands-free tracheostoma valve has been developed. The device consists of two magnetic valves, one which closes the outflow to allow speech, and one which opens to cough. Prototypes were tested in a physical model. Air flow resistance and closing pressures of the speech valve proved to be comparable to those of existing devices. Patients were enthusiastic about the new approach, even though air leakage sometimes occurred.

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The use of a voice prosthesis is an acceptable option for the postlaryngectomy patient. Establishing criteria for patient selection is the most important way to avoid complications. The author describes a simple technique performed under local anesthesia.

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The present exploratory project was undertaken (a) to determine the relative strength of low-frequency energy in the output of one widely used electronic artificial larynx (Servox) and (b) to assess the relative strength of low-frequency energy in vowels produced by users of this type of artificial larynx. We hypothesized that the outputs of electronic artificial larynges and the vowels produced by laryngectomized users of these devices would be characterized by significant deficits in low-frequency energy level. Five users of electronic larynges and 10 normal speakers (5 female and 5 male) provided the speech samples. Results of spectral analyses indicated that there was a significant deficit in low-frequency energy both in the acoustic signals generated by a Servox electronic larynx and in vowels produced by laryngectomized users of this type of electronic larynx. Based on these findings, a second order filter was designed and implemented digitally to compensate for the observed deficit in low-frequency energy. A perceptual experiment was completed to evaluate the effect of low-frequency enhancement on perceived speech quality. Ninety-eight percent (+/- 2%) of the responses of listeners indicated that low-frequency enhanced speech samples had better vocal quality or were more pleasant to listen to than the original speech samples. We conclude that consideration for enhancing low-frequency characteristics is warranted in the design of improved prosthetic devices for alaryngeal speakers.

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The feasibility of using the linear predictive coding (LPC) technique to replace the voicing sources of tracheoesophageal speech was explored. Four vowels, [i], [a], [e], [u], and one diphthong [ou], produced by two male and two female tracheoesophageal speakers were analyzed by the LPC autocorrelation method. Normalized prediction error functions were used to choose the algorithm and the control parameters of the analysis. Poles of the vocal tract transfer function were selected from frames whose normalized prediction errors were close to minimum with criteria derived from transfer functions of normally produced vowels. Vowels were synthesized with the reconstructed transfer function and a synthesized excitation input. Results of an identification task indicated that the synthesized vowels were highly intelligible, and the gender of the speaker was better identified from the synthesized vowels than from the original tracheoesophageal vowels.

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Total laryngectomy patients who depend on a prosthesis for the production of alaryngeal speech often have irregular peristomal anatomy. The standard tracheostoma (speech) valve retainer cannot be intimately adapted to uneven and highly mobile tissue. Fabrication of a custom speech valve retainer is indicated under such circumstances but may be complicated by restricted access to the surgically created stoma. This article describes the clinical and laboratory techniques for the fabrication of a custom tracheostoma valve retainer that displaces the peristomal soft tissues and musculature. This technique permits access for placement of the speech valve and valve retainer in close proximity to the speech button prosthesis. Enclosure of the custom retainer in the recess underlying the peristomal musculature also provides a plug that enhances retention and increases patient confidence during alaryngeal speech. The coordinated efforts of the speech specialist and the prosthodontist in the fabrication of this prosthesis enhances the quality of life for the total laryngectomy patient.

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The development of the tracheostoma breathing valve and its use in conjunction with tracheoesophageal (TE) puncture prostheses has offered an important option to laryngectomized patients who undergo surgical-prosthetic voice restoration. Despite advantages that the tracheostoma breathing valve provides, some TE speakers are unable to utilize the device although they are successful users of the TE puncture voice prosthesis. This paper presents a safe, simple, and successful modification of the tracheostoma breathing valve in a single patient who demonstrated anatomical limitations for its use. Modification procedures are presented and clinical implications are discussed.

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This study evaluated speech rehabilitation outcome and length of training needed for laryngectomized patients who underwent the Blom-Singer tracheoesophageal (TE) puncture procedure. Preoperative patient selection criteria included: 1) acceptable stoma size, 2) adequate motivation and manual dexterity, 3) absence of constrictor spasm. Training focused on coordination of breath control, articulation, muscle relaxation, and proper handling and maintenance of the "duckbill" prosthesis. Speech intelligibility in 12 patients was evaluated following the completion of their speech rehabilitation program, using the CID Everyday Sentences. Each patient was videotaped; the tape then was presented to unbiased listeners who recorded the sentences. The median percentage of intelligibility for the 12 patients was 89.5%; only one patient had a median score less than 60%. The mean length of formal training for the group was only 3.2 hours (range 1 to 7 hours). The percentage of patients attaining speech and the quality of their speech intelligibility was found to be higher than with esophageal speech, which is both time consuming and often difficult to learn. TE puncture followed by proper fitting and training in voice prosthesis usage improves speech rehabilitation outcome for the laryngectomized patient.

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The use of a valve to restore functional speech following a total laryngectomy has been well described. We have encountered problems in both the formation of the tracheo-oesophageal fistula and stenosis of the tracheostome if the valve is used by itself for long periods. A simple technique to establish the fistula is described, and a modification of the valve with a stoma button is suggested.

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In experimental animals a one stage surgical procedure has been developed which at laryngectomy allows for the creation of a wide and patent tracheopharyngeal fistula. An endotracheal artificial larynx has been developed which has been found effective in prevention of aspiration in experimental animals. Bench studies indicate that an adequate voice probably can be obtained with this device.

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Intracordal polymer solution and/or suspension injection has potential in the swelling of paralysed or partially removed vocal cords to the midline laryngeal position. This technique allows the normally functioning cord to vibrate against the swollen one in order to produce sound. Polymeric systems which may possibly be used for the treatment of vocal cords are presented and analysed with special reference to poly(vinyl alcohol). Aqueous poly(vinyl alcohol) solution in concentrations of 3% to 10% (wt/wt) are gelled by glutaraldehyde. The gelation kinetics are followed and the gelation point, final crosslinking density and structure are determined in terms of the initial molar ratio of crosslinking agent to polymer. The mechanical properties of poly(vinyl alcohol) gels are discussed. Finally a proposed technique for the application of these systems for the treatment of certain vocal cord impairments is presented.

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