Rehabilitation of smell and taste functions in total laryngectomy: systematic review

Caldas, Ada Salvetti Cavalcanti; Facundes, Vera Lúcia Dutra; Silva, Hilton Justino da

doi:10.1590/S1516-18462011005000100

Abstracts

BACKGROUND: in total laryngectomy there occurs the transfer of the nasal airflow definitely to the tracheostoma, which could cause a decrease in the perception of smell and taste. There have been recently developed methods of intervention in order to improve performance in laryngectomized smell and taste, although few studies have investigated this issue. PURPOSE: this study aimed to systematically review the evidence of how the techniques involved in the rehabilitation of the functions of smell and taste have an effect on individuals with total laryngectomy. CONCLUSION: in this review all the selected studies demonstrated effective use of rehabilitation techniques for the role of olfaction in laryngectomized. As for taste, there were no proposals in order to intervene directly in this function.

Laryngectomy; Smell; Taste; Olfaction Disorders; Taste Disorders; Rehabilitation

TEMA: na laringectomia total ocorre a transferência do fluxo aéreo nasal definitivamente ao traqueostoma, podendo provocar diminuição na percepção do olfato e do paladar. Recentemente tem sido desenvolvidos métodos de intervenção a fim de melhorar a performance olfativa e gustativa em laringectomizados, embora sejam escassos os estudos que abordam esse tema. OBJETIVO: rever de forma sistemática as evidências de como as técnicas envolvidas na reabilitação das funções do olfato e do paladar tem efeito em indivíduos laringectomizados totais. CONCLUSÃO: nesta revisão todos os estudos selecionados demonstraram eficácia na utilização de técnicas de reabilitação para a função do olfato em laringectomizados totais. Para o paladar não houve propostas para intervir diretamente nesta função.

Laringectomia; Olfato; Paladar; Transtornos do Olfato; Distúrbios do Paladar; Reabilitação

^IOccupational Therapist; Mastering in Pathology at Federal University of Pernambuco, UFPE, Recife, PE - Brazil; Specialist in Public Health from University of Pernambuco - UPE

^IIOccupational Therapist;, Assistant Professor of Occupational Therapy course at the Federal University of Pernambuco, UFPE, Recife, PE - Brazil; Doctor in Neuropsychiatry from Federal University of Pernambuco - UFPE

^IIISpeech Therapist; Assistant Professor II at the Federal University of Pernambuco - UFPE, Recife, PE - Brazil; Doctor in Nutrition from the Federal University of Pernambuco - UFPE

Mailing Address

ABSTRACT

BACKGROUND: in total laryngectomy there occurs the transfer of the nasal airflow definitely to the tracheostoma, which could cause a decrease in the perception of smell and taste. There have been recently developed methods of intervention in order to improve performance in laryngectomized smell and taste, although few studies have investigated this issue.

PURPOSE: this study aimed to systematically review the evidence of how the techniques involved in the rehabilitation of the functions of smell and taste have an effect on individuals with total laryngectomy.

CONCLUSION: in this review all the selected studies demonstrated effective use of rehabilitation techniques for the role of olfaction in laryngectomized. As for taste, there were no proposals in order to intervene directly in this function.

Keywords: Laryngectomy; Smell; Taste; Olfaction Disorders; Taste Disorders; Rehabilitation

INTRODUCTION

Total laryngectomy is a surgical procedure in which there is removal of structures that produce the laryngeal sound and neighbors muscles, with the transfer of the nasal airflow definitely to the tracheostoma¹, compromising the arrival of odor molecules to the olfactory epithelium by nasal inhalation, causing decreasing in smell perception and therefore taste function^2,3.

It has been recently developed methods of intervention to improve smell and taste performance in laryngectomized, especially rehabilitation techniques that provide an increase in nasal airflow with the improvement of the odor molecules arrival in the olfactory neuroepithelium^4,5.

Given the few studies that address this issue, this article aims to systematically review the evidence of how the techniques involved in the rehabilitation of the smell and taste functions has effect on total laryngectomy individuals.

METHOD

A systematic literature review was performed from the PUBMED, MEDLINE (1997 - 2010), OLD MEDLINE (1966 - 1996), LILACS and SciELO data base, being the search of data held in 2010 october.

To search descriptors were used (DESCs) - keywords for retrieving subjects from scientific literature - and free terms (TL) - terms not found in DESC and MESH, but with relevance to the research -, being done through: "laryngectomy" (DESCs) AND "smell" (DESCs); "laryngectomy" (DESCs) AND "taste" (DESCs); "laryngectomy" (DESCs) AND "olfaction disorders" (DESCs); "laryngectomy" (DESCs) AND "taste disorders" (DESCs); "laryngectomized" (TL) AND "smell" (DESCs); "laryngectomized" (TL) AND "taste" (DESCs) and its equivalent in Portuguese and Spanish.

The research was conducted by three researchers independently, following inclusion and exclusion criteria.

The inclusion criteria were original articles (excluding editorials and case study) that approached the total laryngectomy and the smell and/or taste functions rehabilitation in this population with the use of specific techniques, and the manuscripts were published in Portuguese, English and Spanish.

The literature review articles were excluded, as well as those who not specifically proposed interfere in the smell and/or taste functions and those who did not address the total laryngectomy population, such as animal studies.

LITERATURE REVIEW

We found 457 articles from the research of descriptors and free terms, being 183 from the PUBMED, 153 from MEDLINE, 109 from MEDLINE OLD, seven from LILACS, three from SCIELO Brazil and two from SCIELO Colombia. Considering the inclusion and exclusion criteria, there were selected 11 articles for this review, as claimed in Figure 1.

The great diversity observed in the found studies did not allow statistical analysis (methanalysis). The heterogeneity is reflected in the absence of criteria for randomization, sampling and variables diversification considered in the population of each article. So for better presentation of results we chose to consider the following variables of selected articles: author, year, country, sample, average age, time after laryngectomy, test used to assess the smell and/or palate function, intervention technique and results, as can be seen in Table 1.

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The rehabilitation of the smell and taste functions seems to have been evidenced by research from the 2000s. Although the knowledge that the total laryngectomy can cause a decrease in smell and taste acuity have been reported in studies since 1954⁶, only in 1987⁷ the first publication describing a intervention technique with the attempt to reverse these sensory losses were published.

It is believed that this may be related to traditionally be more emphasis on voice rehabilitation⁴, since such changes are more evident in this population, with little perceived changes in the smell functions and taste consequently.

The discovery of the decrease in olfactory and gustatory function in total laryngectomized as well as the possible mechanisms and structures involved in these changes seems to have encouraged research groups to investigate intervention strategies to improve these functions, mainly in the Netherlands, Sweden and Germany^5,8-13.

It is assumed that the growth of larynx cancers and the number of total laryngectomy surgeries in Europe, has driven more and more researchers to investigate this population⁸. Associated with this fact, research has used questionnaires and specific tests to assess the smell and taste functions in order to verify the effectiveness of intervention techniques, verifying in these publications more concern about the quality of life of them.

Another relevant point is the absence of studies in Latin America, suggesting little emphasis on researching this topic. In Brazil, studies on the quality of life and oral communication are preferred by researchers in this region^14,15, although it has been found an article by Brazilian researchers outside of research strategies including the inclusion and exclusion criteria adopted in this review¹⁶.

The diversity of publications in this review may be evidenced by the number of sampling, and studies revealed the occurrence of between 12 and 44 individuals, although it has identified a prevalent variation between 18 and 24 individuals. It is assumed that the small number of individuals surveyed may undermine the inference of these findings for the general population.

In the selected articles, the average age of the subjects assessed was approximately 60 years, which is consistent with studies that indicate the age group 40 to 70 years as the most prevalent age for laryngeal cancer¹⁷.

Another point that should be taken into account in analyzing the results presented in this review is the surgery time, and this time varied from 0 till 20 years, thereby increasing the heterogeneity of the selected studies.

The tests used to evaluate olfactory function in the majority were concerned to make a quantitative analysis using standardized instruments, which suggests a concern with the results presented, as is intended to demonstrate the effectiveness of an intervention technique.

A study with a sample about 44 individuals, was used as a method to evaluate the smell function, the Odor Detection Test (ODT) with presentation of 16 trials with bottles containing 250 mL of solvent odorless dipropylene glycol and the others containing dipropylene glycol phenylethanol¹³. Later, in another publication of the same author, also used this evaluate method in association to the evaluation Smell Disk Test (SDT) which is the submission of eight different odors on floppy disks, and the study confirmed that the SDT represents a test to be faster and simple application and reproducibility¹².

The Sniffin Sticks test battery is another standardized test used in recent publications^3,5,9, having an evaluation as a method to use odors contained in 12 "pens", with an objective test, showing a greater confidence in the presented results.

Subjective tests with questionnaires use, has been widely used to evaluate the smell and taste functions, particularly with respect to self-evaluation and satisfaction with the current situation experienced by the individual. The Olfaction questionnaire, Taste and Appetite (QOTA) represents a subjective test with a study proposed evaluation through multiple-choice questions of the current and previous total laryngectomy surgery situation^8,10,11,13. It is understood that although the questionnaire has well-defined scores, it requires that their use is accompanied by objective tests for better results.

In the evaluation of taste function was noted that the studies used questionnaires and semi-structured interview with subjective approach and proposal self-assessment ^4,8,10,11,13. It is understood that changes in taste function can be considered as a consequence of the decline in olfactory function, which may explain the lack of analysis with standardized tests for the taste function.

It is observed that even in articles that offer only the assessment of gustatory function, subjective tests are used, especially aqueous solutions, with non-standard instruments¹⁸, which demonstrates the lack of more objective studies to analyse this function.

The found intervention techniques in the articles selected for this review primarily describes the use of devices to restore nasal airflow, reconnecting the upper to the inferior airway, as well as techniques whom works the orofacial muscles in order to recover this airflow. But in only one analyzed study observed the possibility of using the speech prosthesis as a intervention technique, and certified low efficiency of this method¹⁹.

Some studies have shown efficacy in the use of "Larynx Bypass" (LB), a flexible tube in order to connect the patient's mouth and tracheostoma to restore the airflow, resulting from the smell improves air circulation in the nasal passage, requiring the patient to relax the palate does not obstruct the nasopharynx^5,7,9.

Research conducted in Germany discusses the practicality of this method and proposes the technique of Scent-Diffusing ventilator (SV), in which a small fan is attached to a mask, carrying the air directly to the nose, allowing the entry of odor molecules passively into nasal cavity⁹.

In both techniques there is evidence of improvement in olfaction, but we see a great improvement through the use of the SV technique compared with the use of the LB technique, as well as being easier to use. In contrast, the cost of this technique is discussed, there is need greater technology, as in LB technique uses only one flexible tube, which suggests less financial support.

The Nasal Airflow-Inducing Maneuver (NAIM) is the most commonly used technique in studies that propose smell and taste functions rehabilitation ^3,4,8,10-13. This device has a proposal to create a negative pressure in the oral and oropharynx cavity to induce nasal airflow, allowing the arrival of odor molecules back to the olfactory neuroepithelium. This technique known as polite yawning, is a "yawn" extended with the simultaneous movement of retraction of the mandible, the mouth floor, the tongue, the base tongue base and soft palate, keeping lips tightly closed¹³.

It was observed that this technique has proven effective in restoring olfactory function, converting individuals with anosmya to resume the ability to perceive odors, both short term and extended periods of use, besides being easy to learn by users.

In research conducted in Sweden with 24 individuals, it was used the NAIM rehabilitation method, noting that half of patients who had anosmya started to perceive odors after being administered a single session of this technique¹¹.

This factor reinforces the importance of investment in rehabilitation proposals, since it is possible to detect changes in a short period of time, resulting in improvement in olfactory function and quality of life of these subjects. These results may provide incentives for researchers to invest in this area and propose new forms of intervention in clinical practice.

In this selected studies it is clear that the intention of researching proposals for rehabilitation is not always reflected in investments in clinical practice, and although there is a concern to encourage this practice⁴ only one study presents the analysis of interventions in clinical and home care³. Given this, we suggest new studies who reported the applicability of these techniques in everyday of professionals who provide care to this population.

We also observe that the various techniques available for the reactivation of smell function do not propose to intervene directly in the taste function. The absence of specific methods to rehabilitate the taste function, such as the lack of standardized tests to assess this function, reiterates the hypothesis that the olfactory changes in total laryngectomyzeds can reflect disorders in taste function and the reactivation of the olfactory function can also improve the taste function in this population.

CONCLUSION

In this review the tests used to evaluate olfactory function in the majority were concerned to make a quantitative analysis using standardized instruments, which suggests a concern with the results presented, as is intended to demonstrate the effectiveness of an intervention technique, but there are no tests to evaluate the taste function tests and specific methods of rehabilitation.

All analyzed studies demonstrated effectiveness in use of rehabilitation techniques for the smell function in total laryngectomized. Of the several techniques available, that who has been most commonly used is Nasal Airflow-Inducing Maneuver (NAIM), being a fast learning method, with obvious results in the reactivation of smell function and may have immediate effects after administration.

There is greater concern in the rehabilitation of olfactory function due to the taste function, considering that the taste function changes in total laryngectomized are a consequence of smell function changes, suggesting that the reactivation of smell function also resonate in taste function improvements.

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