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mise à jour du
30 octobre 2003
Arch otolaryngol head neck
2000;126:726-731
lexique
Rehabilitation of OLFACTION after laryngectomy by means of a nasal airflow-inducing maneuver
- The polite yawning technique -
F Hilgers, F van Dam et al.
Department of ORL Head Neck surgery
Cancer institute Amsterdam (NL)
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Although deterioration of olfaction after total laryngectomy is reported by th majority of patients, this unpleasant side effect ha not received widespread attention. More over, olfactory rehabilitation has been given much less consideration than other more obvious sequelae of this operation ie vocal and pulmonary rehabilitation. In several overviews on the "total rehabili tation of laryngectomees," olfactory problems as a consequence of the laryngectomy were not even mentioned.It was thought that the anosima, noted iminediately after the operation, was an inevitable result of the laryngectomy and that no return of olfactory acuity occurred as long as 8 years after operation. Others however, have reported improvement in olfaction during the first 6 months after surgery and the presence of a relatively normal sense of smeil in some laryngectomees A recent study in our clinic showed that patients who have undergone laryngectomy could be divided into 2 groups on the basis of an odor detection and/or an odor differentiation test, ie, "smellers" and "nonsmellers." These tests were performed without artificial devices to generate a nasal airflow. The results of these "natural" tests indicated that one third of the patients could be classified as smellers. This category of patients reported not only a better sense of smell than the nonsmellers but also a better sense of taste and appetite.
 
The consequences of the loss of the sense of smell can be profound. Anosmia results, for instance, in the loss of the signal function to detect smoke or leaking gas. The inability to detect bodily odors can cause insecurities in daily life, and the inability to perceive agreeable odors or fragrances can be experienced as a significant loss. Since most so-called tastes (eg,chocolate, coffee, tea, meat, etc) are dependent on retronasal stimulation of the olfactory receptors, the perception of such tastes will also be negatively influenced by the loss of the sense of smell.
 
Although factors such as atrophy of the olfactory neuroepithelium and/or bulb may also play a role in the olfactory problems of patients after laryngectomy, restoring nasal airflow is a prerequisite for rehabilitation of olfactory acuity in such patients.The main reason for the lack of an adequate nasal airflow is the disconnection of the upper and lower airways. By creating an artificial airflow with insufflation of the odors into the nose, using squeeze bottles, other nebulizers or a so-called larynx bypass, it became clear that in many laryngectomees the sense of smell is more or less preserved. However, because of their artificial nature and cumbersome application in daily life, these devices to restore nasal airflow are not extensively used. Others have described more unobtrusive methods to generate some degree of nasal airflow by creating volume changes in the pharynx with the mouth closed, such as the buccopharyngeal maneuver, buccopharyngeal sniffing, or glossopharyngeal press, but these also are not widely applied.
 
In our previous study, the smellers significantly more often had developed their own technique to improve olfaction, such as movements of the jaw and/or muscles in the face and floor of mouth and mastication muscles. On the basis of observations in our previous study and on remarks by patients and partners, we developed a nasal airflow-inducing maneuver (NAIM) in which a repeated extended yawning movement is performed, lowering the jaw, floor of niouth, tongue, base of tongue, and soft palate while keeping the lips securely closed. This is easily taught to patients by describing it as yawning with the mouth closed, ie, "polite yawning." This maneuver induces a negative pressure in the oral cavity and oropharynx, which generates a nasal airflow, enabling odorous substances to reach the olfactory epithelium again.
 
We describe an intervention study with this NAIM to assess whether patients can acquire this technique and whether it leads to an improvement of olfactory acuity. [...]
 
polite-yawning
 
polite-yawning
Loss of olfactory acuity after total laryngectomy is a disturbing side effect of this debilitating surgical procedure. The majority of the patients report a complete loss of the sense of smell. In an earlier study, using an ODT and an odor differentiation test, we found that 32% of the patients were still able to smell, whereas 68% were unable to detect or differentiate any of the odorous substances offered in these tests. Patients who applied some sort of personal technique to smell were significantly more often successful in accomplishing these olfactory tests. It also became clear that the loss of olfaction from total laryngectomy was not consistently addressed during rehabilitation sessions.
 
On the basis of the literature and observations made during our previous study, a NAIM was developed and tested in an intervention study. To the best of our knowledge, this is the first study to show a positive effect on the olfactory acuity of patients after laryngectomy by applying a special maneuver. The improvement in a substantial number of the patients, increasing the percentage of smellers from 25% to 57% in this sample, is very promising. Preservation of olfactory ability in patients after laryngectorny by teaching the NAIM is thus an attainable goal in postlaryngectomy rehabilitation, as already postulated by Schwartz et al, who used a buccopharyngeal sniffing technique. Furthermore, it was encouraging that most patients mastered the "polite yawning" technique in one 30-minute session. The patients easily understood the description and demonstration of the technique as a polite yawning movement.
 
As demonstrated by the use of a water or a digital manometer, the NAIM creates a negative pressure in the oral and nasal cavity, thus generating a nasal airflow. Using a comparable method, Tatchell et al" found a nican volunie of nasal airflow of 5.4 L/min, which is about 15% of the norm. They also found that increasing the nasal airflow, by using a laryngeal bypass, increased the olfactory threshold and odor discrimination. It could be demonstrated with this artificial device that laryngectoinees, although generating a slightly but significantly lower an-flow, scored the saine as normal controls. The method by which patients generated a nasal airflow ni the study of Tatchell et al, however, is somewhat unclear. They probably applied some form of personalized technique of buccopharyngeal sniffing but were nevertheless able to generatea nasal air-flow. It can be hypothesized fromvthe results of our study that better and more consistent results can be obtained by teaching the NAIM. The use of a manometer is very helpful in this respect; the simple water manometer, in particular, is an inexpensive and easy to use tool in the instruction of the NAIM during the rehabilitation sessions.
 
Because of the design of this intervention study, with the use of preintervention and postintervcntion olfaction assessments without randornization for treatment or no treatment, some placebo effect might be responsible for the improvement found on the POPS. This might be concluded from the improvements seen ni some of the other QOTA scores (present compared with past odor perception, and gustation) not only in the smellers but also in the nonsmellers. The attention given to their olfaction problem and the identification of the smelling sticks during the instruction of the NAIM might have given some patients the idea that their sense of smell was net as bad as they thought. However, the results of the ODT are net prone to being confounded by a placebo effect. The very stable results in all tested variables (ODT and QOTA scores) in the subset of patients who were analyzed twice with an interval of 10 months can also be considered an indication that the effects mesured are a result of the intervention and not caused by a placebo effect.
 
An interesting observation was that patients who clearly demonstrated an improved sense of smell during testing, with the use of the NAIM, still did net think that their olfaction was improved. They often explained that they still were unable to automatically smell odors in their environment. This implies that patients should be instructed to always use the NAIM when entering a new room or environment and to repeat the maneuver regularly to compensate for the loss of passive smelling, always present during normal nasopulmonary breathing or sniffing.`Olfactory rehabilitation, therefore, should focus not only on the maneuver itself, but also on regular use of the technique during the day, to mimic passive smelling. The present results were obtained with only 1 therapy session in the majority of patients. As with other aspects of postlaryngectomy rehabilitation (eg, voice and pulmonary status), olfactory rehabilitation might benefit from early and repeated attention. Others who might benefit from this polite yawning technique include quadriplegic patients receiving permanent ventilation via a cuffed trachea cannula. It is well known that these patients also suffer from anosmia. Since their cranial nerve function is intact, they should be able to acquire this NAIM as well, thus improving their olfactory acuity.
 
It is interesting that some of our patients who were alrcady able to smell before the intervention still considered their sense of smell improved, because by conscientiously applying the NAIM they were better able to smell at will.
The interesting discrepancy between loss of olfaction and gustation, the latter being much less disturbed alter total laryngectomy than the former, might be explained by the existence of a retronasal route through which odor molecules can reach the olfactory epithelium. In fact, most patients are instructed by their speech therapist during rehabilitation sessions to chew their food carefully to stimulate this retronasal olfaction route. The fact that this is apparently effective also underscores the conclusion that the olfactory neuroepithelium still functions normally after total laryngectomy. An additional explanation for the effect of chewing on olfaction might be that, during chewing, provided the lips stay closed, a small nasal airflow is generated regularly, such as during the NAIM.
 
The criteria used in this study to distinguish between smellers and nonsmellers deserve some attention. The ODT appears to be reliable, considering the concordance of more than 80% between the results obtained in a subset of 22 patients, tested within a 10-month interval. However, the preintervention results of 16% of the patients passing the ODT are somewhat lower than the results of our earlier study, in which we applied both odor detection and discrimination tests." The reason only 1 olfaction test was used in this intervention study was to keep the whole test and instruction session within reasonable time limits to prevent fatiguing and oversaturation of the patient. The use of only 1 test, however, might have led to an underestimation of the number of preintervention smellers, but this will probably also hold truc for the postintervention results. In fact, there is evidence that more patients benefited from the NAIM than can be concluded on the basis of the ODT results. The QOTA indicated an improvement in some additional patients. This led to the assumption that the results of the QOTA also might be useful to judge the effect of the intervention. The QOTA showed a good consistency over time in the subset of 22 patients participating in both olfaction studies within a 10-month interval. Therefore, a POPS score equal to or better than the mean score of a reference group of senior citizens, ie, 10 or more, was considered indicative of normal olfactory acuity. By combining the ODT results and the POPS scores at the preintervention assessment, 30% of the patients could be categorized as smellers, which is much more in concordance with our carlier study and is an additional argument for the potential use of the POPS score of 10 or more as an indication of normal olfaction acuity. The ODT we used is probably a relatively insensitive test; for this type of study, one of the newer olfaction tests, discriminating in a more simplified way between normal olfaction, hyposmia, and anosmia, may be more effective, including the recently described elegant diskette test.
 
In conclusion, olfactory acuity can be rehabilitated after laryngectomy in approximately 50% of the patients by applying a NAIM, best described as repeated yawning with closed lips (polite yawning).
 
larynx
larynx