The Role of Speech Therapists in Olfactory Rehabilitation: a Short Report on Ten Cases of Total Laryngectomy

Introduction: Total Laryngectomy (TL) has to be performed in advanced hypopharyngeal or laryngeal cancer, with the consequence of both the loss of the vocal functions and the impairment or loss of smell and taste. Since less attention is turned towards the recovery of the olfactory function compared to the vocal rehabilitation, the Nasal Airfl ow-Induced Maneuver (NAIM) was proposed as a useful smell recovery method. In this short note, we report the results of the olfactory rehabilitation procedures by performing the NAIM technique in ten total laryngectomized patients with the evaluation of both the subjective olfactory detection and the olfactory discrimination, recognition and identifi cation of odorous substances and we would emphasize the role of speech therapists in this rehabilitative procedure.


Introduction
Speech therapists work to prevent, assess and treat speech, language, cognitive-communication and swallowing disorders in children and adults in order to solve the consequence of various pathological conditions. Among these ones, advanced laryngeal and hypopharyngeal cancer requests the surgical procedure of Total Laryngectomy (TL), consisting on the removal of the whole larynx with the entire hyoid bone. At present in most clinical structures the speech therapist intervention after TL is exclusively aimed to recovery the specifi c speech activity by performing various alaryngeal speech techniques, i.e. by means of the oesophageal voice as well as by the application of voice prostheses. However, in TL the whole disconnection of the upper and lower airways causes deterioration of many other physiological functions in addition to the loss of the vocal one, including a remarkable impairment, and even total loss, of the specifi c senses of smell and taste [1][2][3], that are strictly mutually associated by various anatomical and functional features. Unfortunately less attention is generally turned to this remarkable consequence of TL, that causes an evident decrease in the quality of life in total laryngectomized patients.
As far as the recovery of the olfactory function is concerned, the NAIM technique (the so named "Polite Yawning") [3] is widely suggested for this aim and also adequate modifi cations of the original procedure were proposed to obtain better and more durable results in the regain of an acceptable olfactory function [4]. The NAIM consists of an extended yawning movement together with a simultaneous lowering of the jaw, as well as of both the body and the base of the tongue and the soft palate, while keeping the lips securely closed. In this short report, we would remark the peculiar role played by speech therapists in the rehabilitation of the olfactory function in ten cases of total laryngectomized patients by training them to the NAIM procedure and to stimulate them to frequently repeat the specifi c NAIM exercise both during the specifi c olfactory rehabilitation cycle and after the end of a 4-week treatment period.

Materials and methods
Ten total laryngectomized male patients, aged between 58 and 76 years (mean age 67.30 ± 6.04, median age 67), free from both nasal and pharyngeal concurrent pathologies, as well as from anatomical anomalies, agreed to the proposal to undergo an olfactory rehabilitation cycle performed by speech therapists in addition to the classic voice recovery treatment.
All of them underwent total laryngectomy in different periods for advanced laryngeal cancer; none of them underwent either chemotherapy or radiotherapy after surgery and had at least a 2-year follow up period to evaluate stabilized late adverse effects. All patients already underwent voice rehabilitation and they were using different alaryngeal speech techniques, i.e. the oesophageal voice or voice prostheses. All patients were trained by speech therapists to the NAIM [3], to enable air and odorous substances to reach again the olfactory mucosa in the nasal cavities. The olfactory capability was evaluated with both the subjective olfactory perception and the olfactory discrimination, recognition and identifi cation.

Speech therapist intervention in the olfactory rehabilitation technique
Sessions of the olfactory rehabilitation cycle (each with a duration of 45 min) started at the end of clinical preliminar evaluations to exclude the presence of concurrent both nasal and pharyngeal pathologies, as well as anatomical anomalies, and were performed three times a week for four weeks (4-week treatment period), i.e. for a total of twelve 45-min sessions.
Speech therapists trained patients to the NAIM [3] to provoke a negative pressure both in the oral cavity and the oropharynx to restore the nasal airfl ow, thus to enable odorous substances to reach again the Schultz's olfactory neuronal receptors located within the olfactory mucosa. Patient were required to repeat the NAIM exercises several times at every rehabilitation unit to acquire a good expertise and they were also stimulated to actively use the NAIM as often as possible, as well as in particular after the end of the 4-week rehabilitation cycle.

Subjective olfactory detection
Tests of olfactory detection were performed at three time intervals, i.e. before the beginning of the olfactory rehabilitation cycle, after the third rehabilitation unit, i.e. at the end of the fi rst rehabilitation week, and at the end of the olfactory rehabilitative intervention. A 4% 1-butanol solution in di-propylene glycol was employed to assess the subjective olfactory detection capability of each patient. Patients were asked by speech therapists to express their subjective detected smell intensity by means of a numeric score between 0 (no olfactory detection) and 10 (maximum of olfactory detection). Score mean values of the voted subjective smell intensity at each considered period were calculated and statistical analyses were performed by considering the Student's t-test with signifi cant differences verifi ed when p < 0.01.

Olfactory discrimination, recognition and identifi cation
Patients underwent olfactory discrimination, recognition and identifi cation tests of different odorous substances at three different periods, i.e. before beginning the 4-week olfactory rehabilitation cycle, at the end of the fourth week of treatment cycle and fi nally 12 months after the end of the rehabilitation treatment. The olfactory discrimination, recognition and identifi cation test consisted in sniffi ng sticks each containing a specifi c odorant. Each patient was presented with 26 sticks and everyone had to choose the correct answer among four choices in a questionary. Presentation of each stick was separated by at least 30 seconds. Mean values of the correctly identifi ed substances were calculated. Statistical analyses were performed by considering the Student's t-test with signifi cant differences verifi ed when p < 0.01.

Speech therapist intervention in the olfactory rehabilitation technique
Three 45 min-training sessions were performed weekly by speech therapists and those were repeated during a 4-week period for a total of twelve 45-min sessions. At the beginning of the olfactory rehabilitation cycle speech therapists explained the anatomical and functional changes caused by TL and teached the laryngectomized patients the NAIM technique. Most patients learned the NAIM movements already during the fi rst session of the rehabilitation cycle, however a minority of them found particular diffi culties in NAIM application, therefore they were suggested to provide some minimal modifi cations to the original NAIM technique: in particular, for the patients speaking with the oesophageal voice, they were suggested to reproduce the same action they usually performed for the oesophageal speech. Every patient followed carefully every rehabilitation phase, thus every patient was able to acquire a correct NAIM technique either by applying the original method [3] or by using the above mentioned modifi ed method with an adaptation suggested by speech therapists for each specifi c patient. We performed sessions with a longer duration (45 min vs. 30 min) than that proposed in the original method [3] and we assessed the progress of patients in learning of the NAIM movements, as well as the recovery of the olfactory detection capability, by presenting our patients the 4% 1-butanol solution in di-propylene glycol, i.e. with a subjective detection method, instead of the employ of a digital manometer evaluating a negative air pressure within the oropharyngeal space. During the olfactory rehabilitation cycle, we could observe a signifi cant amelioration of the olfactory detection capability already after the third olfactory rehabilitation unit in comparison to the olfactory detection test performed before the beginning of the olfactory rehabilitation treatment. Moreover, we think particularly relevant the evidence that the olfactory rehabilitation benefi ts were preserved 12 months after the end of the rehabilitation treatment, showing that patients followed continuously the suggestions of speech therapists to perform the specifi c NAIM exercises with or without the modifi cations proposed for each laryngectomized patient.

Subjective olfactory detection
Data of this experimental phase are reported in Table 1. Before beginning the olfactory rehabilitation cycle, the mean value of the olfactory detection was 3.40 ± 1.71 in a score beteween a minimum of 1 and a maximum of 6. After the third rehabilitation unit, the mean value of the olfactory detection was 5.70 ± 1.25, in a score between 4 and 7. Finally, at the end of the rehabilitation cycle (4 weeks), the mean value of the olfactory detection increased up to 8.10 ± 0.74, in a score between 7 to 9. By performing the paired Student's t-test, the signifi cance of the differences between the mean values of the subjective olfactory detection without any rehabilitative intervention and those after the third olfactory rehabilitation session, as well as between this one and the olfactory sensibility at the end of the rehabilitative intervention, were evidenced for a level of p < 0.01 and it was considered as statistically signifi cant. Therefore, it is evident that there was a signifi cant amelioration of the subjective olfactory detection already after the third rehabilitative unit suggesting a peculiar role of the speech therapist intervention already in the earliest phase of the olfactory rehabilitation cycle, i.e. in the fi rst week of the treatment. Moreover it appears particularly interesting, since it showed the very useful activity of speech therapists in teaching their laryngectomized patients the exercises of the NAIM procedure, even considering the progressive increase of the subjective olfactory detection capability during the 4-week rehabilitation cycle.

Olfactory discrimination, recognition and identifi cation
Data of this experimental phase are reported in Table 2 and graphically presented in Figure 1. Patients underwent the fi rst olfactory discrimination, recognition and identifi cation test of odorous substances before performing the fi rst olfactory rehabilitative intervention, but after the fi rst subjective olfactory detection one. The fi rst olfactory discrimination and recognition analysis revealed a mean value of 5.60 ± 1.17 of correctly identifi ed substances among a total of 26 ones. At the end of the olfactory rehabilitation period (4 weeks), the mean value of correctly identifi ed substances was 12.00 ± 1.94.
A third olfactory discrimination, recognition and identifi cation test were performed 12 months after the end of the smell rehabilitative procedure: the mean value of the correctly Table 1: Subjective olfactory detection scores at three different time intervals during the 4-week olfactory rehabilitation cycle.

Conclusion
Data reported in the present short communication showed that the rehabilitation of the olfactory functions should be highly considered in the follow up of patients undergone TL. The NAIM procedure was quickly learned by our ten laryngectomized patients and they continuously performed the specifi c NAIM exercises, since they were much motivated both themselves and by their speech therapists. In the follow up of TL the speech therapist role should be aimed not exclusively towards the recovery of the vocal functions, but also towards the recovery of the olfactory detection, perception, discrimination and identifi cation. We confi rmed the great usefulness of the NAIM procedure and speech therapists were able to adjust the original method to the specifi c need of each patient. Therefore, the role of speech therapists should be considered highly relevant to regain the olfactory function to allow again a good quality of life even after TL surgery.