Journal of
Oral Rehabilitation
Journal of Oral Rehabilitation 2015 42; 136--143
Effect of nasal speaking valve on speech intelligibility under velopharyngeal incompetence: a questionnaire survey S. MIKAMO, N. KODAMA, Q. PAN, N. MAEDA & S. MINAGI
Department of Occlusal and Oral
Functional Rehabilitation, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan
SUMMARY Velopharyngeal incompetence is known as a contributing factor to speech disorders. Suwaki et al. reported that nasal speaking valve (NSV) could improve dysarthria by regulating nasal emission utilising one-way valve. However, disease or condition which would be susceptible to treatment by NSV has not been clarified yet. This study aimed to evaluate the effect of NSV by questionnaire survey using ready-made NSV. Subjects were recruited through the internet bulletin, and NSV survey set was sent to the applicant. Sixty-six participants, who agreed to participate in this study, used NSV and mailed back the questionnaire which included selfevaluation and third-party evaluation of speech intelligibility. Statistical analysis revealed that the use of NSV resulted in significant speech intelligibility improvement in both self-evaluation and third-party evaluation (P < 001). Regarding the type of underlying disease of dysarthria, significant effect of NSV on self-evaluation of
Background Velopharyngeal incompetence is a contributing factor to speech disorders, frequently accompanying disorders such as neurodegenerative disease, cleft palate, congenital paralysis of the soft palate and cerebrovascular disease. Velopharyngeal incompetence implies the presence of hypernasality, inappropriate nasal escape and decreased air pressure during the production of oral speech sounds (1). © 2014 John Wiley & Sons Ltd
speech intelligibility could be observed in cerebrovascular disease and neurodegenerative disease (P < 001) and that on third-party evaluation in neurodegenerative disease (P < 001). Eighty-six percent of subjects showed improvement of speech intelligibility by shutting up nostrils by fingers, and the significant effect of NSV on both self-evaluation and third-party evaluation of speech intelligibility was observed (P < 0001). From the results of this study, it was suggested that NSV would be effective in cerebrovascular disease and neurodegenerative disease, as well as in subjects whose speech intelligibility was improved by closing nostrils. KEYWORDS: velopharyngeal incompetence, articulation, speech intelligibility, questionnaires, amyotrophic lateral sclerosis, cerebrovascular disease Accepted for publication 30 August 2014
When the swallowing reflex is triggered, the pharyngeal stage of the swallow begins, and velopharyngeal closure occurs to close the nasal cavity and prevents food from entering the nose (2). Consequently, it is thought that velopharyngeal incompetence often disturbs velopharyngeal closure for protective and reflexive acts of swallowing as well as for speech (3). Generally, behavioural interventions are reserved for those with mild or inconsistent velopharyngeal doi: 10.1111/joor.12237
EFFECT OF NASAL SPEAKING VALVE ON ARTICULATION incompetence (4). Prosthetic or surgical management is considered for severe and consistent incompetence (5–8). Palatal lift prosthesis (PLP) has been adopted as a prosthetic intervention method for the rehabilitation of articulation problem caused by velopharyngeal incompetence (8–14). However, there are clinically difficult cases for the application of PLP, that is severe vomiting reflex cases, edentulous cases with poor alveolar ridge and so on. Nasal speaking valve (NSV) had been introduced as a prosthetic device which could be used for improving hypernasal speech caused by velopharyngeal incompetence (15, 16). Nasal speaking valve is a removable device, inserted in the nostrils with a custom-made hard outer shell structure. One-way valves inhibiting exhalation through the valve and enabling free inhalation constitute the inner design. This structure might also be effective for a dysphagic patient who suffers from velopharyngeal incompetence. Nasal speaking valve could be used for the cases with severe vomiting reflex or edentulous patient with poor alveolar ridge. However, as custom impression of the nostrils was necessary for the construction of NSV, it could be fabricated only for the patients who could see a specialist doctor. This was a practical obstacle for patient to receive this device and also for the cumulation of epidemiological data on the usability of the device. We therefore invented readymade NSV, which could be made without requiring custom impression of the nostrils. The invention of the ready-made NSV prepared us for accumulation of data on the clinical effect of NSV for general patient population with velopharyngeal incompetence. The accumulation of the information on background disease would help defining diseases susceptible to this treatment. Therefore, this study aimed to evaluate the effect of NSV on articulation problem and swallowing function in velopharyngeal incompetent patients with unspecified background disease.
survey set’ was sent to 139 inquiries from 27 of 47 prefectural areas of Japan. ‘NSV survey set’ consisted of a printed explanation of the study, a consent form document, a pair of ready-made NSV, an instruction manual and a questionnaire. Applicants, who have read and understood the explanation of this study and signed the consent form, were included as a subject in this study. Finally, 44 males and 22 females (mean age: 570 218) participated in this study. Participants used NSV and mailed back the questionnaire. The questionnaire was retrieved from April 2012 to November 2013. The protocol of this study was approved by the Ethics Committee of Okayama University (Approval No. 518). All participants gave written informed consent. Nasal speaking valve Ready-made NSV was used in this study. As shown in Fig. 1, NSV consisted of two cylinder hollow shells with one-way valve on the external end of each cylinder. Two cylinders were connected using a nylon cable. Nitrile rubber band was used to wrap around (a)
(b)
(c)
Materials and Methods Subjects Subject recruitment was made through the internet bulletin (http://www.cc.okayama-u.ac.jp/~2hotetsu/ NSV_TOP.html). The inclusion criteria listed in the internet bulletin were (i) suffering from dysarthria and (ii) closing nostrils with fingers improve speech. ‘NSV © 2014 John Wiley & Sons Ltd
Fig. 1. Ready-made nasal speaking valve (NSV) (a) Ready-made nasal speaking valve. Note that two shells were connected using a nylon cable. (b) Schematic structure of ready-made NSV. Oneway valve opens with inhalation and closes with exhalation. (c) Ready-made NSV in position.
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S . M I K A M O et al. the axial wall of the cylinder to fit subject’s nostril. The one-way valve allowed exhalation but not inhalation through NSV. Questionnaire Questionnaire consisted of the following 7 items. 1 Speech intelligibility without NSV Nine-point rating scale of the Japanese conversational speech intelligibility test (17) shown in Table 1 was achieved by a family member of subject before wearing NSV. Also the same rating scale was used for the self-assessment of speech intelligibility by the subject. 2 Speech intelligibility with NSV Nine-point rating scale of the Japanese conversational speech intelligibility test was achieved by a family member of subject wearing NSV. Also the same rating scale was used for the self-assessment of speech intelligibility by the subject. A decrease of 05 point or more from baseline was considered as ‘improved’, whereas an increase of 05 point or more from baseline was considered as ‘worsened’. 3 Easiness of speaking with NSV Subjective feeling of easiness to speak was assessed using 5-point rating scale, that is from ‘1: extremely difficult to speak’, ‘2: slightly difficult to speak’, ‘3: no change’, ‘4: slightly easy to speak’ to ‘5: extremely easy to speak’. 4 Easiness of swallowing with NSV Subjective feeling of easiness to swallow was assessed using 5-point rating scale, that is from ‘1: extremely difficult to swallow’, ‘2: slightly difficult to swallow’, ‘3: no change’, ‘4: slightly easy to swallow’ to ‘5: extremely easy to swallow’. 5 Change of speech intelligibility by shutting up nostrils
Table 1. The 9-point rating scale of the Japanese conversational speech intelligibility test. Scale Scale Scale Scale Scale
1 2 3 4 5
Intelligible Occasionally unintelligible Understandable if the topic is known Occasionally intelligible Unintelligible
Note that half scores were assigned (e.g. 15) to make totally 9 points scale.
The effect of shutting up nostrils on speech intelligibility was objectively assessed by a family member using 5-point rating scale, that is from ‘1: no change’, ‘3: becomes slightly intelligible’ to ‘5: becomes extremely intelligible’ with half scores assigned to be 2 and 4. 6 Underlying cause of dysarthria 7 Free description of impression about NSV Statistical analysis The change of speech intelligibility test score with and without ready-made NSV was assessed by Wilcoxon signed-rank test. Spearman’s rank correlation coefficient was used to assess the relationship between speech intelligibility test and the age of subject. SPSS (IBM SPSS Statistics ver. 20.0*) was used for the statistical analysis with the significance level of 005.
Results Cerebrovascular disease was the most prominent underlying cause of dysarthria (29 subjects, 44%), followed by neurodegenerative disease (14 subjects, 21%), that is amyotrophic lateral sclerosis (ALS), progressive supranuclear palsy and so on, congenital disease (8 subjects, 12%), that is cleft palate, Pierre Robin syndrome, Down syndrome and so on, parenchymatous defect caused by pharyngeal cancer (three subjects, 5%), and others (12 subjects, 18%), that is traumatic accident, dermatomyositis, side effect of anticancer drug and so on (Table 2). In the neurodegenerative diseases, 12 subjects (857%) of 14 subjects were ALS. Speech intelligibility Results on the self-evaluation and third-party evaluation of speech intelligibility are summarised in relation to the underlying cause of dysarthria in Fig. 2. Figure 2a shows self-evaluation and third-party evaluation of speech intelligibility in all subjects. Selfevaluation of speech intelligibility revealed improvement, no change and disimprovement in 55%, 41% and 4%, respectively. Statistical analysis revealed that the use of NSV resulted in significant improvement in the self-evaluation (P < 001). Third-party evaluation *IBM Corp., Somers, NY, USA. © 2014 John Wiley & Sons Ltd
EFFECT OF NASAL SPEAKING VALVE ON ARTICULATION Table 2. Subjects and underlying diseases Number of subjects
(a)
Total (%)
Age (mean SD, in year)
7
29 (440)
622 174
6
8
14 (212)
594 136
4 3
4 0
8 (121) 3 (45)
281 333 563 119
9 44
3 22
12 (182) 66 (1000)
617 192 570 218
Disease
Male
Cerebrovascular disease Neurodegenerative disease Congenital disease Parenchymatous defect Others Total
22
Female
of speech intelligibility by a family member revealed improvement, no change and disimprovement in 53%, 41% and 6%, respectively. Statistical analysis revealed that the use of NSV resulted in significant improvement in the third-party evaluation (P < 001). Significant effect of NSV on self-evaluation could be observed in cerebrovascular disease and neurodegenerative disease as shown in Fig. 2b,c (P < 001). Significant effect of NSV on third-party evaluation could be observed in neurodegenerative disease as shown in Fig. 2c (P < 001). On the contrary, self-evaluation and third-party evaluation could not be observed in congenital disease and parenchymatous defect as shown in Fig. 2d,e. Of the 36 subjects who showed improvement in self-evaluation by NSV, cerebrovascular disease (13 subjects) was the most prominent followed by ALS (eight subjects). Of the 34 subjects who showed improvement in third-party evaluation by NSV, ALS (10 subjects) and cerebrovascular disease (10 subjects) were the most prominent. Figure 3 shows relation to speech intelligibility score on non-wearing NSV and speech intelligibility improvement by wearing NSV. The vertical axis means how many scale the speech intelligibility improved with NSV and horizontal axis means the initial speech intelligibility without NSV. The size of the bubbles corresponds to the population size, and the number in the bubbles means that of subjects with the same value of the speech intelligibility improved with NSV as well as the initial speech intelligibility without NSV. Speech intelligibility disimprovement was observed below speech intelligibility scale 25 of self-evaluation and 35 of third-party evaluation. © 2014 John Wiley & Sons Ltd
(b)
(c)
(d)
(e)
Fig. 2. Distribution of the number of subjects under non-wearing and wearing NSV condition for subjective and objective evaluation of speech intelligibility. (a) total subjects, (b) cerebrovascular disease, (c) neurodegenerative disease, (d) congenital disease, (e) parenchymatous defect.
Easiness of speaking and swallowing with NSV Self-evaluation of easiness of speaking revealed improvement, no change and disimprovement by NSV in 49%, 27% and 24%, respectively. Self-evaluation of easiness of swallowing revealed improvement, no change and disimprovement by NSV in 18%, 62%
139
140
S . M I K A M O et al. preferable impression for NSV, significant effect of NSV on self-evaluation and third-party evaluation could be observed (P < 001). However, five of those subjects also described unfavourable comments, ‘uncomfortable to breathe (three subjects)’ and ‘aesthetically unsatisfied (two subjects)’. Unfavourable description showed ‘does not fit well’ (27%), ‘uncomfortable to breathe’ (15%), ‘aesthetically unsatisfied’ (12%) and ‘fractured’ (5%). The fractures of NSV included the cylinder fractures during manual handlings, caused by reconnecting a line to adjust the length and wrapping around the cylinder with additional nitrile rubber band. The relationship between the self-evaluation of speech intelligibility and the age of subjects is shown in Fig. 4. No statistically significant correlation could be observed for the relationship (P = 0180).
Discussion
Fig. 3. Relation to speech intelligibility score on non-wearing NSV and speech intelligibility improvement by wearing NSV. Speech intelligibility disimprovement was observed below speech intelligibility scale 25 of self-evaluation and 35 of thirdparty evaluation.
and 20%, respectively. Ten subjects did not respond on the item of easiness of swallowing.
To our knowledge, this is the first study to evaluate the effect of NSV on speech intelligibility. Our results confirm that the use of NSV results in the significant improvement in speech intelligibility for cerebrovascular disease and neurodegenerative disease according to self-evaluation and third-party evaluation. In addition, our study showed significant improvement in speech intelligibility by shutting nostrils with fingers. For the speech treatment program, a nasal obturator was reported to play a key role in the management of nasal emission to maximise the effectiveness of an intensive speech treatment program (18). However,
Change of speech intelligibility by shutting up nostrils Eighty-six per cent subjects showed improvement of speech intelligibility by shutting up nostrils by fingers. In the subjects whose speech intelligibility was improved by shutting up nostrils by fingers, significant effect of NSV on self-evaluation and third-party evaluation could be observed (P < 0001). 8 subjects did not improve by shutting up nostrils by fingers. Additionally, seven of these eight subjects did not show any improvement of speech intelligibility using NSV. Free description of impression about NSV Free description of 41% subjects showed preferable impression for NSV. In the subjects who showed
Fig. 4. Improvement of speech intelligibility by subjective evaluation. Note that the score shows the deduction of speech intelligibility without NSV from with NSV. No significant relationship could be observed between the improvement and age. © 2014 John Wiley & Sons Ltd
EFFECT OF NASAL SPEAKING VALVE ON ARTICULATION complete inhibition of inhalation and exhalation would easily cause ear pain while swallowing saliva because of rhinopharynx pressure changes. Nasal speaking valve was reported by Suwaki et al. (15) in a case report of brain injury as an appliance for the rehabilitation for velopharyngeal incompetence. Nasal speaking valve is different from a simple obturator as it has valve structures to suppress exhalation and allow inhalation through nostrils, which is most effective for avoiding possible ear discomfort caused by the pressure change during swallowing. Shutting nostrils with fingers during speaking and swallowing is a hard task for patients. Wearing NSV allows patients to speak more naturally than occluding nostrils. Although the effect of NSV for experimentally induced velopharyngeal incompetence condition was also reported by Suwaki et al., disease or condition which would be susceptible to treatment by NSV has not been clarified yet. Therefore, the study regarding effectiveness of NSV in various diseases and conditions would be of great importance for the clinical decision making or treatment planning. In previous reports, NSV had been constructed on gypsum cast after taking impression of the nostrils of each subject or patient (15, 16). Although this NSV fits the nostrils well with great availability and relief of hypernasality, several visits to a prosthodontist are necessary for the fabrication. As this study aimed to collect service results from patient of diverse background disease from all over Japan, ready-made NSV was designed. As this ready-made NSV could easily be fit to the nostrils of patient using nitrile rubber bands, either the patient him/herself or the working speech-language-hearing therapist can fit it well. The number of patients who inquired the information of this research through the internet was 139. After sending the materials to these candidates, 66 patients showed agreement to participate in this study by sending back the signed informed consent form. The description sheet stated that candidates were not allowed to use NSV until they agreed to participate in this study. Therefore, despite rather low rate of recovery of 41%, it would be reasonable to estimate the effect of NSV from this sample group. The recruitment method of subjects in this study comprises a limitation. Because it was not random sampling, the prevalence of each background disease © 2014 John Wiley & Sons Ltd
might not represent the patient population. However, the results shown in this subject group would be effective to explore the diseases susceptible to this new treatment modality, NSV. Another limitation of this study is that the evaluation of the effect of NSV was conducted using questionnaire. In fact, ten subjects did not respond to the item on easiness of swallowing, which might be because they did not use NSV during meals. We only could obtain limited information from the questionnaire as subjects had the choice to respond or not respond to all the questions. Speech intelligibility disimprovement was observed below speech intelligibility scale 25 of self-evaluation and 35 of third-party evaluation. In other words, speech intelligibility improvement was observed above speech intelligibility scale 3 of self-evaluation and 4 of third-party evaluation. These scales could be considered to the baseline that NSV was effective. However, Speech intelligibility improvement was also observed below speech intelligibility scale 25 of self-evaluation and 35 of third-party evaluation. Although articulation improvement was observed irrespective of speech intelligibility, it could not be improvement that speech intelligibility scales were
Oral Rehabilitation
Journal of Oral Rehabilitation 2015 42; 136--143
Effect of nasal speaking valve on speech intelligibility under velopharyngeal incompetence: a questionnaire survey S. MIKAMO, N. KODAMA, Q. PAN, N. MAEDA & S. MINAGI
Department of Occlusal and Oral
Functional Rehabilitation, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan
SUMMARY Velopharyngeal incompetence is known as a contributing factor to speech disorders. Suwaki et al. reported that nasal speaking valve (NSV) could improve dysarthria by regulating nasal emission utilising one-way valve. However, disease or condition which would be susceptible to treatment by NSV has not been clarified yet. This study aimed to evaluate the effect of NSV by questionnaire survey using ready-made NSV. Subjects were recruited through the internet bulletin, and NSV survey set was sent to the applicant. Sixty-six participants, who agreed to participate in this study, used NSV and mailed back the questionnaire which included selfevaluation and third-party evaluation of speech intelligibility. Statistical analysis revealed that the use of NSV resulted in significant speech intelligibility improvement in both self-evaluation and third-party evaluation (P < 001). Regarding the type of underlying disease of dysarthria, significant effect of NSV on self-evaluation of
Background Velopharyngeal incompetence is a contributing factor to speech disorders, frequently accompanying disorders such as neurodegenerative disease, cleft palate, congenital paralysis of the soft palate and cerebrovascular disease. Velopharyngeal incompetence implies the presence of hypernasality, inappropriate nasal escape and decreased air pressure during the production of oral speech sounds (1). © 2014 John Wiley & Sons Ltd
speech intelligibility could be observed in cerebrovascular disease and neurodegenerative disease (P < 001) and that on third-party evaluation in neurodegenerative disease (P < 001). Eighty-six percent of subjects showed improvement of speech intelligibility by shutting up nostrils by fingers, and the significant effect of NSV on both self-evaluation and third-party evaluation of speech intelligibility was observed (P < 0001). From the results of this study, it was suggested that NSV would be effective in cerebrovascular disease and neurodegenerative disease, as well as in subjects whose speech intelligibility was improved by closing nostrils. KEYWORDS: velopharyngeal incompetence, articulation, speech intelligibility, questionnaires, amyotrophic lateral sclerosis, cerebrovascular disease Accepted for publication 30 August 2014
When the swallowing reflex is triggered, the pharyngeal stage of the swallow begins, and velopharyngeal closure occurs to close the nasal cavity and prevents food from entering the nose (2). Consequently, it is thought that velopharyngeal incompetence often disturbs velopharyngeal closure for protective and reflexive acts of swallowing as well as for speech (3). Generally, behavioural interventions are reserved for those with mild or inconsistent velopharyngeal doi: 10.1111/joor.12237
EFFECT OF NASAL SPEAKING VALVE ON ARTICULATION incompetence (4). Prosthetic or surgical management is considered for severe and consistent incompetence (5–8). Palatal lift prosthesis (PLP) has been adopted as a prosthetic intervention method for the rehabilitation of articulation problem caused by velopharyngeal incompetence (8–14). However, there are clinically difficult cases for the application of PLP, that is severe vomiting reflex cases, edentulous cases with poor alveolar ridge and so on. Nasal speaking valve (NSV) had been introduced as a prosthetic device which could be used for improving hypernasal speech caused by velopharyngeal incompetence (15, 16). Nasal speaking valve is a removable device, inserted in the nostrils with a custom-made hard outer shell structure. One-way valves inhibiting exhalation through the valve and enabling free inhalation constitute the inner design. This structure might also be effective for a dysphagic patient who suffers from velopharyngeal incompetence. Nasal speaking valve could be used for the cases with severe vomiting reflex or edentulous patient with poor alveolar ridge. However, as custom impression of the nostrils was necessary for the construction of NSV, it could be fabricated only for the patients who could see a specialist doctor. This was a practical obstacle for patient to receive this device and also for the cumulation of epidemiological data on the usability of the device. We therefore invented readymade NSV, which could be made without requiring custom impression of the nostrils. The invention of the ready-made NSV prepared us for accumulation of data on the clinical effect of NSV for general patient population with velopharyngeal incompetence. The accumulation of the information on background disease would help defining diseases susceptible to this treatment. Therefore, this study aimed to evaluate the effect of NSV on articulation problem and swallowing function in velopharyngeal incompetent patients with unspecified background disease.
survey set’ was sent to 139 inquiries from 27 of 47 prefectural areas of Japan. ‘NSV survey set’ consisted of a printed explanation of the study, a consent form document, a pair of ready-made NSV, an instruction manual and a questionnaire. Applicants, who have read and understood the explanation of this study and signed the consent form, were included as a subject in this study. Finally, 44 males and 22 females (mean age: 570 218) participated in this study. Participants used NSV and mailed back the questionnaire. The questionnaire was retrieved from April 2012 to November 2013. The protocol of this study was approved by the Ethics Committee of Okayama University (Approval No. 518). All participants gave written informed consent. Nasal speaking valve Ready-made NSV was used in this study. As shown in Fig. 1, NSV consisted of two cylinder hollow shells with one-way valve on the external end of each cylinder. Two cylinders were connected using a nylon cable. Nitrile rubber band was used to wrap around (a)
(b)
(c)
Materials and Methods Subjects Subject recruitment was made through the internet bulletin (http://www.cc.okayama-u.ac.jp/~2hotetsu/ NSV_TOP.html). The inclusion criteria listed in the internet bulletin were (i) suffering from dysarthria and (ii) closing nostrils with fingers improve speech. ‘NSV © 2014 John Wiley & Sons Ltd
Fig. 1. Ready-made nasal speaking valve (NSV) (a) Ready-made nasal speaking valve. Note that two shells were connected using a nylon cable. (b) Schematic structure of ready-made NSV. Oneway valve opens with inhalation and closes with exhalation. (c) Ready-made NSV in position.
137
138
S . M I K A M O et al. the axial wall of the cylinder to fit subject’s nostril. The one-way valve allowed exhalation but not inhalation through NSV. Questionnaire Questionnaire consisted of the following 7 items. 1 Speech intelligibility without NSV Nine-point rating scale of the Japanese conversational speech intelligibility test (17) shown in Table 1 was achieved by a family member of subject before wearing NSV. Also the same rating scale was used for the self-assessment of speech intelligibility by the subject. 2 Speech intelligibility with NSV Nine-point rating scale of the Japanese conversational speech intelligibility test was achieved by a family member of subject wearing NSV. Also the same rating scale was used for the self-assessment of speech intelligibility by the subject. A decrease of 05 point or more from baseline was considered as ‘improved’, whereas an increase of 05 point or more from baseline was considered as ‘worsened’. 3 Easiness of speaking with NSV Subjective feeling of easiness to speak was assessed using 5-point rating scale, that is from ‘1: extremely difficult to speak’, ‘2: slightly difficult to speak’, ‘3: no change’, ‘4: slightly easy to speak’ to ‘5: extremely easy to speak’. 4 Easiness of swallowing with NSV Subjective feeling of easiness to swallow was assessed using 5-point rating scale, that is from ‘1: extremely difficult to swallow’, ‘2: slightly difficult to swallow’, ‘3: no change’, ‘4: slightly easy to swallow’ to ‘5: extremely easy to swallow’. 5 Change of speech intelligibility by shutting up nostrils
Table 1. The 9-point rating scale of the Japanese conversational speech intelligibility test. Scale Scale Scale Scale Scale
1 2 3 4 5
Intelligible Occasionally unintelligible Understandable if the topic is known Occasionally intelligible Unintelligible
Note that half scores were assigned (e.g. 15) to make totally 9 points scale.
The effect of shutting up nostrils on speech intelligibility was objectively assessed by a family member using 5-point rating scale, that is from ‘1: no change’, ‘3: becomes slightly intelligible’ to ‘5: becomes extremely intelligible’ with half scores assigned to be 2 and 4. 6 Underlying cause of dysarthria 7 Free description of impression about NSV Statistical analysis The change of speech intelligibility test score with and without ready-made NSV was assessed by Wilcoxon signed-rank test. Spearman’s rank correlation coefficient was used to assess the relationship between speech intelligibility test and the age of subject. SPSS (IBM SPSS Statistics ver. 20.0*) was used for the statistical analysis with the significance level of 005.
Results Cerebrovascular disease was the most prominent underlying cause of dysarthria (29 subjects, 44%), followed by neurodegenerative disease (14 subjects, 21%), that is amyotrophic lateral sclerosis (ALS), progressive supranuclear palsy and so on, congenital disease (8 subjects, 12%), that is cleft palate, Pierre Robin syndrome, Down syndrome and so on, parenchymatous defect caused by pharyngeal cancer (three subjects, 5%), and others (12 subjects, 18%), that is traumatic accident, dermatomyositis, side effect of anticancer drug and so on (Table 2). In the neurodegenerative diseases, 12 subjects (857%) of 14 subjects were ALS. Speech intelligibility Results on the self-evaluation and third-party evaluation of speech intelligibility are summarised in relation to the underlying cause of dysarthria in Fig. 2. Figure 2a shows self-evaluation and third-party evaluation of speech intelligibility in all subjects. Selfevaluation of speech intelligibility revealed improvement, no change and disimprovement in 55%, 41% and 4%, respectively. Statistical analysis revealed that the use of NSV resulted in significant improvement in the self-evaluation (P < 001). Third-party evaluation *IBM Corp., Somers, NY, USA. © 2014 John Wiley & Sons Ltd
EFFECT OF NASAL SPEAKING VALVE ON ARTICULATION Table 2. Subjects and underlying diseases Number of subjects
(a)
Total (%)
Age (mean SD, in year)
7
29 (440)
622 174
6
8
14 (212)
594 136
4 3
4 0
8 (121) 3 (45)
281 333 563 119
9 44
3 22
12 (182) 66 (1000)
617 192 570 218
Disease
Male
Cerebrovascular disease Neurodegenerative disease Congenital disease Parenchymatous defect Others Total
22
Female
of speech intelligibility by a family member revealed improvement, no change and disimprovement in 53%, 41% and 6%, respectively. Statistical analysis revealed that the use of NSV resulted in significant improvement in the third-party evaluation (P < 001). Significant effect of NSV on self-evaluation could be observed in cerebrovascular disease and neurodegenerative disease as shown in Fig. 2b,c (P < 001). Significant effect of NSV on third-party evaluation could be observed in neurodegenerative disease as shown in Fig. 2c (P < 001). On the contrary, self-evaluation and third-party evaluation could not be observed in congenital disease and parenchymatous defect as shown in Fig. 2d,e. Of the 36 subjects who showed improvement in self-evaluation by NSV, cerebrovascular disease (13 subjects) was the most prominent followed by ALS (eight subjects). Of the 34 subjects who showed improvement in third-party evaluation by NSV, ALS (10 subjects) and cerebrovascular disease (10 subjects) were the most prominent. Figure 3 shows relation to speech intelligibility score on non-wearing NSV and speech intelligibility improvement by wearing NSV. The vertical axis means how many scale the speech intelligibility improved with NSV and horizontal axis means the initial speech intelligibility without NSV. The size of the bubbles corresponds to the population size, and the number in the bubbles means that of subjects with the same value of the speech intelligibility improved with NSV as well as the initial speech intelligibility without NSV. Speech intelligibility disimprovement was observed below speech intelligibility scale 25 of self-evaluation and 35 of third-party evaluation. © 2014 John Wiley & Sons Ltd
(b)
(c)
(d)
(e)
Fig. 2. Distribution of the number of subjects under non-wearing and wearing NSV condition for subjective and objective evaluation of speech intelligibility. (a) total subjects, (b) cerebrovascular disease, (c) neurodegenerative disease, (d) congenital disease, (e) parenchymatous defect.
Easiness of speaking and swallowing with NSV Self-evaluation of easiness of speaking revealed improvement, no change and disimprovement by NSV in 49%, 27% and 24%, respectively. Self-evaluation of easiness of swallowing revealed improvement, no change and disimprovement by NSV in 18%, 62%
139
140
S . M I K A M O et al. preferable impression for NSV, significant effect of NSV on self-evaluation and third-party evaluation could be observed (P < 001). However, five of those subjects also described unfavourable comments, ‘uncomfortable to breathe (three subjects)’ and ‘aesthetically unsatisfied (two subjects)’. Unfavourable description showed ‘does not fit well’ (27%), ‘uncomfortable to breathe’ (15%), ‘aesthetically unsatisfied’ (12%) and ‘fractured’ (5%). The fractures of NSV included the cylinder fractures during manual handlings, caused by reconnecting a line to adjust the length and wrapping around the cylinder with additional nitrile rubber band. The relationship between the self-evaluation of speech intelligibility and the age of subjects is shown in Fig. 4. No statistically significant correlation could be observed for the relationship (P = 0180).
Discussion
Fig. 3. Relation to speech intelligibility score on non-wearing NSV and speech intelligibility improvement by wearing NSV. Speech intelligibility disimprovement was observed below speech intelligibility scale 25 of self-evaluation and 35 of thirdparty evaluation.
and 20%, respectively. Ten subjects did not respond on the item of easiness of swallowing.
To our knowledge, this is the first study to evaluate the effect of NSV on speech intelligibility. Our results confirm that the use of NSV results in the significant improvement in speech intelligibility for cerebrovascular disease and neurodegenerative disease according to self-evaluation and third-party evaluation. In addition, our study showed significant improvement in speech intelligibility by shutting nostrils with fingers. For the speech treatment program, a nasal obturator was reported to play a key role in the management of nasal emission to maximise the effectiveness of an intensive speech treatment program (18). However,
Change of speech intelligibility by shutting up nostrils Eighty-six per cent subjects showed improvement of speech intelligibility by shutting up nostrils by fingers. In the subjects whose speech intelligibility was improved by shutting up nostrils by fingers, significant effect of NSV on self-evaluation and third-party evaluation could be observed (P < 0001). 8 subjects did not improve by shutting up nostrils by fingers. Additionally, seven of these eight subjects did not show any improvement of speech intelligibility using NSV. Free description of impression about NSV Free description of 41% subjects showed preferable impression for NSV. In the subjects who showed
Fig. 4. Improvement of speech intelligibility by subjective evaluation. Note that the score shows the deduction of speech intelligibility without NSV from with NSV. No significant relationship could be observed between the improvement and age. © 2014 John Wiley & Sons Ltd
EFFECT OF NASAL SPEAKING VALVE ON ARTICULATION complete inhibition of inhalation and exhalation would easily cause ear pain while swallowing saliva because of rhinopharynx pressure changes. Nasal speaking valve was reported by Suwaki et al. (15) in a case report of brain injury as an appliance for the rehabilitation for velopharyngeal incompetence. Nasal speaking valve is different from a simple obturator as it has valve structures to suppress exhalation and allow inhalation through nostrils, which is most effective for avoiding possible ear discomfort caused by the pressure change during swallowing. Shutting nostrils with fingers during speaking and swallowing is a hard task for patients. Wearing NSV allows patients to speak more naturally than occluding nostrils. Although the effect of NSV for experimentally induced velopharyngeal incompetence condition was also reported by Suwaki et al., disease or condition which would be susceptible to treatment by NSV has not been clarified yet. Therefore, the study regarding effectiveness of NSV in various diseases and conditions would be of great importance for the clinical decision making or treatment planning. In previous reports, NSV had been constructed on gypsum cast after taking impression of the nostrils of each subject or patient (15, 16). Although this NSV fits the nostrils well with great availability and relief of hypernasality, several visits to a prosthodontist are necessary for the fabrication. As this study aimed to collect service results from patient of diverse background disease from all over Japan, ready-made NSV was designed. As this ready-made NSV could easily be fit to the nostrils of patient using nitrile rubber bands, either the patient him/herself or the working speech-language-hearing therapist can fit it well. The number of patients who inquired the information of this research through the internet was 139. After sending the materials to these candidates, 66 patients showed agreement to participate in this study by sending back the signed informed consent form. The description sheet stated that candidates were not allowed to use NSV until they agreed to participate in this study. Therefore, despite rather low rate of recovery of 41%, it would be reasonable to estimate the effect of NSV from this sample group. The recruitment method of subjects in this study comprises a limitation. Because it was not random sampling, the prevalence of each background disease © 2014 John Wiley & Sons Ltd
might not represent the patient population. However, the results shown in this subject group would be effective to explore the diseases susceptible to this new treatment modality, NSV. Another limitation of this study is that the evaluation of the effect of NSV was conducted using questionnaire. In fact, ten subjects did not respond to the item on easiness of swallowing, which might be because they did not use NSV during meals. We only could obtain limited information from the questionnaire as subjects had the choice to respond or not respond to all the questions. Speech intelligibility disimprovement was observed below speech intelligibility scale 25 of self-evaluation and 35 of third-party evaluation. In other words, speech intelligibility improvement was observed above speech intelligibility scale 3 of self-evaluation and 4 of third-party evaluation. These scales could be considered to the baseline that NSV was effective. However, Speech intelligibility improvement was also observed below speech intelligibility scale 25 of self-evaluation and 35 of third-party evaluation. Although articulation improvement was observed irrespective of speech intelligibility, it could not be improvement that speech intelligibility scales were
