Velar activity in individuals with velopharyngeal insufficiency assessed by acoustic rhinometry

Abstract

Acoustic rhinometry is routinely used for the evaluation of nasal patency.ObjectiveTo investigate whether the technique is able to identify the impairment of velopharyngeal (VP) activity in individuals with clinical diagnosis of velopharyngeal insufficiency (VPI).MethodsTwenty subjects with repaired cleft palate and inadequate velopharyngeal function (IVF) and 18 non-cleft controls with adequate velopharyngeal function (AVF), adults, of both genders, were evaluated. Area-distance curves were obtained during VP rest and speech activity, using an Eccovision Acoustic Rhinometry system. Volume was determined by integrating the area under the curve at the segment corresponding to the nasopharynx. VP activity (∆V) was estimated by the absolute and relative differences between nasopharyngeal volume at rest (Vr) and during an unreleased /k/ production (Vk). The efficiency of the technique to discriminate IVF and AVF was assessed by a ROC curve.ResultsMean Vk and Vr values (±SD) obtained were: 23.2±3.6 cm3 and 15.9±3.8 cm3 (AVF group), and 22.7±7.9 cm3 and 20.7±7.4 cm3 (IVF group), corresponding to a mean ∆V decay of 7.3 cm3 (31%) for the AVF group and a significantly smaller ∆V decay of 2.0 cm3 (9%) for the IVF group (p<0.05). Seventy percent of the IVF individuals showed a ∆V suggesting impaired VP function (below the cutoff score of 3.0 cm3 which maximized both sensitivity and specificity of the test), confirming clinical diagnosis.ConclusionAcoustic rhinometry was able to identify, with a good discriminatory power, the impairment of VP activity which characterizes VPI.

Análise comparativa da atividade velofaríngea aferida por rinometria acústica e rinomanometria

“…Table 1 shows the mean values of the nasopharyngeal volume at rest and in the production of [k] obtained in 27 subjects with VPD who showed adequate articulation for the plosive. At rest, an average volume of 20.1 cm 3 was observed, which did not significantly differ (p=0.116) from the one reported by Trindade et al (6) in normal individuals (without VPD), indicating equivalent nasopharyngeal dimensions. In the group with VPD, the average volume decreased to 17.4 cm 3 during speech, corresponding to an average reduction of 3.9 cm 3 in absolute terms, and 18% in relative values.…”

“…In regard to the acoustic rhinometry, considering that the variable volume follows a normal distribution, with only a slight deviation to the left (24) , the results for nasopharyngeal volumes at rest and during speech were expressed as mean±standard deviation. For the purposes of this study, we used ΔV=3 cm 3 as the normal limit, that is, values below this limit (ΔV<3cm 3 ) were interpreted as indicative of inadequate velopharyngeal activity (6) .…”

“…The rhinometry assessment was performed in all 41 participants using an Eccovision Acoustic Rhinometer (HOOD Laboratories) and the methodology used by Trindade et al (6) . The technique is based on the measurement of the reflected sound waves (echoes) that emerge from the nasal cavity in response to incident sound waves.…”

“…The auditory-perceptual assessment is the first approach to estimate signs and symptoms of VPD (2)(3)(4) . The use of rating scales (4)(5)(6) and the audio and video recording of speech samples, with evaluation by judges, have been successful strategies to minimize the inherent subjectivity in this type of evaluation (7,8) . However, there is consensus that the subjective evaluation of VPD should be complemented with instrumental methods such as nasopharyngoscopy, videofluoroscopy, nasometry, and rhinomanometry.…”

“…A study developed at the Laboratory of Physiology of the Hospital for Rehabilitation of Craniofacial Anomalies, in Bauru, São Paulo (HRAC/USP) (6) confirmed, by analyzing the volume variation of nasopharynx in the production of the voiceless plosive [k], that the acoustic rhinometry was able to identify the deficit of velar movement featuring VPD in most patients clinically diagnosed with inadequate velopharyngeal function. However, some patients presented results suggesting good velar mobility on rhinometry, despite the VPD.…”