Acoustic Evaluation of Nasality in Cerebellar Syndromes

Although previous studies have reported the occurrence of velopharyngeal incompetence connected with ataxic dysarthria, there is a lack of evidence related to nasality assessment in cerebellar disorders. This is partly due to the limited reliability of challenging analyses and partly due to nasality being a less pronounced manifestation of ataxic dysarthria. Therefore, we employed 1/3-octave spectra analysis as an objective measurement of nasality disturbances. We analyzed 20 subjects with multiple system atrophy (MSA), 13 subjects with cerebellar ataxia (CA), 20 subjects with multiple sclerosis (MS) and 20 healthy (HC) speakers. Although we did not detect the presence of hypernasality, our results showed increased nasality fluctuation in 65% of MSA, 43% of CA and 30% of MS subjects compared to 15% of HC speakers, suggesting inconsistent velopharyngeal motor control. Furthermore, we found a statistically significant difference between MSA and HC participants (p<0.001), and significant correlation between the natural history cerebellar subscore and neuroprotection in Parkinson plus syndromes – Parkinson plus scale and nasality fluctuations in MSA (r=0.51, p<0.05). In conclusion, acoustic analysis showed an increased presence of abnormal nasality fluctuations in all ataxic groups and revealed that nasality fluctuation is associated with distortion of cerebellar functions.