Bradykinesia, rigidity, and involuntary tremor are typical symptoms in parkinson''s disease and motor control abnormalies of oro-facial muscles result in difficulties with control of chewing and swallowing in IPD. Impaired of oral stage of swallowing, in particular, is important to sequential movement of swallowing in PD. Weakened oral facial muscles such as the lips, tongue, and cheeks can result in a longer meal time and release the food in the mouth into the oropharynx without chewing enough. These problems cause not only oral phase problems but also pharyngeal phase problems and increase the risk of aspiration and penetration. Therefore, assessment of oral phase swallowing function in patients with Parkinson''s disease is crucial for preventing aspiration and lung infection. Nevertheless, swallowing handicap evaluation, their tongue pressure, and oral motor ability have seldom been studied. The purpose of this study was to investigate the characteristics of Dysphasia Handicap Index(DHI) and tongue pressure and oral motor ability in patients with idiopathic Parkinson''s disease(IPD) and compared with those of normal adults. In this study, 16 patients with IPD and 16 healthy matched control subjects participated for evaluating Dysphasia Handicap Index, pressure of the tongue, and oral motor ability using Korean-version of Dysphasia Handicap Index(K-DHI), Digital Swallowing Workstation™(Model 7120, KayPentex, USA), and Speech Mechanism Screening Test(SMST). All subjects swallowed 5 mL of water three times per position of the tongue(anterior, middle, posterior, left, right). A total of 15 times of swallowing(3 times each of 5 ml liquid swallowing) was obtained and average of three times for tongue pressure in each position was compared between normal and IPD group.
The results showed that functional(P), physical(P), emotional(E), and total(T) scores in K-DHI were significantly higher in patients with IPD(p<.05). In addition, each tongue pressure(anterior, middle, posterior, left, right) was significantly lower in patients with IPD(p<.05), and anterior tongue pressure, in particular, was lowest in IPD group but there was no significant differences in tongue pressure among the tongue position. Furthermore, oro-motor functional scores were significantly lower in patients with IPD(p<.05) while the structural scores were no significantly different between the two groups(p>.05). Moreover, no significant correlations were found between K-DHI, tongue pressure and oral structure and function scores in patients with IPD(p>.05).
In conclusion, in this study, IPD patients demonstrated high dysphagia handicap index and lower tongue pressure as well as significantly reduced oro-motor functions even in early PD stage. Therefore, early detection and management of swallowing problems should be important and the Korean version of the Dysphasia Handicap Index, tongue pressure, and oro-motor functions can help predict and manage for swallowing problems in patients with IPD.