The effect of levodopa on respiration and word intelligibility in people with advanced Parkinson's disease.
OBJECTIVE
Hypokinetic dysarthria is commonly encountered in Parkinson's disease (PD). Although the etiology of this dysarthria is multifactorial, disorders of respiration may strongly contribute to it. The aim of this study was to evaluate the effects of levodopa on measures of respiration and intelligibility.


METHODS
Vital capacity (VC), sustained vowel phonation (SVP) and phonation quotient (PQ) were determined with and without medication in 25 patients suffering from idiopathic PD. Intelligibility was evaluated by three independent speech pathologists using the word subtest protocol of the Yorkston and Beukelman "Assessment of intelligibility of dysarthric speech" (AIDS).


RESULTS
VC was abnormal in 18/25 patients in the off-condition and 15/25 in the on-condition. SVP was normal in 22/25 patients in the off-state and in all patients in the on-state. PQ was normal in all patients in the off- and on-condition. All three respiratory parameters, as well as intelligibility, improved significantly following administration of levodopa. There were significant differences between men and women for VC and PQ, with men having the highest values for both parameters in both conditions. In none of the two conditions a correlation between respiratory parameters and intelligibility could be demonstrated.


CONCLUSIONS
This study suggests that thoracic mobility is decreased in PD, and that pharmacological treatment results in improvement, but not in normalization. Moreover, it remains unclear to what extent dyskinesias negatively influence respiratory control. Our results also demonstrate improvement of intelligibility after pharmacological treatment of PD. However, this improvement is not solely the consequence of respiratory changes. Further research on the effects of different characteristics on intelligibility is necessary.
De Letter
Miet
M
Department of Oto-Rhino-Laryngology, Center for Speech and Hearing Disorders, Ghent University Hospital, Ghent, Belgium. a.larner@thewaltoncentre.nhs.uk <a.larner@thewaltoncentre.nhs.uk>
Santens
Patrick
P
De Bodt
Marc
M
Van Maele
Georges
G
Van Borsel
John
J
Boon
Paul
P
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000978:Antiparkinson Agents / Q000627:therapeutic use*; D004401:Dysarthria / Q000175:diagnosis / Q000188:drug therapy*; D005260:Female; D006801:Humans; D007980:Levodopa / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D009460:Neurologic Examination / Q000187:drug effects; D010300:Parkinson Disease / Q000175:diagnosis / Q000188:drug therapy*; D010699:Phonation / Q000187:drug effects; D012123:Pulmonary Ventilation / Q000187:drug effects; D012131:Respiratory Insufficiency / Q000175:diagnosis / Q000188:drug therapy*; D012737:Sex Factors; D013065:Speech Intelligibility / Q000187:drug effects*; D013147:Spirometry; D014797:Vital Capacity / Q000187:drug effects
D000978:Antiparkinson Agents; D007980:Levodopa