Voice function and swallowing: effects of levodopa and deep brain stimulation Electrical stimulation of the subthalamic nucleus

Katarina Olfsson, Anders Asplund

(STN) in the central part of the brain is a successful treatment for classical motor symptoms of Parkinson’s disease. However, the effects on voice function and swallowing are smaller and more variable. Four Parkinson patients selected for treatment with STN stimulation were analysed pre-, 6m post-, and 12m postoperatively, focusing on swallowing difficulties, voice intensity and frequency. The aim was to detect effects of stimulation of the STN and of concomitant levodopa medication. Videostroboscopy of vocal folds and examination of swallowing function was performed using a transnasal flexible fiberscope, stroboscope and camera. Voice intensity and frequency were measured during a prolonged [i:] sound produced as loudly as possible while maintaining normal pitch. Voice intensity was measured 30 cm from the mouth using a decibel meter. Comparative measures of voice intensity and frequency were also made during a prolonged [i:] at patient selected level of loudness and pitch, using a calibrated recording system in a sound treated studio. Swallowing function was fiberoptically examined during a test meal and evaluated using a VA-scale. Results indicated rather consistent voice intensities throughout the registration period. Preoperatively patients used voice frequencies higher than their self-selected frequency in order to achieve maximum loudness. Postoperatively, neither the stimulator on and off conditions, nor medicated and nonmedicated conditions showed any differences. In two patients swallowing function had deteriorated postoperatively. Our preliminary results are consistent with related studies that show voice production and swallowing are not highly responsive to STN stimulation.

Katarina Olfsson,1 Anders Asplund,2
1 Norrlands Universitetssjukhus, Umeå, Sweden 2Umeå Universitet, Umeå, Sweden

Anders Asplund Forskningsingenjör
Institutionen för Klinisk Vetenskap
Enheten för Logopedi
901 87 Umeå
090-785 38 62
Department of Clinical Science
Speech and Language Pathology
+46 907853862
anders.asplund@logopedi.umu.se
http://www.umu.se/clin_sci/logopedi/