Neurosurgical Intervention in Parkinson’s Disease: Effects on Speech and Oromotor Function

D Theodoros, A Farrel1, E Ward, P Silburn, B Hall

The study examined the effects of neurosurgical intervention in Parkinson’s disease (PD) involving pallidotomy, thalamotomy, and deep brain stimulation (DBS) on the speech characteristics, speech intelligibility, and oromotor function of a group of 22 participants with PD. The surgical group’s perceptual speech ratings (32 dimensions), and performances on the Frenchay Dysarthia Assessment (reflexes, respiration, laryngeal, palatal, lip and tongue function) and the Assessment of Intelligibility of Dysarthric Speech (percentage word and sentence intelligibility, words per minute, communication efficiency) were compared pre- and post-surgery, and with the performances of a group of 25 non-neurologically impaired individuals matched for age and gender. In addition, the study evaluated a group of 16 participants with PD who had not undergone surgery, in order to control for disease progression. Results revealed that neurosurgical intervention did not significantly change the surgical participants’ perceived speech production, intelligibility, or oromotor function despite significant post-operative improvements in scores of general motor function and level of disease severity. Possible reasons proposed for the disparate outcomes between speech production and motor function following surgery related to differences between speech and limb function, the site of lesion or stimulation, and the role of nondopaminergic lesions, and sensory impairments, in the development of speech disorders in PD.