Intra-participant variability in Parkinson's disease: An electropalatographic examination of articulation

Effects of medication and subthalamic nucleus deep brain stimulation on tongue movements in speakers with Parkinson's disease using electropalatography: a pilot study

Parkinson's disease (PD) affects speech in the majority of patients. Subthalamic nucleus deep brain stimulation (STN-DBS) is particularly effective in reducing tremor and rigidity. However, its effect on speech is variable. The aim of this pilot study was to quantify the effects of bilateral STN-DBS and medication on articulation, using electropalatography (EPG). Two patients, PT1 and PT2, were studied under four conditions: on and off medication and ON and OFF stimulation. The EPG protocol consisted of a number of target words with alveolar and velar stops, repeated 10 times in random order. The motor part III of the Unified Parkinson Disease Rating Scale (UPDRS) indicated significantly improved motor scores in the ON stimulation condition in both patients. However, PT1's articulation patterns deteriorated with stimulation whereas PT2 showed improving articulatory accuracy in the same condition. The results revealed different effects of stimulation and medication on articulation particularly with regard to timing. The study quantified less articulatory undershoot for velar stops in comparison to alveolars. Furthermore, the findings provided preliminary evidence that stimulation with medication has a more detrimental effect on articulation than stimulation without medication.

Physiological investigation of dysarthria: recent advances

Recent years have seen the development and introduction of a range of new physiological instruments for investigating various aspects of articulatory function in persons with dysarthria. Included among these techniques are electromagnetic articulography (EMA), electropalatography (EPG), and pressure-sensing EPG. The aim of this paper is to describe and evaluate these techniques, highlighting their relative advantages, disadvantages, and specific applications in assessing articulation in speakers with dysarthria associated with a variety of neurological disorders. Emphasis will be given to those instruments that enable researchers and clinicians to examine articulatory functions in 3-dimensions, such as 3D-EMA (AG500) and 3D-EPG. In addition the application of pressure-sensing EPG and ultrasonography will be outlined. Each of these physiological techniques will be fully described in terms of their component hardware and underlying principles of operation. The use of each technique in the assessment of dysarthria will be illustrated wherever possible by reference to specific case examples, and especially cases drawn from various neuropathological groups. Research findings reported to date based on each of the above physiological instruments will be reviewed and the research summarized.

Kinematic analysis of lingual function in dysarthric speakers with Parkinson's disease: An electromagnetic articulograph study

Dysarthria in people with Parkinson's disease (PD) has been widely studied. However, a limited number of studies have investigated lingual function during speech production in this population. This study aimed to investigate lingual kinematics during speech production using electromagnetic articulography (AG-200 EMA). The PD group consisted of eight dysarthric speakers with PD and was matched with a group of eight controls. The tongue tip and tongue back movements of all participants during sentence production were recorded by EMA. Results showed that, perceptually, the participants with PD were mildly dysarthric. Kinematic results documented comparable (for alveolar sentence production) and increased (for velar sentence production) range of lingual movement in the PD group when compared to the control group. Lingual movement velocity, acceleration, and deceleration were also increased in the PD group, predominantly for the release phase of consonant production during sentence utterances. The PD group had longer duration in the production of alveolar consonant and comparable duration in the production of velar consonant. The results of the present study suggest the presence of impaired lingual control in individuals with PD. Increased range of articulatory movement, primarily in the release phase of consonant production, may account for articulatory imprecision in this population.