Parkinson Disease: Robin DA

Narayana S, Jacks A, Robin DA, Poizner H, Zhang W, Franklin C, Liotti M, Vogel D, Fox PT. · Research Imaging Center, Honors College, The University of Texas Health Science Center, San Antonio, 7703 Floyd Curl Drive MSC 6240, San Antonio, TX 78229-3900, USA. · Am J Speech Lang Pathol. · Pubmed #19029533 No free full text.

Abstract: PURPOSE: To explore the use of noninvasive functional imaging and "virtual" lesion techniques to study the neural mechanisms underlying motor speech disorders in Parkinson's disease. Here, we report the use of positron emission tomography (PET) and transcranial magnetic stimulation (TMS) to explain exacerbated speech impairment following subthalamic nucleus deep brain stimulation (STN-DBS) in a patient with Parkinson's disease. METHOD: Perceptual and acoustic speech measures, as well as cerebral blood flow during speech as measured by PET, were obtained with STN-DBS on and off. TMS was applied to a region in the speech motor network found to be abnormally active during DBS. Speech disruption by TMS was compared both perceptually and acoustically with speech produced with DBS on. RESULTS: Speech production was perceptually inferior and acoustically less contrastive during left STN stimulation compared to no stimulation. Increased neural activity in left dorsal premotor cortex (PMd) was observed during DBS on. "Virtual" lesioning of this region resulted in speech characterized by decreased speech segment duration, increased pause duration, and decreased intelligibility. CONCLUSIONS: This case report provides evidence that impaired speech production accompanying STN-DBS may result from unintended activation of PMd. Clinical application of functional imaging and TMS may lead to optimizing the delivery of STN-DBS to improve outcomes for speech production as well as general motor abilities.

Solomon NP, Robin DA. · Army Audiology & Speech Center, Walter Reed Army Medical Center, Washington, DC 20307-5001, USA. · Parkinsonism Relat Disord. · Pubmed #16105745 No free full text.

Abstract: BACKGROUND: Fatigue and the accompanying perception of effort are often heightened in Parkinson's disease. OBJECTIVES: To compare performance on three sense-of-effort tasks between patients with PD and matched neurologically normal control subjects. METHODS: Sixteen PD subjects and 16 normal subjects performed three tasks to assess sense of effort: self-ratings of effort using direct-magnitude estimation, generating pressures at various levels of effort, and sustaining a submaximal level of effort. The latter two tasks were done with handgrip and tongue elevation. RESULTS: Two of the three tasks successfully differentiated the groups. Subjects with PD provided significantly higher ratings of effort for general daily activities and for speech. During the constant-effort task, pressure curves decayed more rapidly for the PD subjects. CONCLUSIONS: Performance by PD subjects on the constant-effort task resembled that by normal adults who were pre-fatigued in previous experiments. Results support greater than normal sense-of-effort related to fatigue in PD, and provide preliminary validation of a performance-based physiologic task to assess abnormal sense of effort in this population.

Solomon NP, Robin DA, Luschei ES. · Department of Communication Disorders, University of Minnesota, Minneapolis 55455, USA. · J Speech Lang Hear Res. · Pubmed #10668667 No free full text.

Abstract: Weakness and fatigue in the orofacial system often are presumed to contribute to the dysarthria associated with neuromotor disorders, although previous research findings are equivocal. In this study, tongue strength, endurance, and stability during a sustained submaximal effort were assessed in 16 persons with mild to severe Parkinson disease (PD) and a perceptible speech disorder. The same measures were taken from one hand for comparison. Only tongue endurance was found to be significantly lower in these participants than in neurologically normal control participants matched for sex, age, weight, and height. Analyses of data from a larger sample comprising the present and retrospective data revealed lower-than-normal tongue strength and endurance in participants with PD. No significant correlations were found between tongue strength and endurance, interpause speech rate, articulatory precision, and overall speech defectiveness for the present and previously studied participants with PD, bringing into question the influence of modest degrees of tongue weakness and fatigue on perceptible speech deficits.