Parkinson Disease: Pari G

Frank C, Pari G, Rossiter JP. · St Mary's of the Lake Hospital, Kingston, ON. · Can Fam Physician. · Pubmed #16893149 links to  free full text

Abstract: OBJECTIVE: To review the clinical features of Parkinson disease (PD) and other causes of motor parkinsonism with an emphasis on diagnosis in elderly patients. SOURCES OF INFORMATION MEDLINE: and Google Scholar were searched for original research articles describing clinical diagnosis of parkinsonism. Consensus statements and articles summarizing diagnostic criteria for parkinsonian syndromes were also reviewed. Most evidence was levels II or III. MAIN MESSAGE: Diagnosis of PD is made clinically and can be challenging. In older patients, PD can present with general functional decline and nonspecific symptoms. Clinical criteria for diagnosing PD and the TRAP mnemonic can be helpful. A 2-week trial of levodopa-carbidopa treatment can be considered. Specific signs and a minimal response to levodopa treatment suggest other causes of parkinsonism. Clinical features of other causes of parkinsonism are reviewed in the article. CONCLUSION: Parkinsonism and PD are common in older patients. Family physicians should consider parkinsonism in the differential diagnosis of patients who have falls and exhibit general functional decline.

Perretta JG, Pari G, Beninger RJ. · Department of Psychology, Queen's University, Kingston, Ontario, Canada. · Cogn Behav Neurol. · Pubmed #16340390 No free full text.

Abstract: OBJECTIVE: To assess performance on two nondeclarative (implicit) memory tasks of Parkinson disease (PD) patients without dementia in the earlier or later stages of the disease (Hoehn and Yahr Scale scores of 1-2.5 or 3-4, respectively). BACKGROUND: Different subtypes of nondeclarative memory appear to depend on different components of frontostriatal circuitry. Performance on a probabilistic classification learning (PCL) task was impaired by striatal damage (eg, in PD or Huntington disease) but not by circumscribed frontal lobe damage. On the other hand, performance on the Iowa Gambling Task (IGT) was impaired by damage to the prefrontal cortex. METHOD AND RESULTS: On the PCL, the learning of the control (age- and education-matched) group (n = 19) and the early PD group (n = 16) was comparable with each other, and both groups showed better performance than the later PD group (n = 16). On the IGT, the control group learned better than both of the PD groups. The control and early PD groups were similar on measures from the Wisconsin Card Sorting Test, Stroop Test, Mini-Mental State Examination, and Beck Depression Inventory II. CONCLUSIONS: The PCL and IGT tasks appear to rely on different parts of the frontostriatal circuitry in patients with early PD. The current finding that IGT performance was impaired in early PD implies ventromedial prefrontal cortical dysfunction early in the disease.

Chan F, Armstrong IT, Pari G, Riopelle RJ, Munoz DP. · Centre for Neuroscience Studies, Queen's University, Kingston, Ont., Canada K7L 3N6. · Neuropsychologia. · Pubmed #15721191 No free full text.

Abstract: In contrast to their slowed limb movements, individuals with Parkinson's disease (PD) produce rapid automatic eye movements to sensory stimuli and show an impaired ability to generate voluntary eye movements in cognitive tasks. Eighteen PD patients and 18 matched control volunteers were instructed to look either toward (pro-saccade) or away from (anti-saccade) a peripheral stimulus as soon as it appeared (immediate, gap and overlap conditions) or after a variable delay; or, they made sequential saccades to remembered targets after a variable delay. We found that PD patients made more express saccades (correct saccades in the latency range of 90-140 ms) in the immediate pro-saccade task, more direction errors (automatic pro-saccades) in the immediate anti-saccade task, and were less able to inhibit saccades during the delay period in all delay tasks. PD patients also made more directional and end-point errors in the memory-guided sequential task. Their inability to plan eye movements to remembered target locations suggests that PD patients have a deficit in spatial working memory which, along with their deficit in automatic saccade suppression, is consistent with a disorder of the prefrontal-basal ganglia circuit. Impairment of this pathway may release the automatic saccade system from top-down inhibition and produce deficits in volitional saccade control. Parallel findings across various motor, cognitive and oculomotor tasks suggest a common mechanism underlying a general deficit in automatic response suppression.