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Pathophysiology of Parkinson's Disease
Author(s) -
McLeod J. G.
Publication year - 1971
Publication title -
australian and new zealand journal of medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.596
H-Index - 70
eISSN - 1445-5994
pISSN - 0004-8291
DOI - 10.1111/j.1445-5994.1971.tb02561.x
Subject(s) - substantia nigra , neuroscience , basal ganglia , resting tremor , globus pallidus , medicine , efferent , parkinson's disease , spinal cord , indirect pathway of movement , muscle tone , subthalamic nucleus , central nervous system , disease , deep brain stimulation , psychology , pathology , afferent
Summary: Parkinson's Disease is a disorder of the extrapyramidal system, and its major clinical manifestations are rigidity, tremor and akinesia. The extrapyramidal system takes origin from the cerebral cortex and from basal ganglia and other subcortical nuclei. It controls movement by its influence on the alpha and gamma motoneurones in the spinal cord through the reticulospinal, vestibulospinal and rubrospinal tracts. The rigidity of Parkinson's Disease is basically of a plastic type; the cogwheel effect is caused by the superimposed tremor. The increased muscle tone may be caused by an increase in the background gamma efferent activity to the muscle spindles, or by hyperexcitability of the alpha motoneurones. The frequency of the resting tremor in Parkinson's Disease is 3–5 cycles/sec. It is caused by an imbalance of excitatory and inhibitory activity to the ventrolateral nucleus of the thalamus which results from disease of the substantia nigra and globus pallidus. The spontaneous rhythmical activity is transmitted to the periphery by way of the pyramidal tract and section or disease of this tract will abolish the tremor. The mechanism of the akinesia, loss of postural control, and gait disturbance in Parkinson's Disease is not clear but is probably related to disease of the substantia nigra, since experimental lesions of the structure result in poverty of movement.