ABSTRACT
Parkinson’s disease (PD) is a progressive, neurodegenerative condition that was once thought to affect only motor function but is known to have widespread effects in the central and autonomic nervous systems. Though the etiology is unknown, many signs and symptoms of PD stem from a loss of dopaminergic cells mostly in the substantia nigra pars compacta (SNC). This loss prevents adequate communication with the striatum, which is imperative for proper motor control. Rigidity reflects an increase in muscle tone associated with disorders of the basal ganglia and differs from spasticity. Spasticity is generally seen in disorders of the upper motor neuron such as stroke and multiple sclerosis and creates a spastic “catch” like a clasp knife, which is noted only with increasing speed. Slowness of movement, or bradykinesia, is the last “cardinal” feature of PD. Besides the fading of the SNC, a hallmark pathological sign is the presence of intracellular inclusions known as Lewy bodies.
