multisystem neurodegenerative
Parkinson’s disease (PD) is the second most common neurodegenerative disorder after Alzheimer’s disease (AD) (Moore, Shpiner, & Luca, 2019). PD has been traditionally considered as a pure movement disorder secondary to focal degeneration of dopaminergic neurons in the substantia nigra, but, in recent years, the clinical phenotype has been better illuminated, showing that PD is a multisystem neurodegenerative disorder with motor and non-motor features. Among motor symptoms and signs, the cardinal ones (bradykinesia, rest tremor, and rigidity) are mainly the loss of dopaminergic neurons, but those involving posture, balance, and gait are largely secondary to degeneration of nondopaminergic pathways and significantly contribute to impairment and disability in advanced PD patients (Moore, Shpiner, & Luca, 2019). Nonmotor features result from multiple neurotransmitter deficiencies in the central and peripheral nervous system and include psychiatric such as: depression, apathy, hallucinations, and delusions. Autonomic includes constipation, orthostatic hypotension, and urinary and genital disturbances. Cognitive impairment such as: involvement of executive functions, memory, sleep disorders, olfactory dysfunction, and pain that together contribute to worsening the quality of life and patient’s disability (Moore, Shpiner, & Luca, 2019).
Cardinal motor features of Parkinson’s disease (PD) include bradykinesia, rest tremor, and rigidity, which appear in the early stages of the disease and largely depend on dopaminergic nigrostriatal denervation (Moore, Shpiner, & Luca, 2019). Intermediate and advanced PD stages are characterized by motor fluctuations and dyskinesia, which depend on complex mechanisms secondary to severe nigrostriatal loss and to the problems related to oral levodopa absorption, and motor and nonmotor symptoms and signs that are secondary to marked dopaminergic loss and multisystem neurodegeneration with damage to nondopaminergic pathways (Moore, Shpiner, & Luca, 2019). Nondopaminergic dysfunction results in motor problems, including posture, balance and gait disturbances, and fatigue, and nonmotor problems, encompassing depression, apathy, cognitive impairment, sleep disturbances, pain, and autonomic dysfunction. There are a number of symptomatic drugs for PD motor signs, but the pharmacological resources for nonmotor signs and symptoms are limited, and rehabilitation may contribute to their treatment (Moore, Shpiner, & Luca, 2019).
