What are the clinical signs and symptoms of Parkinson's disease (PD)?

From the Guidelines

Parkinson's disease is characterized by a distinct set of clinical signs and symptoms, including resting tremor, bradykinesia, rigidity, and postural instability, which are a result of progressive degeneration of dopaminergic neurons in the substantia nigra/striatum, as described in the 2020 study by 1. The primary motor symptoms of Parkinson's disease include resting tremor, which typically begins in one hand and resembles a pill-rolling motion; rigidity, felt as increased resistance during passive movement of limbs; bradykinesia, which is slowness of movement affecting daily activities; and postural instability, leading to balance problems and falls, as outlined in the study by 1. Some key points to consider when diagnosing Parkinsonian syndromes include:

• The estimated interval between initial loss of dopaminergic neurons and the appearance of symptoms is approximately 5 years, after approximately 40% to 50% of the dopaminergic neurons in the substantia nigra have been lost, as noted in the study by 1.
• Other features of Parkinson's disease include autonomic dysfunction, behavioral changes, and dementia, which can significantly impact the patient's quality of life, as discussed in the study by 1.
• The clinical presentation of Parkinson's disease is related to progressive degeneration of the dopaminergic neurons in the substantia nigra projecting to the striatum, leading to dopamine deficiency in the basal ganglia and disruption of movement control pathways, as explained in the study by 1. Non-motor symptoms of Parkinson's disease are equally important and include:
• Depression
• Anxiety
• Cognitive impairment
• Sleep disorders like REM sleep behavior disorder
• Constipation
• Urinary problems
• Sensory disturbances such as pain or numbness, as mentioned in the study by 1. It is essential to note that correctly diagnosing a Parkinsonian syndrome on clinical features alone can be quite challenging, and imaging remains an essential diagnostic tool in the evaluation of a patient presenting with Parkinsonian symptoms, as stated in the study by 1.

From the Research

Clinical Signs and Symptoms of Parkinson's Disease

The clinical signs and symptoms of Parkinson's disease (PD) can be divided into motor and non-motor features.

• Motor symptoms include:
  • Cardinal signs: rest tremor, bradykinesia, rigidity, and loss of postural reflexes 2
  • Secondary motor symptoms: hypomimia, dysarthria, dysphagia, sialorrhoea, micrographia, shuffling gait, festination, freezing, dystonia, and glabellar reflexes 2
  • Gait disturbance, impaired handwriting, grip force and speech deficits 3
• Non-motor symptoms include:
  • Autonomic dysfunction 2, 4
  • Cognitive/neurobehavioral abnormalities, such as dysexecutive syndrome and visuospatial disturbances 2, 4
  • Sleep disorders 2, 4
  • Sensory abnormalities, such as anosmia, paresthesias, and pain 2
  • Anxiety, depression, and gastrointestinal dysfunction 5

Diagnosis and Differentiation

The diagnosis of PD is based on clinical criteria, as there is no definitive test for the disease 2.

• The presence and specific presentation of motor and non-motor features are used to differentiate PD from other parkinsonian disorders 2, 6
• Absence of rest tremor, early occurrence of gait difficulty, postural instability, dementia, hallucinations, and the presence of dysautonomia, ophthalmoparesis, ataxia, and other atypical features may suggest diagnoses other than PD 2