Signs and Symptoms of Parkinson's Disease
Parkinson's disease is characterized by four cardinal motor symptoms (bradykinesia, resting tremor, rigidity, and postural instability) along with numerous non-motor symptoms that significantly impact quality of life and may appear before motor manifestations. 1
Cardinal Motor Symptoms
- Bradykinesia: Slowness of movement and decreased amplitude of movement
- Resting tremor: Typically 4-6 Hz, asymmetric, and most prominent at rest
- Rigidity: Increased muscle tone throughout the range of passive movement
- Postural instability: Loss of postural reflexes, typically occurring later in disease progression 1, 2
These motor symptoms typically appear after approximately 40-50% of dopaminergic neurons in the substantia nigra have been lost 1.
Secondary Motor Symptoms
- Hypomimia (masked face)
- Dysarthria (speech difficulties)
- Dysphagia (swallowing difficulties)
- Sialorrhea (excessive salivation)
- Micrographia (small handwriting)
- Shuffling gait
- Festination (involuntary acceleration when walking)
- Freezing (sudden inability to move)
- Dystonia (sustained muscle contractions)
- Glabellar reflexes 2
Non-Motor Symptoms
Non-motor symptoms are significant contributors to disability and may appear before motor symptoms 1. These include:
Autonomic Dysfunction
- Orthostatic hypotension
- Urinary urgency/incontinence
- Constipation
- Sexual dysfunction
- Excessive sweating 1
Cognitive and Neuropsychiatric Symptoms
- Cognitive impairment (ranging from mild to dementia)
- Depression
- Anxiety
- Hallucinations (especially in advanced disease)
- Impulse control behaviors 3, 4
Sleep Disorders
- REM sleep behavior disorder
- Insomnia
- Excessive daytime sleepiness 5
Sensory Symptoms
- Anosmia (loss of smell)
- Paresthesias
- Pain 2
Nutritional Changes
- Weight loss (common with disease progression)
- Changes in eating behavior
- Increased energy expenditure associated with dyskinesias and rigidity 6
Disease Progression and Complications
As Parkinson's disease progresses, patients may develop:
- Contractures (fixed deformities that don't respond to dopaminergic therapy)
- Levodopa-induced dyskinesias
- Worsening of postural instability and gait difficulties
- Increased cognitive decline
- More pronounced autonomic dysfunction 1
Clinical Pearls and Pitfalls
- Early warning signs: Non-motor symptoms like anosmia, REM sleep behavior disorder, and constipation may precede motor symptoms by years 5
- Red flags for alternative diagnoses: Absence of rest tremor, early gait difficulty, early postural instability, early dementia or hallucinations, early dysautonomia, ophthalmoparesis, ataxia, and poor/no response to levodopa suggest diagnoses other than idiopathic Parkinson's disease 1, 2
- Medication-induced parkinsonism: Always consider medications that block dopamine receptors as potential causes of parkinsonian symptoms 1
- Nutritional monitoring: Regular monitoring of nutritional status, body weight, and vitamin levels (particularly vitamin D, folic acid, and vitamin B12) is recommended throughout the course of the disease 6
Early recognition of both motor and non-motor symptoms is crucial for timely diagnosis and management of Parkinson's disease, potentially improving quality of life and functional outcomes for patients.