Parkinson’s Disease Flashcards
What is Parkinson’s Disease?
• Parkinson’s disease (PD) is a long-term degenerative disorder of
the central nervous system
- Symptoms generally come on slowly, over time
- Mainly affects the motor system
- Average life expectancy following diagnosis is between 7 and 14 years
- Currently no cure for PD
Epidemiology of PD
In 2015, PD affected ~6.2 million people worldwide and resulted in about 117,400 deaths
• In Canada, ~1 in every 500 people are affected by PD - ~6,600 new cases per year
• Typically, PD occurs in people over 60 years of age - Prior to age of 50, considered young-onset PD
• Males are more often affected than females
Clinical Presentation – Motor Symptoms
Remember TRAP!
These are the most recognizable symptoms of PD:
(Resting) Tremor Rigidity
Akinesia (aka Bradykinesia) Postural instability
Motor Symptoms: Resting tremor
- At rest!
- Slow velocity
- Asymmetrical
- Tremors may affect chin, jaw, arms, legs
- “Pill-rolling”
- The most common presenting symptom
- 30% of PD patients do not show tremor
Motor Symptoms: Rigidity
- Occurs in over 90% of patients
- Characterized by increased resistance - The “cogwheel” phenomenon
- Increased muscle tone and contraction
- Present through the range of passive movements of a limb
- E.g. flexion, extension, or rotation about a joint
- Can occur in neck, shoulders, hips, wrists, ankles - Proximally & distally
Motor Symptoms: Bradykinesia
- The most characteristic clinical feature - Present in every single case of PD
- Slowness in performing activities of daily living
- Loss of spontaneous movements & gesturing
- Monotonic and hypophonic dysarthria (speech)
- Loss of facial expressions (hypomimia) and decreased blinking
- Drooling
- Reduced arm swing while walking
Motor Symptoms: Postural Instability
- Loss of postural reflexes
- Generally, manifestation of late stage PD
- Can lead to impaired balance and frequent falls
- Most common cause of falls
- Along with freezing of gait
- Contributes significantly to risk of hip fractures
Clinical Presentation – Non-Motor Symptoms
Psychiatric Disturbances
Autonomic Disturbances
Cognitive Impairment
Sleep Disturbances
Sleep Disturbances
Insomnia/fractured sleep
- Narcolepsy
- REM behavior disorder (RBD)
Cognitive Impairment
- Executive function deficit
- Dementia
- Hallucinations
Autonomic Disturbances
- Constipation
- Sexual dysfunction
- Orthostatic hypotension
Psychiatric Disturbances
Depression
- Anxiety
- Apathy
How does Parkinson’s Disease all happen?
Let’s start with the Basal Ganglia (BG) What is the BG? Dorsal Striatum Globus Pallidus Substantia Nigra Subthalamic Nucleus
Dorsal Striatum
- Caudate
* Putamen
Globus Pallidus
• Externa, Gpe • Interna, Gpi
Substantia Nigra
- Pars compacta
* Pars reticula
What does the BG do?
Sets the overall “tone” or
“motivation” for action
- Part of a system that focuses actions - Picks the correct ones
- Output of BG dictates the likelihood that movements will occur
- BG is organized into loops
- Speaks to different brain regions,
integrates information
BG Loops
Cognitive Loop
Visual/Oculomotor Loop
Affective Loop
Motor Loop
Motor Loop
- To move or not to move?
- Putamen, Globus Pallidus and
Substantia Nigra
Affective Loop
- Emotional component
- Desire, apathy, impulse
Visual/Oculomotor Loop
Scanning environment
- Spatial recognition
Cognitive Loop
- Turns on/off regions of frontal lobe
- Task switching
- Priority setting
What happens to the BG in PD patients?
Main pathological characteristics of PD are cell death in the BGà Substantia Nigra
- Up to 70% of the dopamine (DA) secreting neurons in the SN are affected
- Leads to DA depletion in the SN and the nigrostriatal DA pathway
- Dysfunctional motor loop of the BG
- TRAP
What’s Dopamine’s role?
DA neurons in the SN form strong connections with the dorsal striatum, globus pallidus and the motor cortex - These are excitatory connections - Dorsal striatum (motor) has dense expression of (D1 and D2) dopamine receptors - DA is main driver of motor cortex activation There are a number of compensatory mechanisms that can mask early symptoms of PD
