Parkinson's Disease Flashcards
What are the major functions of the basal ganglia?
- motor control
- eye movement loop
- goal-directed behavior loop
- social behavior loop
- emotion loop
What are specific motor control functions of the basal ganglia?
o Initiation and execution of movement
o Prevention of unwanted movements through inhibitory control
o Direct and indirect pathways that work together to help create desired movement
What type of eye movements is the basal ganglia involved with?
saccadic eye movement
_________ elevates the effects of the basal ganglia and its modulation on movement
Dopamine
What inhibits dopamine?
ACh
- can quickly interrupt ongoing motor behavior in response to salient environmental stimuli
What are the primary neurotransmitters in direct and indirect pathways?
GABA and Glutamate
Dopamine has a _____ effect which leads to what?
dopamine has a dual effect which leads to a powerful decrease in suppression of thalamus by basal ganglia and leads to facilitation of movement
What are general signs and symptoms of basal ganglia dysfunction?
- Difficulty initiating, continuing, or stopping movement
- Muscle tone abnormalities
o Rigidity – affects flexors more than extensors - Increased involuntary movements
What is hemiballismus?
hyperkinetic movement disorder characterized by violent involuntary limb movements on 1 side of body (affects proximal limbs)
- rotatory nature
What is chorea?
Chorea – jerky, involuntary movements (affects distal limbs)
What is athetosis?
involuntary muscle contractions cause writhing movements
What are some of the characteristics of the patient population we see Parkinson’s Disease (PD) in?
- Older adults (> 60 y/o), mean age of onset – early 60s
- Men > women
- Decreased prevalence in black and Asian populations
What’s the difference between primary and secondary parkinsonism? Where does PD fall within these classifications?
- Primary Parkinsonism (PD) = Parkinson’s disease
- Secondary Parkinsonism – similarities in clinical impairments w/o perfectly fitting the molds for PD
o PD as a result of something else: infectious/postencephalitic, atherosclerosis, toxic, drug-induced
Explain the pathophysiology behind PD.
- Degeneration of dopaminergic neurons in the basal ganglia (loss of DA stores in substantia nigra)
- As disease progresses, other regions of brains involved as well as impaired modulation of other neurotransmitters
How is PD diagnosed? What is the gold standard?
- Diagnosis of exclusion
o Only definitive way to diagnosis PD is post-mortem exam of the brain
When do we see motor symptoms develop in relation to when the disease process starts?
- Motor symptoms do not appear until ~ 60% neurodegeneration has already occurred in basal ganglia
Describe bradykinesia, hypokinesia, and akinesia. How do they differ?
- Bradykinesia – slow movements
- Hypokinesia – small movements
- Akinesia – absence of movements
- Movements shrink down in amplitude and force with more complex tasks harder than simple commands
Define rigidity and describe the presentation commonly seen with PD.
- Rigidity – passive resistance to stretch independent of velocity
o Felt uniformly in all directions (asymmetrical early then eventually whole-body movement)
o Seen proximal first
o Leads to increased cognitive load, emotional stress, energy expenditure of movements
Long term effects of rigidity
o Long term effects: decreases ROM, contractures, postural deformities
Lead pipe vs cogwheel rigidity
lead pipe - sustained resistance
cogwheel - jerky, ratchet-like (lead pipe + tremor)
Define tremor and describe the presentation commonly seen with PD. What body parts are most common?
- Tremor - involuntary, rhythmic muscle contraction leading to shaking movements in one or more parts of the body
o Resting tremor early on
o Hand and foot are most common
o Tends to be mild, low frequency
What leads to postural instability in PD?
- abnormal postural responses
- small functional limits of stability
- difficulties with self-initiated movements
- reduced anticipatory postural adjustments and control
- abnormal patterns of activation
- midline disorientation
- rigidity, weakness, loss of ROM, freezing, medication side effects
What are the 3 top risk factors for falls in PD patients?
- Postural instability
- Disease severity
- Gait impairments (most notably Freezing of Gait)
What are additional risk factors for falls identified?
- Dementia
- Depression
- Postural hypotension
- Involuntary movements from long-term medication use
Explain the specific difficulties those with PD have with complex motor planning tasks.
- Sequential movements – poor motor planning
- Transitioning between movements
o Motor preservation (fingers typing then continue when going to pick up glass of water)
What is the difference between a continuous and episodic gait characteristic?
Episodic changes, such as freezing of gait, can come on suddenly and randomly.
Continuous changes are changes in your gait that happen all the time while walking, such as walking more slowly than expected
What are the continuous gait impairments seen with PD
o Overall hypokinetic presentation (slow steps, reduction in arm swing, minimal trunk rotation, LE rigidity, axial rigidity)
o Increased variability and asymmetry
o Poor postural control
o Festinating gait
o Increase tendency for retropulsion and/or anteropulsion
- What are the episodic gait impairments seen with PD? What happens to these as the disease progresses?
o Festinating gait pattern
o Midline disorientation (anteropulsive or retropulsive)
o En Bloc turning (turn in a uniform, rigid presentation)
o Freezing of gait
Turn into continuous gait impairments as the disease progresses
List common non-motor symptoms seen with PD
- Pain and paresthesias
- Visual impairments
- OH
- Fatigue
- Dementia
What types of pain patterns do we see with PD? What are common areas?
- Musculoskeletal and neuropathic
o Central pain thought to be due to abnormal modulation of pain caused by dopamine deficiency
Common areas:
- lower back
- legs
- shoulders
- face
What are the two subtypes of PD and how do they differ?
- Postural Instability Gait Disorder phenotype
o Postural instability and gait disturbances
o More significant disease course - Tremor-Dominant phenotype
o Demonstrate fewer problems with bradykinesia or postural instability
o Lower prevalence of non-motor symptoms
o Less likely to develop dementia and other cognitive deficits
Which subtype has the better prognosis overall?
- Tremor-Dominant phenotype