Parkinson's Disease Flashcards
Pathophysiology
Pars compacta section of substantia nigra recieves overall loss of dopamine –> increased activity of indirect pathway –> increased inhibition of movement
5 Classic features of parkinson’s
- Rest tremor (toe rolling)
- Rigidity
- Bradykinesia
- Loss of postural stability (test with pull test)
- Flexed posture
Variable features of parkinson’s
- Freezing of gait (address by aiding in weight shift)
- Dystonia
- Micrographia (small amplitude of writing)
- Orthostasis (side effect of sinemet)
- “bradycrania”
- Dementia (later stages)
- depression
4 implications of flexed posture
- loss of trunk rotation
- loss of pelvic rotation
- smaller step lengths
- influence ability to shift weight
Stages and Descriptions of Parkinson’s Disease (Hoehn and Yahr)
Stage 1: unilateral (UL tremor, foot drop/drag)
Stage 2: bilateral
Stage 3: mild-mod disease, postural instability, physically independent (+ pull test)
Stage 4: req assistance for standing and walking
Stage 5: confined to bed or w/c
Circuitry through the Basal Ganglia
Direct (facilitation of movement) and Indirect (inhibition of mvt) pathways through putamen and globus pallidus –> substantia nigra –> thalamus –> back to cortex
*health movement = balancing act between direct and indirect
4 Circuitry loops through Basal Ganglia
- Sensorimotor Loop - select appropriate motor response, inhibit inappropriate response
- Occulomotor loop - ocular deviations in BG disorders
- Association loops- issues crossing info across cortex; role in stimulus response tasks and implicit memory
- Limbic Loops- filtering appropriate emotional responses
Lewy Bodies
abnormal collection of alpha-synuclein proteins is a hallmark of Parkinson’s; as the disease progresses, more and more lewy bodies and lewy neurites move through brainstem and into cortex (substantia nigra is one the the early levels of the brainstem affected)
Differential Diagnoses of Parkinson’s
- Normal Pressure Hydrocephalus
2. Parkinsonism
Cause of PD, age of onset
no known cause yet, small genetic component (earlier onset)
normal age of onset is after 50
Normal Pressure Hydrocephalus: similarities and differences in parkinson’s disease
Similarity: presentation of shuffled gait with low postural stability
Difference: NPH presents with gait symptoms first, manifested later in PD
Similarity: enlarged ventricles on MRI
Difference: with spinal tap, increased pressure in Ventricular System with NPH, NOT with PD (no inc pressure)
NPH treatment: shunt via catheter in spinal canal; resolves gait presentation
Parkinsonism: Cause
Drug induced: psychiatric medications (antipsychotic meds)
Parkinsonism: Symptoms
- Progressive supranuclear palsy (presentation of eye dysfunction; usually upgaze first)
- Multisystem atrophy (umbrella term for degeneration in 3 different tracts- can get symptoms from any)
Progressive Supranuclear Palsy; pathogenesis and prognosis
Roll of superior colliculi is integration of visual information. Dysfunction in SC –> limitation in occulomotor function. Specifically affects CN IV (sits between SC and IC) –> innervation for superior oblique oculomotor mucle –> upgaze usually affected first
*prognosis = 4 years post diagnosis
Multisystem Atrophy; types, tracts affected, and presentations
- Olivo Cerebellar Atrophy: cerebellar tracts, intention tremor
- Striatoniagral Degeneration: gait dysfunctions, tremors, slowed movements
- Shy Drager Syndromes: ANS dysfunction; severe hypotenstion (prognosis = 5yrs)
Medications used in PD
- Levadopa/Carbidopa (Sinement)- for bradykinesia
- Dopamine Agonists - increase dopamine in synapse
- Anticholonergics - block ACH, aid in tremor modification
- Neuroprotective - slow degenerative process
- Amantadine (Symmetrel)- dopamine agonist
- COMT inhibitors
- Tolcapone (Tasmar)
Levadopa/Carbidopa (Sinemet)
- purpose
- biological effect
- side effects
- Administration
purpose: helps in bradykinesia, if too much- aberrant movements
Biological effect: prevent breakdown of levodopa in the gut
Side effects:
- postural hypotension
- dyskinesia
- psychosis
Administration: only in small doses; loses effectiveness over time; on/off periods during the day