Disorders of the Basal Ganglia Flashcards
What makes up the basal ganglia (aka the extrapyramidal system)?
- striatum (caudate and putamen)
- globus pallidus
- substantia nigra
- subthalamic nucleus
what is the pyramidal system
corticospinal and corticobulbar tracts
Parkinson’s disease pathophys
-loss of DA neurons in substantia nigra=less direct pw inhibition and more indirect pw stimulation of medial globus pallidus
=net increased inhibitory output of GPm to VL thalamic motor nuclei=less stim to motor cortex=clinically slow or absent movements
hyperkinetic disorders of the basal ganglia
-there is a net decrease of medial globus pallidus (GPm) output=reduced inhibition of VL thalamic motor nuclei=greater stimulation of motor cortex=xs motor activity
etiologies of parkinsonism
- use of dopamine antagonist meds
- toxic exposure to manganese of CO2
- multiple ischemic infarctions of the basal ganglia
- survivors of the encephalitis lethargica epidemic
- Parkinson’s dz-progressive degenerative d/o of unknown cause
What are the primary clinical signs of PD?
- resting tremor
- rigidity
- bradykinesia
- impaired postural reflexes
resting tremor in PD
- prominent when pt sitting or reclining
- most often involves distal upper limbs asymmetrically (sometimes chin or lower limbs)
- worse with stress
- pill-rolling
rigidity in PD
- rigid arm may not naturally swing as the pt walks
- cogwheeling=ratchet or jerky feeling created by tremor when the rigid limb is moved
bradykinesia in PD
=slowness or lack of movement
- may rock several times to get off a cahir, stooped, multiple steps to tirn around
- pt may freeze feet to the floor
- manual tasks are slow and clumsy
- eyeblinking slower
- may drool
impairment of postural reflexes in PD
- balance instability while standing or walking
- least responsive to dopaminergic medication
secondary signs found in pts with PD
- masked facies
- hypophonic speech
- micrographia
- ANS involvement: severe constipation, bladder dysfunction, or orthostatic hypotension
- REM behavior sleep disorder
how is PD diagnosed
- primarily clinically
- at least 2/4 primary clinical signs should be present
pathology of PD
-loss of pigmented dopaminergic neurons in the substantia nigra, many of which have alpha-synuclein-positive-eosinophilic-cytoplasmic inclusions called LEWY bodies
what are the synucleinopathy?
- Lewy body dementia, multiple system atrophy, PD
- accumulation of alpha-synuclein appears to play a central role in the degenerative process
PD treatment
-L-dopa and Carbidopa (decarboxylase inhibitor, limits peripheral catabolism of L-dopa before it enters the brain)
