Basal Ganglia Flashcards
Where is dopamine produced?
Substantia Nigra
What does the motor loop link?
the putamen, globus pallidus, and ventral lateral thalamic nucleus to the motor and premotor cortex
What is the role of the motor loop?
movement selection and action, regulating muscle contraction, force, multi-joint movements, and sequencing.
What does the motor circuit regulate?
- Muscle contraction
- Muscle force
- Multi -joint movements
- Sequencing of movements
what is a hypokinetic disorder?
- excessive inhibition
- parkinson’s
what are hyperkinetic disorders
- Huntington’s disease
- Dystonia
- Tourette’s disorder
- Dyskinetic cerebral palsy
Parkinson’s Disease
Neurodegenerative disorder of subcortical gray matter in the basal Ganglia
•Dopamine loss in PD = lose inhibitory control of indirect loop and excitatory control over direct loop = decreased movement
Parkinson’s Disease epidemiology
- Occurs throughout ethnic groups, lowest among Asian and African descent, highest incidence among Caucasians
- More Predominant in males
- Mean age of onset : Early to mid 60s
Cardinal Signs of PD
TRAP
•Tremor(resting)- diminishes with effort, increases with stress/fatigue
•Rigidity- NOT velocity dependent, common in trunk, extremities and neck
•Akinesia/bradykinesia- Correlates best with severity of loss of dopamine
•Postural instability- NOT common early in diagnosis
Movement symptoms of PD
- Tremor
- Rigidity
- Bradykinesia
- Postural instability
- Micrographia
- Festinating gait
- Freezing
- Soft speech
- Masked face
- Sialorrhea and dysphagia
Non-movement symptoms of PD
- Anosmia
- Anxiety
- Apathy
- Bone health
- Breathing difficulty
- Cognitive changes
- Constipation & nausea
- Dysautonomia
- Fatigue
- Hallucinations
- Pain & sensory disturbances
- Sleep disorders
Diagnosing PD
- No diagnostic tests
- based on clinical examination
- gold standard: neuropathological exam at autopsy
Supportive Criteria for diagnosing PD
- Clear & dramatic response to dopamine therapy
- Levodopa-induced dyskinesia
- Resting tremor of a limb
- Diagnostic testing:
- loss of olfaction
- abnormal cardiac MIBG scintigraphy
Negative criteria for diagnosing PD
- Unequivocal cerebellar abnormalities
- Downward vertical supranuclear gaze palsy
- Frontotemporal dementia
- Parkinsonism restricted to lower limbs >3 years
- Treatment with dopamine receptor blocker
\6. Absence of response to levodopa - Unequivocal cortical sensory loss
- Normal functional neuroimaging of dopaminergic system
- Documentation of alternative condition known to produce parkinsonism
Prognosis of PD
- progressive and no cure
•Shift from unilateral to bilateral involvement
•Increasing rigidity and postural flexion
•Increasingly limited mobility and increasing need for assistance
•Eventually w/c and/or bed-bound
•Cause of death usu. pneumonia
Stage 1 PD
Unilateral symptoms-temor, stiffness, slowed movement
Stage 1.5 PD
Unilateral symptoms plus axial involvement_ postural problems
Stage 2 PD
Bilateral involvement and minor sxs: swallow, talk, and decrease in facial expression
Stage 2.5 PD
Bilateral involvement: recovers on pull test
Stage 3 PD
Bilateral Involvement worsened. Postural instability noticed. Person is still independent
Stage 4 PD
Severe disability, able to walk or stand unassisted, but will need help with AD L
Stage 5 PD
Person is confined to w/c or bed, needs total assistance
Early presentation of PD
- Tremor
- Micrographia
- Slowness with ADL’s
- Voice changes
- Difficulty maneuvering in bed
- Lack of arm swing with gait
- Dragging the foot with walking
After 5 years of PD
- Motor Fluctuations
- Wearing off
- On-off phenomena
- Narrowing therapeutic window
- Loss of postural control; retropulsion
- Gait freezing and Festination
- Cognitive Changes
- Medication side effects: dyskinesia, dystonia
Medical management of PD
- Primary objective is to maximize control over the “target” signs and symptoms.
- select the appropriate drug(s) for each symptom
- adjust dose and frequency of drug administration over time
•The patient’s therapeutic response to any individual drug may change over time and requires regular visits and frequent communication between the medical team, the patient, and caregiver(s) to maintain the best management of the disease with the fewest side effects possible.
Carbidopa/levodopa (Sinemet)
Most effective; prolongs capacity to perform iADLs
Dopamine agonists (Mirapex, Requip)
Work by copying actions of dopamine in the brain
COMT inhibitors
inhibits enzyme responsible for metabolism of levodopa
MAO inhibitors (Eldepryl)
slow the metabolism of dopamine
Anticholinergic agents (Cogentin)
used for treatment of tremor in younger pts
Deep brain stimulation of PD
- used in advanced PD
- surgical implantation of electrodes into brain
What should be tested with ROM in PD?
- rigidity
- posture assessment
- limited cervical and trunk rotation
- hip flexor tightness
Strength in PD
- should be wnl
- 5x sit to stand: > 16 sec is correlated w fall risk
Coordination in PD
- Movements bradykinetic, small, fatigue with repetition
- NO dysmetria
- Dyskinesias
Pain in PD
- msk
- central neuropathic
Oculomotor and visual in PD
- Visuoperceptual deficits
- Abnormalities ATYPICAL in early stages of idiopathic PD
- Impaired/bradykinetic saccades in late stages
is there olfactory disturbance in PD?
Yes
Proprioception in PD
- Decreased sensory integration:
* joint position sense, postural orientation
Kinesthetic awareness in PD
- decreased
•larger limb displacement required in order to detect movement
Cognition in PD
- Dementia: Planning, Decision-making, Goal-directed behavior
- Strong correlation between attention and the ‘pace’ domain of gait
- Gait velocity, step length, and step time
- Associations with gait variability and executive dysfunction
MOCA scoring
<26= mild cognitive impairment
< 21= PD dementia
