74 - Basal Ganglia Function Flashcards
Akinesia
Complete or partial loss of muscle movement
Difficulty in initiating movement is sometimes called akinesia, sometimes called bradykinesia.
Chorea
Dance-like, involuntary, rapid movements. Can be associated with Huntington disease, rheumatic fever, systemic lupus erythematosus, and other conditions
Brief, sudden, random, twitch-like movements of limbs or facial muscles. They resemble fragments of normal voluntary movement.
Bradykinesia
Slowness in the execution of movement
Difficulty in initiating movement is sometimes called akinesia, sometimes called bradykinesia.
Athetosis
Slow, twisting, writhing movements, with larger amplitude than chorea, commonly involving the hands
Hemiballismus
Jerking and twitching movements of one side of the body (involuntary violent flinging or jerking of a limb or limbs in an uncoordinated manner caused by a lesion of the contralateral subthalamus)
Can also be ballismus
Dyskinesia
Defect in voluntary movement.
Freezing of gait
Freezing of gait (Frozen gait syndrome) can occur in patients with Parkinson’s disease. (This symptom can also be associated with primary progressive frozen gait, a disease with many names.) Parkinson’s Disease patients with this symptom can suddenly be unable to start walking or just stop moving forward while walking. First appears as hesitation in starting to walk or turn. There has been considerable research to develop better rehabilitation treatments. Various sensory cuing methods (auditory, visual) have proved useful.
Festinating gait
Abnormal gait, small shuffling steps and the absence of arm swing that normally accompanies walking. As disease progresses the patient tends to walk faster to prevent a fall due to flexed posture which alters their center of gravity. (festinating gait)
A cardinal symptom of Parkinson’s disease
What structures comprise the basal ganglia?
1 - Caudate
2 - Putamen
3 - Globus pallidus (internal and external segments - GPi and GPe)
4 - Subthalamic nucleus
5 - Substantia nigra (pars reticulata and pars compacta (the pigmented part))
What is an alternate set of terms to describe the basal ganglia?
- Corpus striatum
- Neostriatum
- Paleostriatum
Corpus striatum
Neostriatum + paleostriatum
Neostriatum
Neostriatum = striatum = putamen + caudate nucleus
Paleostriatum
Paleostriatum = pallidum = globus pallidus
Which neurotransmitters are important in the nigrostriatal pathway?
SNc projection to striatum (caudate and putamen) releases dopamine
- Several different subtypes of dopamine receptors
- Dopamine can have excitatory or inhibitory effects depending on receptor type.
Which neurotransmitters are important in the corticostriate pathway?
Corticostriate projections are excitatory and release glutamate onto medium spiny neurons in striatum
Which neurotransmitters are important in pathway from the striatum to the GPe and GPi
Striatum = putamen + caudate GPe = globus pallidus external GPe = globus pallidus internal
Medium spiny neurons of striatum are projection neurons to GP. They always release GABA, an inhibitory transmitter.
Is GABA usually excitatory or inhibitory?
Inhibitory
Is glutamate usually excitatory or inhibitory?
Excitatory
What are the cardinal symptoms of Parkinson’s disease?
1 - A rhythmic tremor at rest (4-to-6 Hz tremor)
2 - Increased muscle tone or rigidity - often cogwheel like characteristics
3 - Slowness in the execution of movement (bradykinesia)
4 - Severe slowness of movement can evolve into lack of movement (akinesia). Patient may lack normal facial movements (masked facies). Difficulty in initiating movement is sometimes called akinesia, sometimes called bradykinesia.
What are other symptoms seen in Parkinson’s?
- Flexed posture and Postural reflex impairment
- Abnormal gait, small shuffling steps and the absence of arm swing that normally accompanies walking. As disease progresses the patient tends to walk faster to prevent a fall due to flexed posture which alters their center of gravity. (festinating gait)
- Reduced blinking
- Micrographia, small handwriting
- Loss of automaticity of movement: Patient has to exert more voluntary control of previously automatic and well –learned movements.
- Freezing of gait
Which neurotransmitter system is most damaged in Parkinson’s disease? Which parts of the basal ganglia does this include?
The degeneration of dopaminergic projection to striatum from substantia nigra is most severely damaged
What are the symptoms of Huntington’s disease?
- Chorea - a type of involuntary movement
- Dementia
- Voluntary movements slower than normal
Lesions in which location will cause hemiballismus?
Hemiballismus on one side of body is often associated with a lesion in the contralateral subthalamic nucleus.
What are the four loops of the basal ganglia?
1 - Body movement loop
2 - Oculomotor loop
3 - Prefrontal loop
4 - Limbic loop
