16 - Basal Ganglia

Question 1

what is the basal ganglia?

Answer 1

collection of gray matter nuclei located deep within the white matter of the cerebral hemispheres

Question 2

what kind of movement disorders can patients with basal ganglia lesions develop?

Answer 2

hypokinetic or hyperkinetic movement disorders

Question 3

if a patient has a hypokinetic disorder what is this disease called and the effects?

Answer 3

Parkinson’s disease (hypokinetic): rigidity, slowness, and marked difficulty initiating movements

Question 4

if a patient has a hyperkinetic disorder what is this disease called and the effects?

Answer 4

Huntington’s disease (hyperkinetic): uncontrolled involuntary movements produce a random pattern of jerks and twists

Question 5

What are the two inputs to the basal ganglia?

Answer 5

Putamen - Most cortical inputs are excitatory and use glutamate

Substantia nigra pars compacta - Dopaminergic nigrostriatal pathways that is excitatory to some cells and inhibitory to others

Question 6

What are the two basal ganglia outputs and where do they convey information? what are the outputs considered, inhibitory or excitatory?

Answer 6

Substantia nigra pars reticulate conveys information for the head and neck

The internal segment of the globus pallidus conveys information for the rest of the body

These output pathways are inhibitory and use GABA

Question 7

What is the most important input nucleus of the striatum for motor control pathways?

Answer 7

Putamen

Question 8

How can you differentiate between upper motor neuron issues and basal ganglia issues?

Answer 8

Upper motor neuron lesion usually lead to a spastic-type rigidity (aka “clasp-knife rigidity”)

Basal ganglia disorders tend to be more continuous throughout attempts to bend the limb, and thus lead to plastic, or lead pipe, rigidity

Question 9

For the Basal Ganglia Internal Connections describe the direct pathway?

Answer 9

Striatum to Internal segment of globus pallidus (GPi) or the substantia nigra pars reticulate (SNr)

Question 10

For the Basal Ganglia Internal Connections describe the indirect pathway?

Answer 10

Striatum to External segment of globus pallidus (GPe) to Subthalamic nucleus (STN) to GPi or the SNr

Question 11

what is the net effect of excitatory input from the cortex through the direct pathway?

Answer 11

excitation of the thalamus

Question 12

what is the net effect of excitatory input from the cortex through the indirect pathway?

Answer 12

inhibition of the thalamus, resulting in inhibition of movements through connections back to the cortex

Question 13

what does bradykinetic mean?

Answer 13

slowed movements

Question 14

how are bradykinetic disorders caused?

Answer 14

by increased inhibitory basal ganglia outflow to the thalamus

Question 15

what is dystonia? name an example and how it can be treated?

Answer 15

The patient assumes abnormal, often distorted positions of the limbs, trunk, or face that are more sustained or slower than in athetosis

Focal dystonias include torticollis, which involves the neck muscles; blepharospasm, which involves the facial muscles around the eyes, and spasmodic dysphonia, which involves laryngeal muscles

injection of botulinum toxin into the affected muscles

Question 16

what is athetosis?

Answer 16

characterized by twisting movements of the limbs, face and trunk that sometimes merge with faster choreic movements, giving rise to the term choreoathetosis

Question 17

what is Ballismus?

Answer 17

Movements of the proximal limb muscles with a larger-amplitude, more rotatory or flinging quality than chorea

Question 18

what is Chorea?

Answer 18

Is applied to movement disorders characterized nearly continuous involuntary movements that have a fluid or jerky, constantly varying quality (dancing-like)

Question 19

what is a major cause of Chorea?

Answer 19

Huntington’s disease ( autosomal dominant neurodegenerative disorder).