Disorders of basal ganglia function

Question 1

Define extrapyramidal.

Answer 1

The term “extrapyramidal” refers to those parts of the motor system that are not directly “pyramidal”, that is not the corticospinal tracts (upper motor neurons).
- It always includes the basal ganglia and often is considered to include cerebellar systems.

Question 2

What is oxidative stress?

Answer 2

Oxidative stress refers to the adverse effects on tissues of reactive oxygen species (free radicals).

Question 3

Define parkinsonism.

Answer 3

Parkinsonism is the phenotypic description of a patient with bradykinesia, poor postural responses and rigidity from any cause (it is not always due to Parkinson’s disease).

Question 4

Define Parkinson disease.

Answer 4

Parkinson disease is a dopamine deficiency syndrome characterized by bradykinesia, poor postural responses, rigidity and tremor (not all are present in any one patient).

Question 5

Define delayed postural reflexes.

Answer 5

Delayed postural reflexes refers to a delay in the normal righting responses that permit stance and gait.

Question 6

What is a resting tremor?

Answer 6

Resting tremor is a tremor that occurs with the hands resting in the lap or at the sides when walking or standing.

Question 7

What does “cogwheel” refer to?

Answer 7

Cogwheel is a term referring to an irregular, ratchety resistance to passive movement which is the superimposition of tremor over rigidity.

Question 8

Define festination.

Answer 8

Festination is shortening of stride such that the patient takes many short steps to cover a distance.
- They may become propulsive if they cannot catch up with their center of gravity.

Question 9

Define chorea.

Answer 9

Chorea is a random, purposeless, involuntary twitching movement.

Question 10

Define athetosis.

Answer 10

Athetosis is a purposeless, involuntary writhing movement.

Question 11

Define hemiballism.

Answer 11

Hemiballism is a purposeless, involuntary flinging or flipping movement of a limb.

Question 12

Define dystonia.

Answer 12

Dystonia is an abnormal sustained twisting posture of a part of the body.
- It may affect the entire body or only a small part.

Question 13

Define hypophonia.

Answer 13

Hypophonia is a pathological loss of power in the voice.

Question 14

What are the functions of the extrapyramidal system?

Answer 14

The extrapyramidal system is responsible for sustained postures, resting tone and patterned movements.

Question 15

What is the cause of Parkinson disease?

Answer 15

Parkinson disease is due to selective degeneration of substantial nigra and other pigmented CNS neurons.
- ultimately idiopathic

Question 16

What are the symptoms of Parkinson disease?

Answer 16

The symptoms of Parkinson disease include:

• Rigidity
• Bradykinesia
• Delayed postural reflexes
• Difficulty initiating movements
• Resting tremor
• None of these is present in all Parkinson patients

Other common symptoms include:
   - Mask face
   - Stooped posture
   - Increased flexor tone
   - Drooling
   - Shuffling
   - Seborrhea
   - Orthostasis
   - Decreased blinking
   - Soft voice (hypophonia). 
It is often asymmetrical (especially at the onset).

Question 17

What is the pathology of Parkinson disease?

Answer 17

Dopamine is deficient in the brains of patients with Parkinson disease.
- Oxidative stress on cells is one theory of development of Parkinson disease.

Question 18

What are the treatments for Parkinson disease?

Answer 18

• Dopamine agonists/ dopamine enzymatic degradation inhibitors
  
  • Levodopa => dopamine precursor; crosses BBB
  • Carbidppa => block dopa decarboxylase, preventing generation of peripheral dopamine from levodopa, limiting side effects.
• Blockers of acetylcholine

Question 19

What problems complicate treatment of Parkinson patients?

Answer 19

• Parkinson patients may notice wearing off of drugs or unpredictable “on-off” phenomena (like turning off a switch).
• Over-treatment of Parkinson’s disease will result in abnormal movements at rest (such as chorea or athetosis) and hallucinations.
• Nightmares, orthostasis and nausea.

Question 20

What surgical treatments are available for Parkinson disease

Answer 20

The surgical treatments that are available for Parkinson disease include:

• Thalamotomy (better for tremor)
• Palidotomy (better for rigidity, bradykinesia)
• Stimulation (subthalamic nucleus).

Question 21

What is essential tremor?

Answer 21

Essential tremor is a common condition that may be hereditary.

• It is more frequent with age, but may start early.
• The usual course is for gradual progression.

Question 22

How do you recognize essential tremor?

Answer 22

The tremor appears with sustained postures and is often obvious with movements (an action tremor).

• It may start in hands (most often) but involve neck and jaw frequently.
• Alcohol often improves this tremor, although being nervous makes all tremors worse.
• It may be familial (usually autosomal dominant).

Question 23

What are the available treatments for essential tremor?

Answer 23

The effective treatments are beta blockers and primadone/mysoline.
- Thalamotomy or stimulator implantation may be necessary.

Question 24

What are potential causes of chorea and athetosis?

Answer 24

Chorea and athetosis are commonly due to:

• Long-term exposure to neuroleptics
• Excess of dopamine stimulating medicine
• Huntington’s disease
• Choreoathetotic variety of cerebral palsy.
  
  • Uncommonly, choreoathetosis may be due to various intoxications and poisonings, severe metabolic disturbances, encephalitis, autoimmune disease, Wilson’s disease (of copper metabolism) or pregnancy.