Neurology

Question 1

Where are UMN located?

Answer 1

Travels within the CNS from the brain to synapse with circuits involving the LMN/peripheral nerves

Question 2

Where are LMN located?

Answer 2

• Projects outside the CNS to synapse with muscle
• In most instances, this equates to the motor nerves in the PNS

Question 3

What happens if an UMN is damaged?

Answer 3

• The distal portion (separated from the cell body) degenerates
• UMN input is mainly inhibitory, so reflex arcs
• Existing reflexes are stronger and easier to elicit
• Some normally inhibited reflexes become apparent
• Muscle tone increases

Question 4

What is the result of UMN dysfunction?

Answer 4

• Reduced movement (paresis) or no movement (plegia)
• Increased tone
• Present or increased reflexes
• Disuse atrophy occurs with time

Question 5

What happens if a LMN is damaged?

Answer 5

• The distal portion (separated from the cell body) degenerates
• The innervated muscles cannot be stimulated to contract
• The innervated muscle fibres die
• Existing reflexes are weaker or absent
• Muscle tone reduces
• Muscle mass decreased rapidly and severely

Question 6

What is the result of LMN dysfunction?

Answer 6

PRAT:
- Paresis or plegia
- Reflexes are reduced
- Atrophy is severe and rapid
- Tone reduced

Question 7

Distinguish the speed of neurogenic atrophy from LMN disease and disuse atrophy from orthopaedic disease.

Answer 7

Neurogenic - occurs over days

Disuse - occurs over weeks

Question 8

Distinguish the severity of neurogenic atrophy from LMN disease and disuse atrophy from orthopaedic disease.

Answer 8

Neurogenic - can be severe, may cause loss of entire muscle mas

Disuse - usually mild to moderate, never causes loss of all the muscle mass

Question 9

Distinguish the distribution of neurogenic atrophy from LMN disease and disuse atrophy from orthopaedic disease.

Answer 9

Neurogenic - localised to the innervated muscles of the affected nerve or nerves (so usually focal, but may be generalised with generalised nerve disease)

Disuse - not localised to the distribution of a specific nerve

Question 10

What are the cardinal neurological presentations that prompt neurological examination?

Answer 10

• Abnormal gait, stumbling or falling
• Abnormalities of the head and face
• Apparent blindness or deafness
• Abnormal behaviour – particularly episodic
• Exercise intolerance
• Incontinence abnormal behaviour