Motor Neuron Disease

Question 1

What is motor neuron disease?

Answer 1

A groups of progressive neurological disorders which destroy motor neurons

Question 2

What is the epidemiology of MND?

Answer 2

Lifetime risk of 1:400.
Men 2x more likely to be affected.
90% are sporadic with 10% being familial

Question 3

What is the aetiology of MND?

Answer 3

MND is associated with misfolding of the TDP-43 protein

Question 4

What are the different types of MND?

Answer 4

Amyotrophic lateral sclerosis,
Primary lateral sclerosis,
Progressive muscular atrophy,
Progressive bulbar palsy

Question 5

Describe features of amyotrophic lateral sclerosis

Answer 5

Presents with LMN signs in arms and UMN signs in legs.

Question 6

Describe features of upper motor neuron lesions

Answer 6

Disuse atrophy,
Increased tone +/- ankle clonus,
Hyperreflexia,
Positive babinski sign
Spastic paralysis

Question 7

What are the signs of a lower motor neuron lesion?

Answer 7

Marked atrophy,
Flaccid paralysis
Fasciculations,
Reduced tone,
Reduced/absent reflexes,
Normal Babinski

Question 8

In what conditions can UMN lesions be seen?

Answer 8

Strokes,
Amyotrophic lateral sclerosis,
Multiple slcerosis

Question 9

In what conditions can lower motor neuron lesions be seen?

Answer 9

Peripheral nerve trauma,
Spinal muscular atrophy,
Amyotrophic lateral sclerosis,
Guillain barre syndrome,
Poliomyelitis

Question 10

Describe features of primary lateral sclerosis

Answer 10

UMN signs only

Question 11

Describe features of progressive muscular atrophy

Answer 11

LMN signs only. Will affect distal muscles before it affects proximal.

Question 12

Describe features of progressive bulbar palsy

Answer 12

Palsy of tongue, muscles of chewing/swallowing and facial muscles due to loss of function of brainstem nuclei.
Has worst prognosis

Question 13

What are some clues which point towards motor neuron disease?

Answer 13

Asymmetrical limb weakness,
Mixture of upper and lower motor neuron signs,
Wasting of small muscles of the hands,
Fasciculations,
Absence of sensory signs,
Doesn’t affect extra-ocular muscles,
No cerebellar signs,
Abdominal reflexes are preserved

Question 14

What are the investigations for MND?

Answer 14

Clinical diagnosis so investigations are primarily to tule out other causes:
Protein electrophoresis,
MRI of brain and spinal cord,
EMG and nerve conduction studies.

Question 15

What is the management of MND?

Answer 15

Riluzole - stimulates glutamate receptors, used in ALS but only prolongs life by 3 months.
Respiratory care - Non-invasive ventilation (BIBAP) used at night
Percutaneous gastrostomy tube (PEG) - nutrition