Motor Neurone Disease

Question 1

What is the definition of Motor Neurone DIsease

Answer 1

A progressive neurodegenerative disorder of cortical, brainstem and spinal motor neurons (lower and upper motor neurons)

Question 2

What are the subtypes of MND?

Answer 2

• Amyotrophic Lateral Sclerosis (ALS)
• Progressive Muscular Atrophy Variant
• Progressive Bulbar Palsy Variant
• Primary Lateral Sclerosis Variant

Question 3

What is Amyotrophic Lateral Sclerosis (ALS)?

Answer 3

AKA Lou Gehrig’s disease

Combined degeneration of upper AND lower motor neurones resulting a mix of LMN and UMN signs

Question 4

What is Progressive Muscular Atrophy Variant?

Answer 4

Only LMN signs

Better prognosis

Question 5

What is Progressive Bulbar Palsy Variant?

Answer 5

Dysarthria

Dysphagia

Wasted fasciculating tongue

Brisk jaw jerk reflex

Question 6

What is Primary Lateral Sclerosis Variant?

Answer 6

UMN pattern of weakness

Brisk reflexes

Extensor plantar responses - Babinski

NO LMN signs

Question 7

What is the aeitology and risk factors involved with MND?

Answer 7

• There is an unknown aetiology
• Free radical damage and glutamate excitotoxicity have been implicated

Pathology:

• > Progressive motor neurone degeneration and death
• > Gliosis replacing lost neurones

The disease is also associated with frontotemporal lobar dementia

Question 8

What is the epidemiology of MND?

Answer 8

• Rare (incidence = 1/50,000)
• Mean onset age = 55yrs
• 5-10% have a family history with autosomal dominant inheritance

Question 9

What are the presenting symptoms of MND?

Answer 9

Progressive motor neurone degeneration and death

Gliosis replacing lost neurones

Question 10

What are the signs of MND on physical examination?

Answer 10

There’s a combination of UMN and LMN

LMN:
Muscle wasting  
Fasciculations   
Flaccid weakness  
Hyporeflexia 

UMN:
Spastic weakness
Extensor plantar response
Hyperreflexia

Sensory exam - should be NORMAL

Question 11

What are the appropriate examinations

Answer 11

• Bloods (Mild elevation in Creatine Kinase - CK, ESR, Anti-GM1 ganglioside antibodies)
• Electromyography (EMG)
• Nerve conduction studies - often normal
• MRI - exclude cord compression and brainstem lesions
• Spirometry - assess respiratory muscle weakness