Motor Neuron Disease

Question 1

Define motor neuron disease

Answer 1

A group of neurodegenerative disorders characterised by progressive destruction of UMN and anterior horn cells in brain and spinal cord

Question 2

4 types of MND

Answer 2

1. ALS - amyotropic lateral sclerosis
2. Progressive bulbar and pseudobulbar palsy
3. Progressive muscular atrophy
4. Primary lateral sclerosis

Question 3

ALS features

Answer 3

1. Most common type

2. Damage in anterior horn and motor cortex so both UMN and LMN signs

Question 4

Progressive bulbar palsy and pseudobulbar palsy features

Answer 4

1. Affects cranial nerves 9-12

2. UMN + LMN signs

Question 5

Progressive muscular atrophy features

Answer 5

1. Anterior horn damage - LMN

2. Affects distal muscle groups before proximal

Question 6

Primary lateral sclerosis features

Answer 6

1. Loss of Betz cells in motor cortex - UMN signs (spasticity)
2. Rare

Question 7

Epidemiology of MND

Answer 7

1. More common in men

2. Median age onset = 60

Question 8

Signs and symptoms of MND

Answer 8

1. Upper limbs: decreased dexterity, stiffness, intrinsic hand muscle wasting, shoulder abduction
2. Lower limbs: tripping, stumbling spastic gait, foot drop
3. Overall: muscle atrophy + spasticity
4. Aspiration pneumonia

Question 9

UMN signs

Answer 9

1. Spasticity
2. Increased muscle tone
3. Hyper-reflexia
4. Babinski sign

Question 10

LMN signs

Answer 10

1. Decreased muscle tone/atrophy
2. Fasciculation
3. Hypo-reflexia

Question 11

Investigations for MND

Answer 11

1. Mainly clinical examination + history.
2. MRI/CT - rule out structural causes
3. Lumbar puncture - rule out inflammatory causes

Question 12

Management of MND

Answer 12

1. Riluzole - glutaminergic inhibitor, NMDA receptor antagonist
2. Symptomatic treatment -
   drooling - amytriptiline
   spasticity - baclofen
   joint pain - analgesic ladder
   resp failure - NIV support and feeding via gastronomy
3. Palliative - mainly 3 years survival at most