Motor Neurone Disease

Question 1

What is MND

Answer 1

Cluster of neurodegenerative disease characterised by selective loss of neurones in motor cortex, cranial nerve nuclei and anterior horn cells.

Upper and lower morin neurones can be affected but there is no sensory loss or sphincter disturbance.
MND never affects eye movements.

Question 2

How does MND present?

Answer 2

> 40 years median 60
Stumbling spastic gait
Foot drop and proximal myoaphty
Weak grip
Weak shoulder abducntion
Aspiration pneumonia
UMN signs:
spasticity, hyperreflexia, extensor plantar reflex
LMN signs - wasting, fasciculations of tongue, abdome. back and thigh
Speech/swallowing/respiratory failure affected in bulbar palsy

Doesn’t affect extra ocular muscles
No cerebellar signs

Question 3

How is MND diagnosed?

Answer 3

Suspect in patients with mixed UMN and LMN signs
Confirm with electromyography EMG - shows acute denervation reduced action potentials with increased amplitude

Brain/cord MRI to exclude structural causes - cord compression and myelopathy
LP to exclude inflammatory causes

Question 4

What are the variants of MND?

Answer 4

Amytrophic lateral sclerosis - loss of motor neurones in motor cortex and anterior horn of the cord so combined UMN and LMN signs:
LMN in arms and UMN in legs

Progressive bulbar palsy - only affects cranial nerves 9 to 12

Progressive muscular atrophy - anterior horn cell lesion so LMN signs only. Affects distal muscle groups before proximal

Primary lateral sclerosis - loss of Beta cells in motor cortex: mainly UMN signs, marked spastic leg weakness

Question 5

Describe bulbar palsy and the signs seen. Causes?

Answer 5

Disease of the nuclei of cranial nerves 9 -12 in the medulla
LMN lesion of the tongue an muscles of talking and swallowing
Flaccid fasciculation tongue - sack of worms
Jaw jerk is normal or absent
Speech is quiet, hoarse o nasal

Causes:
MND
Guillan - Barre
Polio
Myasthenia gravis
Tumour
Central pontine myelinolysis

Question 6

What differentiates MND from MS and myasthenia?

Answer 6

MND has no sensory loss or sphincter disturbance where as MS does

MND never affects eye movements whereas myasthenia can.

Question 7

What is corticobulbar palsy?

Answer 7

UMN lesion of muscles of swallowing and talking due to bilateral lesions above the mid-pons e.g. corticobulbar tracts (MND, MS, stroke, central pontine myelinolysis)

Signs:
Slow tongue movements, slow deliberate speech
Jaw jerk hyperreflexia, palatal and pharyngeal hyperreflexia,
pseudobulbar affect - weeking unprovoked, giggling (emotional incontinence without mood change)

Question 8

Management of MND?

Answer 8

Conservative:
MDT - neurology, palliative, hospice, PT, OT, speech therapist, dietician, social service, GP.

Pharm:
Riluzole
Inhibits glutamate release and NMDA antagonist
Mainly in ALS
Prolongs life by 3m

Excess saliva:
Positioning, oral care, suction
Antimuscarinic - glycopyrroonium bromide

Dysphagia:
Blend food
Gastrostomy

Spasticity
Exercise
Orthotics

Communication difficulty:
Augmentative, alternative equipment

Respiratory care:
NIV at night