Motor neurone disease

Question 1

What are the features of MND?

Answer 1

Fasciculations 
Mixture of UMN and LMN signs
Wasting of small hand muscles/tibialis anterior is common
Progressive muscle weakness throughout body affecting limbs, trunk, face and speech
Increased fatigue when exercising
May c/o being more clumsy
May c/o slurred speech (dysarthria)
No sensory signs/symptoms
No affect on extraocular muscles
No cerebellar signs
No loss of abdominal reflexes 
Sphincter dysfunction, if present, is late feature

Question 2

What are the different types of MND?

Answer 2

Amyotrophic lateral sclerosis (ALS; most common):
Typically LMN signs in arms and UMN signs in legs

Primary lateral sclerosis:
UMN signs only

Progressive muscular atrophy:
LMN signs only
Affects distal muscles before proximal
Carries best prognosis

Progressive bulbar palsy:
Palsy of tongue, muscles of chewing/swallowing and facial muscles due to loss of function of brainstem motor nuclei
LMN signs only
Carries worst prognosis

Question 3

What investigations are carried out to diagnose MND?

Answer 3

Based on clinical presentation and excluding other conditions

Nerve conduction studies - show normal motor conduction (excludes neuropathy)

EMG - shows reduced number of action potentials with increased amplitude

MRI - usually performed to exclude differential diagnosis of cervical cord compression and myelopathy

Question 4

What is the management fro MND?

Answer 4

Riluzole:
Prevents stimulation of glutamate receptors
Mainly used in ALS
Prolongs life by 3 months

Respiratory care:
Non-invasive ventilation, usually BiPAP, used at night
Prolongs life by 7 months

Supporting patient and family:
MDT
Advanced directives
EoL care