Motor Neurone Disease

Question 1

What is motor neurone disease?

Answer 1

-Disease of motor neurones
=LMN in spinal cord
=LMN in brain stem
=UMN in cerebral cortex

-Neurodegenerative pathology

Question 2

Describe the neurodegenerative pathology of MND

Answer 2

-Degeneration of neurons
-Associated with inclusion bodies
-Containing misfolded proteins

Question 3

Describe prognosis of MND

Answer 3

-Cause unknown (5-15% genetic)

-Progressive, fatal, currently incurable
=Progressive weakness: immobility, loss of speech, dysphagia, dyspnoea

-ALS: 2-5 years (amyotrophic lateral sclerosis), PBP (progressive bulbar palsy): 6 months-3 years
-50% die within 3 years

Question 4

Prevalence of MND

Answer 4

-Uncommon below 40
-Mean age of onset 50-60 (increasing incidence with age)
-x6 more common in 70s than 50s
-2/100,000

Question 5

First presentations of MND

Answer 5

functional effects of muscle weakness, such as loss of dexterity, falls or trips

speech or swallowing problems, or tongue fasciculations (this is known as bulbar presentation)

muscle problems, such as weakness, wasting, twitching, cramps and stiffness

breathing problems, such as shortness of breath on exertion or respiratory symptoms that are hard to explain

effects of reduced respiratory function, such as excessive daytime sleepiness, fatigue, early morning headache or shortness of breath when lying down

behavioural changes

emotional lability (not related to dementia)

frontotemporal dementia

Question 6

Clinical manifestations of MND

Answer 6

-Weakness
-Generally of voluntary musculature: limbs, speech, swallowing, breathing
-Tends to spare eye movements, bladder, bowels

AML: LMN arms, UMN legs
Primary lateral sclerosis: UMN only
Progressive muscular atrophy: LMN only, distal >proximal
Progressive bulbar palsy: palsy of tongue, muscles of chewing/swallowing, facial muscles, worst prognosis

-Asymmetrical limb weakness, often first noticed in upper limbs, fatigue when exercising, clumsiness, dropping things, tripping, slurred speech
-Dysarthria
-(Tongue) fasciculations
-Weakness of foot and ankle and dorsiflexion
-Reduced grip strength
-Difficulty swallowing and choking on food
-Present after 40
-Wasting of the small hand muscles/ tibialis anterior
-Absence of sensory signs
-Does not affect external ocular muscles
-No cerebellar signs
-Spastic
-Unsteady gait
-Painful muscle spasms
-Foot and head drop
-Fronto-temperoal dementia
-Abdominal reflexes preserved and sphincter dysfunction late feature

Question 7

Features of LMN disease

Answer 7

-Wasting
-Fasciculation
-Reduced tone and reflexes

Question 8

Features of UMN disease

Answer 8

-Spasticity, increased tone
-Brisk TR
-Extensor Plantar Response

Question 9

Various clinical terms for MND

Answer 9

-ALS (amyotrophic lateral sclerosis)
-Progressive muscular atrophy (LMN only, distal>proximal)
-Progressive bulbar palsy

Question 10

Diagnosis of MND

Answer 10

-Clinical: progressive LMN/UMN signs, no other signs in general (no sensory deficit)
-Supporting evidence: EMG, NCS (nerve conduction studies).

-Normal motor conduction
-Electromyography= reduced number of action potentials with increased amplitude (ongoing, chronic denervation)
-MRI to exclude cervical cord compression and myelopathy

Question 11

MND management

Answer 11

-Aids for mobility/ limb use
-Swallowing management
-Communication management
-Breathing support
-Emotional support
-Riluzole (prevents stimulation of glutamate receptors, amyotrophic lateral sclerosis, 3 month prognosis increase)
-BIPAP at night, 7 months benefit
-PEG tube
-Quinine muscle cramps/ baclofen
-Antimuscarinic for excessive salvia
-Benzo for breathlessness worsened by anxiety

50% die within 3 years