Motor Neuron Disease (MND)

Question 1

Briefly describe MND

Answer 1

A cluster of neurodegenerative diseases characterised by loss of neurons in motor cortex, cranial nerve nuclei and anterior horn cells.

Question 2

Upper and lower motor neurons can be affected. True or false?

Answer 2

True - get mixed signs

Question 3

Is there sensory loss in MND?

Answer 3

No

Question 4

Is there sphincter disturbance in MND?

Answer 4

No

Question 5

Does MND affect eye movements?

Answer 5

No - distinguishes it from myasthenia

Question 6

What are the types of MND?

Answer 6

Amyotrophic lateral sclerosis (ALS)
Progressive bulbar palsy
Progressive muscular atrophy
Primary lateral sclerosis

In some patients there is a combination of clinical patterns

Question 7

Describe ALS

Answer 7

Archetypal MND
50% of patients
Loss of motor neurons in cortex and anterior horn of the cord, so combined UMN and LMN signs

Question 8

In amyotrophic lateral sclerosis, typically LMN signs are seen where?

Answer 8

In arms

UMN signs in legs

Question 9

In ALS what are some poor prognostic signs?

Answer 9

Bulbar onset
Increased age
Reduced FVC

Question 10

Describe primary lateral sclerosis

Answer 10

Rare
Mainly UMN signs
Marked spastic leg weakness and pseudobulbar palsy

Question 11

Describe progressive muscular atrophy

Answer 11

LMN signs only
Affects distal muscles before proximal
Carries best prognosis than ALS

Question 12

Describe progressive bulbar palsy

Answer 12

Only affects CNs IX- XII
Palsy of tongue, muscles of chewing/ swallowing and talking due to loss of function of brainstem motor nuclei

Carries worst prognosis

Question 13

What age does MND rarely present before?

Answer 13

40

Question 14

How does MND present?

Answer 14

Weakness 
Stumbling, spastic gait
Foot drop
Proximal myopathy
Difficulty rising from chair 
Weak grip
Shoulder abduction 
Aspiration pneumonia

Look for UMN signs - spasticity, brisk reflexes, up going plantars AND LMN signs - wasting, fasiculation of tongue, abdomen, thigh, back

Is speech or swallow affected?

Question 15

What is the life expectancy from symptom onset?

Answer 15

3-4 years

Question 16

MND is associated with what type of dementia in 15% of cases?

Answer 16

Frontotemporal - affects personality and behaviour

Question 17

What types of respiratory symptoms occur?

Answer 17

SOB on exertion, orthopnia

Can lead to respiratory failure

Question 18

In ALS can UMN and LMN signs be present in the same muscle

Answer 18

Yes

Question 19

The cause of MND is unknown. What are some theories?

Answer 19

Premature aging of motor cells
Too much glutamate - excitotoxicity
Genetic component
Exposure to heavy metals and agricultural chemicals
Chronic calcium deficiency, an association with hyperparathyroidism

Question 20

Is there usually pain?

Answer 20

No

Question 21

Is the weakness and wasting usually symmetrical?

Answer 21

Yes in 75% and usually in extremities.

Wasting usually begins in hands and spreads. May be unilateral, but develops to bilateral.

Question 22

Why does fasiculation occur?

Answer 22

Occurs as surviving axons branch out to new motor units and attempts to innervate them.

Fasiculations = motor units discharging spontaneously

Question 23

How is MND diagnosed?

Answer 23

Clinical signs and symptoms
May be confirmed with electromyography- shows denervation and fibrillation (reduced number of action potentials with increased amplitude)

Nerve conduction studies - will be normal (useful to exclude multi focal neuropathy)

Question 24

What investigations should be done?

Answer 24

Electromyography
Nerve conduction studies - shows normal motor conduction
MRI - exclude structural causes (will be normal)
LP to exclude inflammatory causes
TFTs to exclude hyperthyroidism
Calcium
Bloods - elevated CK due to muscle breakdown

Question 25

What is death usually caused by?

Answer 25

Bronchopneumonia as a result of aspiration

Question 26

What is Riluzole?

Answer 26

Sodium channel blocker - An inhibitor of glutamate release and NMDA receptor antagonist - the only medication to show improved survival Usually recommended as soon as possible

Question 27

By how many months does Riluzole increase survival by typically?

Answer 27

3 to 5 months Most effective if disease has bulbar signs

Question 28

What type of approach should be taken in terms of treatment management?

Answer 28

MDT approach - neurologist, palliative care team, physio, OT, SALT, dietician, social services, GP

Question 29

How can spasticity be reduced?

Answer 29

Baclofen - a GABA agonist Exercise Orthotics

Question 30

What can be done for drooling?

Answer 30

Amitriptyline or propantheline | Glycopyrronium bromide

Question 31

How do you identify those with respiratory insufficiency?

Answer 31

Reduced FVC

Question 32

When is NIV typically used?

Answer 32

When the patient is sleeping. During the day respiratory effort by diaphragm is supplemented by accessory muscle use to maintain levels of oxygenation. When entering REM sleep -> sleep paralysis, so diaphragm struggles on own.

Question 33

There are a number of clues which point towards a diagnosis of MND what are they?

Answer 33

Fasiculations The absence of sensory signs/symptoms Mixture of LMN and UMN signs Wasting of the small hand muscles/ tibialis anterior is common Doesn’t affect external ocular muscles No cerebellar signs Abdominal reflexes usually preserved and sphincter dysfunction if present is late feature

Question 34

What does amyotrophic mean?

Answer 34

Loss of muscle tone

Question 35

In Amyotrophic Lateral Sclerosis, the amyotropic part means loss of muscle tone, what does the lateral sclerosis refer to?

Answer 35

Damage to the lateral corticospinal tracts - basically means there is spastic paraparesis. It is rare to see loss of muscle tone and spastic parapsresis together - except in MND

Question 36

In MND there are bulbar and pseudo bulbar features in 25% of people. What symptoms does this included?

Answer 36

``` Dysphagia Dysarthria Nasal regurg (palate weakness) Choking Tongue may be immobile ```

Question 37

What is bulbar palsy?

Answer 37

Diseases of the nuclei of CN IX to XII in the medulla Signs: a LMN lesion of the tongue and muscles of talking and swallowing - facial expression normal - dysphagia, drooling, nasal regurgitation - flaccid, fasiculating tongue - speech quiet, hoarse or nasal - gag reflex absent - emotions not affected - jaw jerk is normal or absent Causes not just MND, also Guillian Barre, Myasthenia Gravis, brainstem tumours, central pontine myelinolysis, syringobulbia

Question 38

What is corticobulbar palsy?

Answer 38

UMN lesion of muscles of swallowing and talking due bilateral lesions above the mid pons e.g corticobulbar tracts - affects CN V, VII, IX, X, XI, XII Commoner than bulbar palsy Expressionless face Difficulty chewing Dysphagia, drooling, nasal regurgitation Slow, deliberate speech Tongue - spastic pointed, no wasting or fasiculation, slow movement Exaggerated gag reflex and jaw jerk Pseudobulbar affect - weeping unprovoked by sorrow or mood incongruent giggling Causes: ALS, PSP, MS, Stroke, injury or malignancy of high brainstem

Question 39

The first sign of ALS may appear in hand or arm - difficultly with simple tasks e.g buttoning shirt or Turing key in lock. In other cases symptoms initially affect one leg - tripping more. When symptoms begin in arms or legs= limb onset ALS Others first notice speech or swallowing problems. What is this termed?

Answer 39

Bulbar onset ALS

Question 40

Patients with MND often have no cognitive impairment in early stages. True or false

Answer 40

True Important to plan for the future early - discuss wishes for end of life care

Question 41

What does electromyography (EMG) show in MND?

Answer 41

Denervation and fibrillation - denervation may not be present in PLS EMG : a needle electrode inserted into a muscle to record the electrical activity produced by the muscle - will show reduced number of action potentials with increased amplitude

Question 42

How will nerve conduction studies appear?

Answer 42

Normal Useful to exclude Multifocal neuropathy NCS measures how fast an electrical impulse moves through nerve. (EMG detects whether the muscle is working properly in response to the nerve stimulus)

Question 43

What does paraparesis mean?

Answer 43

Partially unable to move legs

Question 44

Are there cerebellar signs?

Answer 44

No