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Neurology > Motor Neuron Disease (MND) > Flashcards

Motor Neuron Disease (MND) Flashcards

1
Q

Briefly describe MND

A

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

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2
Q

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

A

True - get mixed signs

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3
Q

Is there sensory loss in MND?

A

No

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4
Q

Is there sphincter disturbance in MND?

A

No

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5
Q

Does MND affect eye movements?

A

No - distinguishes it from myasthenia

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6
Q

What are the types of MND?

A

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

In some patients there is a combination of clinical patterns

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7
Q

Describe ALS

A

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

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8
Q

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

A

In arms

UMN signs in legs

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9
Q

In ALS what are some poor prognostic signs?

A

Bulbar onset
Increased age
Reduced FVC

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10
Q

Describe primary lateral sclerosis

A

Rare
Mainly UMN signs
Marked spastic leg weakness and pseudobulbar palsy

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11
Q

Describe progressive muscular atrophy

A

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

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12
Q

Describe progressive bulbar palsy

A

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

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13
Q

What age does MND rarely present before?

A

40

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14
Q

How does MND present?

A 
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?

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15
Q

What is the life expectancy from symptom onset?

A

3-4 years

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16
Q

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

A

Frontotemporal - affects personality and behaviour

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17
Q

What types of respiratory symptoms occur?

A

SOB on exertion, orthopnia

Can lead to respiratory failure

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18
Q

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

A

Yes

19
Q

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

A

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

20
Q

Is there usually pain?

A

No

21
Q

Is the weakness and wasting usually symmetrical?

A

Yes in 75% and usually in extremities.

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

22
Q

Why does fasiculation occur?

A

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

Fasiculations = motor units discharging spontaneously

23
Q

How is MND diagnosed?

A

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)

24
Q

What investigations should be done?

A

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

25
Q

What is death usually caused by?

A

Bronchopneumonia as a result of aspiration

26
Q

What is Riluzole?

A

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

27
Q

By how many months does Riluzole increase survival by typically?

A

3 to 5 months

Most effective if disease has bulbar signs

28
Q

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

A

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

29
Q

How can spasticity be reduced?

A

Baclofen - a GABA agonist
Exercise
Orthotics

30
Q

What can be done for drooling?

A

Amitriptyline or propantheline

Glycopyrronium bromide

31
Q

How do you identify those with respiratory insufficiency?

A

Reduced FVC

32
Q

When is NIV typically used?

A

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.

33
Q

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

A

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

34
Q

What does amyotrophic mean?

A

Loss of muscle tone

35
Q

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

A

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

36
Q

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

A 
Dysphagia
Dysarthria 
Nasal regurg (palate weakness)
Choking 
Tongue may be immobile
37
Q

What is bulbar palsy?

A

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

38
Q

What is corticobulbar palsy?

A

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

39
Q

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?

A

Bulbar onset ALS

40
Q

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

A

True

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

41
Q

What does electromyography (EMG) show in MND?

A

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

42
Q

How will nerve conduction studies appear?

A

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)

43
Q

What does paraparesis mean?

A

Partially unable to move legs

44
Q

Are there cerebellar signs?

A

No

Neurology (31 decks)

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