Motor Neurone Disease Flashcards
What are motor neurone diseases (MND’s)?
A group of neurodegenerative disorders that selectively affect motor neurons
What are motor neurons?
The cells that control voluntary movement of muscles of the body
What are some examples of MND’s?
- Amyotrophic lateral sclerosis (ALS)
- Progressive bulbar palsy (PBP)
- Pseudobulbar palsy
- Progressive muscular atrophy
- Primary lateral sclerosis
Which type of MND accounts for most cases?
ALS
What proportion of MND’s are PBP?
Around 2/10
What muscles are first affected in PBP?
Those involved in talking, chewing and swallowing
How common is progressive muscular atrophy?
Uncommon
What are the muscles first affected in progressive muscular atrophy?
Small muscles of hands and feet
What is often absent in progressive muscular atrophy?
Muscle spasticity
How common is primary lateral sclerosis?
Rare
Where does primary lateral sclerosis mostly cause weakness?
Leg muscles
What other problems may develop in primary lateral sclerosis?
- Clumsiness of hands
- Speech problems
What parts of the motor system are affected in MND?
Anterior horn cells of the spinal cord and motor cranial nuclei
Does MND affect UMN or LMN’s?
Mixture
What is the result of the mixed effect of MND on UMN and LMN’s?
A mixed picture of muscular paralysis with LMN signs predominating
What is the current focus of aetiological hypotheses of MND?
Abnormalities of mitochondrial function causing oxidative stress in motor neurones
What is the underlying cause of MND?
Unkown
What do 5% of people with MND have in terms of causes?
A familial form of the disease thought to be due to a mutation in the superoxide dismutase-1 gene
What are the risk factors for MND?
- Over 50
- Male
- Family history
- Frontotemporal dementia
What is the typical onset of the presentation of ALS?
Focal with a particular muscle group affected first
What are the three recognised focal patterns of onset in ALS?
- Limb onset
- Bulbar onset
- Respiratory onset
What is the most common pattern of onset in ALS?
Limb onset
Where does limb onset ALS typically affect first?
The upper limbs
What upper limb signs/symptoms may present in limb onset ALS?
- Dropping objects
- Difficulty manipulating objects
- Wrist drop or stiffness
- Cramping of hands
- Wasting of intrinsic hand muscles
- Fasciculations of muscles of limbs
Where may limb onset ALS occasionally first present?
The legs
What are the leg signs/symptoms that a patient may present with in limb onset ALS?
- Foot drop
- Gait disorder
- Sensation of heaviness in one or both legs
- Tendency to trip
- Excessive fatigue when walking
What are some diagnostic pointers of limb-onset ALS?
- Asymmetrical distal weakness
- Brisk reflexes occurring in wasted limb
- Absence of major sensory symptoms/pain
- Relentless progression of symptoms and signs
Bulbar onset accounts for what percentage of ALS?
20%
What is usually the first sign of bulbar onset ALS?
Slurring of speech
What causes the slurring of speech in bulbar onset ALS?
Impaired tongue movement
What are some other symptoms of bulbar onset ALS?
- Dysphagia
- Emotional lability
- Difficulty eating
- Drooling
- Dysarthria and dysphonia
- Choking events
What is meant by emotional lability in bulbar onset ALS?
Inappropriate laughing or crying
What are the signs and symptoms of respiratory onset ALS?
- Dyspnoea
- Orthopnoea
- Clinical features resulting from overnight hypoventilation
What are some clinical features of overnight hypoventilation seen in respiratory onset ALS?
- Waking
- Unrefreshing sleep
- Hypersomnolence
- Early morning headaches
What type of motor neurone signs and symptoms are seen in ALS?
Mixed UMN and LMN
Which rarer variant of MND presents with purely UMN features?
Primary lateral sclerosis
Which rarer variant of MND presents with purely LMN features?
Progressive muscular atrophy
What are features of LMN dysfunction?
- Weakness
- Atrophy
- Fasciculations
- Hyporeflexia
What are features of UMN dysfunction?
- Weakness
- Hypertonia
- Hyper-reflexia
- Upgoing plantar responses
Are there any specific investigations to confirm MND?
No
What is the aim of investigations used in a patient with suspected MND?
To confirm consistent features and exclude other possible pathologies
What investigations may be performed in suspected MND?
- Electrophysiological studies
- CT/MRI
- Blood tests
- Muscle biopsy
What electrophysiological studies may be performed in suspected MND?
- EMG
- Nerve conduction studies
What can EMG and nerve conduction studies show in MND?
Characteristic patterns when interpreted carefully
What may an EMG specifically show in MND?
Fibrillation and fasciculations
What might nerve conduction studies specifically show in MND?
Normal motor and sensory conduction
What can a CT/MRI be useful for in patients with suspected MND?
Excluding other pathologies with similar presentations
What blood tests can be useful in excluding other conditions in suspected MND?
- Vit B12
- Folate
- HIV serology
- Lyme disease serology
- CK assay
What can a muscle biopsy be useful for excluding in suspected MND?
Myopathic conditions
Why are there many potential differentials for MND?
They depend on the mode of presentation, clinical findings and co-morbidities
What are some examples of potential differentials for MND?
- Benign cramp fasciculation syndrome
- Cervical radiculomyopathy
- Inclusion body myositis
- Diabetic amyotrophy
- Guillain-Barre syndrome
- Myasthenia gravis
- Peripheral neuropathy
- Thyrotoxicosis
- Stroke
Is MND curable?
No
Over what period does MND usually (but not always) lead to death?
A few years
What often precedes death in MND?
A period of distressing disability
What is the mainstay of treatment in MND?
Supporting patient through the disease and offering palliative care when needed
What measures can be helpful in giving supportive and palliative care in MND?
- MDT approach
- Physiotherapy
- Occupational therapy
- Speech therapy
- Communication enhancement
- Dietetic support
- Respiratory Physiotherapy
- PPV
What team members may be useful in the MDT approach to managing MND?
- GP
- Primary care nurses
- OT
- Physiotherapy
- Speech therapists
- Dieticians
- Respite care providers
- Neurologists
Why can physiotherapy, OT and SALT involvement be useful in MND?
To maintain strength and utility of affected motor functions and allow use of aids to overcome disabilities
Why is dietetic support important in patients with MND?
To ensure adequate hydration and nutrition whilst the patient can have oral intake
What may be needed if a patient with MND can no longer have oral intake?
Insertion of gastrostomy tube
How can communication be enhanced in patients who have MND?
- Picture boards
- IT-based solutions
How does respiratory physiotherapy help in MND?
To clear secretions
Who with MND should receive PPV?
Those who are unable to maintain adequate ventilation
What are the advantages of PPV in those who need it with MND?
- Machines are small and portable
- Improves QoL and survival
What is the only drug with proven disease-modifying effect in MND?
Riluzole
What is Riluzole?
A neuroprotective glutamate-release inhibitor
How much can Riluzole prolong life in MND?
2-4 months
What symptoms can be managed by medication in MND?
- Drooling
- Muscle cramps and spasticity
- Respiratory distress
- Depression
- Pain
How can drooling be medically managed in MND?
Anticholinergics e.g. hyoscine
How can muscle cramps and spasticity be managed in MND?
- Diazepam
- Baclofen
- Phenytoin
What medications can be useful in treating respiratory distress in MND?
Opiates
What medications can be used to treat depression in MND?
Anti-depressants
What medications can be used to treat pain in MND?
- Oral morphine
- SC diamorphine
- Fentanyl patches
When is opiate pain relief particularly useful in MND?
In the palliative phase
What are the potential complications of MND?
- Respiratory failure
- Pneumonia
- UTI
- Constipation
- Spasticity
- Depression
- Loss of speech
- Immobility
- Bed sores
- Death
