Motor Neurone and Neuromuscular Disorders Flashcards
What is motor neurone disease?
It is a degenerative neurological disorder characterised by progressive weakness of the bulbar (muscles involved in speech and swallowing), limb, thoracic and abdominal muscles.
In MND there is damage to the anterior horn cells in the spinal cord and the mortor cranial nerves.
Describe the different types of MND?
Most common:
-ALS (amyotrophic lateral sclerosis)
Other rarer types are:
- Progressive bulbar palsy
- Progressive muscular atrophy
- Primary lateral sclerosis
Describe the most common presentations of ALS?
Tends to be a pattern of focal weakness affecting a particular set of muscles 1st:
- Limbs (by far most common)
- Bulbar
- Respiratory (rare)
Describe the classical signs and symptoms of a patient presenting with ALS?
Limb weakness (usually upper limb initially)
May notice fasciculations (initially in the muscles but may also occur in the tongue)
Usually a later sign but may have slurred speech.
What are the 2 most common manifestations of MND which can lead to death?
Respiratory failure and death.
Pneumonia due to infection or aspiration. (can’t cough and may have a poor swallow)
What is myasthenia gravis?
It is autoimmune condition affecting the neuromuscular junction causing weakness with characteristic fatiguability.
Outline the classical presentation of myasthenia gravis?
Commonly presents with muscle weakness worsening throughout the day.
May present as a ptosis (occular muscle weakness)
Tends to affect proximal muscles more.
In a minority of patients may present as isolated limb weakness.
What is the progression of myasthenia gravis?
In 15% disease only affects the eyes.
Majority of patients will develop general disease within a year.
Spontaneous remission is rare. Remission induced by medication will usually occur within the 1st 3 years.
Periods of illness, medication and pregnancy can all precipitate a myasthenia crisis.
How can you investigate for myasthenia gravis?
Ice test:
Placing a pack of ice over the eye in which there is a ptosis for 3 mins will alleviate the ptosis if it is caused by myasthenia.
Autoantibody testing
Neurophysiological testing will be normal
CT scan looking for a thymoma
Which condition is closely linked with myasthenia gravis?
Thymoma (20% people with myasthenia gravis will get this)
All so related to other autoimmune conditions
Which antibodies are associated with myasthenia gravis?
AChr antibodies (acetylcholinesterase receptor antibodies) and MuSK (muscle-specific tyrosine kinase)
What is a myasthenia crisis?
An exacerbation of the condition potentially precipitated by medication, illness or pregnancy.
It is characterised by weakness of the muscles of ventilation or pharyngeal muscles which can lead to respirator compromise.
It is a neurological emergency.
How should you manage a myasthenia crisis?
Monitor vital capacity.
Intubation.
What treatment options are available in myasthenia gravis?
Acetylcholinesterase inhibitors provide temporary symptomatic treatment of muscle weakness.
Anti-immune drugs:
- Steroids
- Azathioprine
- Ciclosporin
Thymectomy is of benefit if there is a thymoma present
