Diagnosing Weakness Flashcards
What are the 2 functions of the upper motor neurone?
What happens if the UMN dies?
- start the message
- stop the message
if the UMN dies, the muscle does not know how to stop, as the message continues
this results in increased tone - spasticity
What are the different levels of weakness?
- neurologically unexplained
- upper motor neurone
- lower motor neurone
- neuromuscular junction
- muscle fibre
What part of the brain / spinal cord is damaged if there is weakness on one half of the body / all four limbs / both legs / one limb?
- one half of the body - cerebral hemisphere
- all four limbs - high cervical spinal cord
- both legs - low cervical spinal cord
- one limb - spinal root or peripheral nerve
What pattern of weakness is present in generalised distal weakness and generalised proximal weakness?
- generalised distal weakness - peripheral neuropathy
- generalised proximal weakness - myopathy myasthenia
What is meant by monoplegia, hemiplegia, diplegia and quadriplegia?
monoplegia:
- affects one limb only - usually an arm
hemiplegia:
- affects one side of the body including arm, leg and trunk
diplegia:
- affects symmetrical parts of the body (arms or legs)
quadriplegia:
- affects all four limbs
What are the 4 stages involved in investigating weakness?
1 - history:
- explore the symptoms
- what? where? how long?
2 - examination:
- clinical findings
- muscle volume, strenght, tone, reflexes, involuntary movements
3 - tests:
- genetics, pathology (biopsy and imaging)
- looking for gene defects or abnormal muscle structure
4 - function:
- EMG and NCS
What are the causes and clinical findings of an upper motor neurone problem?
causes:
- stroke
- infection
- tumour
- degeneration
clinical findings:
- brisk reflexes
- pathological reflexes
- mild atrophy
- stiffness
WHat are the causes and clinical findings of a lower motor neurone disorder?
causes:
- infection
- toxin
- radiation
- degeneration
- trauma
clinical findings / localisation:
- anterior horn
- radiculopathy
- two or more nerves
- generalised peripheral neuropathy
- single nerve injury
What are the signs of a LMN axonal lesion?
- weakness +/- numbness
- reduced relflexes
- muscle wasting
- fasciculation
What are the 2 main conditions affecting the neuromuscular junction?
- myasthenia
- myasthenic syndrome
What are the symptoms and signs of a problem at the neuromuscular junction?
- proximal weakness
- fatigability
- worse as the day goes by
- normal sensation
- normal reflexes
- repetitive nerve stimulation (RNS)
What are the 2 main disorders resulting from problems with muscle fibres?
- myopathy
- myositis
What are the symptoms and signs of muscle disease?
- progressive weakness - usually proximal
- normal sensation
- normal reflexes
- normal tone
- moderate wasting
- can be congenital, inherited, metabolic, toxic or mitochondrial
What is motor neurone disease?
What causes it?
a disease of motor neurones which is progressive
- can be idiopathic (unknown cause)
- 5-10% cases have a genetic cause (familial basis)
- can be caused by toxins, viruses, trauma or combinations
- tends to be sporadic (here and there)
Where do UMN and LMNs originate?
UMN originate in frontal motor gyrus - brainstem and spinal cord
LMNs have their cell bodies in the spinal cord
What happens in ALS?
Cells in the CNS and PNS start dying and there is cellular apoptosis
the lysosomes then digest the cells
What are the symptoms and signs of motor neurone disease?
- painless
- no loss of feeling
- progressive bulbar palsy - weakness in the tongue, the face and the palate
- dyphasia
- dysarthria
- nasal regurgitation and aspiration
What is life expectancy with MND?
Which functions are preserved in this condition?
life expectancy is 3-5 years - it is progressive with no remission
- normal cognition
- eye muscles are preserved
- sphincter function is preserved
- sexual activity is preserved
What are the different clinical forms of MND?
- progressive muscular atrophy (PMA)
- primary lateral sclerosis (PLS)
- progressive bulbar palsy (PBP)
- MND - FTD
How are EMG and NCS performed?
UMN - LMN - muscle
What is invovled in generating a nerve impulse and it travelling to form a spinal nerve?
- impulse generated in the cortex and passed to the anterior horn cell via CST or CBT
- LMN exits the spinal cord forming ventral rootlets
- the body of the sensory neurone lies in the dorsal ganglion
- dorsal ganglion has a peripheral arm and the axon, which travels all the way to the brainstem
- the dorsal and ventral roots come together to form spinal nerves
What features of the motor system can be measured?
- amplitude
- duration
- latency
- conduction velocity
- F-wave
