NEURO: Part 8 Flashcards
What is Uhtoff’s phenomenon
A worsening of symptoms due to exposure to higher the n normal temperature - MS
What is Lhermitte’s sign
In MS, an electrical sensation that runs down the back when bending the neck - CHARACTERISTIC of MS
What factors increase risks of relapses in MS
COLD
Influenza
Gastroenteritis
Biomarkers for MS
- Oligoclonal bands (found in lumbar puncture - proteins present in the CNS but not the blood)
Signs of Myasthenia Gravis in the eyes
MUSCLES OF EYES AFFECTED INITIALLY:
- ptosis - levator palpeerde superioris
- diplopia - due to weakness of extra ocular muscles
- Symptoms worsen when watching television, reading or driving in bright conditions
Isolated symptoms to eye is called ocular myasthenia graves
Signs of Myasthenia Gravis when eating
- DYSPHAGIA (weakness of oesophageal muscles)
- Weakness of muscles of mastication
- Velopharyngeal insufficiency (regurgitation of food and liquids into nose than down the throat)
Signs of myasthenia graves when speaking
- Dysarthria
2. Hypophonia and nasal quality
Signs of myasthenia graves in the fcae
Weakness of facial expression muscles: Can’t keep mouth closed, dropping eye lids
THEY LOOK SAD
What is a dangerous red sign of myasthenia graves
Muscles that control breathing - dyspnea and limb movement is affected = takes years to occur
Results in myasthenic crisis
What is myasthenic crisis
When paralysis of res muscles occur
Pathophysiology of myasthenia graves
- Antibodies produced against nicotinic cholingeric receptor or muscle-specific kinase
- Deposition of complex anti-ACHr IgG and complement at post-synaptic membranes = destruction of receptors
What condition is MG in females associated with
THYMIC HYPERPLASIA
RA
SLE
pernicious anaemia
What conditions are associated in males with MG
THYMIC ATROPHY?TUMOUR
RA
SLE
What causes transient MG
D-PENICILLAMINE TREATMENT
WILSON’S DISEASE
Differential diagnosis of MG
- MS
- Hyperthyroidism
- Acute Guillain-Barre syndrome
- Lambert-Eaton myasthenic syndrome
What is Lambert-Eaton syndrome
- Causes defective ACh release at neuromuscular junction but weakness IMPROVES after exercise compared to MG
Physical examination done in MG
- Ask patient o do repetitive movements (allows us to see ptosis)
- Curtain sign : Holds a patient’s eye open which will lead to the other eye closing
FBC in MG
- autoantibody for AChR (not very sensitive in ocular myasthenia gravis)
- If negative, look for MUSK protein antibodies
Diagnostics for MG
- Electromyography
- ICE Test
- Edrophonium test
- CXR / CT/MRI
- Pulmonary function test
What do we look for in EMG for MG
- Repetitive nerve stimulation as muscle fibres are easily fatigued in MG
What do we look for in the ice test
- Apply ice for 4-5 mins to eyelids: ACh esterase is inhibited at lower temperatures
Positive if there is greater than 2mm rise in the eye lid after ice is removed
Role of CXR in myasthenia graves
- Mediastinum widening (thymoma or hyperplasia of thymus)
Role of MR in myasthenia graves
Eliminates lesions of cranial nerves and ocular muscles
Mediastinal widening
How are symptoms of MG controlled
ACh esterase inhibitor
Immunosuppression treatment for MG
- ORAL PREDNISOLONE (increase dose per week)
- Bosphosphonates to stop osteoporosis
- METHOTREXATE or ORAL AZATHIOPRINE if disease becomes more general
Surgical intervention for MG
Thymectomy
When is a thymectomy done
If onset is less than 50 years or poorly controlled with AChesterases
How to treat myasthenic crisis
- PLASMAPHERESIS (antibody removal) and IV immunoglobulin to stop trigger of relapses
Define apraxia
Disorder of consciously organised pattern of movement or impaired ability to recall acquired motor skill
How is movement fine-tuned
- First we think about the idea of movement
- Activate upper motor neurones in pre-central gyrus
- Impulses travel down LMB and motor units via corticospinal tract
- Modulating activity of cerebellum and basal ganglia
- Further modification of movement depending on sensory feedback
What type of motor neurone are LMNs
Alpha motor neurone
How is muscle tone regulated
- Stretch receptor sin the muscle are innervated by gamma motor neurones
- Muscle stretched -> afferent impulse from muscle spindles -> reflex partial contraction of muscle
What are stretch receptors in the muscle called
MUSCLE SPINDLES
Potential sites of damage along motor pathway
- Motor nuclei of cranial nerves
- Motor neurones in spinal cord
- Spinal ventral roots
- Peripheral nerves
- NMJ
- Muscle
Physical examination of UMN signs
- EVERYTHING GOES UP
Brisk reflexes - tension + jaw reflexes
Babinski sign
Limb muscle weakness
What is babinski’s sign
Planters are upturned on stimulation