PP Flashcards
Pathophysiology - GBS
Demyelinating neuropathy of peripheral nerves - T cell mediated attack
Can also be axonal
Proximal weakness, distal sensory loss
Recent infection
Pathophysiology - CMT disease
Progressive loss of motor and sensory
Demyelinating of PNS
Pathophysiology - MS
Demyelination of central nerves due to genetic mutation in Schwann cells
Pathophysiology - LEMS
Weakness, Walking through treacle
Autoantibodies versus calcium channels at NMJ
60% associated with small cell lung Ca (molecular mimickry)
Inhibitory neurotransmitters
e.g. GABA act through ligand gated Cl- channels which hyperpolarise the postsynaptic neuron
Lesion above level of spine (reflex)
Hyperreflexia
Lesion at level of spine (reflex)
Hyporeflexia
Pathophysiology - Myasthenia Gravis
Fatiguable
Antibodies versus NICOTINIC ACh receptor
Several mechanisms of damage:
- complement mediated
- macrophage mediated
- blockade
- internalisation
Young women onset associated with thymic hyperplasia
Old men onset associated with thymic atrophy
Thymoma, any age group
THYMECTOMY NO HELP
Pathophysiology - Neuromyotonia
Stiff, spontaneous activity of muscles
Antibodies versus voltage-gated K channel presynaptic
Pathophysiology - Frey syndrome
Parasympathetic fibre branch of TG nerve supplying parotid gland get diverted so you sweat instead of salivate.
Surgery or trauma.
Pathophysiology & symptoms - Common peroneal nerve palsy
Lateral popliteal nerve compressed against head of fibula causing foot drop and numbness on lateral dorsum of foot and lower leg. Toes dragging, weak ankle eversion.
Occurs early in CMT
Pathophysiology & symptoms - Meralgia parasthetica
Lateral cutaneous nerve of the thigh compressed as it passes under inguinal ligament (hand in pocket or crossing legs, skinny jeans)
Causes tingling and numbness to lateral aspect of thigh.
Pathophysiology & symptoms - Saturday night palsy
Radial nerve compression by fracture of upper arm, or by leaning on it and compressing it as it winds around the humerus (drunk)
Wrist and finger drop amd numbness in snuff box
Rapidly progressing symmetrical shoulder/hip weakness. Glove & stocking sensory loss.
GBS
Recent infection / viral illness and now rapid onset muscle weakness
GBS
Dysphagia, difficulty speaking, diplopia, proximal>distal weakness of limbs
2 disorders - how would you diagnose one over the other?
Myasthenia gravis or lambert eaton myasthenic syndrome (LEMS)
Differentiate by seeing whether exercise exacerbates or relieves fatigue…
In MG, exercise exacerbates fatigue.
In LEMS, exercise temporarily improves muscle strength.
(Also remember, MG is more common in females.. Mya = female name… LEMS is more common in males.. Lambert sounds like a male name!)
If a patient has LEMS, what are you concerned about and what treatment would you consider?
In addition to the usual treatments (immunosuppressants, IVIg, plasmapheresis) you would be considering whether they have a SMALL CELL CANCER of the lung or a thymoma, in which case you would treat the cancer to improve the LEMS.
Difficulty releasing grip, muscle cramps, myokymia, muscle twitching / fasciculations
Neuromyotonia aka Isaac’s syndrome
Note associated with small cell cancer and thymoma
Autonomic dysfunction + CN symptoms (e.g. bulbar, eyes) + muscle weakness or flaccid paralysis
Recent ingestion of raw meat
What is PP, potential diagnosis, investigation and treatment?
Botulism
Ingestion of botulinum toxin which affects presynaptic SNARE proteins which affect ACh release
Stool cultures (or serum) will show toxin
Treat with antitoxin
