Myasthenia Flashcards
Where is affected here
Neuromuscular junction
Which ones are acquired?
Myasthenia gravis
Transient neonatal myasthenia gravis (born to mothers with MG)
Infantile botulism
Which one is congenital?
Congenital myasthenic syndromes
Give some general info on autoimmune myasthenia
Acetylcholine receptor antibody - ocular and generalised
Fatigue
Isolated ptosis and ocular weakness
Crisis: Respiratory and bulbar - dysarthria/nasal speech
Investigations in autoimmune myasthenia
AChR abs
Anti MUSK abs
Receptive nerve stimulation
Treatment for autoimmune myasthenia
Pyridostigmine
Prednisolone
Immuno suppression
Plasma exchange
Ventilation
Thymectomy
What is infantile botulism
Infant botulism is caused by anaerobic bacteria
Ventilation is needed
Give me information on presynaptic CMS
5% are presynaptic - CHAT (choline acetlytransferase)
Give me information on synaptic CMS
10% are synaptic (basal lamina-associated)
COLQ (collagen tail of ACHE)
Give me information on postsynaptic CMS
85% are postsynaptic
e subunit of ACHR - Rapsyn - Dok-7
Slow channel
Most common
Autsomal dominant
Postsynaptic
Quinidine and Fluoxedine - normalise AChR opening time
Fast channel
Very rare
No distinguishing factors
Treatment: Cholinesterase inhibitors and 3,4-diaminopyridine
Low AChR expression
Half of all identified CMS patients
> 60 different mutations - most mutations in e subunit
Treatment: Cholinesterase inhibitors and 3,4-diaminopyridine
MuSK-Dok7-Rapsyn pathway
Specific receptor thyrsine kinase
Activer by agrin released by motor neurons through LPR4
Agrin - triggers AChR collection via rapsyn
MuSK is coactivated by Dok-7
Rapsyn deficiency
Neonatal/antenatal - Arthogryphosis multiplex (joint stiffness), respiratory disorder and severe progression
Mild forms in childhood and adulthood
Initially severe in infancy and may recover in adolescence
Dok-7 myasthenia
Irish
LGMD phenotype
When do Congenital Myasthenic Syndromes start
Childhood
Are Congenital Myasthenic Syndromes more or less common than autoimmune MG
Less - 1 in 50,000 in Europe
Currently, how many genes are responsible for CMS
20
How does CMS progress in adulthood
It gets worse; Scoliosis
Is CMS Autosomal recessive or dominant
Family history - most are Autosomal Recessive
What triggers CMS
Infections
Pregnancy
Menstrual periods
What is associated with mortality in CMS
Acute respiratory failure
Treatment for CMS?
Favourable effect of cholinesterase inhibitors, but several types worsen with
Are the same symptoms like fatigability and ptosis present in CMS
Yes, although ptosis is hard to recognise in a child
Are reflexes preserved
Yes
What does AChR antibody affect
Ocular and generalised
What does Anti MUSK antibody affect
Bulbar and Respiratory
What is the clinical presentation of CMS
Hypotonia
Ophthalmoplegia
Ptosis
Dysphonia
Dysphagia
Facial paresis
Muscle fatigability
