Myasthenia Gravis: Questions With Solutions (Pass!)
is muscle weakness constant or fluctuating in MG? Right Ans - fluctuating
pathophys of MG? Right Ans - - autoimmune dz characterized by weakness
& fatigability of skeletal muscles d/t dysfunction of NMJ
- T-cell based attack against ACh receptors resulting in impaired signal
transmission
which immunoglobulin is active during MG? Right Ans - IgG
what is ocular MG? Right Ans - dz is limited to eyelids/ EOMs -- what
usually brings some people into office
what underlying condition do 10-15% of pt's have? 60-70%? Right Ans - -
thymoma
- more common: thymus hyperplasia
what procedure can significantly improve MG, and in some cases resolve?
Right Ans - thymectomy
can specific drugs cause MG? Right Ans - no, but they can induce or
exacerbate sxs
where do you see weakness in general MG? Right Ans - - ocular muscles
- limbs
- respiratory
- bulbar muscles
does everyone have AChR antibodies? what do others have? Right Ans - -
no
- a lot have Muscle-specific receptor tyrosine kinase (MuSK)
most common presenting symptom? Right Ans - ptosis, diplopia
examples of specific muscles that fatigue during daily activity? Right Ans - -
jaw muscles w/ eating
, - oropharyngeal m fatigue causing dysphagia and dysarthria
no AChR MG and MuSK MG have the same cause? Right Ans - - no, it
appears to be different (not sure what though...)
how is MuSK MG different from AChR MG? Right Ans - •Much LOWER
incidence of thymus disease
•Females > males
•OCULOBULBAR form with diplopia, ptosis and dysarthria - this combo not
seen by itself as much in AchR + AG
how does tx change with MuSK MG vs AChR MG? Right Ans - MuSK:
- doesn't respond to thymectomy or ACh inhibitors
- need to use rituximab
does everyone have AChR or MuSK MG? Right Ans - - no, some can be
seronegative -- presents/responds same as AChR MG
are distal or proximal typically affected? Right Ans - proximal
respiratory muscle involvement can lead to what? Right Ans - myasthenic
crisis
Which of the following is accurate about the etiology and epidemiology of MG?
•MG is idiopathic in most patients
•In younger patients, MG is more common among males
•Antifungal medications are common causes of MG, whereas MG caused by
antibiotics is rare
•MG is primarily a disease of the elderly, with a mean age of onset of 62 years
in both males and females Right Ans - •MG is idiopathic in most patients
what age can MG occur at? Right Ans - any age, even kids -- though may be
transient
female age of onset? male? Right Ans - Female: 20s/30s and 70-85
Male: 70-80
is muscle weakness constant or fluctuating in MG? Right Ans - fluctuating
pathophys of MG? Right Ans - - autoimmune dz characterized by weakness
& fatigability of skeletal muscles d/t dysfunction of NMJ
- T-cell based attack against ACh receptors resulting in impaired signal
transmission
which immunoglobulin is active during MG? Right Ans - IgG
what is ocular MG? Right Ans - dz is limited to eyelids/ EOMs -- what
usually brings some people into office
what underlying condition do 10-15% of pt's have? 60-70%? Right Ans - -
thymoma
- more common: thymus hyperplasia
what procedure can significantly improve MG, and in some cases resolve?
Right Ans - thymectomy
can specific drugs cause MG? Right Ans - no, but they can induce or
exacerbate sxs
where do you see weakness in general MG? Right Ans - - ocular muscles
- limbs
- respiratory
- bulbar muscles
does everyone have AChR antibodies? what do others have? Right Ans - -
no
- a lot have Muscle-specific receptor tyrosine kinase (MuSK)
most common presenting symptom? Right Ans - ptosis, diplopia
examples of specific muscles that fatigue during daily activity? Right Ans - -
jaw muscles w/ eating
, - oropharyngeal m fatigue causing dysphagia and dysarthria
no AChR MG and MuSK MG have the same cause? Right Ans - - no, it
appears to be different (not sure what though...)
how is MuSK MG different from AChR MG? Right Ans - •Much LOWER
incidence of thymus disease
•Females > males
•OCULOBULBAR form with diplopia, ptosis and dysarthria - this combo not
seen by itself as much in AchR + AG
how does tx change with MuSK MG vs AChR MG? Right Ans - MuSK:
- doesn't respond to thymectomy or ACh inhibitors
- need to use rituximab
does everyone have AChR or MuSK MG? Right Ans - - no, some can be
seronegative -- presents/responds same as AChR MG
are distal or proximal typically affected? Right Ans - proximal
respiratory muscle involvement can lead to what? Right Ans - myasthenic
crisis
Which of the following is accurate about the etiology and epidemiology of MG?
•MG is idiopathic in most patients
•In younger patients, MG is more common among males
•Antifungal medications are common causes of MG, whereas MG caused by
antibiotics is rare
•MG is primarily a disease of the elderly, with a mean age of onset of 62 years
in both males and females Right Ans - •MG is idiopathic in most patients
what age can MG occur at? Right Ans - any age, even kids -- though may be
transient
female age of onset? male? Right Ans - Female: 20s/30s and 70-85
Male: 70-80
