NMJ Flashcards
1
Q
Disorders of NMJ
A
- presynaptic
- synaptic
- postsynaptic
2
Q
Presynaptic disorders
A
- Lambert-Eaton myasthenic syndrome
- Botulism
- Magnesium
3
Q
Synaptic disorders
A
-N agents
4
Q
Postsynaptic disorders
A
- MG
- curare
5
Q
Myasthenia Gravis- etiology
A
- ab’s to nACHR
- sporadic (but high freq of B8 and DR3)
- seen w other autoimmune diseases (thyroid)
- younger women, older men
6
Q
MG- clinical sx’s- 3 general characteristics
A
- Fluctuating weakness- excessive fatigability
- Ocular m’s affected first- ptosis and diplopia
- clinical response to cholinergic drugs
7
Q
MG- diagnosis
A
- anti-ACHR Ab’s (55% of ocular MG and 80% of generalized MG)
- MUSK ab’s (M specific tyrosine kinase)
- EMG- decremental response on repetitive stim (U-shaped)
- Tensilon (edrophonium test)- SE’s of bradycardia, ventricular arrhythmias
8
Q
MG- tx
A
- ACHase inhibitors (Mestinon)
- prednisone
- plasma exchange/ IVIG
- thymectomy
9
Q
MG- drugs that can exacerbate or unmask
A
- neuromuscular blockers
- excessive ACHase medication
- BOTOX
- Aminoglycosides!!!!!
10
Q
Lambert-Eaton Myasthenic Syndrome
A
- ab’s against voltage-gated Ca channels on presynaptic n terminal
- presynaptic abnormality of ACH release- weakness
- assoc with SCCL!!
11
Q
Lambert-Eaton Myasthenic Syndrome- clinical presentation
A
- proximal weakness, loss of DTRs (vs MG), myalgias, dry mouth, impotence
- oropharyngeal and ocular m’s (but not as affected as in MG)
- strength improves after exercise
12
Q
Lambert-Eaton Myasthenic Syndrome- lab data
A
- voltage-gated Ca channel ab’s
- low amplitude motor responses that facilitate (increase) after a brief period of exercise
- incremental response on fast repetitive stimulation
13
Q
Lambert-Eaton Myasthenic Syndrome- tx
A
- first look for and treat malignancy!!
- ACHase inhibitors
- immunosuppression
- IVIG
14
Q
Botulism
A
- toxin blocks presynaptic mech’s for release of ACH
- dry, sore mouth and throat, blurred vision, diplopia, N/V (sx’s begin from top down)
- tx- ICU monitoring
15
Q
Nerve gases- clinical features
A
(Sarin and VX- organophosphate compounds)
- inhibit ACHase at NMJ to cause cholinergic crisis
- sx’s- miosis, inc secretions, bronchospasm, abd cramps, diarrhea, seizures
- death- resp failure
