Disorders of NMJ Flashcards
What is a Cogans signs? When do you see it?
Also known as lid twitch sign.
In Myasthenia Gravis
In which population would you typically seen MG?
Young women and older men
What are the clinical symptoms that define MG?
- Fluctuating weakness
- Typical ocular signs (ptosis & diplopia first). Then dysarthria, dysphagia, limb and neck weakness.
- Responds to cholinergic drugs.
What are the EMG findings for MG?
- decrease in muscle response after repetitive stimulation
2. Increased jitter on single fiber
Tx for MG?
Anticholinesterase drugs o Prednisone o Immunosuppressive agents o Plasma exchange/IVIg (in crisis/presurgery) o Thymectomy (notforpurelyocular)
In double seronegative MG, what antibodies are commonly seen?
Anti-LRP4 abs
How does double seronegative MG px?
Milder sx, frequent ocular involvement
List the 3 features of MUSK syndrome?
Oculopharyngeal weakness
o Neck, shoulder, respiratory weakness
o Indistinguishable from abs positive
What is the initiating factor of an MG crisis?
How does it px?
Post infection or certain drugs.
TAchy, cold/faint skin, aspiration, diffuse weakness, resp failure.
What is the initiating feature for Cholinergic crisis.
How does it px?
Excess anticholinesterase meds
Miosis, fasciculations, brady, warm, flushed skin.
What features do MG crisis and Cholinergic crisis share in common?
Muscle weakness, sweating, agitation, disorientation, urinary and fecal urgency.
Pathology of LEMS (Lambert Eaton Myasthenic syndrome?
Autoimmune attack against presynaptic VGCCS -> not enough Ach released
How does LEMS present clinically?
Proximal weakness, loss of DTR,myalgias, dry mouth.
What sx is present in LEMS that is not as severe as in MG?
Oropharyngeal & ocular weakness
What are the EMG results for LEMS?
Low motor response that increases after exercise
Incremental response on fast repetitive stimulation
