Myasthenia Gravis (Exam 4) Flashcards
Myasthenia Gravis
-Acquired - autoimmune - progressive disease characterized by muscle weakness
-Remissions and Exacerbations
-Results from a reduction of acetylcholine receptors
Myasthenia Gravis Exacerbations are associated with
Emotional stress
Pregnancy
Illness
Heat
Myasthenia Gravis typically peaks within
2 years of onset
Severity of Myasthenia Gravis
Depends:
Mild motor neuron disturbances to respiratory failure
Types of MG
Ocular (face) and Generalized
1/2 patines present with reports about vision problems
What is the most common type of myasthenia gravis?
Ocular (around face) type
MG typically originates in
Face
Neck
Jaw
Arm + Leg are affected later in disease process
Myasthenia Gravis: Presenting Symptoms
50% Ocular Symptoms
15% Bulbar symptoms
<5% present proximal limb weakness alone
MG Ocular Symptoms
Ptosis (droopy eyelid)
-fluctuates throughout any given day
-may be unilateral / bilateral (even switch eyes)
Diplopia (double vision)
-initially sense of blurred vision
What is the name for a droopy eyelid?
Ptosis
MG Bulbar symptoms
-Dysarthria (marbles in mouth)
-Dysphagia (swallowing)
-Fatigable chewing
Diagnosis of MG depends on
If it is ocular or general symptoms
- Bedside Test
- Serologic Test
- Nerver conduction test (EMG)
Diagnosis of MG: Bedside Test
Sentives , but many false-postives
Use only with a patient with ptosis (improvement can be seen)
Tensilon Test
Ice Pack Test
Tensilon Test
Bedside test done for ptosis MG
Tensilon - acetylcholinesterase inhibitor; onset 30-45 secs; duration 5-10 min
Given IV - watch eyelids:
ptosis will improves if MG
Ice Pack Test
Bedside Test done for ptosis MG
Based on principle of improving neuromuscular transmission at lower muscle temperatures
Surgical glove of ice on lid x 2 minutes; remove ice; immediately assess potois
Will improves if MG
What lab values helps asses for the presences of autoantibodies in MG?
Acetylcholine receptors antibodies
Muscle specific tryamine kinase antibodies
MG: Drug Therapy
Acetylcholinesterase inhibitors (anticholinesterase)
-pyridostigmine bromide (common) / neostigmine
MG: Acetylcholinesterase inhibitors
First line treatment
Can produces relief in minutes
May require day-to-day variation in dosing
When is short term treatment usually ordered?
Ordered until medication take effect
Prior to surgery
Myasthenic crisis
MG: Short Term Treatment
- Intravenous immunoglobulin (IVIG)
- Plasmapheresis (plasma exchange)
Intravenous immunoglobulin (IVIG)
Short Term Treatment
An injection of nonspecific antibody (immunoglobulin) that works by dialing down the immune systems production of its own antibodies, much as warm air tells a thermostat to stop pumping out heat
Plasmapheresis
Short Term Treatment
-IV line used to remove antibodies from plasma to decrease symptoms
Plasmapheresis Changes timeline
6 exchanges over a 2-week period w/ weekly or monthly follow ups prn
MG: Surgical Management
Thymectomy
Thymectomy
Removal of thymus because the gland seems to enhance AChR antibodies
Done early in diagnosis (2 years within onset of symptoms)
MG Patient: Hospital Admission Typically r/t
-Respiratory tract infection
-Acute myasthenic crisis
Care of MG is focused on
Neurologic deficits and their impact on ADLS
MG Patient: Teaching
Balanced diet that can be easily chewed / swallowed (semi-solid best)
-What causes flares
-Complication of disease
-Complication of therapy
-Support groups avaiable
MG: Medication schedules
Schedule so peak action during mealtime
Myasthenic VS Cholinergic crisis
Myasthenic Crisis:
-Caused by not enough Anticholinesterase Drugs (too little ACH)
Cholinergic Crisis:
-Caused by too many anticholinesterase drugs (too much ACH)
Features common to both Myasthenic and Cholinergic Crisis
-Apprehension
-Restlessness
-Dyspnea
-Dysphagia
-Generalized weakness
-Respiratory failure
Unique Features of Myasthenic Crisis
Increased V.S
Bowel / Bladder incontinence
Absence of cough / swallow reflex
Improvement of symptoms with Tensilon test
Unique Features of Cholinergic Crisis
Flaccid paralysis
Hypersecretions (saliva - sweat - tears)
N/V/D
Abdominal cramps
Worsening symptoms with Tensilon Test
Tensilon test with myasthenic crisis
Improvement of symptoms
