3- Myasthenia Gravis & MS Flashcards
What is the most common disorder of neuromuscular transmission?
Myasthenia gravis
Who is affected by myasthenia gravis?
Bimodal
20s-30s, 60s-80s
What are the 2 types of myasthenia gravis?
Ocular, generalized
What is myasthenia gravis?
Autoimmune attack to ACh receptors at the NMJ leading to muscle fatiguability and weakness
What is the hallmark of myasthenia gravis?
Fluctuating weakness/ fatigue of:
Ocular- most common
Bulbar- speech, chewing, swallowing
Facial muscle weakness- “myasthenic sneer”
Neck- “dropped head syndrome”
Limbs- UE > LE
Respiratory muscles- “myasthenia crisis”
When is the weakness and fatigue a/w myasthenia gravis worse?
End of day, after exercise
What triggers may worsen myasthenia gravis?
Anything that causes stress on the body
What drugs should be avoided in pts with myasthenia gravis?
Fluoroquinolones
Beta blockers
Hydroxychloroquine
What tests (although not confirmatory) performed on PE may indicate MG?
Upward gaze x 1 min = ptosis
Ice pack test w/ ptosis = improved sxs
What will electrophysiologic studies (NCS and EMG) show for a pt with MG?
Decreased response on repetitive nerve stimulation
Fatiguability
How is MG diagnosed?
Serologic tests- AChR Ab, MuSK Ab
CT/ MRI chest- thymic hyperplasia/ thymoma
(Edrophonium/ Tensilon test = immediate increase in muscle strength, no longer used)
How would you be able to distinguish between MG and ALS?
ALS does not have ptosis or diplopia
Lambert-Eaton myasthenic syndrome is an AI disease often a/w malignany and due to reduced ACh release in the NMJ. How would you distinguish these sxs from those of MG?
Proximal muscle weakness
Sxs worse in am and improve with exercise
What is used for symptomatic tx of MG?
Pyridostigmine- AChE inhibitor
What meds are used for chronic immunotherapies in the tx of MG?
Glucocorticoids, Azathioprine- immunomodulating agents
What meds are used for rapid (short acting) immunomodulating therapies in the tx of MG?
Plasma exchange, IVIG immune globulin
What is the surgical therapy for MG?
Thymectomy
What MG treatment has rapid onset and improves strength (limb/ bulbar > ocular), and what is the caution with use?
Pyridostigmine
Cholinergic SEs
Not sufficient monotherapy (add immunotherapy)
What is the 2nd leading cause of permanent disability in young adults?
MS
MS is an immune mediated inflammatory demyelinating disease of CNS that leads to what?
Plaques/ demyelination → affects nerve transmission
What is the imaging test of choice for MS?
MRI w/ and w/o contrast
(shows plaques +/- black holes/ brain atrophy)
What is the hallmark of MS?
Symptomatic episodes occur months- years apart and affect different anatomic locations (separation of time and space)
What is the most common type of MS?
Relapsing-remitting disease (RRMS)
What is the 1st attack of MS?
Clinically isolated syndrome (CIS)
What type of MS is defined as clearly defined relapses with full recovery or some deficit?
Relapsing-remitting disease (RRMS)
What type of MS is defined as initially RRMS w/ gradual worsening and typically occurs 10-20 yrs after MS dx?
Secondary progressive (SPMS)
What type of MS is defined as progressive sx increase from disease onset with no remission and is the most aggressive type?
Primary-progressive (PPMS)
What is defined as transient worsening of MS due to elevated body temp?
Uhthoff phenomenon
Most common clinical presentation of RRMS is a young adult with episodes of what sxs that occur over hours- days and resolve over weeks to months?
Paresthesia-sensory (most common initial feature)
Optic neuritis
Weakness
On PE pt notes an electrical shock sensation down back/ limbs with neck flexion. What is this called and what condition is it a/w?
Lhermitte sign, MS
On PE pt notes a defective pupillary reaction to light which you believe is due to optic nerve dysfunction. What is this called and what condition is it a/w?
Marcus Gunn pupil (affected pupil does not constrict in response to bright light)
MS
Nystagmus, incoordination, and tremor are signs of cerebellar involvement with what condition?
MS
Hyperreflexia, (+) Babinski sign, and clonus are UMN signs a/w what condition?
MS
How is MS diagnosed?
CNS lesion dissemination in time and space
Clinical findings + MRI findings (plaques)
What is the key principle of the McDonald criteria used in the diagnosis of MS?
Demonstration of CNS lesions disseminated in space and time
Damage in more than one place in CNS
Damage has occured more than once
Additional tests used to dx MS might include analysis of CSF. What would you expect to see?
Oligoclonal bands
(appearance/ pressure N, total WBC N in 2/3 of pts)
Evoked potential studies such as electrical agents generated in CNS by peripheral stimulation of sensory organ and tools used to measure time a stimulus takes to reach the cerebral cortex are used to detect abn CNS function and can contribute to what dx?
MS
Can abn MRI changes indicative of MS be found in clinically healthy patients?
YES, but should still refer for workup
MS tx varies based on type. What is first line tx for relapsing-remitting MS (RRMS)?
Disease modifying therapy
(primary and secondary progressive MS types are more difficult to treat and have fewer effective tx options)
What is the role of disease modifying therapies (immune modulating meds) in the management of MS?
Not a cure
Decrease relapse rate, slower accumulation of MRI lesions, continuted indefinitely
What should first be ruled out in the tx of an acute exacerbation of MS?
Infection
What is the goal of tx of an acute exacerbation of MS and what is the tx?
Speed recovery time from attack
Glucocorticoids (IV methylprednisone) = 1st line
+/- ACTH (steroid alternative), plasma exchange/ plasmapheresis (if poor response to steroids)
When should a pt with MS be admitted?
Unable to manage at home, severe relapses
What MS pts should be referred?
All pts with MS should be followed by a neurologist
Why is a multidisciplinary approach for sx management in patients with MS critical?
At risk for developing many other sxs
(ex. depression, spasticity, bladder dysfunction, gait impairment)
Eventual disability is common with MS dx, how much is life expectancy typically reduced by?
7-14 years
