movement disorders Flashcards
what is an autoimmune disorder of NMJ in which anti-acetylcholine receptor antibodies at the post synaptic membrane
myasthenia gravis
what are two main associations in myasthenia gravis
thymic hyperplasia (70%)
thymoma (10%)
weakness in myasthenia gravis is in what pattern
Weakness is descending (starts from the top and moves down)
• Muscle fatigue after sustained/repetitive action : better with rest
weakness in myasthenia gravis is in what pattern
• Weakness is descending (starts from the top and moves down)
• Muscle fatigue after sustained/repetitive action: better with rest
when are symptoms the worst in myasthenia gravis
at night
what are bedside tests in myasthenia gravis
o Worse when counting to 20 quickly
o Upward gaze –> ptosis; relieved by icepacks
o Outstretched arms –>slow downward drift
o Normal reflexes
what are investigations for myasthenia gravis
• Most specific: anti-AChR antibodies
• Most sensitive: single fiber electromyography
• Nerve stimulation test : decrement in evoked potential
• Anti-MuSK antibodies
• CT : thymoma/thymic hyperplasia
• Tensilon test: giving IV anticholinesterase: temporary rapid improvement
how is thymoma related to myasthenia gravis
1) thymus gland is critical for immune system, teach t-cells to distinguish btwn self +nonself
2) in thymoma, process can become dysregulated leading to production of autoreactive T cells
3) these damaged t-cells tell B cells to produce autoantibodies against AchR + Musk which decrease release of Ach
what is affected in Lambert-Eaton myasthenic syndrome
autoantibodies against presynaptic calcium channels
what type of cancer does LEMS present with
SCLC
how do symptoms improve in LEMS
symptoms improve with repeated muscle stimulation
what symptoms do LEMS present with
Presents with proximal muscle weakness and hyporeflexia
what is the tx of myasthenia gravis
•Anticholinesterases (pyridostigmine) :↑ availability of Ach at NMJ
• Immunosuppressants (steroids, azathioprine) if no response/relapse on Tx
• Thymectomy is indicated if thymoma is seen on CT (malignant potential), or if no thymoma but <50 years old & anti AchR antibodies +ve
what is botulism
o History of consumption of contaminated food (clostridium botulinum: anaerobic spore forming bacteria –> neurotoxin production)
what does botulism affect
cleaves SNARE protein no Ach release
nuscarinic symptoms
incremental response = presynaptic disorder
what is organophosphate exposure
-accidental exposure to agricultural pesticides
-irreversible inhibition of Ache
highhhhhhh Ach stimulatiom in both nicotonic and muscarinic
what is gullian barre syndrome
• Acute inflammatory demyelinating symmetrical ascending polyneuropathy
• Preceded by URTI or diarrhea (especially campylobacter jejuni/EBV/CMV)
what does GBS present with symptoms
• Progressive ascending symmetrical distal limb weakness +/- numbness
• Loss of reflexes
• Autonomic: postural hypotension, cardiac arrhythmias, ileus, bladder atony
• May progress to respiratory muscles –>respiratory failure • May progress to facial muscles –> bilateral lower CN 7 palsy
investigations in GBS
• CSF: elevated protein, normal cells # & sugar (albumin-cytological dissociation)
• Nerve conduction studies –> slowing of motor conduction: most
• Antibodies against GQ1b seen in Miller-Fisher syndrome (rare variant affecting CN to eye muscles =ophthalmoplegia & ataxia)
tx for GBS
No role for steroids
Mainstay: IVIg or plasma exchange
ivi g med in GBS contraindicated in who
igA defecient
what is CHRONIC INFLAMMATORY DEMYELINATING POLYNEUROPATHY (CIDP)
•Chronic form of Gullian-barre syndrome (chronic relapsing course)
• Slowly progressive weakness, often involving neck flexors • Areflexia is common; may also have loss of vibration sense
• Steroids are effective & treatment is required for many years. IVIg also useful
what is meningitis
Serious infection of the meninges in the brain or spinal cord, due to sepsis or direct extension (otitis media, sinusitis, cranial injury, CSF leak)
what is classic triad of meningitis
acute bacterial meningitis:
1)fever
2)nuchal rigidity
3) altered mental status
May also present with headache, vomiting, seizures, photophobia