Myasthenia Gravis and

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Myasthenia Gravis and Guillan Barre Syndrome
Submitted to AskTheNeurologist.Com in
2007 Author Anon.
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Myaesthenia Gravis
A disease consisting of muscle weakness due to
a variable block of neuromuscular transmission in
which there is an immune-mediated decrease in the
number or function of acetylcholine receptors
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(No Transcript)
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Neuromuscular transmission

• Action potential arrives at synapse
• Calcium enters via Ca channels (LEMS)
• ACh vesicles released
• ACh binds to postsynaptic receptors
• Muscle AP resulting in contraction
• Enzyme ( ACHE ) breaks down ACh

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Associated factors

• Female gt Male
• Often associated conditions
• - Thymoma
• - Thyrotoxicosis
• - SLE
• - RA
• - Other autoimmune conditions

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Symptoms

• Diplopia
• Ptosis
• Dysarthria
• Dysphagia
• Limb weakness
• Fluctuative fatiguability is hallmark
• NO SENSORY SYMPTOMS

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Examination

• Weakness of EOMs
• Ptosis
• Limb weakness
• Fatiguability
• SENSATION IN TACT

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Exacerbating factors

• Infection
• Hypothyroidism
• Poor compliance
• Drugs - Aminoglycosides
• - Beta Blockers
• - Many others!
• IV CONTRAST

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Diagnostic tests

• Tensilon ( edrophonium )
• EMG ( decrement )
• Ach receptor Abs

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Further Investigations

• Chest CT scan
• Monitoring of Ach R Ab level
• VITAL CAPACITY during exacerbations

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Treatment

• Anticholinesterase drugs
• - Pyridostigmine ( Mestinon)
• Thymectomy
• Steroids ( may worsen initially)
• Azathioprine ( Imuran)
• Cyclosporine
• IVIG or plasmapharesis

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Prognosis

• Most patients can be managed successfully with
  drug treatment
• Occasionally fatal due to respiratory
  complications including aspiration pneumonia

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Case 1

• 75 year old man with malignant thymoma and
  metastasis
• Seropositive MG for 2 years ( controlled with
  pyridostigmine only)
• Hospitalised in ITU because of aspiration
  pneumonia
• Severe deterioration, family consulted regarding
  intubation

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Case 2

• 19 year old male soldier, admitted to ER with 3
  hour history of worsening diplopia, dysphagia and
  general weakness.
• On examination BP 70 / 30, Pulse 40
• blurred vision when each eye examined separately
• Pupils dilated and not reactive

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Case 2 continued

• 2 hours later, another soldier admitted with a
  similar problem ( from same base)

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Guillan Barre Syndrome

• Acute Demyelinating Polyneuropathy

MYELIN
AXON
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Guillan Barre Syndrome
Acute Demyelinating Polyneuropathy
MYELIN
AXON
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History

• Often follows minor infection
• - URTI
• - Diarrhoea ( Campylobacter)
• Progressive symmetrical limb weakness
• Usually affects legs first and ascends
• Proximal gt Distal weakness
• Frequent sensory complaints
• Progresses over no more than 4 weeks

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Examination

• Limb weakness
• May ascend to affect facial muscles
• Decreased or absent reflexes
• In severe cases where there is axonal damage
  muscle wasting may occur

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Autonomic instability

• Tachycardia
• Other cardiac irregularities
• Labile blood pressure
• Sweating
• Pulmonary dysfunction
• Sphincter disturbances
• Paralytic ileus

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Investigations

• LP High protein with normal cell count
• Nerve conduction studies reveal slowing of nerve
  conduction
• Both abnormalities may lag behind clinical course

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Treatment

• IVIG and plasmapharesis
• Steroids contraversial
• Respiratory support if necessary
• General supportive care e.g. s.c heparin

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Monitoring

• Neurological examination
• Complaints of dyspnea
• Cardiac monitor
• Blood pressure
• Vital capacity

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Prognosis

• Self limiting
• Improvement expected to begin by 4 weeks
• About ¾ recover completely
• 20 remain with mild deficits
• 5 die - Respiratory failure
• - Autonomic instability

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Submitted to AskTheNeurologist.Com in
2007 Author Anon.