Slide 1: Myasthenia Gravis and Guillan Barre Syndrome Submitted to AskTheNeurologist.Com in 2007 Author Anon.
Slide 2: 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 of functioning acetylcholine receptors”
Slide 4: Neuromuscular transmission 1. Action potential arrives at synapse 2. Calcium enters via Ca channels (LEMS) 3. ACh vesicles released 4. ACh binds to postsynaptic receptors 5. Muscle AP resulting in contraction 6. Enzyme ( ACHE ) breaks down ACh
Slide 5: Associated factors • Female > Male • Often associated conditions: - Thymoma - Thyrotoxicosis - SLE - RA - Other autoimmune conditions
Slide 10: Further Investigations • Chest CT scan • Monitoring of Ach R Ab level • VITAL CAPACITY during exacerbations
Slide 11: Treatment • Anticholinesterase drugs - Pyridostigmine ( Mestinon) • Thymectomy • Steroids ( may worsen initially) • Azathioprine ( Imuran) • Cyclosporine • IVIG or plasmapharesismyasthenia gravis and GBSSlide 12: Prognosis • Most patients can be managed successfully with drug treatment • Occasionally fatal due to respiratory complications including aspiration pneumonia
Slide 13: 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
Slide 14: 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
Slide 15: Case 2 continued • 2 hours later, another soldier admitted with a similar problem ( from same base)
Slide 18: History • Often follows minor infection - URTI - Diarrhoea ( Campylobacter) • Progressive symmetrical limb weakness • Usually affects legs first and ascends • Proximal > Distal weakness • Frequent sensory complaints • Progresses over no more than 4 weeks
Slide 19: 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
Slide 21: Investigations • LP – High protein with normal cell count • Nerve conduction studies reveal slowing of nerve conduction • Both abnormalities may lag behind clinical course
Slide 22: Treatment • IVIG and plasmapharesis • Steroids contraversial • Respiratory support if necessary • General supportive care e.g. s.c heparin
