1 / 26

Neuromuscular disorders

Neuromuscular disorders. Myasthenia gravis Eaton Lambert syndrome Botulism. MYASTHENIA GRAVIS. AUTOIMMUNE DISORDER ANTIBODIES DIRECTED TOWRDS THE ACETYLCHOLINE RECPTORS AT POST SYNAPTIC MEMBRANE AFFECTS ANY AGE BUT MAINLY AGE 20-30 YEARS 2 FEMALE >1 MALE ROLE OF THYMUS.

fisk
Download Presentation

Neuromuscular disorders

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Neuromuscular disorders Myasthenia gravis Eaton Lambert syndrome Botulism

  2. MYASTHENIA GRAVIS • AUTOIMMUNE DISORDER • ANTIBODIES DIRECTED TOWRDS THE ACETYLCHOLINE RECPTORS AT POST SYNAPTIC MEMBRANE • AFFECTS ANY AGE • BUT MAINLY AGE 20-30 YEARS • 2 FEMALE >1 MALE • ROLE OF THYMUS

  3. Role of the thymus • Abnormalities of the thymus in 80 % • Production of T-cell lymphocytes which participate in the immune responses

  4. Pathophysiology • Neuromuscular junction is composed of • I-Presynaptic nerve ending which contains the synaptic vesicles(Ach) • II.Synaptic cleft • III-postsynpatic membrane:Ach receptors • Reuptake of the Ach by choline-estetrase

  5. Clinical features I • Fatigability

  6. DEFINITION • FAILURE TO SUSTAIN A MAINTAINED OR REPEATED CONTRACTION OF STRIATED MUSCLES

  7. Clinical features II • Onset usually insidious • Fluctuating weakness • Weakness at the end of the day • Extraocular muscles (ptosis) • Bulbar muscles • Limbs • generalized

  8. Clinical features III • Onset can be fulminant • With involvement of respiratory muscles • Weakness may be provoked by : • Infection, hypo k., hypocalcemia • Drugs : • Quinine.betablockers,phenytoin • Sedatives (diazepam) • Antibiotics • Surgery,pregnancy

  9. Clinical exam I • Look for fatigability • Examine motor power :first movement is normal • Repeat movements; weakness will appear • All muscles should be examined • Induce fatigue (no change of power in normal individual)

  10. Clinical exam II • Every thing else is normal • Reflexes unaffected • No wasting • No deformity • Tone is normal • No sensory change

  11. Clinical exam III • May be associated with diseases • Malignancy • Autoimmune disorders. • Then look for associated features

  12. Test to be used in the clinic :Tensilon test • Technique: • Inject edrophonium (10 mg in 1cc) • First 2 mg (0.2 cc) • If no hypotension or hypersensitivity • Inject the rest (8mg) • Result: • Weakness improves within 1-2 minutes

  13. CRISiS • I- Myasthenic crisis • II-Cholinergic crisis

  14. I.Myasthenic Crisis • Precipitating factors • Infections • Changes of drugs • Pregnancy • Surgery

  15. II-cholinergic crisis • Excessive use of anticholinergic medication • Myosis,diarrhea, • increased salivation • Abdominal cramps • bradycardia

  16. Investigations I • Logical (immune disorder) • Look for antibodies in serum EMG • Repetetive stimulation test • Technique : • Exert repetetive stimulation o nerve (ulnar) at 3,10,30-50 (tetanization) and look for response -> decremential response • Single fiber EMG :increased jitter.=delayed NMJ transmision

  17. Investigations II • Biopsy of the neuromuscular joint • And electron microscope study • Severe Loss of receptors • Look for the thymus by CXR,CT,MRI

  18. Neonatal MG • 12-16 % of infant born to myasthenic mother have myasthenic features (ptosis,weakness,poor cry and suck) • Last up to 6 weeks • Due to transplacental transfer of maternal circulating anti-Ach receptor antibodies • Temporary administration of anti choline esterase agents may be needed

  19. Treatment I • 1-Anticholine esterase agents • A-Short acting :neostigmine (Prostigmine) • B-Long acting : pyridostigmine (Mestinon) • 20.60 and 180 mg • 2-4 times a day • SE : increased bronchial secretions bronchspasm,miosis,diarrhea,abdominal cramps,bradycardia

  20. Treatment II • Reduce circulating antibodies • Plasmpheresis

  21. Treatment III :immunemodulation • Steroids • Immunosupressants • IVIG

  22. Treatment VI Thymus • Thymectomy • Thymic hyperplasia ? More common :70%

  23. EATON LAMBERT SYNDROME I • Male > female • Later onset • Associated with oat cell carcinoma of the lung in 70% • Affects mainly lower extremities • Clinically initial fatigability-weakness which improves on continuing the effort • Due to impairment of the Ach release in the presynaptic part

  24. E-L syndrome II • Neurophysilogy:incremental response • Treat the underlying cause

  25. Botulism • Bacterial :clostridium botilinum an anaerobic spore forming bacteria -> very strong toxin • May be present in improperly canned food • In raw meat • Toxin impairs pre-synaptic Ach release • Leads to severe weakness and autonomic features

  26. Botulism • Supportive treatment • Tracheostomy • Death in about 15 % • Botulinum toxin (Botox) is used in dystonia, spasticity and for cosmetic purposes

More Related