Wednesday, March 4, 2009

Myasthenia Gravis

A 35 year old woman presents to the clinic with a chief complaint of double vision. She reports intermittent and progressive worsening double vision for approximately 2months, rarely at first, but now every day. She works as a computer programmer and the symptoms increase the longer she stares at the computer screen. She had also noted a drooping of her eyelids, which seems to worsen with prolonged working at the screen. Both symptoms subside with rest. She is generally fatigued but has noted no other weakness or neurological symptoms. Her medical history is unremarkable. Physical examination is notable only for the neurological findings. Cranial nerve examination discloses impaired lateral movement of the right eye and bilateral ptosis, which worsen with repetitive eye movements. Motor, sensory and reflex examinations are otherwise unremarkable.

what is the likely diagnosis?

Myasthenia Gravis

what is the pathogenesis of this disease

An autoimmune disease where the body produce atibody towards the post synaptic Ach receptors.Also,the antibodies also attack the acethylcholine(Ach) at the synatic cleft.The net effects are decrease number of ffuncctional Ach receptor and functional Ach

explain the pathophysiology of each signs and symptoms.

patient comes to the hospital with the complaints of fatigue, ptosis and also double vision.Destruction of the receptors cause diminished transmission of the nerve impulse across the neuromuscular junction. Muscle depolarization is not achieved, therefore, muscle weakness develop.The signs and symptoms of MG depends on which muscle involve:

  • extra ocular muslces :double vision
  • levator palpebral superioris:ptosis
  • upper esophagus :dysphagia
  • palatalmuscle :dysathria
  • diaphragm :respiratoryfailure

Usually,fatigue develop due to repetitive stimulation or prolonge use.This occur due to decrease number of available neurotrasmitter and the numbers of functional Ach receptor.

what are the investigations and the significant of it?
  • TensillonTest
admistration of cholinesterase inhibitor will cause improvement of muscle power.This will increase the number of Ach in the synaptic cleft.
  • antibody towards the Ach receptor
  • chest Xray
autoimmune disease may associate with thymoma or thymic hyperplasia.

what treatments should be considered

  • cholinesteraseinhibitor
  • plasmapheresis,corticosteroid
  • thymectomy
[happy study]

Ainaa Ismail



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