InsideSurgery Medical Information Blog

Details of surgical procedures, pathophysiology, signs and symptoms, and treatment of medical diseases,medical and surgical eponyms, and surgeons and surgery in the news

  • Home
  • Eponyms
  • Abbreviations
  • Terms of Use
  • Privacy Policy
  • Contact

Myasthenia Gravis

March 12, 2013

Pathophysiology of Myasthenia Gravis

Myasthenia gravis is a progressive autoimmune disease caused by autoantibodies directed agains the nicotinic cholinergic (or acetylcholine) postsynaptic receptors of the neuromuscular junction

Signs and Symptoms

1) muscular weakness and fatigability on exertion, with some recovery with rest
2) often presents with ptosis, vision problems, dysarthria, and difficulties chewing and swallowing
3) facial sneer
4) asymmetrical limb weakness
5) can involve diaphragm with respiratory difficulty in late stages

Characteristic Test Findings

Laboratory

1) positive edrophonium (Tensilon) test
2) positive antiacetylchone receptor antibody assay
3) red cell aplasia

EMG

4) decreased action potentials on repetitive nerve stimulation

Histology and Gross Pathology

1) atrophy of type 2 muscle fibers
2) lymphocytic infiltrates
3) flattening of post synaptic folds

Associated Conditions

1) 60% with thymic hyperplasia
2) 15% with thymomas
3) increased incidence of hyperthyroidism (6%)
4) increased incidence of rheumatoid arthritis and lupus (SLE)

myasthenia gravis thymoma

Chest radiograph showing solid mass causes by thymoma (arrow)

Treatment

1) pyridostigmine (anticholinesterase drug)
2) thymemctomy often causes dramatic improvement
3) plasmapheresis
4) intravenous immunoglobulin
5) immunosuppressive drugs (steroids, cyclosporin, azathioprine, mycophenolate mofetil)

Biochemistry

1) type 2 hypersensitivity reaction
2) marked by increased complement activation

Epidemiology

1) female to male, 3:1
2) affects women at age 10-30 years; men, age 50-60 years
3) affects 1/7500

Tips for USMLE

1) if question describes a 24 year old office worker who experiences facial weakness and slurred speech after talking on the phone that resolves 15 minutes after she stops, think myasthenia gravis
2) can be distinguished from other neuromuscular disorders because there are normal deep tendon reflexes and no sensory deficits
3) key pathologic fact is a decrease in number of acetylcholine receptors at the neuromuscular junction

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

Categories

  • Acupuncture
  • Amputation Surgery
  • Anesthesia
  • Appendix Surgery
  • Articles
  • Bird Flu
  • BP Oil Spill Health Risks
  • Breast Surgery
  • Cancer
  • Cardiac Surgery
  • Cardiology
  • Case Reports
  • Clinical Trials – Published
  • Colon Surgery
  • Complementary and Alternative Medicine
  • Coronavirus
  • Critical Care
  • Dental and Oral Surgery
  • Dermatology
  • Devices and Technology
  • Drug-Drug Interactions
  • Ebola
  • Endocrinology
  • Eye Surgery
  • For Professionals
  • Gallbladder Surgery
  • Gastroenterology
  • General
  • Grand Rounds
  • Hand Surgery
  • Head and Neck Surgery
  • Healthcare Law
  • Hematology
  • Hernia Surgery
  • Hip Surgery
  • History of Surgery and Medicine
  • Hyperbaric Oxygen
  • Infectious Disease
  • Interviews
  • Liver Surgery
  • Medical Eponym Bios
  • Medical Mnemonics
  • Medical News Wire
  • Medical Trivia
  • Medical Words and Abbreviations
  • Musings
  • Nanomedicine
  • Neck Surgery
  • Neurology
  • Nutrition
  • ObGyn Surgery
  • Oncology
  • Orthopedic surgery
  • Pancreas Surgery
  • Pediatric Surgery
  • Pediatrics
  • People
  • Pharmacology
  • Plastic Surgery
  • Pulmonology
  • Rectal Surgery
  • Rheumatology
  • Small Bowel Surgery
  • Spleen Surgery
  • Stomach Surgery
  • Surgery and Medicine Quotations
  • Surgical Procedure Videos
  • Surgpedia
  • Thoracic Surgery
  • Tip of the Day
  • Transplant Surgery
  • Trauma Surgery
  • Uncategorized
  • Urology Surgery
  • USMLE
  • Vascular Surgery

Archives

© 2021 InsideSurgery.comĀ® · All rights reserved.
This material may not be published, broadcast, rewritten, or redistributed without the express written consent of InsideSurgery.com.
This website uses cookies to improve your experience. We'll assume you're ok with this, but you can opt-out if you wish. Cookie settingsACCEPT
Privacy & Cookies Policy

Privacy Overview

This website uses cookies to improve your experience while you navigate through the website. Out of these cookies, the cookies that are categorized as necessary are stored on your browser as they are essential for the working of basic functionalities of the website. We also use third-party cookies that help us analyze and understand how you use this website. These cookies will be stored in your browser only with your consent. You also have the option to opt-out of these cookies. But opting out of some of these cookies may have an effect on your browsing experience.
Necessary
Always Enabled

Necessary cookies are absolutely essential for the website to function properly. This category only includes cookies that ensures basic functionalities and security features of the website. These cookies do not store any personal information.

Non-necessary

Any cookies that may not be particularly necessary for the website to function and is used specifically to collect user personal data via analytics, ads, other embedded contents are termed as non-necessary cookies. It is mandatory to procure user consent prior to running these cookies on your website.

SAVE & ACCEPT
Inside Surgery
  • Home
  • Eponyms
  • Abbreviations
  • Terms of Use
  • Privacy Policy
  • Contact