Myasthenia gravis: an animated, cited guide
This page needs JavaScript for its animations. The outline and key answers are below, and every claim in the full version carries a numbered citation.
Not medical advice. Myasthenia Gravis Companion is an educational synthesis of published literature. It does not replace a clinician.
What is in it
- What myasthenia gravis is Who gets it, the numbers, the muscles it reaches.
- The neuromuscular junction One nerve impulse in slow motion, and the safety factor.
- Antibodies at the junction AChR, complement, MuSK and LRP4, animated.
- Weakness over a day Why muscles tire with use and recover with rest.
- Diagnosis Antibodies, nerve tests, single-fibre EMG, a calculator.
- MGFA class & scores MGFA classes I to V, MG-ADL and QMG, scored live.
- The differential Lambert-Eaton, botulism, ALS, eye and muscle disease.
- Pyridostigmine, animated Buying time at the receptor, dose by dose.
- The treatment ladder From symptom relief to immunotherapy and biologics.
- Thymectomy over the years The thymus, thymoma and the MGTX trial.
- Complement & FcRn inhibitors The newer biologics, trial week by trial week.
- Myasthenic crisis Triggers, the breathing numbers, ICU care.
- Drugs that can worsen MG A cited checker: antibiotics, magnesium and more.
- Nursing care Assessment, timing the doses, teaching, documentation.
- Living with MG Pregnancy, surgery, exercise, vaccines, work.
- Toward a cure CAR-T, B-cell targets and the evidence for each route.
- History & people From Willis in 1672 to the biologics.
- Flashcards, quiz and glossary Revision for students.
- Sources Every reference behind the guide.
Common questions
What is myasthenia gravis?
Myasthenia gravis (MG) is an autoimmune disease of the neuromuscular junction, the point where a nerve passes its signal to a muscle. Antibodies, most often against the acetylcholine receptor, weaken that signal, so voluntary muscles tire with use and recover with rest. Sensation, reflexes and the pupils stay normal.
What are the first symptoms of myasthenia gravis?
Most often the eyes: a drooping eyelid (ptosis) or double vision. In a large Japanese series ptosis was the first symptom in about three quarters of people and double vision in about half. Weakness can then reach the face, speech, chewing and swallowing, the neck, the limbs and the breathing muscles, and it is typically worse later in the day.
How common is myasthenia gravis?
Estimates differ. MedlinePlus gives about 20 per 100,000 people worldwide, while a 2021 meta-analysis pooled 12.4 per 100,000. Prevalence has been rising, partly because of earlier diagnosis, longer survival and more people diagnosed in later life.
How is myasthenia gravis diagnosed?
With the clinical picture plus tests: a blood test for acetylcholine receptor antibodies (positive in about 85 to 90 percent of generalized and 50 to 70 percent of ocular MG), then MuSK and LRP4 antibodies if negative; repetitive nerve stimulation, where a fall of 10 percent or more between the first and fourth or fifth response is abnormal; single-fibre EMG, the most sensitive test; and chest imaging to look for a thymoma.
What is a myasthenic crisis?
Weakness of the breathing or swallowing muscles severe enough to need ventilation. About 15 to 20 percent of people with MG have at least one, most often in the first two to three years, and infection is the commonest trigger. It is a medical emergency, treated in intensive care with breathing support and plasma exchange or intravenous immunoglobulin.
How is myasthenia gravis treated?
Pyridostigmine eases symptoms; corticosteroids and steroid-sparing drugs such as azathioprine calm the immune response; thymectomy helps many people with acetylcholine receptor antibodies; plasma exchange or intravenous immunoglobulin are used for rapid worsening; and newer biologics block complement (eculizumab, ravulizumab, zilucoplan) or the FcRn receptor (efgartigimod, rozanolixizumab, nipocalimab). Which treatment is right is decided with a neurologist.
Which drugs can make myasthenia gravis worse?
Telithromycin and quinine are contraindicated in MG, and fluoroquinolone antibiotics carry a US boxed warning. Labels also warn about aminoglycosides, macrolides, some heart drugs, neuromuscular blockers, botulinum toxin, D-penicillamine and immune checkpoint inhibitors, and intravenous magnesium can worsen weakness. Guidance says listed drugs can still be used when needed, with monitoring, so decisions rest with the treating clinician.
Can people with myasthenia gravis have children?
Yes, usually, with planning. About a third worsen during pregnancy and a similar share after delivery, and published guidance describes close follow-up through pregnancy and after delivery. Some drugs, such as mycophenolate and methotrexate, are stopped before conception. About one baby in ten has temporary weakness (transient neonatal myasthenia) from the mother's antibodies, which fades within weeks.