Myasthenia gravis affects children and neonates as well as adults. There will be weakness noticed in children too. There might be a weak cry and difficult movement of muscles or delayed milestones.
In adults, extraocular muscle weakness is the most common affection seen in maximum patients . The hallmark of the myasthenia gravis is fatiguability or tiredness of the voluntary muscles . Many patients present with bulbar muscle weakness and limb weakness which is often seen first in the proximal limbs and then in distal limbs. Since it is a chronic disorder, signs and symptoms are visible only after there is 30% reduction or destruction of the receptor sites and till then there is no evident sign.
Typically, extraocular muscle weakness is asymmetric and can be noticed easily. Drooping eyelids or ptosis occurs after straining the eyes for a long time as muscles give up after continuously using them due to a deficiency of acetylcholine at the neuromuscular junction.
Other common symptoms occurring out of fatiguability are slurred speech, diplopia or blurred vision, difficulty in chewing and dysphagia, weakness in arms and legs, chronic muscle fatigue, dyspnea, unstable gait, dysarthria i.e. difficulty in speaking or talking and impaired speech.
Weakness of muscles is typically least in the morning and progresses as the day progresses. Weakness increases as there is increased exertion and gets better with rest. Proximal muscle weakness is more often seen than distal muscle weakness.
The anti-acetylcholine receptor antibody test is a very specific test which is done to diagnose myasthenia gravis . This is a very reliable test and is positive in almost 90% of the patients. Antistriated muscle antibody is another sensitive test to be diagnose myasthenia gravis. Muscle weakness should be tested for different parts of the body:
If any of the above tests is positive, i.e. there is fatigue at the end of the set time, it reveals that the patient is suffering from myasthenia gravis.
Single fiber electromyography might be performed  . Repeated electrical impulses are given to the muscle fibers of the patient and electrodes are placed in to the muscle fiber to check for action potentials changes of the muscle fiber. This is a very specific test for myasthenia gravis and helps confirm the diagnosis.
Ice test: Application of ice will characteristically improve the weakness in the patients muscle and this is a very important non-invasive test to be performed. The basis of performing this test is that at lower temperatures acetylcholinesterase is inhibited, leaving more acetylcholine available at the junctions. Thus the patient can perform better as weakness is less .
Edrophonium test: Intravenous edrophonium bromide or tensilon will cause inhibition of breakdown of acetylcholine and thus improve weakness temporarily . This test is usually performed only after all the other tests have failed to give an accurate result.
Pharmacology includes medication and immunosuppressive agents like corticosteroids, cyclosporine, plasmapheresis and intravenous immunoglobulin. Thymectomy is another option for people who have thymoma.
Acetylcholineesterase inhibitors and immunomodulations are the most important modalities of treating patients with myasthenia gravis. They mostly prevent the acetylcholine from degrading and the weakness of the muscles thus reduces. This remains the initial line of treatment followed by corticosteroids as per need. Long term corticosteroids should be avoided as they may lead to further complications like osteoporosis, weight gain, diabetes etc.
Plasmapheresis is a procedure where the plasma is exchanged with fresh plasma which helps in removing out the circulating antibodies from the body. The new plasma contains lesser acetylcholine antibodies, reducing muscle weakness and fatiguability. This is short term relief for the patient especially if they undergo surgery. Exercise helps in a better prognosis.
The prognosis is good today as science has advanced a lot. Patients earlier had 3 to 4 % morbidity but now it has reduced further. Long term use of medications will give these patients a near normal life with very minimal complications. The only threat for these patients is the weakness affecting their respiratory muscles. This might lead to a need for supportive respiration i.e. ventilator support.
Myasthenia gravis is an autoimmune disorder. It is the result of antibodies against the acetylcholinesterase receptors present at neuromuscular junctions which are responsible for muscular movements. These circulating antibodies cause weakness of the body by blocking acetylcholine receptors at the neuromuscular junctions.
Certain drugs may induce myasthenia gravis e.g. Penicillamine, Antibiotics, lithium, Beta-adrenergic receptor blocking agents.
Myasthenia gravis affects people of both the sexes but is more commonly seen in women of the age group 20 to 40 years. It also affects people who have thymus gland abnormalities. More commonly, it is seen in people who have other autoimmune disorders. The female to male ratio is 3:2 whereas in children the ratio is typically 5:1.
Voluntary muscles of the body move by the excitatory impulses sent by nerves to the muscle through the neuromuscular junctions. In myasthenia gravis, the circulating antibodies block the receptors for acetylcholine at the neuromuscular junction leading to failure of transmission of efferent impulses to the muscle.
The acetylcholine receptor present in the motor end plate is called nicotinic acetylcholine receptor. Myasthenia gravis usually causes blocking or destruction of this receptor sites placed all over the body leading to weakness of varying degrees in voluntary muscles . In a healthy person, the nerve carries impulses from the brain and passes on to the muscles through the neuromuscular junction where the neurotransmitter acetylcholine is released. This neurotransmitter then causes excitation of the receptor sites present on the muscular end of the junction.
In a myasthenia gravis patient, the nicotinic receptor sites are destroyed much faster than the body can repair and there is around 80% reduction in the receptor sites . Even though acetylcholine is present, there aren’t enough receptor sites to bring about purposeful muscle movements.
Myasthenia gravis might be prevented by avoiding ingestion of certain drugs which may cause this disease. However, it is essentially an autoimmune disorder and there is no exact way of preventing it.
Myasthenia gravis is an autoimmune disorder affecting the neuromuscular junctions between nerves and muscles affecting voluntary movements. It causes muscle weakness in varying proportions depending on the degree of affection.
It is also known as Goldflam disease and affects the voluntary group of muscles . The term “Myasthenia gravis” literally originates from the Greek and Latin words which mean “grave muscular weakness.”
Myasthenia gravis is an autoimmune disorder which affects the neuromuscular junction (the junction where the nerve synapses meet the muscle fiber and transmits the impulse carried from the brain to the muscle). There are circulating antibodies that block the receptors for the neurotransmitter acetylcholine which are present at the junction and thereby do not allow the voluntary muscle to contract and produce movement.
This is a chronic disorder and gradually many of the receptor sites are destroyed leading to fatigability. There is drooping of eyelids on repeated eye strain, difficulty in swallowing or chewing, slurred or impaired speech, weakness of hands, fingers, legs. There may be weakness of head and difficulty in holding the head up straight. The weakness is least in the morning and keeps on increasing as the day progresses and the most important aspect of this weakness is that there is amelioration of weakness on rest.
This disease also affects children and neonates if the mother has the disease at the time of conception. Ice test, tensilon test and electromyography are the basic tests done for investigating this disease. Prognosis is good and patients are kept on long term acetylcholinesterase inhibitors, intravenous immunoglobulin and plasmapheresis.