Treatment for MG
We will outline in a later chapter how, just as the method of making a positive diagnosis of MG has developed, so also has the treatment. The important point being that in the last seventy years, MG has gone from being an almost unknown fatal disease to the current situation in which the symptoms can be controlled so that today we have ageing Myasthenics in our community.
There are different forms of treatment for MG, although often they are used together.
Non-immunological symptoms treatment accepts the immunological abnormality as a fact of life and compensates for its affects at the neuro-muscular junction by allowing the released ACh to work longer. Pyridostigmine (Mestinon), the anti-cholinesterase drug most commonly used, does nothing to cure MG or attack the rogue antibodies but assists the patient in coping by improving muscle strength temporarily with each dose. Other drugs in the same category are Ephedrine and Spironolactone.
Mestinon comes in 60 mg and 10 mg tablets, as well as a slow release 180 mg dose. Group members have come to realise that it is important to discuss the dosage with the Doctor, particularly if they are experiencing stomach cramps, diarrhoea, flickering eye lids and body cramps (indicating a relative overdosing). Mestinon assists the patient to a level where optimum strength is restored, but attempts to raise that level of strength by increasing the dose may have the reverse effect and actually increase the weakness. Where the dose is too high a Cholinergic Crisis may occur which is the result of an overdose of the medication. The dose of Mestinon that works for a particular person may be very different to that required for someone else and a degree of trial and error may be required to get the best dose.
It is important to realise that, because Mestinon does not treat the underlying autoantibodies, immoderate or severe MG it is not enough and even at the optimum dose it may not relieve the symptoms or fully prevent weakness.
Immunological Disease Treatment concentrates on reducing the antibodies which cause such destruction to the muscle receptor’s AChR. Certain drugs suppress the body’s immune system (immunosuppressants) and are helpful in treating the cause of MG.
Corticosteroids (Prednisolone) (not to be confused with anabolic steroids taken by some athletes) are known to reliably improve MG after a delay of two to six weeks. It is generally known that such drugs have side effects in chronic use (see later section). By suppressing immunity generally, they raise the risk of infection but by taking reasonable steps to avoid being in certain environments this risk can be minimised. It is also of great importance that a patient who is on steroids should advise the surgeon and anaesthetist when facing surgery.
Dentists, optometrists, podiatrists and any health professionals with whom you have contact, should also be made aware that you suffer from MG and the medication you have been prescribed.
Patients being treated with steroids need to be aware that beneficial effects
may take some time to be felt as the body needs to adjust.
Azathioprine (Imuran) suppresses anti–body production. The point to note about Imuran is that it can take up to a year to be effective. It may be used by itself or in conjunction with Mestinon and or steroids.
Mycophenylate another recently introduced immuno-suppressant drug with a similar action to Imuran is currently finding its place in the treatment of MG.
Plasmapheresis (Plasma Exchange) is a procedure where blood is separated into cells and plasma (which contains the antibodies). The plasma is then replaced with healthy plasma. This is not a long term treatment but is said to “buy time” while other treatments are becoming effective. It is very effective in patients with more severe MG. Strength usually improves after three days and lasts for about four weeks. This is a particularly useful procedure to strengthen the patient prior to surgery such as Thymectomy, or while patients are slowly responding to tablet immune suppression. It requires large intravenous lines which are unpleasant
IV Ig intravenous immunoglobulin (Intragam). A procedure of injecting slowly into a vein the pooled antibody protein fraction from normal blood.
This probably works in MG by providing enough antibody in general that the body makes less of its own, including the undesirable AChR. Like Plasmapheresis it needs to be repeated at least every few weeks and is in short supply as it relies on thousands of blood donors. However, unlike plasma exchange it only requires a little intravenous line to be given.
Thymectomy. The Thymus Gland is seen as the producer of these rogue antibodies. It has also been found that tumours (Thymomas) may develop in the Thymus Gland in about 10% of patients with MG. In the majority of cases these tumours are benign, however in a small number of cases they have been found to be malignant (Spread and invade local tissues).
Removal of the Thymus Gland (Thymectomy) for reasons other than MG was practised long before it was noticed that this surgery had a marked affect on about 15% of MG patients. On occasions MG patients (under 45 years of age), without Thymomas, but are antibody (AChR) positive may be recommended to undergo a Thymectomy. Some show great improvement, most have some benefit, but some do not improve post surgery.
Because we do not wish to enter the enormously complex world of medical research, we simply make some observations from the responses of MG sufferers within the group who have had the surgery. The surgery is major with the healing period being slow due to the need for the MG still to be treated using Steroids, and if there is to be a reduction of MG symptoms this takes place over a very long period (up to five years). So patients should not be disheartened if they do not see a dramatic change overnight.
In this booklet it is only possible to speak generally of these treatments and it will obviously be important to discuss your individual situation with your Doctor. Hopefully it does give you some idea of the range of treatments available and the reasons they may be being used. Remember, this booklet is produced by a group of people many of whom can say “Been there done that” and are happy to share their experience.
Some neurologists consider it is an important benefit to join the MG Friends Support Group and attend their gatherings.