I have been told I need a muscle biopsy. Why?
There are three common reasons for being referred to the Malignant Hyperthermia Unit for a muscle biopsy.
- You experienced a reaction to an anaesthetic that raised the suspicion of MH.
- MH has been found in your family and there is no DNA test available in your family.
- MH has been found in your family, a DNA test is available in your family but you have had a negative DNA test.
Other reasons for being referred to the MH Unit for biopsy
- You, or a relative have a muscle disease that may be associated with a risk of MH, such as central core disease.
- You developed heat stroke after exercise or muscle cell breakdown after exercise (rhabdomyolysis) and your neurologist has recommended a biopsy
I live a long way from a testing centre; can I have the test done at my local hospital?
No. The laboratory tests are highly specialised and the muscle samples need to be taken to the lab within 15 minutes of the muscle biopsy in order for the tests to be reliable.
The four geographical locations available for testing in Australia and New Zealand are:
- Melbourne, Victoria
- Westmead, New South Wales
- Perth, Western Australia
- Palmerston North, New Zealand
What does the muscle biopsy involve?
The muscle biopsy involves taking a small sample of muscle from the outer part of your thigh. The biopsy is a surgical procedure through an incision (cut) in the skin which is usually 5–7 cm long.
The procedure is performed in the operating theatre and usually takes no more than 45 minutes to one hour.
You meet an anaesthetist before surgery who will check your health status and discuss the procedure in detail, giving you the opportunity to ask any questions. You may be offered a choice of general or regional (spinal, epidural or nerve block) anaesthesia but the procedure cannot be done with local anaesthetic only. Different institutions will have slightly different instructions so please click on the link to download instructions relevant to your institution.
Specific instructions for patients at Palmerston North Hospital
Specific instructions for patients at Royal Melbourne Hospital
Specific instructions for patients at Westmead Hospital
Specific instructions for patients at Royal Perth Hospital
How do I look after my wound?
The wound is covered with a clear dressing. It is safe to shower with this dressing on, but you should not bathe or go swimming. In about 2–3 days the dressing will start to peel off around the edges. You will receive a second dressing in your discharge pack, remove the old dressing and cover the wound with the second one. As it starts to peel off, it can be removed and does not need to be replaced.
What if my wound starts to get more painful, reddened or yellow discharge appears?
Wound infection is an uncommon complication, occurring in less than 1% of muscle biopsies. You will need to see your GP for a check and probably start on antibiotics.
When will I get the result of my biopsy?
We will have your results the same day as the biopsy. A member of the MH team will visit you before you leave the hospital and explain the result and what steps need to be taken.
What do I do if my result is negative?
A negative result means you are not at risk of developing MH. For any future operations, no specific precautions relating to MH need be taken.
If you were having the biopsy because you suffered a suspected MH reaction, other family members can be reassured that they are not at risk of developing MH.
However, if you are having the biopsy because a family member had a reaction and you have a negative result, while you and your immediate descendants (children and grandchildren) are fine, other blood relatives may still need to be tested. It is better to check with the doctor at the time of the biopsy.
What do I do if my result is positive?
A positive result means you are at risk of developing MH. The anaesthetist will explain in detail what this means for you. You will have the opportunity to ask any questions and be given more information to take away with you explaining more about MH.
A positive result does not mean that you cannot have surgery, it means that your anaesthetist will need to take extra precautions to prepare the anaesthetic machine for you, and that alternative safe anaesthetic drugs must be used.
Because MH is a genetic condition there is a 50% chance that your children may inherit MH from you.
You should wear or carry some form of alert about your condition so that people are aware of it in an emergency. The unit you attend for your biopsy will help you with this.
There is an association between exertional heat stroke and MH, so we advise against extreme sporting events in high temperatures.
Will I have pain following the biopsy?
If you have a spinal anaesthetic, the local anaesthetic will last for around six hours, and you will have weakness and numbness of your legs for this period. As this wears off you will start to experience some pain and discomfort around the site of the muscle biopsy. If you chose a general anaesthetic, you will still be comfortable from the pain relief given in theatre initially but will require more once this wears off. Pain killers will be prescribed to ease this, and you will be given a script for analgesia on discharge. The pain is similar to a torn muscle and is usually managed with routine painkillers. Paracetamol and Ibuprofen are given most commonly. As some people are unable to tolerate Ibuprofen due to asthma or stomach ulcers, an alternative such as Tramadol or Codeine will be prescribed for the first couple of days.
How long will the pain last?
This varies between patients. Patients experience pain for an average of six days (ranging from 0–60 days) and use pain killers for an average of three days.
How big will my scar be?
The scar is usually 5–7cm long and is located midway on the outer thigh. In a survey of muscle biopsy patients, 96% described their scar as either hardly noticeable or acceptable. 4% described their scar as poor.
Are there any complications of the muscle biopsy?
All surgical procedures carry the small risk of infection.
Many patients have some numbness around the scar initially. This usually gets better within a week or two but can take up to 6 months to fully resolve. Very rarely the numbness persists.
Rarely the area of the biopsy can bleed, resulting in swelling and pain at the site. This will usually settle with compression bandages.
Post-operative pain is usually well controlled with simple analgesics and rest.
Most people can return to work in less than a week unless their job is very strenuous.