Frequently Asked Questions

Category: MH and Pregnancy

Is dantrolene (the antidote for MH) considered safe to use in obstetrics should an MH episode occur?

While dantrolene can be given to a pregnant woman, it does cross the placenta and there are side effects in the neonate. This again is just a risk and would have to be weighed against the expected benefit. Weakness in the neonate might be expected and must be looked for and treated appropriately. An article published in 1988 suggests that at low dose, there are no problems. (Am J Obstet Gynecol., Oct 1988;159(4):831-4.

Is an epidural safe for a malignant hyperthermia susceptible patient?

Epidurals are safe for MH affected individuals and safe for the baby as well. All measures should be taken to decrease your stress during labor and delivery.

Doctor's tell me that local anesthesia is OK, and I only need to worry about the generals. Is that statement true?

All local anesthetics are safe.

Safe and Unsafe Anesthetics

A comprehensive list of anesthetics that are safe for MH susceptible patients, and those that are known triggers for MH

How will I know if I am having an MH reaction? I'm afraid I will fall asleep and not know?

There is no report of an MH reaction occurring during labor and delivery unless triggering general anesthetic agents are given. You need not worry about this happening while you are asleep naturally. The pain management you will receive is very safe.

Wouldn't it be safer to schedule the procedure, i.e., schedule a C-section? That way the anesthesia would be controlled.

No – deliver the baby vaginally if recommended by your obstetrician. There are many risks other than MH associated with anesthesia for the C-section, the mother and the baby. Vaginal delivery with labor analgesia is perfectly safe for the MH-susceptible patient.

Do I need to specify to the anesthesia care provider any particular drugs or amounts to use or avoid?

No, just remind the staff that you are MH susceptible when you arrive in the labor suite.

Should the baby be treated as MH susceptible?

We have to assume your child is susceptible; but, as long as you are receiving safe anesthesia, your baby is not at risk either. Of interest, there are very few reports of infants triggering with MH, even when an individual is later proven to have MH. MH-susceptible baby pigs do not trigger consistently either. There is apparently some protection offered by immaturity. Your baby boy will not be at risk with the epidural or from local anesthesia used for the circumcision.

My internist has told me to avoid drugs such as phenergan because it is related to anti-psychotic drugs that can cause an MH-like reaction. Is this true? If so, which drugs should I avoid that may be present during delivery?

Your internist is advising you well, but very conservatively. Some anti-psychotic agents cause a condition called neuroleptic malignant syndrome (NMS), which looks something like MH but has a different underlying cause.

Nonetheless, the conservative approach is to avoid this class of drugs in MH-affected patients. Phenergan is used for nausea in the hospital; it is unlikely you would need it, but it would be reasonable to avoid this class.

The drugs used for labor analgesia are safe.

Neuroleptic Malignant Syndrome Information Service