Thought I would share my only experience of Anaesthetics. Was involved in an explosion at work which nearly wiped me out anyway (40% burns and touch and go for a week or two). Anyway after 4 weeks I needed some skin grafts so they put me under (this was in 1984 so wasnt aware of malignant hypothermia etc) all appeared to go well until coming round when I couldnt spit out the intubation tube.. I was sort of choking... as I was still incredibly dozy I dont know what happened or what the nurse did but I survived. Guess my throught muscles didnt work to well due to the MC.

Type of Myotonia: Beckers

Country: UK

Pete,

Thanks so much for sharing. I'm glad everything went well although it sounds like the block wasn't much fun. When one of my daughters had to have two inguenal hernias repaired the anesthesiologist was so freaked out by the MC that they did the whole thing with locals. She was only 8 years old and said she stopped counting at 100 shots. Needless to say she has a fear of needles to this day.

Kev, I had exactly the same thing happen to me in the 70s when I had surgery before I was diagnosed with MC. My mom actually had cardiac arrest and woke up with paddle burns - but at least she woke up!

I was just speaking with Dr. Tobin who is the main consulatant for the Malignant Hyperthermia Association and he said the for those of us with MC the succinylcholine is the main culprit, even more so than the inhaled anesthetics. This is a paralyzing agent used for intubation and to keep you from moving around during surgery. The most common trade name is Anectine, so my Medic Alert necklace says "NO ANECTINE" since paramedics and ER staff often give it. There is a much safer alternative for surgery called vecuronium which my family has used with no problem. It wears off quickly and doesn't seem to affect potassium levels as much.

There's a good web page on Wikipedia about succinylcholine you might want to read:

Suxamethonium Chloride/Succinylcholine Information

It's also a good idea to get cholinesterase levels checked before surgery. The higher your levels, the less likely you are to react to the paralyzing agents. Older studies on MC seemed to indicate that we have lower levels than a normal person, probably because of the constant firing of the muscles depleting it. If your levels are low, there are many drugs you need to avoid. I'll paste the list in below.

It's especially important for those of us with Thomsen's to let our affected family members know that some of the drugs being used for Alzheimer's can deplete cholinesterase and make MC worse.

Jan


Drugs to avoid
Drugs containing Succinylcholine - e.g. QUELICIN & ANECTINE

These drugs are commonly given as muscle relaxants prior to surgery. That means that victims of this deficiency cannot receive certain anesthetics.

A dose that would paralyze the average individual for 3 to 5 mins can paralyze the enzyme deficient individual for up to 2 hours. The neuro-muscular paralysis can go on for up to 8 hours.

If this condition is recognized by the anesthesiologist early, then there is rarely a problem. Even if the patient is given succinylcholine, he can be kept intubated and sedated until the muscle relaxation resolves.


Drugs containing Mivacurium - e.g. MIVACRON

Mivacron is also a muscle relaxant that is used prior to inserting a tube for breathing.


Drugs containing Pilocarpine - e.g. SALAGEN

Salagen is used to treat dry mouth. As the name suggests, dry mouth is a medical condition that occurs when saliva production goes down. There are lots of different causes of dry mouth including side effect of various drugs.

Drugs containing Butyrylcholine

Use of butyrylcholine is not common. It can be used to treat exposure to nerve agents, pesticides, toxins, etc.

Drugs containing Huperzine A and Donepezil

These drugs are used to slow the progression of Alzheimer's disease.

Drugs containing Propionylcholine and Acetylcholine

Drugs containing Parathion

Parathion is used as an agricultural pesticide. Exposure to pesticides with Parathion should be avoided.

Procaine drugs e.g. NOVOCAINE

This drug is injected before and during various surgical or dental procedures or labor and delivery. Procaine causes loss of feeling in the skin and surrounding tissues.

Type of Myotonia: Thomsen's MC

Country: US

Hi Jan:

Do you know if it's the novocaine itself or the epinephrine they tend to put in it that's the problem?

Type of Myotonia: Becker Myotonia

Country: USA

Procaine (trade name is Novacain) is a sodium channel blocker like other anesthetics and that in itself isn't a problem. They do add epinephrine to it because it is a pretty strong vasodilator.

However the issue addressed in the article I posted was the fact that it has to be broken down by pseudocholinesterase which we may be deficient in with MC (the other types apparently don't use the same pathway). It's seldom used any more for dental anesthesia or other local anesthetic except for trigger point injections for some reason.

UC Davis has a website with information on neuromuscular diseases and they even say on there that the stiffness is thought to be caused by a deficiency in cholinesterase. (I'll post that along with the link at the bottom of this message.) They say it is "true cholinesterase" and pseudocholinesterase is a bit different.

Here's the definition of the two types from Mayo Medical Laboratories. This is the page that gives the test code for checking serum levels of pseudocholinesterase:

Mayo Labs Cholinesterase Test


From Mayo Medical Laboratories:

Serum cholinesterase, often called pseudocholinesterase (PCHE), is distinguished from acetylcholinesterase or "true cholinesterase," by both location and substrate.

Acetylcholinesterase is found in erythrocytes, in the lungs and spleen, in nerve endings, and in the gray matter of the brain.

It is responsible for the hydrolysis of acetylcholine released at the nerve endings to mediate transmission of the neural impulse across the synapse.

PCHE, the serum enzyme, is also found in liver, pancreas, heart, and white matter. Its biological role is unknown.

The organophosphorus-containing insecticides are potent inhibitorscof the true cholinesterase and cause depression of PCHE. Low values of PCHE are also found in patients with liver disease. In general, patients with acute hepatitis and chronic hepatitis of long duration will show a 30-50% decrease in PCHE values, while patients with advanced cirrhosis and carcinoma with metastases will show a 50-70% decrease.
Essentially normal values are seen in chronic hepatitis, mild cirrhosis, and obstructive jaundice.

PCHE metabolizes the muscle relaxants succinylcholine and mivacurium, and therefore, alterations in PCHE will influence the physiologic effect of these drugs.

In normal individuals (approximately 94% of the population) certain drugs and other agents, such as dibucaine and fluoride, will almost completely inhibit the PCHE activity.

A small number of patients (<1% of the population) are homozygous for an atypical gene controlling PCHE. These individuals generally have low levels of PCHE which are not inhibited by dibucaine and fluoride, will not hydrolyze the drugs succinylcholine and mivacurium rapidly enough, and may enter a period of prolonged apnea.

In addition to fluoride and dibucaine alleles, a "silent gene" has also been identified which shows little or no activity. More recently, the J and K variants also have been identified. All combinations of heterozygotes of the various alleles have been found. This is important because these atypical enzymes will show varying levels of enzyme activity and resistance to dibucaine although the patients clinically show prolonged apnea.

-----------------------

You may remember I've cautioned everyone about both pesticides and compounds fluorine/fluorides including fluoridated drinking water because of this effect. The weedkiller, 2,4-D is different in that it directly affects the function of the chloride channel.

I was planning to get my levels checked this month even before the topic came up because I was exposed to a broken refrigeration line at a grocery store a few weeks ago and have had trouble breathing ever since. It contained an older type of refrigerant that had fluorine.

Anyway, back in the 40s and 50s the researchers seemed to think that a cholinesterase deficiency was actually the cause of MC, but now they know it's likely just an effect. Here's the UC Davis website: with an excerpt from the section on MC:

Myotonia and Cholinesterase Deficiency


Protein muscle chloride channel

Gene Location 7q35

Abstract Disease subtype: Thomsen's disease; Becker's disease.

Myotonia congenita is a rare inherited disorder in which an abnormality of the skeletal muscle membranes causes an unusually exaggerated response to stimulation (hyperexcitability). It is caused by a genetic mutation involving the chloride channel of the muscles.

The disorder is thought to involve the deficiency of a muscle enzyme known as true cholinesterase. As a result, muscle relaxation after contraction (myotonia) is slow in affected individuals, and affected muscles may be abnormally stiff and rigid. Muscle stiffness, particularly in the legs, may be enhanced by cold and inactivity.

Type of Myotonia: Thomsen's MC

Country: US

Thank you Pete!!!!

Type of Myotonia: Beckers

Country: United States of America