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Re: Is this a type of Myotonia?

It does sound like either hyperkalemic periodic paralysis or paramyotonia congenita. Both are caused by mutations in the sodium ion channel in the gene SCN4A. You can get DNA testing at Fullerton Genetics Lab or Athena Diagnostics. I would ask for a referral to a geneticist who can help set up the testing.

Also if you haven't seen this site, it has lots of information on HyperKPP and PMC:
http://hkpp.org

Jan

Type of Myotonia: Thomsen's

Country: US

Re: Is this a type of Myotonia?

So that is how myotonia presents itself? Good to know. ( I was worried it was only in the hands, or something, or was more discrete than that (I heard references to being unable to let go during a handshake)).

I've had genetic testing for the "six most likely" genes for periodic paralysis (which probably included SCN4A?), and it came back negative. I've heard that something like 30% of people with periodic paralysis don't have a mutation in those six genes, so I'm trying to get enough information to decide whether to continue pursuing periodic paralysis or try to find a different type of specialist and get a new hypothesis. (I don't see my doctor until January, so have to make the decision on getting a second opinion on my own for now).

Type of Myotonia: ???

Country: USA

Re: Is this a type of Myotonia?

Jennifer, did you have an EMG to look for myotonic discharges? That is usually the first step toward getting a diagnosis for a myotonic disorder. Sometimes with paramyotonia congenita the muscle has to be chilled for the myotonia to show up, so they immerse your arm in ice water or have you hold an ice pack over it first (usually the bicep).

There are over 50 gene mutations associated with myotonia in the SCN4A gene. What you want to request is gene sequencing. That means they will look at all the single nucleotide polymorphisms for that gene and determine if you have any variants that might be causing the symptoms. Fullerton Genetics Lab is very good...I would personally recommend them.

One of the best teams for diagnosing periodic paralysis would be Dr. Griggs and Dr. Tawil at the University of Rochester:

Dr.Robert Griggs

You can make an appointment through the MDA clinic. There are several others across the country. If you want to email me I can try to get you some names close to where you live.

Diet and avoiding triggers can make a huge difference in the sodium channel mutations. Here are a few links:
Diet for Patients with HyperKPP and PMC
How to Determine What Triggers Attacks

Jan

Type of Myotonia: Thomsen's

Country: US

Re: Is this a type of Myotonia?

I have not had an EMG (though I'm meeting with my GP tomorrow to ask how to get one. The doctor I am seeing in January is being vague about what his next steps are, and I suspect he only does genetic testing (since he's a neurogeneticist)).

If my GP can't help me, what sort of doctors would normally do an EMG, especially one with a chilled muscle? I've been to our local Neuromuscular specialist and he was no help at all. He said "it's not neuromuscular" after a five minute visit, and when I pressed him he said it "just wasn't". and refused to perform tests. If I knew WHY he thought it wasn't, then at least I'd have something to tell my other doctors.

I've looked over my genetic report and can't tell how many mutations they looked for on each gene, or even which genes were tested. " HHPPD PANEL; Hypokalemic and Hyperkalemic Periodic Paralysis Disorders NextGen DNA Sequencing Panel (6 Genes)" is the most it says.

I'll email you to learn about other doctors, thanks so much for the help!

I'm actually very lucky in that I've been documenting my symptoms when I collapse for over five years, and have a daily food and symptom diary since a few months before the stiffness/weakness got so pronounced. As near as I can tell, my two main triggers are being hungry and current or past exertion (I haven't noticed any particular type of food giving me symptoms, including those high in potassium, though i tend to pair every meal with a carb). The diet you linked is very interesting, since it mirrors what I've come up with trial and error (eating carbs frequently, but with a protein to stabilize my blood sugar, small frequent meals over large ones)

Type of Myotonia: ???

Country: USA

Re: Is this a type of Myotonia?

Hi, Jennifer
The genes tested for (NGS332) are:

CACNA1S (114208); CLCN1 (118425); KCNJ18 (613236); KCNJ2 (600681); SCN4A (603967); SLC12A3 (600968)

If you Google the numbers in prn you will find detailed descriptions of the phenotypic disorders that they create.

Your condition (if it involves one of those tested) may fall in between those described.

Also; If you were positive for any of the defects tested, then you should have been informed. Call up and ask, If you were negative they will probably tell you.

Good hunting

Joe

Type of Myotonia: scn4a

Country: NC US

Re: Is this a type of Myotonia?

Thanks so much! I have no idea why it didn't occur to me to google the test number. (I suppose 'modern medicine' and 'the internet' still haven't associated themselves in my brain).

The test report does say "negative", just not anything about the specific genes, so I assume that I'm negative for them all. It sounds like I might get an EMG soon, just waiting to hear back from a neurologist.

Type of Myotonia: ???

Country: USA

Re: Is this a type of Myotonia?

Hi, Jennifer
Here is a page to help. This address is for a chart that is well down the page but the whole page is useful. It is written for doctors so you may have to do other reading to support your understanding of it.
I used the chart for self diagnosis when I got no other help. I suggest printing the chart and marking out the things that obviously do not apply to your condition.

neuromuscular.wustl.edu/mtime/mepisodic.html#clinical

Paste the address into the address bar of your browser.

Joe Gilbert

Type of Myotonia: Scn4a PAM?

Country: NC US

Re: Is this a type of Myotonia?

Thank you so much!

That chart indicates that Paramyotonia tends to have very mild weakness associated with it, so that seems to imply that Hyperkalemic Periodic Paralysis is more likely because of my severe weakness. I've heard the two conditions can co-occur, though, and wonder how that presents itself.

Type of Myotonia: ???

Country: USA