Do you know why your muscles lock up? - UnlockNDM

Do you know why your muscles lock up?

Are you worried that your muscles “lock up” when you perform everyday tasks, or do you experience an unexpected inability to move during an activity, such as climbing stairs or standing up from a chair, which sometimes may even cause you to fall? Do you sometimes feel like your muscles remain stiff, yet at the same time they feel weak? Have you experienced unexplained stiffness in your face that has affected your ability to speak or eat?

You may be experiencing “myotonia”, which is a symptom associated with a group of rare diseases that affect muscles called non-dystrophic myotonia, or NDM.^1,2

Symptoms of NDM vary, however people with NDM commonly experience “locking” of their muscles during everyday tasks and movements; often describing these experiences as stiffness, cramps or weakness.² Some people also experience muscle pain and fatigue.^3,4 You may not experience problems with your muscles all the time, as NDM can be triggered or made worse by certain situations.²

If this sounds like it could be you, this site is here to help you learn more about NDM.

References

Diaz-Manera J. EMJ. 2021;6[2]:37-46
Hahn C, Salajegheh MK. Iran J Neurol 2016;15:46–53
Trip J, et al. J Neurol 2009;256:939–947
Vereb N. J Neurol. 2021; 268(5): 1708–1720

UK-NDM-2202-00002 June 2022

Foods to avoid on a low-potassium diet*

Fruit^1,2
Vegetables^1,2
Beans/legumes^1,3
Other^1-3

Avocado
Artichoke
Baked beans
Bran cereal

Apricots
Beetroot
Kidney beans
Dairy (eg yoghurt, milk)^†

Bananas
Brussel sprouts
Lentils
Nuts

Dried fruits eg dates, raisins and prunes
Broccoli (cooked)
Brown rice

Grapefruit
Okra
Salt substitutes

Kiwi
Parsnip
Wholewheat bread and pasta

Mango
Potatoes (processed or with skin on)

Melons
Cooked spinach

Nectarines
Tomato (concentrated, eg. Tomato puree)

Oranges and orange juice

Papaya

Pomegranate and pomegranate juice

Fruit^1,2

Avocado

Apricots

Bananas

Dried fruits eg dates, raisins and prunes

Grapefruit

Kiwi

Mango

Melons

Nectarines

Oranges and orange juice

Papaya

Pomegranate and pomegranate juice
Vegetables^1,2

Artichoke

Beetroot

Brussel sprouts

Broccoli (cooked)

Okra

Parsnip

Potatoes (processed or with skin on)

Cooked spinach

Tomato (concentrated, eg. Tomato puree)
Beans/legumes^1,3

Baked beans

Kidney beans

Lentils
Other^1-3

Bran cereal

Dairy (eg yoghurt, milk)^†

Nuts

Brown rice

Salt substitutes

Wholewheat bread and pasta

*Meat and fish contain a moderate amount of potassium but they are an important source of protein so shouldn’t be avoided; ^†Dairy products contain potassium but are an important source of calcium so should be consumed in moderation

References

WebMD. Low-potassium diet: what to know? Available at: https://www.webmd.com/food-recipes/low-potassium-diet-foods ; Accessed February 2022
St Georges Kidney Patients Association. Eating on a low potassium diet. Available at: https://www.sgkpa.org.uk/main/eating-well-on-a-low-potassium-diet-2 ; Accessed February 2022
NHS. Information for people on a low potassium diet. Available at: https://www.nth.nhs.uk/content/uploads/2019/02/PIL1061-Information-for-people-following-a-low-potassium-diet-Final-11.02.19-LP.pdf ; Accessed February 2022

NDM type¹
Symptoms^2,3
Which type of ion channel? ^2,3
How is it inherited?^2,3

Thomsen myotonia congenita
(also called Thomsen myotonia or autosomal dominant myotonia congenita)
Lower limbs tend to be more affected, although can also affect the arms, hands and face. Stiffness may be worse when you first try to move after a period of inactivity, and may ease as you ‘warm up’.
Chloride (Cl-)
Autosomal dominant

Becker myotonia congenita
(also called Becker myotonia, Becker disease, generalized myotonia, recessive generalized myotonia or autosomal recessive myotonia congenita
Lower limbs tend to be more affected, although can also affect the arms, hands and face. Stiffness may be worse when you first try to move after a period of inactivity, or if you are startled, and may ease as you ‘warm up’. Sometimes people with Becker myotonia congenita experience temporary weakness after an episode of myotonia.
Chloride (Cl-)
Autosomal recessive

Paramyotonia congenita
(Also called Eulenburg disease, paralysis periodica paramyotonia, paramyotonia congenita of von Eulenburg, PMC or von Eulenburg’s disease)
Myotonia mainly affects hands and face and gets worse with exercise. Cold is also a key trigger of myotonia, and muscle weakness after an episode of myotonia may last hours or sometimes days.
Sodium (Na+)
Autosomal dominant

Sodium channel myotonia, SCM:
myotonia permanens and myotonia fluctuans, acetazolamide-responsive myotonia (ARM) previously known as Potassium aggravated myotonias (PAM)
Potassium-aggravated myotonia is a rare form of NDM that affects all areas of the body. Myotonia attacks are triggered by eating potassium-rich foods. Symptoms may fluctuate widely from day to day (myotonia fluctuans) or are constant and severe (myotonia permanens).
Sodium (Na+)
Autosomal dominant

Other closely related sodium disorders with myotonia
(including hyperkalemic paralysis or hyperPP)
Myotonia is usually mild, and often involves the eyelids, hands, and tongue. Attacks of weakness can occur at any time and are commonly triggered by rest following exercise, fasting, eating potassium-rich foods or stress.
Sodium (Na+)
Autosomal dominant

References

Stunnenberg B. Muscle Nerve. 2020 Oct; 62(4): 430–444
Hahn C, Salajegheh MK. Iran J Neurol 2016;15:46–53
Matthews E, et al. Brain 2010:133; 9–22

NDM type¹

Thomsen myotonia congenita

(also called Thomsen myotonia or autosomal dominant myotonia congenita)

Becker myotonia congenita

(also called Becker myotonia, Becker disease, generalized myotonia, recessive generalized myotonia or autosomal recessive myotonia congenita

Paramyotonia congenita

(Also called Eulenburg disease, paralysis periodica paramyotonia, paramyotonia congenita of von Eulenburg, PMC or von Eulenburg’s disease)

Sodium channel myotonia, SCM:

myotonia permanens and myotonia fluctuans, acetazolamide-responsive myotonia (ARM) previously known as Potassium aggravated myotonias (PAM)

Other closely related sodium disorders with myotonia

(including hyperkalemic paralysis or hyperPP)
Symptoms^2,3

Lower limbs tend to be more affected, although can also affect the arms, hands and face. Stiffness may be worse when you first try to move after a period of inactivity, and may ease as you ‘warm up’.

Lower limbs tend to be more affected, although can also affect the arms, hands and face. Stiffness may be worse when you first try to move after a period of inactivity, or if you are startled, and may ease as you ‘warm up’. Sometimes people with Becker myotonia congenita experience temporary weakness after an episode of myotonia.

Myotonia mainly affects hands and face and gets worse with exercise. Cold is also a key trigger of myotonia, and muscle weakness after an episode of myotonia may last hours or sometimes days.

Potassium-aggravated myotonia is a rare form of NDM that affects all areas of the body. Myotonia attacks are triggered by eating potassium-rich foods. Symptoms may fluctuate widely from day to day (myotonia fluctuans) or are constant and severe (myotonia permanens).

Myotonia is usually mild, and often involves the eyelids, hands, and tongue. Attacks of weakness can occur at any time and are commonly triggered by rest following exercise, fasting, eating potassium-rich foods or stress.
Which type of ion channel? ^2,3

Chloride (Cl-)

Chloride (Cl-)

Sodium (Na+)

Sodium (Na+)

Sodium (Na+)
How is it inherited?^2,3

Autosomal dominant

Autosomal recessive

Autosomal dominant

Autosomal dominant

Autosomal dominant

References

Stunnenberg B. Muscle Nerve. 2020 Oct; 62(4): 430–444
Hahn C, Salajegheh MK. Iran J Neurol 2016;15:46–53
Matthews E, et al. Brain 2010:133; 9–22