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Symptoms of NDM

People with NDM can experience a range of symptoms, but the severity and triggers of symptoms may vary.1 The common symptom shared by all people with NDM is myotonia.

People with NDM may struggle to exercise or even carry out simple movements such as walking up the stairs.2

“I can no longer pick up my son or hold him when he is given to me.”

— KT, Becker myotonia

Myotonia means that after a muscle is used (a muscle contraction), it does not relax as quickly as it should. For people with NDM, myotonia may feel like stiffness, cramps or as if their muscles “freeze” or have “locked up”. Depending on which muscles are most affected, myotonia symptoms may make some daily activities troublesome, from using stairs, chewing, releasing a fist, or getting up from a chair.1,3 NDM tends to only affect skeletal muscles.3

If you think you are experiencing myotonia, this does not necessarily mean you have NDM. NDM is a rare disease, and there are other conditions where myotonia is also a symptom. To get an accurate diagnosis you will need a thorough medical investigation and it may be necessary to see a doctor with additional training in conditions like NDM, at a specialist centre.

NDM is not a single condition, it is a group of disorders, which share similar symptoms. The areas of the body that are affected, symptom severity and triggers differ according to NDM type.

Some people with NDM find that their muscles get bigger, which is called muscle hypertrophy.3 Whereas, others may experience their muscles weakening, which is called myopathy. People with NDM can also feel pain in their muscles, although for some myotonia will be pain-free.4 Around half of people with NDM report feeling fatigue, which means excessive tiredness that may not be cured by rest.

If your symptoms are affecting your quality of life, or if you are experiencing pain, you should speak to your doctor about how this can be managed.4 It is important to remember that NDM is a rare disease, and many doctors will have never met or treated anyone with NDM before. Preparing for a visit to the doctor can help you to help them understand the challenges you face.

Symptoms of NDM can change from day to day, and people with NDM often describe their symptoms as unpredictable.1,5 Tracking your symptoms in a diary may help you see when they are better or worse, and help you unlock any patterns. This information may also be useful for your healthcare team to understand how NDM is affecting your quality of life, and to help them develop a care plan specifically for you.

References
  • Hahn C, Salajegheh MK. Iran J Neurol 2016;15:46–53
  • Diaz-Manera J. EMJ. 2021;6[2]:37-46
  • Matthews E, et al. Brain 2010:133; 9–22
  • Vereb N. J Neurol. 2021; 268(5): 1708–1720
  • Heatwole CR, et al. Muscle Nerve 2013;47:632-648

UK-NDM-2202-00008 February 2022

Foods to avoid on a low-potassium diet*

  • Fruit1,2
  • Vegetables1,2
  • Beans/legumes1,3
  • Other1-3
  • 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

  • Fruit1,2

    Avocado

    Apricots

    Bananas

    Dried fruits eg dates, raisins and prunes

    Grapefruit

    Kiwi

    Mango

    Melons

    Nectarines

    Oranges and orange juice

    Papaya

    Pomegranate and pomegranate juice

  • Vegetables1,2

    Artichoke

    Beetroot

    Brussel sprouts

    Broccoli (cooked)

    Okra

    Parsnip

    Potatoes (processed or with skin on)

    Cooked spinach

    Tomato (concentrated, eg. Tomato puree)

  • Beans/legumes1,3

    Baked beans

    Kidney beans

    Lentils

  • Other1-3

    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
  • Symptoms2,3
  • 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)

  • Symptoms2,3

    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