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Skeletal Muscle Channelopathies

Skeletal muscle channelopathies are rare neuromuscular diseases that cause symptoms of episodic muscle weakness or paralysis or a difficulty in relaxing muscles (the muscles can feel stuck or cramped) after they are contracted. Approximately 1 in 100 000 people in the UK has a muscle channelopathy.

Muscle channelopathies are genetic conditions caused by mutations in genes that code for proteins in muscles called ion channels. Ion channels act like gates. When these channels or “gates” open and close positively or negatively charged ions like potassium or sodium can move in and out of the muscle cell creating an electrical signal. Muscle contraction occurs when this electrical signal moves along the muscle membrane.

There are different types of ion channels in the muscle membrane and each one can malfunction. This means there is more than one muscle channelopathy including:

  • Hypokalaemic periodic paralysis
  • Hyperkalaemic periodic paralysis
  • Andersen-Tawil syndrome (ATS)
  • Myotonia congenita
  • Paramyotonia congenita
  • Sodium channel myotonia (sometimes called potassium sensitive myotonia)

Nerve Channelopathies

Nerve channelopathies include episodic pain syndromes and peripheral nerve hyperexcitability (PNH) disorders. Episodic pain syndromes are genetic disorders including:

  • Familial episodic pain syndrome
  • Paroxysmal extreme pain disorder
  • Inherited erythromyalgia
  • Congenital insensitivity to pain

PNH disorders can be genetic or may be acquired e.g. related to an autoimmune condition.

General information

The muscle and nerve channelopathy clinic is run by Dr Matthews. If you are referred to the clinic it will be to determine whether you have a muscle channelopathy. If you already have a diagnosis you may still be referred for treatment. When you attend clinic you will be asked questions about your symptoms and be examined. You may also have neurophysiology tests (electrical recordings of the nerves and muscles), blood tests (including the option of genetic tests) and an ECG (electrical recording of the heart). An MRI scan of your muscles may be arranged. A muscle biopsy is not routinely needed to make a diagnosis of muscle channelopathy but may be performed in complex cases.

Treatment options include lifestyle and exercise advice including input from a neurophysiotherapist and drug treatments to help control the muscle and nerve symptoms.

The clinic has close links with genetic and cardiology colleagues who may also be asked to be involved in your care.