Skeletal muscle channelopathies
Skeletal muscle channelopathies are rare neuromuscular diseases that cause symptoms of episodic muscle weakness/paralysis or cause difficulty in relaxing muscles (the muscle can feel stuck or cramped) once they are contracted. They affect approximately 1 in 100 000 people in the UK.
They are genetic conditions. Each one is caused by a mutation in a gene that encodes key ion channels that are expressed in muscle.
Ion channels
Ion channels act as gates, opening and closing on command when we want to contract or relax our muscles. Muscle contraction occurs when an electrical signal is conducted along the muscle membrane. The electrical signal is made when positively or negatively charged ions like potassium or sodium move in or out of the muscle cell via one of these specialised channels or “gates”.
Ion channels are therefore very important in controlling muscle excitability and contraction. There are many ion channels in the muscle membrane and each one can malfunction causing different symptoms. This means there is more than one type of muscle channelopathy. Broadly speaking however they are divided into two main groups based on the symptoms they cause:
As these are very rare conditions most general physicians will only see 1 or 2 people with these disorders during their career. Our specialist clinic at the National Hospital for Neurology and Neurosurgery was created to provide a central service that has experience and expertise in diagnosing and managing these conditions. It is directly funded by NHS England to promote equality in health care for rare diseases. Even if a diagnosis of a channel problem has already been made then you may still refer a patient to us for advice on management and treatment of their muscle symptoms.
