Generally, the diagnosis is made through a muscle biopsy, in which a sample of muscle is taken and examined under a microscope. This is done in one of two ways: either a small piece of muscle is taken under general anaesthetic (avoiding the drugs which may cause malignant hyperthermia) or a small sample is removed through a needle biopsy.
Muscle from people affected by Central core disease has a distinctive pattern, with core structures centrally located within the muscle cells. It is important to note however that these structures are also seen in other unrelated conditions. It is important, therefore, for the muscle sample to be considered in conjunction with the physical signs and symptoms and/or molecular tests, in order for a diagnosis of central core disease to be made.
In families where the mutation is known to occur in the RYR1 gene, molecular testing is available. This involves taking a blood sample and analysing the DNA for the presence of a mutation. This process can take up to several months to complete.