Central Core Disease

Central core disease (CCD) is a rare neuromuscular disorder that is most often characterized by weakness in the legs, but occasionally affects other muscles groups. CCD is not progressive. It is occasionally the result of a spontaneous gene mutation, but most of the time it is an inherited disorder. CCD’s inheritance is autosomal dominant, meaning that only one parent needs to pass the defective gene on for an affected person to have the disease. This faulty gene can come from either parent, and it can affect either sex.

CCD gets its name from the abnormal cores that are found in the muscle cells and run the length of the muscle fiber. Visible only under a microscope, these cores appear empty, as if there is no metabolic activity. They also lack mitochondria. Responsible for a cell’s energy production, mitochondria are the principal source of energy of a cell. For unknown reasons, however, there is no correlation between the number of fibers with these cores and the severity of the disease. In fact, it has been estimated that as many as 40 percent of those people who have cores found in their muscle cells have no symptoms of CCD.

One possible explanation for the core’s existence is a faulty calcium release mechanism in the cell. Under normal circumstances, when a muscle contracts, the nervous system sends a signal causing a burst of calcium to be released. The calcium stays in the cell long enough to start a contraction and then drains out.

For patients with CCD, calcium leaks into the main part of the cell even when the muscle isn’t contracting. Because of this, there is less calcium available to provide the burst for the contraction. The constant presence of calcium might also destroy the mitochondria, thus creating the "cores."

The most common symptom of CCD is weakness in the legs. This weakness prevents people with the disorder from running or jumping, and makes climbing stairs difficult. The degree of weakness is highly variable, but only in rare cases is CCD disabling. Nevertheless, orthopaedic injuries are not uncommon in CCD, especially hip dislocations, which are due to a lack of muscular development around the hip. Other orthopaedic problems often associated with CCD include scoliosis, foot deformities, and muscle contractures in the knee and hip.

Symptoms of CCD usually begin within the first year of life, and infants often have poor muscle tone (floppiness) and fatigue, easily tiring out even when feeding. As a child with CCD grows, his or her strength builds, but weakness persists, often delaying motor development,  such as sitting, by months and walking by a few years.

If a doctor suspects that a patient has CCD, a muscle biopsy will confirm the diagnosis. During a muscle biopsy, the doctor removes a small sample of the muscle tissue and sends it to a laboratory for testing. However, reaching the point of testing for CCD might not be easy. CCD is a rare disorder, and its symptoms can be so mild that it might sometimes takes years before the proper diagnosis is made. CCD is sometimes misdiagnosed as Limb-Girdle muscular dystrophy.

Treatment and management
There is no specific treatment for CCD, but its symptoms can be treated. Treatment might include physical therapy and prescribed exercises. While aquatic exercises are considered a good program for patients with CCD, the verdict is still out on other forms of exercise, which, in some cases, cause muscle cramps and stiffness. For some patients with CCD, surgery might be an option. The risks of surgery, however, might outweigh its potential benefits.

For reasons that are unclear, people with CCD are susceptible to a life-threatening condition known as malignant hyperthermia. Malignant hyperthermia is an inherited condition that causes muscle rigidity and uncontrollable fever in reaction to the administration of certain anesthetics. One of the most common anesthetics, a combination of halothane and succinylcholine, is among those that can cause this reaction. It is therefore very important that you consult your doctor if you are considering any type of surgery. Surgery is possible for patients with CCD, it just requires extra precautions. Since CCD is an inherited disorder, surgical precautions should be taken for children of people with this disorder even if the children have no symptoms of CCD. Malignant hyperthermia is such a serious condition that some doctors advise patients with CCD to wear a MediAlert bracelet in case of an accident or emergency.

If a healthy diet and lifestyle are maintained, there is no reason why patients with CCD shouldn’t have a normal life expectancy and lead full active lives. As with many other conditions, education about CCD and local support groups can be the greatest tools for managing the disorder and preventing complications. The following organizations can provide additional information about CCD:

Muscular Dystrophy Association
3300 E. Sunrise Drive
Tucson, AZ 85718
(800) 572-1717

National Institute of Neurological Disorders and Stroke
P.O. Box 5801
Bethesda, MD 20824
Phone: (800) 352-9424

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This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. For additional health information, please contact the Center for Consumer Health Information at the Cleveland Clinic (216) 444-3771 or toll-free (800) 223-2273 extension 43771. If you prefer, you may visit www.clevelandclinic.org/health/ or www.clevelandclinicflorida.org. This document was last reviewed on: 4/15/2001