Central core disease

Definition

Central core disease (CCD) is an inherited muscle disorder that affects many of the voluntary muscles necessary for movement. The hips and legs are particularly affected. Although central core disease is disabling, it is not fatal.

Description

First described in 1956, central core disease is one of a group of muscle disorders, or myopathies, named for certain abnormalities found in the muscle biopsies of people with the syndrome. CCD occurs when the central parts, or cores, of certain muscle cells are metabolically inactive, meaning they do not produce energy correctly. This happens because the cores lack a substance called mitochondria, the energy-producing parts of the muscle cells.

According to the Muscular Dystrophy Association, a muscle cell produces thousands of proteins during its lifetime. With all of the inheritable diseases of muscle, an altered gene leads to an absence of, or abnormality in, one of the proteins necessary for normal functioning of a muscle cell.

Scientists are pursuing a number of promising leads in their quest to understand the causes of CCD. New research suggests that muscle cells that have difficulty regulating calcium may cause central core disease.

Although CCD is not a progressive illness, different people experience varying degrees of weakness. Some children with CCD show mildly delayed motor milestones, then catch up and appear only slightly uncoordinated. Others have more severe delays, but also catch up somewhat and are able to walk and move about, although with more limitations. Some children use braces for walking, and a few use wheelchairs.

Genetic profile

Central core disease is inherited as a dominant trait, meaning that an individual with CCD has a 50% chance of passing the disorder on to each child. There are also occurrences of sporadic inheritance , which means that a gene alters spontaneously to cause the disorder in a person with no family history of the disease. In 1993, researchers identified the abnormal gene responsible for CCD. This finding has been important in understanding what causes central cores in the muscle and why the muscles of people with CCD are weak. According to scientific findings, an abnormality in a gene on chromosome 19 may lead to the disease.

Demographics

The disease becomes noticeable in early childhood, when muscle cramps are often present after exercising or performing other physical activities. Central core disease is often seen as "floppiness" in a newborn baby, followed by periods of persistent muscle weakness.

Signs and symptoms

Symptoms of central core disease are usually not severe; however, the disease can be disabling. A mild general weakness and hip displacement are key characteristics of the disease. Individuals with CCD reach motor skill milestones much later than those without the disorder. A child with the disease cannot run easily, and jumping and other physical activities are often impossible.

Other long-term problems caused by CCD include hip dislocation and curvature of the spine, a condition known as scoliosis . Central core disease also causes skin rash, muscular shrinkage, endocrine abnormalities, heart problems, or mental problems.

Diagnosis

The diagnosis of central core disease is made after several neurological tests are completed. These tests involve checking an individual's coordination, tendon reflexes such as the knee-jerk reaction, walking ability, and the ability to rise from a sitting position. A serum enzyme test might also be performed to measure how much muscle protein is circulating through the blood.

Treatment and management

Treatment measures greatly depend on the severity of the individual's symptoms, especially the degree of muscle weakness that is involved. Treatment measures include surgical procedures, pain management, muscle stimulation therapy, and physical therapy.

According to the Muscular Dystrophy Association, people who have central core disease are sometimes vulnerable to malignant hyperthermia (MH), a condition brought on by anesthesia during surgery. Malignant hyperthermia causes a rapid, and sometimes fatal, rise in body temperature, producing muscle stiffness. When susceptible individuals are exposed to the most commonly used general anesthetic, their muscles can become rigid and their body temperatures can rise to dangerous levels.

Prognosis

Fortunately, the outlook for children with this disease is generally positive. Although children with central core disease start their life with some developmental delays, many improve as they get older and stay active throughout their lives.