Charcot-Marie-Tooth disease is a group of progressive disorders that affect the peripheral nerves. Peripheral nerves connect the brain and spinal cord to muscles as well as sensory cells that detect sensations such as touch, pain, heat, and sound.
Symptoms of Charcot-Marie-Tooth disease usually begin in adolescence or early adulthood, but onset may occur anytime from early childhood to mid-adulthood. Symptoms vary in severity. Some people never realize they have the disorder, but most have a moderate amount of physical disability, and a small percentage of people experience severe weakness. Many people with this disorder lead active lives and have normal life expectancies.
Typically, the earliest symptoms involve muscle weakness in the feet, which can cause foot abnormalities such as high arches (pes cavus) or curled toes (hammer toes). It may become difficult to hold up the foot or to walk on the heel of the foot. These difficulties may cause a higher than normal step (or gait) and can increase the chance of ankle injuries and tripping. As the disease progresses, muscles in the lower legs usually weaken, but leg and foot problems rarely require the use of a wheelchair.
Later symptoms may include muscle weakness in the hands, causing difficulty with daily activities such as writing, fastening buttons, and turning doorknobs. Because signals to sensory cells can be disrupted in Charcot-Marie-Tooth disease, people with this disorder may also notice some numbness, feel pain in the feet and lower legs, or experience a decreased sensitivity to heat and cold. In rare cases, sensory loss can include gradual hearing impairment and deafness.
Different types of Charcot-Marie-Tooth disease can be distinguished by the abnormality that disrupts nerve function and by the genetic cause. Type X Charcot-Marie-Tooth disease is caused by mutations in a gene on the X chromosome, one of the two sex chromosomes. Type 1 Charcot-Marie-Tooth disease is characterized by abnormalities in myelin, the protective substance that covers nerve cells. Type 2 Charcot-Marie-Tooth disease is characterized by abnormalities in the fiber, or axon, that extends from a nerve cell and transmits nerve impulses. In intermediate forms of Charcot-Marie-Tooth disease, abnormalities occur in axons and myelin. Type 4 Charcot-Marie-Tooth disease affects either the axon or myelin. Types 1, 2, 4, and intermediate forms are further categorized by subtypes (such as 1A, 2A, 4A). Subtypes are distinguished by the specific gene that is altered.
No universal system is used to classify types of Charcot-Marie-Tooth disease, and sometimes other names are used to describe this disorder. For example, Roussy-Levy syndrome is a form of type 1 Charcot-Marie-Tooth disease (type 1B). Dejerine-Sottas syndrome is a severe, early childhood form of Charcot-Marie-Tooth disease that may be type 1 or type 4 (depending on the specific gene that is altered).
Posts: 1078 | From Fairland | Registered: Apr 2006
| IP: Logged |
The Lyme Disease Network is a non-profit organization funded by individual donations. If you would like to support the Network and the LymeNet system of Web services, please send your donations to:
The
Lyme Disease Network of New Jersey 907 Pebble Creek Court,
Pennington,
NJ08534USA http://www.lymenet.org/
UBBFriend: Email this page to someone!
Printer-friendly view of this topic