Wednesday, November 23, 2011

Charcot Marie Tooth Disease

We’ll return to the skin discussion soon, but I’ve seen two cases of a relatively rare neurological disease walk in the door in the last week, so I thought it would be worth it to talk about it.

Charcot Marie Tooth is a disease that affects the myelin sheaths that cover the nerves in the body.  If we think of a nerve as being an electric wire transmitting signals, myelin is like the insulation around the wire to make the signal travel faster to its destination.  It is precisely a defect in the myelin that causes the signals that the brain sends out to be slower and inconsistent.

The nerves that have to travel the farthest are usually the first to be effected in Charcot Marie Tooth.  Therefore, the small muscles in the feet and legs tend to show the first signs of the disease.  Because these muscles are not being stimulated in a normal fashion, they begin to get smaller and tighten up.  The calf muscles get so small that patient’s legs have been compared to “stork legs” or “upside down champagne bottles.”  The tightening causes the toes to permanently curl up, the arch to be extremely high, and the Achilles tendon to be so tight that you can only walk on the ball of the foot.  As you can imagine, this makes it very difficult to keep your balance when walking.

The disease is progressive, meaning that it starts without any obvious warning, and it worsens year after year.  Due to its slow onset and progressive nature, someone can go years without being diagnosed.  It will become more and more difficult to walk and the pressure on the forefoot can be so dramatic that deep calluses and even ulcerations can form on the ball of the foot.  As the disease progresses, the hand muscles can become involved.

If there is a bright side to this condition, it is that it does not affect a person’s ability to think or their memory.  Their lifespan is expected to be normal.  However, if gone untreated for decades, it may confine a person to a wheelchair.  We’ll discuss next week how to detect the early signs of the disease, the diagnostic tests that can help, and the treatments available.