Rising arch signals developing nerve disease

Conway McLEAN, DPM

Bob had never been particularly athletic, and was always considered a serious “klutz,” although he noticed his motor skills becoming more troublesome as a young adult. Bob thought of himself as a bit of nerd, which was mostly due to the fact he was never any good at sports. In his early 20’s, some falls he suffered while simply walking were mildly disconcerting, but skinned knees were the only result, except, of course, his wounded pride. Bob was in reasonable health, at least he told himself so, despite always being very cold intolerant, which was difficult, living in a northern clime as he did. That, and his lack of stamina, were his only health issues. Or so he thought.

Over time, the falls became more frequent, which was also around the time he began to notice a change in the appearance of his feet. It seemed like his arches were changing, becoming higher, more pronounced. His shoes no longer fit him well, which he found quite strange. Bob had heard of people whose arches had fallen, but never the reverse. This was what stimulated him to see a podiatrist, who diagnosed him with a cavus foot type. This can be a simple, inherited variation of normal anatomy, yet the doctor seemed disturbed to learn that this was a new finding, and not previously the case.

Bob was sent for a study of his nerves, a test that was quite uncomfortable. Real discomfort, though only emotional, was experienced when he learned the ability of his nerves to transmit a signal was impaired, and distinctly delayed. This news triggered a referral to a neurologist, a nerve doctor. Another detailed exam was performed, along with an extensive history, and this was followed by the decision to perform genetic testing (which required only a sample of blood, fortunately).

Bob was given a diagnosis of Charcot-Marie-Tooth disease, an inherited disorder of the peripheral nervous system (those nerves not residing in the spinal cord and brain). He knew little about his family’s genetic health history, but apparently this meant that his mother had passed on the genes for the condition. It also carried with it the news that his symptoms could become more severe. And there was no cure, although research is ongoing.

The three physicians who first identified it gave the disease its name back in 1886. CMT (from doctors Charcot, Marie and Tooth) is also called Hereditary Motor and Sensory Neuropathy, which means that it affects nerves controlling voluntary muscles, as well as those that provide different sensations. Some typical features include weakness of the foot and lower leg muscles, which can result in foot drop (where the individual is unable to pick up the foot sufficiently to walk without stumbling). Tripping and falls are a common problem. Another effect of this lower leg weakness is the structural changes which can occur. The arch becomes higher over time, often a few years. It is this change that causes them to seek out a foot specialist. A characteristic anatomical change is the classic “stork leg” deformity, where the lower leg looks noticeably different due to muscle wasting.

Bob soon found out that in Charcot Marie Tooth disease, he had inherited a disease that interferes with the nerve’s ability to transmit a signal. The specialized covering of a nerve cell, the sheath, allows the speedy transmission of information, but this covering doesn’t function correctly in CMT. Without an intact nerve cell and sheath, peripheral nerve cells are unable to activate target muscles or relay sensory information from the limbs back to the brain.

Bob was especially unhappy to hear that there isn’t a cure for CMT, but physical therapy, occupational therapy, braces and other orthopedic devices, and even orthopedic surgery can help individuals cope with the disabling symptoms of the disease. There has been a virtual explosion in new designs for ankle-foot braces (also called an AFO), and these can make a surprising difference in the ability to walk without falling. Ankle braces can help prevent ankle sprains by providing support and stability during activities like walking or climbing stairs. High-top shoes or boots can also provide support for weak ankles.

Bob was prescribed muscle strength training, as well as a stretching regimen. He began his therapy shortly after the diagnosis was made. This is important since strength training is most useful if it begins before nerve degeneration and muscle weakness progress to the point of disability. A muscle strengthening program, regularly performed, may delay or reduce muscle atrophy. Stretching was part of his plan to prevent or reduce the joint deformities that result from uneven muscle pull on bones. Exercises to help increase endurance were instituted, to prevent the fatigue that results from performing everyday activities that require strength and mobility. He was told that aerobic activity was good for maintaining cardiovascular fitness and overall health. Low-impact or no-impact exercises, such as biking or swimming, rather than activities like walking or jogging, are preferable. These cause much less stress on fragile muscles and joints.

Naturally, there is on-going research into finding a cure, or at least better treatments. One promising area of research involves gene therapy experiments. Research with cell cultures and animal models has shown that it is possible to deliver genes to the nerve sheath cells, where the problem seems to be. Another area of research involves the use of nerve growth factors, such as the hormone androgen, to prevent nerve degeneration. Vitamin C has also been studied as a treatment for CMT. Even a component of curry called curcumin is being studied.

Bob is still going, still working. Fortunately, he does not have a physically demanding job, so his livelihood remains viable. He is more careful about his diet than he used to be. But he has to be careful about his activity levels, conserving energy where he can, and scheduling those things requiring exertion strategically. In severe cases, patients can end up in a wheelchair, but Bob is hoping not to require such assistance, and follows his physical therapy program religiously. A specialized foot-ankle brace allows him to walk better, and more safely.

CMT-type neuropathies are inherited disorders, and they are fairly common. Also, they are often progressive. This group of diseases significantly affect quality of life but not longevity, and so take a major toll on not just patients, but their families as well. Unfortunately, despite on-going research, there is no cure, only treatments developed to ameliorate the symptoms, and help keep you going. As Bob often says, sometimes, that’s all you can do.

Editor’s note: Dr. Conway McLean is a podiatric physician now practicing foot and ankle medicine in the Upper Peninsula, having assumed the practice of Dr. Ken Tabor. McLean has lectured internationally on surgery and wound care, and is board certified in both, with a sub-specialty in foot orthotic therapy. Dr. McLean welcomes questions, comments and suggestions at drcmclean@penmed.com.