Caring for the CMT-affected foot
Diane Lareau, 35, of Linwood, Mass., always knew there was something wrong, but her mother kept telling her she was just pigeon-toed and that putting her shoes on the wrong feet would fix the problem.
It didn’t, and by her late teens, she remembers, her toes were “all bent and just a mess. It looked like a bird’s claw on both feet. I was actually almost walking on the outsides of my ankles.”
She also had extremely high arches, so that her feet looked like humps. Lareau finally saw a specialist in her senior year of high school, with urging from the school nurse, and the problem acquired a name: Charcot-Marie-Tooth disease, or CMT (see “Faulty Wiring").
“They gave me these hard plastic insoles to put inside your shoes for support for the arches, supposedly to help you walk. Those didn’t work so great.”
|The typical CMT-affected foot has a high arch and “hammer” toes.|
Later, in her late 20s and pregnant, Lareau fell from her front porch and wound up in the emergency room. The only good thing about the experience was that a doctor there referred her to an orthopedic surgeon who understood the problems of the CMT-affected foot: weakness, some loss of sensation, and progressive changes in shape caused by the action of muscles that aren’t receiving the right nerve signals.
Keeping it simple
|Foot orthotics can often realign the pronated or supinated foot, reducing stress on weight-bearing joints.|
In CMT, “the typical problems with feet are the shape of the arches and the difficulties with the joints that walking with abnormally shaped feet causes,” says neurologist Michael Shy, an MDA research grantee at Wayne State University in Detroit, where he also co-directs the adult MDA clinic and directs a special CMT clinic. “Not every single person who has CMT has high arches. Some people have flat feet. But many patients have abnormal feet.”
Another common problem is hammer toes, so named because the toes are curved into a shape resembling the hammers that piano keys activate.
Patients’ needs vary, Shy says. Some can get by with simple inserts in their shoes, while others need ankle-foot orthoses (AFOs), which are lightweight (usually plastic) braces that stabilize the lower leg and foot.
Only a minority of people with CMT-related foot deformities need surgery, Shy says.
“In my opinion, when foot deformity is so severe that patients walk on the sides of their feet or when [a high arch] is extreme, it’s worth considering surgery,” Shy says. “Also, when hammer toes are so severe that patients are developing calluses or blisters on the tops of their toes, many would consider surgery to straighten the toes.”
The Wayne State clinics provide what Shy describes as “a little bit of a unique resource.” Treating patients from 37 states and some 15 countries, the specialists in every aspect of CMT start with a conservative approach before venturing into surgical territory to treat CMT.
“Generally, we start with shoe inserts and AFOs” to align the foot, Shy says.
“It’s extremely uncommon that somebody doesn’t need some sort of orthotic,” says Steven Hinderer, a physician specializing in physical medicine and rehabilitation at Wayne State. (An orthotic, or orthosis, is any supportive device, although the first term is more often used to mean a shoe insert and the second to mean other kinds of appliances.)
People with CMT also need a good walking or athletic shoe with a removable insole to make room for the orthotic, Hinderer says. He likes New Balance and Brooks shoes.
“We recommend that people take hold of the shoe and try to twist the forefoot on it. If it’s flexible, it’s not going to give you the support you need. You want one that’s fairly rigid.”
The key to foot orthotics, he says, is “to get the ankle and hindfoot in as close to neutral, or normal, alignment as we possibly can.”
If the patient is walking on the outsides of the feet — supination — or the insides — pronation — Hinderer generally puts a small pad on the bottom of the foot orthosis. “We’re holding the whole foot in good alignment. The advantage is that it puts the weight-bearing joints [where bones meet] into their normal position so they’re not being given extra stress.”
If there’s any flexibility left in the foot, Hinderer says, there’s usually a way to hold it in better alignment. “Orthotists [brace makers] are pretty creative folks.”
But misshapen feet and weak ankles aren’t the only problem in CMT.
Another common factor in the disease is a weakening of the muscles in the front part of the lower leg, those that pull the front of the foot back and off the ground during walking. When those muscles are weak, the foot tends to flop down as the person walks, so that he trips over his own feet.
|Diane Hardin, 57, holds one of her plastic, open-backed AFOs, which she says give her more flexibility than orthoses that run up the back of the leg.|
When foot drop is the first problem in CMT, Hinderer says, an off-the-shelf type of AFO, made of strong, light carbon fiber, works well.
“They’re not a custom fit, but they’re very thin, very lightweight, and from that standpoint very nice,” Hinderer says. “But more often than not, we see folks who have had foot changes already, and that off-the-shelf type of device doesn’t accommodate the foot changes at all.”
A custom-fitted, plastic AFO with a hinge at the ankle joint — for uneven ground, stairs and driving — is probably the most commonly prescribed device.
As for vertical support, Hinderer likes AFOs that go up the back of the leg, although, with a carbon fiber AFO, he says, you can make some that go up the sides and come around to the front. “We like a symmetric arrangement, either up the back or up both sides.”
Carbon fiber AFOs are stronger and more expensive than plastic but provide more options. “You can do more at the ankle with how you adjust and position,” Hinderer says. “And in terms of design, it’s more open. It’s cosmetically perhaps a little better.”
A single standard plastic AFO, Hinderer says, goes for about $500. Carbon fiber AFOS are about double that. Insurers usually pay for AFOs, but not for shoe inserts.
“The biggest thing is that orthotics must fit extremely well to be effective,” Hinderer says. “People will tolerate orthotics that don’t fit well and keep trying to wear them. They’ll say, ‘I wear them three hours and they’re killing me.’ It shouldn’t be that way. If it’s fitting really well, the way it should, you should forget it’s on.”
Michael Shy cautions his patients to beware of “miracle” braces. “None of these work for all people,” he says. “Advertising for special braces should be viewed with caution.”
When Diane Lareau read about carbon fiber AFOs on the Internet, she decided to have some made for her, at a cost of $1,200 each. Fortunately, her insurance company paid for them.
“I was excited because they’re supposed to be so strong, but what they don’t tell you is there’s no support for your heel. They’re just a flat base.”
For the new AFOs to work for her, Lareau found out she’d need to wear them with shoe inserts, which cost at least $150 each and which her insurance won’t pay for. “So, unfortunately,” she says, “these babies are hanging in my closet until I can get the money to get them.” She’s staying with her old AFOs for now.
Steven Hinderer says foot surgery is “something people should hold off on, in my opinion, until they’ve really pursued good orthotic fitting, and, if need be, physical or occupational therapy to supplement that.
“If they’re not getting the results they want, then perhaps surgery is a consideration. But most often we’ve been able to accomplish a great deal with noninvasive methods.”
When Hinderer or any other member of the Wayne State team wants to get an opinion about surgery, he’s likely to call Robert Meehan, an assistant professor in the Orthopaedic Surgery Department at WSU, and a specialist in repairing feet and ankles.
Meehan doesn’t rush into surgery either.
“Typically you start off with conservative measures first,” he says. He recommends a trial of changing shoes and bracing. If those don’t work, “then you talk surgical options, typically,” he says.
“If a patient comes to me with the fact that they’ve broken maybe two or three braces during the course of a year, and [the braces] aren’t holding the deformity, that’s a case where you’d start thinking about surgical options.”
In general, Meehan advises people to postpone surgery until they’re in their 20s or 30s, because muscle imbalances in CMT are still evolving over time. “If they feel the deformity is progressing and it’s unbraceable, then we recommend it,” he says. “But we don’t recommend it as a preventive measure.”
Phasing out fusions
“Foot surgery is common in CMT, but the types of foot surgery performed are changing,” Michael Shy says.
“One or two generations ago, many of the procedures were a triple arthrodesis, which involves bone fusions to stabilize ankles. These are done less frequently now. There’s a concern that any surgery involving bone fused to bone will cause significant arthritic problems, including pain, after a number of years.” (Arthritis is any inflammation of the joints.)
|In the triple arthrodesis procedure, three joints (A, B and C) are fused and immobilized, holding the foot in a corrected position. The operation is performed less often now than in the past, because it interferes with the foot’s ability to act as a shock absorber.|
Instead, current surgical approaches more typically involve tendon transfers [moving tendons] and procedures to correct the angle at which the foot strikes the ground, Shy says, in an attempt to prevent future arthritic complications. (See “Moving Tendons.”)
“When children had triple arthrodeses in the past, it was a horrible thing, because it knocked out their growth plates and left them with a short, stubby foot,” Meehan says. That kind of procedure can lead to arthritis by early adulthood, he says.
Another woman with CMT, Diane Hardin, now 57 and living in Madison Heights, Mich., remembers having triple arthrodeses on both feet back in 1961 in Ohio, when she was 12 years old.
“I was so pigeon-toed that I tripped over my own feet. I would step on each foot as I walked. It was just called birth defects at that time.” Her doctor, wisely, told the family to wait until she was fully grown before attempting to fix the problem. “I wasn’t diagnosed [with CMT] until after the birth of my second child.
“Basically, my feet are completely fused except for the ankle and one joint in the center,” she says, “so I don’t have a lot of flexibility. I walk very flat-footed because of it.”
Until she was well into adulthood, it didn’t seem to cause many problems. “I honestly would not have been walking all those years at all if it was not for the surgery,” she says. But as she got older, things began to bother her, particularly her left hip and her back.
Her left leg, it was found, is about half an inch longer than her right, something that occurs in the general population fairly often. But that small problem plus the fusion of her feet bones may have been an unfortunate combination.
The joints of the back of the foot, Meehan says, “control a lot of your side-to-side motion, and they’re a big part of shock absorption when you walk. So if you take that joint out [by fusing it], then you take away the shock absorption capability, so you tend to get arthritis in other joints, which take up the load,” he says.
Recently, Hardin had surgery to remove a disc and fuse the third and fourth vertebrae in her back. That, a lift in her right shoe, new AFOs and a substantial weight loss have, she says, restored her mobility and relieved her pain. She believes if her leg length difference had been identified earlier, she might have been spared at least some of the pain she’s endured over the years.
Meehan says he tries to avoid triple arthrodesis procedures unless a severe deformity is already causing arthritis in the foot joints. “It definitely holds the deformity in place,” Meehan says of this fusion surgery. “It provides you excellent correction. There’s no doubt about that. And it’s relatively easy to do.” But most of the time, it’s less than ideal.
|The Achilles tendon and plantar fascia often tighten up and can be surgically released. Tendons can be transferred to new positions, such as from the inside to the outside or top of the foot.|
“The big move among the foot surgeons is to do osteotomies, which are cuts in the bone to put the bones in a better position, to reshape the bones, rather than doing fusions, which take motion away and don’t hold up over time,” Meehan says. (Toes, however, may need to be fused.)
“Sometimes the problem can be as simple as a tight heel cord — Achilles tendon — that needs to be released,” he says.
A band of connective tissue (fascia) that runs from the heel bone to the ball of the foot on the sole (plantar surface) often tightens up as well. A plantar fascia release loosens this connective tissue.
When deformity is involved, Meehan says, “you can do tendon transfers, using what good motor strength they have left and moving it to an area where there’s a deficiency.
“Typically, they have a very strong posterior [back] tendon on the inside of the foot, and typically that’s one of the strong deforming forces. So we try and release that from the inside and move it to the outside of their ankle, to work in an area where they were strength-deficient.” Tendons can also be transferred to the top of the foot to help with lifting it during walking.
|Neurologist Michael Shy examines Justin Wilton, 6, who may have CMT. A diagnostic workup for this disorder generally includes a careful family history, a physical exam, measurements of the speed and intensity of nerve impulses traveling between the spinal cord and muscles, and DNA testing.|
About half the time, Meehan says, muscles (which are attached to bones via tendons) retrain themselves to work in a new position. The rest of the time, a transferred muscle simply acts like a piece of rope holding the foot in place.
The procedure “redistributes the forces on the foot and puts the foot in a better position, so functionally you’re better off,” he says.
Since 1998, Diane Lareau has had tendon transfers on both feet, as well as procedures to release her tight Achilles tendons, remove bony protrusions from each foot, straighten her toes and cut the tendons underneath them. After her surgeries, Lareau was able to walk well with AFOs and New Balance shoes.
After trying all kinds of expensive compression and moisture-removing stockings, she says, “When it comes down to it, men’s tube socks work wonderfully. You turn them inside out so the seam doesn’t wreck your toes.” She compensates for being unable to walk very far by doing yoga for her lower body and a regular gym workout for her upper body, which isn’t as much affected by her CMT.
“The thinner you are the better your legs are. And that’s the only reason I have the will power to stay thin.”
It’s been called everything from “shark’s tooth disease” to “charcoal tooth disease,” and it’s usually (and understandably) referred to by its acronym, CMT. But Charcot-Marie-Tooth disease is actually a fairly common nerve disorder, with an uncommon name.
Like many diseases lacking a clear cause, CMT was originally named for three doctors who first described it. In 1886, Jean-Martin Charcot and Pierre Marie in France and Howard Henry Tooth in England identified what they thought, erroneously, was a spinal cord disease.
We now know that CMT is a genetic disease of the peripheral nerve fibers, long “wires” that bundle together to form cablelike structures, or nerves, that run between the spinal cord and the periphery (outside edges) of the body. The motor nerves carry signals that cause muscles to move, and the sensory nerves send signals back to the cord that convey pain, temperature, vibration and other sensations.
CMT affects some 30 people per 100,000. Since the early 1990s, more than 20 genes that, when flawed, can cause CMT, have been identified. Some of these genes are needed in the nerve fibers, while others are needed to form and maintain myelin, the insulating coating around each fiber.
Either way, the symptoms are similar: mild to severe weakness, especially in the hands and feet, often accompanied by mild to moderate loss of sensation and less often by burning or tingling pain in those areas, beginning in childhood or adolescence.
Sources: Robert Meehan, orthopedic surgeon, and Michael Shy, neurologist, Wayne State University, Detroit