Charcot-Marie-Tooth Disease

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Charcot-Marie-Tooth Disease

By Janet Goodard, BSN, RN, CCRC, CCAP Posted on: April 1, 2009

http://nursing.advanceweb.com/editorial/content/editorial.aspx?cc=196885

Though more common than muscular dystrophy, Charcot-Marie-Tooth disease (CMT)

has far less name recognition.

CMT is a neurological disorder; those with the disease slowly lose normal use of

feet, legs, hands and arms as nerves to extremities degenerate and muscles

become weakened because of loss of stimulation by affected nerves, according to

the Charcot-Marie-Tooth Association (CMTA). Many patients experience loss of

sensory nerve function.

Causes & Genetics

CMT is a group of disorders with more than 50 known genetic causes. Most forms

are dominantly inherited; if either the mother or the father is affected, each

child will have a 50 percent chance of inheriting the disorder. There are also

recessive and X-linked patterns of inheritance; it is estimated 10 percent or

more of cases are new mutations.

CMT is usually classified as type 1 or type 2, depending on whether the genetic

abnormality affects the myelin sheaths that surround the axons (CMT1) or

primarily causes deterioration of the axons (CMT2).

The most common type, CMT1A, accounts for about 70 percent of all cases and

results from a duplication of a gene that encodes a protein component of the

myelin sheaths.1,2

Symptoms

Although the onset can occur at almost any age, most people with CMT1 are

symptomatic by the second decade of life. People with CMT2 frequently present

later, even in their 40s or 50s.

Initial symptoms characteristically include distal muscle weakness and atrophy,

and reduced sensation in a stocking-glove distribution - feet and lower legs,

the hands. As the intrinsic muscles weaken and atrophy, resulting muscle

imbalances produce contractures, shortening of muscles and surrounding

connective tissue. This leads to a variety of orthopedic deformities such as

high-arched feet (pes cavus) and hammertoes, which are common.1-3

As the disease progresses, weakness in muscles responsible for ankle

dorsiflexion results in a foot drop, causing tripping and ankle sprains. This is

accompanied by a " steppage gait, " in which the patient adopts a high step to

avoid scraping toes on the ground.

Tightening of the heel cord causes toe walking, and weakness of the muscles

innervated by the ulnar nerve causes the fingers to curl ( " claw hand " ). Other

problems include scoliosis, fatigue and loss of energy, and neuropathic pain. It

is important to note CMT does not affect intelligence or life expectancy.1-3

Orthopedic Solutions

Currently, there are no effective pharmacological treatments that alter the

progression of CMT.

However, through appropriate management, patients should expect to have long,

productive lives. The first step toward appropriate management is to learn which

health professionals are best suited to provide information and treatment.

A neurologist typically makes the diagnosis; a neurologist, physiatrist, or

primary-care physician can continue to manage care. Most patients will also be

under the care of other specialists including podiatrists and/or orthopedists.

Generally, the earlier gait abnormalities are corrected, the fewer problems

patients will have in the future. Some will benefit from in-shoe orthotics to

prevent pronation or supination; others will need more aggressive treatments

such as bracing or corrective surgery.

An orthotist may provide custom-fitted braces called ankle-foot orthoses (AFOs),

which stabilize the ankle and reduce steppage gait. Some AFOs will hold the foot

at a fixed 90-degree angle while others incorporate a moveable ankle joint,

allowing the foot to move up and down.

Ankle fusions are done less frequently now, but tendon transfers and osteotomies

are sometimes performed to correct the biomechanics of the foot and to reduce

arthritic complications. Hammertoes generally are not surgically corrected

unless they are causing other complications.

Patients with CMT need to be vigilant about foot care, wearing well-fitting

footwear and avoiding trauma that could result in skin breakdown.4

Physiatrists and/or physical therapists can play an important role in

recommending the most appropriate orthotics or leg bracing. Success of these

devices depends not only on fit and function but also on acceptance by the

patient, who should return to the orthotist if adjustments are necessary to

relieve pain or irritation.

Gentle Exercise

Exercise recommendations, tailored to each individual's needs, can be made by

any member of the treatment team. Exercise in moderation can help control weight

and maintain cardiovascular fitness. Certain exercises strengthen less affected

muscles that compensate for the more affected muscles, maintain flexibility and

reduce contractures. Exercise programs like gentle yoga can be beneficial and

adaptable to each individual.

If the hands have significant weakness and/or joint deformity, an occupational

therapist can suggest alternative ways to perform daily activities to promote

joint and energy conservation, and provide assistive devices, such as

buttonhooks, key turners and jar openers.

A caution regarding treatments: People with CMT should be informed vincristine

(a chemotherapy agent known to be harmful) and other neurotoxic medications may

worsen symptoms.5 Vincristine can cause profound peripheral neuropathy symptoms

particularly in those with demyelinating types of CMT including those who are

asymptomatic. A comprehensive list of these medications is available at

www.cmtausa.org/med_alert.php.

Although there is limited direct evidence these medications exacerbate CMT, it

is important to be aware of this potential.

The Nurse's Role

Assuring patients receive appropriate care is fundamental; preparing patients to

face the lifelong challenge of coping with CMT is equally important. With

extensive patient contact, nurses are ideally positioned to help coordinate the

care of CMT patients, enable them to develop a healthy attitude and provide them

with information needed to manage their condition over the long term.

Education is primary and often begins prior to the patient's first clinic visit.

First contact can include answering questions about CMT. Sending a pamphlet

about CMT prior to the first visit is helpful. Encourage the patient to keep a

running written list of questions to discuss to maximize every visit.

Other educational needs include basic CMT information, its inheritance,

community resources, current research as well as specific information on foot

care, exercise and pain management. Schedule time during each visit to address

individual education issues. A one-page handout that includes information on

organizations, support groups and community resources is beneficial.

After diagnosis, CMT patients are frequently overwhelmed. Nurses can offer

educational materials for home review and reference. Excellent low-cost or free

materials are available from The National Institute of Neurological Disorders

and Stroke (www.ninds.nih.gov), the Muscular Dystrophy Association (MDA,

www.mda.org), the CMTA (www.cmtausa.org) Many are unaware CMT is under the MDA

umbrella of diseases/disorders. By registering with the local MDA office, a

person with CMT may receive services, including reimbursement for cost of leg

braces not covered by third party payers.

The Promise of STAR

Research in genetics has increased optimism among those seeking to treat and

cure CMT. " We now are able to replicate this disorder in the laboratory and. can

begin testing new treatments that will ultimately lead to clinical trials in

people, " according to E. Shy, MD, chairman of the CMTA Medical Advisory

board, director of the CMT Clinic and co-director of the Neuromuscular Program

at Wayne State University, Detroit.

Scientific and technological advances have enabled the CMTA to implement an

initiative, the Strategy to Accelerate Research (STAR), designed to lead to new

treatments for CMT within 3-5 years and possibly to a cure within 10 years.

Spearheaded by an international collaboration of researchers, the STAR

initiative will initially focus on CMT, type 1A.

References

1. Gondim, F., de Oliveria, G., & , F. (2007). Hereditary neuropathies of

the Charcot-Marie-Tooth disease type. Retrieved Nov. 21, 2008 from the World

Wide Web: http://emedicine.medscape.com/article/1173484-overview

2. Hashmat, A., Daud, Z., & Brannagan, T. (2007). Charcot-Marie-Tooth and other

hereditary motor and sensory neuropathies. Retrieved Nov. 21, 2008 from the

World Wide Web: http://emedicine.medscape.com/article/1173104-overview

3. National Institute of Neurological Disorders and Stroke. (2007).

Charcot-Marie-Tooth disease fact sheet. Retrieved Jan. 21, 2009 from the World

Wide Web:

http://www.ninds.nih.gov/disorders/charcot_marie_tooth/detail_charcot_marie_toot\

h.htm

4. Kedlaya, D. (2005). Charcot-Marie-Tooth disease. Retrieved Jan. 21, 2009 from

the World Wide Web: http://emedicine.medscape.com/article/1232386-overview

5. Weimer, L., & Podwall, D. (2006). Medication-induced exacerbation of

neuropathy in Charcot-Marie-Tooth disease. Journal of Neurological Sciences,

242(1-2), 47-54.

Janet Goodard is a nurse at the P. Murtha Neuroscience & Pain Institute,

stown, PA. Dana Schwertfeger, director of member services at the

Charcot-Marie-Tooth Association, contributed to this article.