Charcot-Marie-Tooth Disease (Hereditary Motor Sensory Neuropathy)
Overview
Beginning in the first or second decades of life, individuals with CMT present with symmetric, slowly progressive distal motor neuropathy of the legs and arms leading to weakness and atrophy of the distal muscles of the legs and hands. Individuals with CMT often have markedly depressed deep tendon reflexes, weak ankle dorsiflexion, and high arched feet (pes cavus). Sensory loss is common and can easily be demonstrated by loss of vibratory sensation. In patients with sensory changes, pain can be a significant contributor to disability. There also can be an associated sensorineural hearing loss. Individuals with CMT may have scoliosis and/or hip dysplasia, but in almost all cases, CMT does not affect cognitive function or life expectancy.
Other Names & Coding
G60.0, Hereditary motor and sensory neuropathy
Prevalence
Genetics
CMT1 involves autosomal dominant conditions with a primary effect on myelination of peripheral nerves. There are 3 main types of CMT1 with the most common (CMT1A) reflecting duplication of a 1.5Mb segment of chromosome 17p11 and subsequent overexpression of the PMP22 gene. [van: 2014] PMP22 codes for peripheral myelin protein 22, a protein that is important to myelin sheath function. A deletion in the PMP22 causes a separate neuromuscular condition, hereditary neuropathy with predisposition to pressure palsy (HNPP). Importantly, patients with deletion of duplication or deletion of PMP22 may have larger deletions encompassing additional genes and complicating the phenotype. In cases complicated by multiple affected systems or cognitive delays, consider additional testing, such as a microarray study to fully define the deletion/duplication. CMT1B is also autosomal dominant with mutations in the MPZ gene, coding for the myelin protein zero. Mutations in LITAF, EGR2, and NEFL genes cause CMT1C, CMT1D, and CMT1E, respectively.
CMT 2 is less common than CMT1 and results from abnormalities in axons of peripheral nerves with normal myelin. The most common form, CMT2A, is due to a mutation in the MFN2 gene responsible for the production of Mitofusin2, a protein associated with mitochondrial fusion. Other genes that have been associated with CMT2 include RAB7 (CMT2B), GARS (CMT2D), NEFL (CMT23) HSP27 (CMT2H), and HSP22 (CMP2I).
CMT3, also called Dejerine Sottas disease, is a severe demyelinating neuropathy beginning in infancy – a phenotypic description. Although other genes may be associated with it, specific point mutations in the MPZ and PMP22 are found most often.
CMT4 refers to a group of autosomal recessive demyelinating motor and sensory neuropathies, many of which are very rare and may only be found in a small number of people or certain ethnic populations due to founder effects. CMT4 may be associated with leg weakness in childhood with a fast progression to inability to walk in adolescence.
CMTX is X-linked and due to point mutations in the GJB1 gene encoding connexin-32, a protein made by the Schwann cells that are responsible for producing the myelin sheath. These patients may have transient stroke-like symptoms and abnormal MRIs. [Wang: 2016]
Prognosis
Practice Guidelines
There are no formal published practice guidelines for CMT, but a multidisciplinary approach to care is most beneficial and care guidelines are beginning to emerge. [McCorquodale: 2016] [Corrado: 2016]
Roles of the Medical Home
Clinical Assessment
Overview
Pearls & Alerts for Assessment
Toe-walkingToe-walking may be idiopathic or due to brain, spinal cord, or nerve abnormalities. CMT is one of the causes that should be considered, especially in the absence of other systemic findings. See Toe-Walking.
Individuals with CMT may present in a variety of waysAttention to the possibility of an underlying neuropathy should be given in those with toe-walking, cavovarus feet, flat feet, or foot drop (due to weakness in ankle dorsiflexion), problems with balance, hip dysplasia, or scoliosis.
Screening
Of Family Members
For Complications
Diagnostic Criteria
Parents may already know if they have type 1 (demyelinating), type 2 (axonal), and their subtype, making genetic testing for the child easier and less expensive since the NCV/EMG step can be skipped.
Clinical Classification
Differential Diagnosis
Distal myopathies: In most muscle disorders (myopathies and muscular dystrophies), weakness is proximal, involving shoulders and hips; in most neuropathic disorders such as CMT, muscle weakness is distal, involving hands and feet. However, there are many exceptions, including a variety of distal myopathies. Mutation in dysferlin (DYSF), caveloin3 (CAV3), desmin (DES), and titin (TTN) are relatively common distal myopathies that should be considered, especially if genetic testing for CMT is normal or NCS/EMG is not clearly neuropathic.
Metabolic and neurodegenerative disorders: Since myelin is largely composed of lipids, any disruption of lipid metabolism can cause abnormal myelin formation, either centrally, peripherally, or both. Leukodystrophies such as X-linked adrenoleukodystrophy, infantile neuroaxonal dystrophy, and peroxisomal disorders (Refsum disease, Zellweger syndrome) and others often include peripheral neuropathy in addition to central demyelination. Friedreich’s ataxia (FA) is a relatively common degenerative condition that begins with gait abnormalities due to distal weakness in childhood or adolescence. Ataxia and peripheral neuropathy are prominent findings. Patients with FA can also have prominent cardiomyopathy.
Medical Conditions Causing Charcot-Marie-Tooth Disease (Hereditary Motor Sensory Neuropathy)
History & Examination
Current & Past Medical History
Family History
Developmental & Educational Progress
Physical Exam
Ask about muscle cramps, pain in hands or feet, frequently sprained ankles, fatigue.
Growth Parameters
Monitor weight for obesity. It is best to discuss this early and prevent it from happening since it can further stress walking and other activities. See Obesity in Children &Teens.
Neurologic Exam
Deep tendon reflexes are usually absent or decreased (proximal <distal). Heel cords may be tight. The child might toe-walk and have cavo-varus feet or pes cavus. The child may have foot drop when walking, which may be described as “foot-slap” by the parents. Vibratory sensation is usually reduced in the lower extremities. Although more difficult to detect clinically, sensation may also be reduced in the feet. The patient/family should do visual checks for sores or bruising every night.
Testing
Sensory Testing
Genetic Testing
Other Testing
Sometimes a motion analysis lab or a gait lab test is performed to determine patterns of walking and inform decisions by physical therapists/orthopedic physicians regarding casting vs. bracing vs. surgery.
Specialty Collaborations & Other Services
Pediatric Neurology (see NM providers [5])
Occupational Therapy (see NM providers [17])
Physical Therapy (see NM providers [12])
Pediatric Orthopedics (see NM providers [7])
Prosthetics & Orthotics (see NM providers [1])
Treatment & Management
Overview
Pearls & Alerts for Treatment & Management
Orthotics and bracesMany children/adolescents with CMT are prescribed ankle foot braces/orthotics but don’t like to/will not wear them. In patients with milder weakness, good footwear including high-topped shoes and solid ankle support may be almost as helpful and may be more likely to be worn.
PainPatients with CMT may have a lot of foot and muscle pain that may be debilitating, especially if there is a large sensory component to the neuropathy. Cognitive behavioral therapy and/or preventive medications, such as gabapentin, may be helpful.
How should common problems be managed differently in children with Charcot-Marie-Tooth Disease (Hereditary Motor Sensory Neuropathy)?
Prescription Medications
Systems
Neurology
New or increasing neurologic symptoms, such as pain, should be monitored for and treated as necessary. Gabapentin is usually the first choice in the control of chronic pain in children and adolescents. Also see Pain in Children with Special Health Care Needs.
Degree of disability should also be monitored, especially in walking/running and using hands. Although there is no specific natural history study to cite, the feeling among neuromuscular clinicians is that a decline in abilities is often noted during and after growth spurts. Assistive devices such as braces, orthotics, wheelchairs, specialized utensils, and writing implements should be prescribed when necessary with input from physical and occupational therapists.
A multidisciplinary clinic will have access to physical therapy and occupational therapy to maximize walking and fine-motor function with exercise or the use of orthotics or adaptive aids for daily living, such as larger, easier to grasp pens and eating utensils. School performance, particularly physical education and fine motor skills should also be monitored and a 504-accommodation letter provided as needed. See Sample Letter Requesting a 504 Plan for Charcot-Marie-Tooth (Medical Home Portal) ( 96 KB).
Specialty Collaborations & Other Services
Neuromuscular Clinics (see NM providers [1])
Pediatric Neurology (see NM providers [5])
Musculoskeletal
Specialty Collaborations & Other Services
Pediatric Orthopedics (see NM providers [7])
Ask the Specialist
One of my adolescent patients with CMT and abnormal feet is going to a podiatrist who plans a fairly invasive surgery. Is this necessary?
Surgeries on children/adolescents with CMT are complex, both the decision to do surgery and the various issues of CMT as individuals with CMT may not respond in the same way as a person without CMT and nerves may be more sensitive to damage during an operation. A visit to an orthopedic surgeon specializing in neuromuscular conditions may be helpful.
Resources for Clinicians
On the Web
Charcot-Marie-Tooth Hereditary Neuropathy Overview (GeneReviews)
Detailed information addressing clinical characteristics, diagnosis/testing, management, genetic counseling, and molecular
pathogenesis; from the University of Washington and the National Library of Medicine.
Helpful Articles
Murphy SM, Laura M, Fawcett K, Pandraud A, Liu YT, Davidson GL, Rossor AM, Polke JM, Castleman V, Manji H, Lunn MP, Bull K,
Ramdharry G, Davis M, Blake JC, Houlden H, Reilly MM.
Charcot-Marie-Tooth disease: frequency of genetic subtypes and guidelines for genetic testing.
J Neurol Neurosurg Psychiatry.
2012;83(7):706-10.
PubMed abstract / Full Text
Miller LJ, Saporta AS, Sottile SL, Siskind CE, Feely SM, Shy ME.
Strategy for genetic testing in Charcot-Marie-disease.
Acta Myol.
2011;30(2):109-16.
PubMed abstract / Full Text
Clinical Tools
Letters of Medical Necessity
Sample Letter Requesting a 504 Plan for Charcot-Marie-Tooth (Medical Home Portal) ( 96 KB)
A sample of a short letter requesting that school personnel allow the child to self-monitor physical activity, and allow the
child extra time for timed tests.
Medication Guides
Neurotoxic Medications (CMT Association)
A list of medications that should be avoided for patients with CMT, even those that are fairly asymptomatic.
Resources for Patients & Families
Information on the Web
Charcot-Marie-Tooth Association
A nonprofit organization focused on research into treatments for CMT and information for patients and families.
Charcot-Marie-Tooth Disease Fact Sheet (NINDS)
Authoritative answers to common questions about Charcot-Marie-Tooth disease, including what research is being done and additional
sources of information; National Institute of Neurological Disorders and Stroke.
National & Local Support
List of MDA Care Centers (MDA)
Provides addresses and phone numbers of MDA Care Centers in each state; Muscular Dystrophy Association
Muscular Dystrophy Association
The Muscular Dystrophy Association (MDA) covers many conditions including CMT, Duchenne muscular dystrophy, and spinal muscular
atrophy. More information about these conditions, how to register, and clinic locations can be found here.
Studies/Registries
Clinical Trials in Charcot-Marie-Tooth (clinicaltrials.gov)
Studies looking at better understanding, diagnosing, and treating this condition; from the National Library of Medicine.
Services for Patients & Families in New Mexico (NM)
Service Categories | # of providers* in: | NM | NW | Other states (3) (show) | | NV | RI | UT |
---|---|---|---|---|---|---|---|---|
Neuromuscular Clinics | 1 | 1 | 2 | 3 | 3 | |||
Occupational Therapy | 17 | 1 | 22 | 24 | 37 | |||
Pediatric Neurology | 5 | 5 | 18 | 8 | ||||
Pediatric Orthopedics | 7 | 4 | 8 | 16 | 10 | |||
Physical Therapy | 12 | 9 | 7 | 40 | ||||
Prosthetics & Orthotics | 1 | 1 | 1 | 1 | 10 |
For services not listed above, browse our Services categories or search our database.
* number of provider listings may vary by how states categorize services, whether providers are listed by organization or individual, how services are organized in the state, and other factors; Nationwide (NW) providers are generally limited to web-based services, provider locator services, and organizations that serve children from across the nation.
Authors & Reviewers
Authors: | Lynne M. Kerr, MD, PhD |
Tara M. Newcomb, CGC, MS | |
Reviewer: | Russell Butterfield, MD, PhD |
Bibliography
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Management of Charcot-Marie-Tooth disease: improving long-term care with a multidisciplinary approach.
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PubMed abstract / Full Text
Miller LJ, Saporta AS, Sottile SL, Siskind CE, Feely SM, Shy ME.
Strategy for genetic testing in Charcot-Marie-disease.
Acta Myol.
2011;30(2):109-16.
PubMed abstract / Full Text
Murphy SM, Laura M, Fawcett K, Pandraud A, Liu YT, Davidson GL, Rossor AM, Polke JM, Castleman V, Manji H, Lunn MP, Bull K,
Ramdharry G, Davis M, Blake JC, Houlden H, Reilly MM.
Charcot-Marie-Tooth disease: frequency of genetic subtypes and guidelines for genetic testing.
J Neurol Neurosurg Psychiatry.
2012;83(7):706-10.
PubMed abstract / Full Text
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