Encyclopedia of Health and Medicine

Charcot-Marie-Tooth (CMT) disease 317
cal vertebrae (bones of the neck). The damage is
permanent and eventually restricts the movement
of the neck. Pressure against the NERVE roots of the
spinal cord may cause tingling or loss of sensation
in the shoulders and arms. Sometimes the pressure
also causes weakness of the muscles in the upper
back and the arms. Cervical spondylosis is more
common in people over age 60.
Symptoms of cervical spondylosis include
• stiffness in the neck
• HEADACHE
• PAIN along the back of the neck that radiates
into the shoulders and upper arms
• abnormal sensation in the upper back and
arms, sometimes extending to the hands and
fingers
The diagnostic path includes X-RAY of the neck
and upper back, which typically reveals the
changes in the alignment of the vertebrae as well
as the formation of bone spurs and calcifications
within the disks. Additional imaging procedures
such as COMPUTED TOMOGRAPHY (CT) SCAN, MAGNETIC
RESONANCE IMAGING (MRI), and myelogram (injection
of radio-opaque dye into the spinal column)
often show the degree to which the spondylosis
compresses the nerve roots or, when degeneration
is severe, the spinal cord itself.
Treatment options include NONSTEROIDAL ANTI-
INFLAMMATORY DRUGS (NSAIDS) to relieve inflammation
and pain. A soft cervical collar that
immobilizes the neck allows the muscles of the
neck to relax, helping inflammation to recede.
Injections of steroid medications can often reduce
inflammation that does not respond to other treatments.
Heat and PHYSICAL THERAPY aid HEALING and
restoration of movement. Though cervical
spondylosis is a chronic and progressive condition,
most people are able to obtain relieve through a
combination of medical and lifestyle methods.
See also ANKYLOSING SPONDYLITIS; BACK PAIN; BONE
SPUR; CHRONIC PAIN; LIFESTYLE AND HEALTH.
Charcot-Marie-Tooth (CMT) disease An inherited
neuromuscular disorder in which the myelin
sheath that covers and protects the PERIPHERAL
NERVES deteriorates. The loss of the myelin sheath
allows NERVE signals to escape from the nerves
before they reach their destinations. CMT is the
most common inherited neuromuscular disorder
in the United States, affecting about 150,000
Americans. CMT is slowly progressive though not
fatal, with symptoms typically beginning in late
ADOLESCENCE or early adulthood.
There are numerous forms of CMT, each arising
from MUTATION of different genes that encode the
proteins that form the myelin sheath. The most
common is CMT1, which occurs in three autosomal
dominant variations that cause abnormal
structure in the myelin sheath:
• CMT1A results when the person inherits an
extra copy of the GENE on CHROMOSOME 17 that
encodes peripheral myelin protein 22 (PMP-
22), causing excessive production of PMP-22.
• CMT1B occurs as a result of mutations to the
gene that encodes myelin protein 0 (MP-0).
• CMT1C results from mutations to genes that
encode for other peripheral myelin proteins,
though researchers have not yet identified the
mutations.
Other forms of CMT include
• CMT2, in which there are defects in the axons
of the peripheral nerves rather than in the
structure of the myelin sheath
• CMT3, also called Dejerine-Sottas disease,
which results from mutations to the MP-0 or
PMP-22 gene and causes severe symptoms
beginning in the first year of life
• CMT4, in which various gene mutations cause
symptoms that begin in childhood and progress
to complete loss of motor function of the lower
extremities by adolescence
• CMTX, which arises from a mutation in the
connexin 32 gene on the X chromosome and
causes more severe symptoms in males
Occasionally CMT occurs as a spontaneous
mutation, without family history of the disease,
and may affect any of the genes that encode for
myelin proteins.
Symptoms and Diagnostic Path
Symptoms affect primarily the legs and feet in
most forms of CMT, though in some forms may