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demyelinations

Demyelinations are processes involving loss or damage of the myelin sheath surrounding axons in the central and peripheral nervous systems. Myelin facilitates rapid action potential conduction; its loss slows impulses, causes conduction block, and leads to a range of neurological symptoms depending on the affected regions.

Demyelination occurs in a spectrum of diseases. In the CNS, examples include multiple sclerosis, optic neuritis,

Pathophysiology typically involves autoimmune or inflammatory attacks on myelin or the cells that form it (oligodendrocytes

Diagnosis combines clinical assessment with investigations. CNS involvement is evaluated by MRI, which shows focal or

Treatment is disease- and context-specific. Acute attacks are typically treated with high-dose corticosteroids; severe cases may

Prognosis varies by disease; some are monophasic and recover, others are relapsing or progressive. Early diagnosis

acute
disseminated
encephalomyelitis,
and
neuromyelitis
optica
spectrum
disorders.
In
the
peripheral
nervous
system,
demyelinating
neuropathies
include
Guillain-Barré
syndrome
and
chronic
inflammatory
demyelinating
polyneuropathy.
Demyelination
can
also
be
secondary
to
toxins,
metabolic
disorders
(such
as
vitamin
B12
deficiency),
infections
(eg,
progressive
multifocal
leukoencephalopathy),
ischemia,
or
genetic
leukodystrophies.
in
the
CNS
and
Schwann
cells
in
the
PNS),
producing
slowed
conduction
or
conduction
block
and
focal
deficits.
Clinical
manifestations
vary
with
location
and
may
include
vision
loss,
weakness,
numbness,
ataxia,
or
autonomic
symptoms.
disseminated
white
matter
lesions.
Cerebrospinal
fluid
can
reveal
oligoclonal
bands
and
an
elevated
IgG
index
in
MS.
Nerve
conduction
studies
show
slowed
conduction
in
demyelinating
neuropathies;
evoked
potentials
aid
localization.
require
plasmapheresis
or
IVIG.
Disease-modifying
therapies
are
used
for
MS
and
related
disorders;
GBS
and
CIDP
respond
to
IVIG,
plasmapheresis,
steroids,
and
immunosuppressants.
Rehabilitation
supports
outcomes.
and
therapy
can
reduce
disability.