cause in the vast majority of cases has been found to be a specific
problem with the chemical "neurotransmitters" that
regulate communications between different groups of nerve cells
in the brain. Brain cells in the lateral hypothalamus that produce
a neurotransmitter called hypocretin or orexin are lost.
Why does this loss of nerve cells (neurons)
occur? An explanation is being sought. We have know for some years
that narcolepsy is strongly associated with specific HLA types
(see below), a phenomenon that has been noted in many autoimmune
disorders (conditions in which the body mounts an immune defense
against its own tissues. However, it has not been shown with any
certainty that narcolepsy is an autoimmune disorder and that autoimmune
mechanisms are responsible for the loss of hypocretin (orexin)-containing
nerve cell bodies.
-Only rare cases have been reported of narcolepsy
arising as the consequence of such structural causes as brain tumors,
brain infections and head injuries. CT/MRI scans of the brain are
normal in the vast majority of cases.
can "run in families" such that
some individuals appear genetically predisposed to develop it.
However, it is not a genetic disorder per se in humans. Some breeds
of dogs do develop narcolepsy on a genetic basis.
-The onset of narcolepsy sometimes follows
stressful events, but such does not indicate that it is a psychological
narcolepsy a rare condition?
at all! It is roughly as common as MS (multiple sclerosis) in
the United States.
How is narcolepsy diagnosed?
-A careful history, followed by specific
sleep center studies (both an overnight sleep monitoring and a
multiple sleep latency test).
introvertible history of cataplexy is far more diagnostic of
narcolepsy than a multiple sleep latency test, since both false
negative and false positive MSLTs occur frequently.
narcolepsy be diagnosed by a "blood test"?
Such is a common misimpression that resulted from the discovery
that most (but not quite all) narcoleptics share particular HLA
types (genetically determined markers on white blood cells that
are used to determine tissue compatibility--for example, to assess
one's ability to donate a kidney to a possible recipient without
high likelihood that the transplanted kidney will be rejected).
HLA types are evaluated with a blood test.
-There are two reasons why these tests cannot
be used to diagnose narcolepsy:
some definite narcoleptics who even have cataplexy will come
out negative on these tests.
an even greater problem is that up to 25% of the general population
will show the same HLA typing that has been associated with
here to continue...
FOR MORE INFORMATION ON DISORDERS
OF EXCESSIVE SLEEPINESS,
CLICK HERE TO VISIT THE NEW SLEEP SITE.