Multiple Chemical Sensitivity or Multi-Sensory Sensitivity?
(c) 2007 Albert Donnay, adonnay@mcsrr.org
People with Multiple
Chemical Sensitivity (MCS) are hypersensitive to
chemicals they absorb through their skin (such as
cosmetics), inhale (such as perfume), and ingest (such
as alcohol and medications). The majority of MCS cases
also meet diagnostic criteria for chronic fatigue
syndrome and/or fibromyalgia.
Less commonly recognized
is the extensive overlap of MCS with multi-sensory
sensitivity, also known as MUSES syndrome. People with
MUSES are not just hypersensitive to chemicals but also
to all or most other types of sensory stimuli,
including:
bright sunlight, loud
noise, hot weather, light touch on their skin (shirt
tags bother their neck), and spicy foods (they eat
blander food than before their illness).
Some even notice increased
sensitivity to vibration when near moving trucks or
trains, and increased sensitivity to electromagnetic
fields when near desktop computers.
The only known cause of
MUSES syndrome is carbon monoxide poisoning, which has a
long-lasting effect on sensory nerves.
The bad news for people with MUSES is that they suffer more than people with pure MCS, whose symptoms are triggered only by chemical exposures and at most one or two other types of sensory stimuli.
The good news for people
with MUSES, however, is that, unlike MCS, their illness
is associated with an easily testable, treatable and
curable oxygen deficiency.
Blood gas testing of
arterial and venous samples (taken from the same elbow
without a tourniquet) shows that the arterial level of
oxygen going into their body is normal but that too much
oxygen remains in their veins. This proves that people
with MUSES are having trouble absorbing oxygen from
their blood into their tissues, resulting in low oxygen
consumption or tissue hypoxia.
The most important blood
gas measures to consider are the artero-venous (a-v)
difference in the partial pressure of oxygen (PO2),
which is abnormal if less than 55mmHg, and the a-v
difference in oxygen saturation (O2Sat), which is
abnormal if less than 30mmHg.
Consistent with low oxygen
consumption, people with MUSES usually also have lower
than normal carbon dioxide output (PvCO2-PaCO2 less than
7mmHg), showing impaired oxidative metabolism.
Other symptoms associated
with tissue hypoxia include frequent headaches,
shortness of breath, depression, anxiety, chronic
fatigue, and fibromyalgia-like muscle pain.
Fortunately, these and
other symptoms of multi-sensory sensitivity--including
chemical sensitivity--respond well to supplemental
oxygen, which is the standard treatment for tissue
hypoxia. (Note that the use of oxygen for any medical
purpose requires a prescription from a physician.)
People with MUSES who take
supplemental oxygen at home for just two hours per day
should begin to notice some improvement within a week.
Three to four months of daily treatment are usually
needed, however, before they are able to stop taking the
oxygen without their symptoms returning. Unfortunately,
this therapy does not help people with pure MCS who do
not have tissue hypoxia.
For more information, see
"What you need to know about carbon monoxide poisoning"
at
www.mcsrr.org or call MCS Referral & Resources at
410-889-6666.
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