Viral Anosmia:
Frequently Asked Questions With Answers From
Mick O'Hareã
A Note From The Editor, Karl L. Wuensch
I met Mick through the Anosmia Community at
Yahoo (a once useful site that has been destroyed by porno spam). He was one of
the most active members of that group, and is now a moderator of the Dysosmia
(Smell Disorders) Community at Yahoo. Mick developed viral anosmia in June
of 1998. He has educated himself regarding the causes and treatment of this
condition and has shared his knowledge, and personal details of his experience,
with others. If you have questions of Mick, I recommend that you join the Dysosmia (Smell Disorders) Community at Yahoo and post your
questions there.
Below are
a number of questions and answers relating to viral anosmia, how it affected me
and my subsequent treatment and recovery from it. This is not meant to be a
full treatise on the condition, but it answers a few of the common questions I
am often asked. Readers should bear in mind that I have no medical training.
What is
viral anosmia?
Viral anosmia is a total lack of olfaction
caused by an upper respiratory infection (URI) virus destroying the cells of
the olfactory epithelium through a process known as necrosis. The virus enters
the cells and destroys them from within leading to a lack of smell. Usually
only the olfactory receptor cells are destroyed but some doctors believe the
olfactory nerve or the nasal serous glands can also be damaged
. A more technical explanation can be found at Tim Jacob's
Anosmia Page in the Causes of Olfactory Disorders section labeled: iii)
Prior Upper Respiratory Infection (URI)
How do I
know if I have viral anosmia?
You don't for sure because the diagnosis is one
of absence. If no other cause can be found it is likely to be caused by a
virus. In many cases the rapid, immediate onset of anosmia can be traced to an
incidence of URI (a cold, influenza, or sinus infection). This is usually
enough to convince a physician that the URI was the cause, but by the time a
patient visits a doctor, the virus itself has often gone. Concurrent URI and
anosmia usually indicates viral-induced anosmia, but care must be taken to rule
out other causes.
What if I didn't have any symptoms of cold or 'flu?
Remember that 25% of rhinoviruses (the viruses
that cause colds) have no symptoms. The virus may be present in your nose but
that doesn't mean you'll have a sore throat and streaming nose. It is possible
that the only symptom may be the anosmia itself. Your doctor may describe this
condition as idiopathic anosmia (or anosmia with no known cause) - however,
this may still be a case of viral anosmia.
Does a
specific virus cause anosmia?
Nobody is
certain, although it seems unlikely. Any URI virus seems capable of causing
anosmia if its protein coat matches a key on your olfactory cells. It appears
that viral anosmia is a matter of bad luck: the virus cells match an individual's
olfactory receptor cells in very few cases. But in those in which it does,
viral anosmia occurs.
Can a virus
also destroy my taste as well?
Yes it
can. In my case this happened. Remember that true taste from the tongue's tastebuds comprises only salt, sweet, bitter and sour - and
possibly a fifth taste known as umami - see the
document Anosmia and Taste.
Most of what we perceive as taste is actually flavour, a process almost
identical to smelling that is generated by the olfactory receptors as food is
chewed and its odour rises through the back of the
nose to be detected as flavour. In most cases of viral anosmia smell and
flavour are lost when the olfactory epithelium is destroyed but taste remains
intact. In my case all three were lost, but I must stress that this is a rare
scenario.
Is the
virus still present and causing my anosmia?
No, the
virus dies quickly when attacked by the body's immune system. Usually, by the
time viral anosmia is apparent and diagnosed, the virus that caused it is long
dead.
Do people
recover from viral anosmia?
Yes they
do. Some recover spontaneously. The recovery rate is not known - figures are
vague and badly researched, ranging from 18% of all cases in one study to 66%
in another. Yet another study suggests that two thirds of all viral anosmia
victims will have recovered at least some of their smell within four years.
Bearing in mind that 'some of your smell' is arguably as little as 1% and that four years is a long time, this is not a good
prognosis. However, many people who become viral anosmics
and recover quickly will not report their situation to any medical practitioner
so it can be assumed that more people recover than have been recorded in any
study. The cells of the olfactory epithelium can regenerate, so spontaneous
recovery is certainly possible.
So others
do not recover?
Some
people do not recover at all and remain permanently anosmic. Others recover partially, others recover tastes and smells that are
distorted.
What are distorted
smells?
Most - if
not all - people, when recovering from viral anosmia, seem to go through a
phase where their smell and flavour perception is distorted. This is known as parosmia.
Smells are either inaccurate, dreadfully unpleasant or both. Many people pass
through this phase to normal, or near normal perception, although it is often
still reduced in acuity. Others remain stuck in the distorted phase, which can
be terribly depressing.
Is there
any treatment for the symptoms of viral anosmia?
The
standard medical line is that viral anosmia is not treatable and nearly all
physicians will say that this is the case. At present, as far as I am aware,
only Dr Robert I Henkin of the Taste and Smell Clinic in Washington DC,
USA offers treatment for the condition with varying reports of success.
After contracting viral anosmia in June 1998 I was first treated by Dr Henkin in May 1999. No 'alternative' therapies have proved
to be successful. You can read the story of my illness, treatment and the
medical science behind in a feature I wrote in 2005 for the British weekly
science magazine New Scientist, for
which I work: The
Unbearable Absence of Smelling. If you would prefer to finish the FAQ
before reading the feature, the link is repeated at the foot of the page
What form
did the treatment take?
After
numerous physical and chemical (blood, urine, saliva, nasal mucus, etc) tests I
was diagnosed as a viral anosmic with parosmia. I was
treated immediately with haloperidol, an antipsychotic drug. Dr Henkin told me I was suffering from parosmia
because my brain was failing to interpret correctly the signals from my damaged
olfactory receptors. Later, in November 1999, when the distortions had
diminished but actual smell/flavour acuity failed to improve he suggested I
take another drug called theophylline (a well-known
drug more widely used for treating asthma). This drug increased the presence in
my olfactory cells of a growth factor known as cyclic AMP and found in nasal
mucus. Cyclic AMP acts on olfactory stem cells allowing them to create new
cells which carry odour to the olfactory nerve and
are necessary for humans to be able to smell things. At first the theophylline seemed to have little effect, so, in February
2000 and again in October 2000, I took a very short course of oral steroid - dexamethasone - to kickstart the
olfactory process. This was successful and was measured both objectively in the
clinic and subjectively, by myself. All the drugs were taken in pill form.
Was the
treatment successful?
Apparently
yes. The haloperidol quickly reduced the level of distortions and theophylline (especially after the two bursts of dexamethasone) has gradually improved my acuity to the
point where it is now fully restored. Of course, one person's success is not
cast-iron proof that the treatment works.
How did my
viral anosmia start?
It began
with a sore throat that became progressively more painful for a week following
which a very stuffy head cold began, with a cough, fatigue and painful limbs.
After congestion began, anosmia set in. However, the viral symptoms can vary
widely.
How long
did recovery take?
I
suffered with parosmia from around August 1998 to May
1999 when I began treatment with haloperidol. The distortions were gone within
three weeks. Acuity recovered more slowly. Treatment for this using theophylline began in November 1999 and, to date, progress has been slow and gradual. My acuity is now
around 100%. However, progress was not linear, there were many ups and downs -
one day I'd taste something, a week later it would be gone again, only after
time did flavours/smells return and persist. I also
suffered for a long time from taste extinction - I'd taste the first mouthful
of a food or drink, and subsequent bites would have no flavour. I still
experience this on occasion.
Do the
drugs have any side-effects?
They can
do. Haloperidol is a strong antipsychotic and can cause drowsiness, insomnia,
depression and some central nervous system effects such as a marked twitching
of the hands. However, the doses used in treatment for parosmia
are tiny - I took only 0.5mg per day which my own GP described as minuscule. I
had no side-effects at all. Theophylline is a xanthine ,
a group of drugs which includes caffeine and its side-effects are almost
identical, including nausea, headache, gastrointestinal disturbances,
palpitations and insomnia. I started on a dose of 400mg per day in November
1999 and moved up to 600mg in February 2000. Side-effects usually present
themselves immediately with theophylline and rarely
appear with prolonged dosage, in fact there are no known long-term dangers in
taking this drug. I have probably had more headaches and neck ache since taking
the drug but no really bad effects at all. In any case, the benefit outweighs
the disadvantages. I have now moved back to 300mg per day. The dexamethasone is a corticosteroid and there are many
unpleasant effects associated with such drugs taken long-term. However, my
course was 24mg taken over the course of two days on two separate occasions. I
was sleepless on both occasions but this may have been due to the jetlag
experienced from my flight from
Could the
recovery have been spontaneous?
It could
have, although the coincidences were remarkable. Within three weeks of starting
haloperidol, the distortions were gone, as predicted by Dr Henkin.
Treatment with theophylline was also successful,
although much slower than Dr Henkin suggested. However,
the two treatments with dexamethasone , both boosted olfaction - objectively and subjectively.
What convinced me of the efficacy of theophylline was
that when, unilaterally and much, I suspect, to Dr Henkin's
irritation, I tried to wean myself off theophylline,
I began to suffer olfactory loss again. This was after three years of
apparently successful theophylline treatment.
Restarting theophylline restored olfaction. Bear in
mind, however, that many physicians and ENTs eschew
Dr Henkin's theories. The bottom line is I have no
proof that his treatment worked because I am a single case that could just
amount to a series of coincidences. Other people have had different experiences
and outcomes with the treatment. However, I personally am reasonably satisfied
that the treatment was successful in my case.
What else
might I expect?
Very
often, late-onset (ie non-congenital) anosmics suffer from depression and viral anosmics are no different. I found the depression very intense, others find it easier to cope. But in the first few
months the feelings can be very powerful and people, on very rare occasions,
have been known to contemplate suicide. If the depression is particularly bad
you should see a healthcare professional without delay. The situation is often
exacerbated by the fact that unless they have experienced anosmia, your friends
and family may consider that your complaint sounds trivial and you will
encounter statements such as 'It could be worse' or 'at least you don't have to
smell the cat litter'. You may need to explain that such comments are not
helpful.
If I think
I'm a viral anosmic, what should I do?
First you
should rule out any other cause for anosmia (the second most common cause is a
blow to the head), some of which, in rare cases, can be life-threatening.
Insist on an MRI, CAT scan and a sinus X-ray and also a visit to an ENT doctor.
However, if you can match your anosmia to a single instance of URI with no
previous history of allergic or sinus infection then it is highly likely that your
anosmia is of viral origin.
What other
conditions might I have?
The
differential diagnoses of viral anosmia are many. They range from inflammation
caused by allergies or sinus infection, through head injury, to tumours of the olfactory groove and frontal lobe of the
brain. Be reassured though, that such tumours
generally cause anosmia with a gradual onset. Viral anosmia is almost
instantaneous.
Are there
any reliable sources of information regarding viral anosmia on the internet?
Tangible,
reliable info is few and far between and all the major anosmia sites and
discussion forums are already detailed on the home page of this website.
However, for the best overview of all causes of anosmia, in brief and
straightforward terms, I'd recommend Tim Jacob's
Anosmia Page.
The Unbearable Absence of Smelling
Last updated 22. September 2005
ã Copyright 2004, 2005, Mick O'Hare - All rights reserved.
Addendum
Taste
Extinction. In
response to queries about "taste extinction," Mick noted that this
term is used by Dr. Henkin
and Professor
Tim Jacob, and he explained it, in layman's terms, in this way:
"This occurs because olfactory cells can only fire once every so often. If
you have fewer than the normal quotient they all fire upon the first contact
with an odour (or flavour) and are used up in that
first instance. In people with a normal olfactory system the cells share
the workload, and taste/smell can be maintained for
much longer. however, even in those with normal systems,
tastes/smells diminish after the first bite, just not by as much.
Franni Ferrero's Experience with
Viral Anosmia
Biopsies of Human
Olfactory Epithelium -- search for "viral"
Contact Information for the Webmaster,
Dr. Karl L. Wuensch
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This page most recently revised on 22. September 2005.