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November 18, 2010
Objectives: To develop an understanding of olfactory disorders
To develop an understanding of synesthesia
Question: What can happen if you lose your sense of smell? Danger wise….also think about memory.
Objectives
Know the overall epidemiology of olfactory dysfunction (OD)
Understand the olfactory circuitry List the main presentations & types of
smell dysfxcn Name the main tests of olfactory
function Review several of the major causes of
OD, their w/u & possible treatments
The Circuitry
6 million receptor cells in roof of nasal chamber
Axons project thru the cribiform plate of the ethmoids
Join to form the olfactory bulbs at base of frontal lobe
These project to the olfactory cortex in the subventricular zone
CN I
Types of Smell Disorders
A redneck died and left his entire estate to his beloved widow…
But she can’t touch it until she’s 14.
Did you hear they’ve raised the minimum age for alcohol for rednecks to 32 years….
They want to keep alcohol out of high school.
Types of Smell Disorders
Anosmia : NO smell Hyposmia : decreased smell
Also called microsmia & partial anosmia Dysosmia : distortion Phantosmia : smell w/o stimulus Hyperosmia : Abnormally acute Olfactory agnosia : Bilateral or unilateral
Smell Disorders
Presentation
As per type of smell disorder : No smell, less smell, “weird” smells
Taste problems One of earliest sx/sign of
Alzheimers Parkinson’s
Can it be lethal ? Yes ! When ?
Can’t smell : Spoiled food, Fire, gas leak (45% of pt.s)
How can you tell if someone has a real olfactory disorder?
The “ideal” test: Needs to assess for: Any sense What level of sense Different smells Malingering Laterality (bi- or uni-)
U Penn Smell ID Test (UPSIT) Threshold Olfactory Tests
Smell Test
The UPSIT
Commercial Most used Self-administered in 10-15 minutes Scored in < 1 minute by non-med person Available in various languages 40 “scratch & sniff “ patches Pt. chooses from 4 answers & must
choose 1 Can detect malingering
The UPSIT
Dysfunction classified as Mormosmia, anosmia, mild, moderate or severe microsmia, or probable malingering
Threshold olfactory tests A dilutional series of a stimulus odor
Uses an ascending concentration trial Must answer ‘yes’ or ‘no’
Other Tests
Pocket Smell test Brief Smell ID Test Squeeze bottle odor threshold test
All commercial
How do you know when your’re staying in a redneck hotel?
When you call the front desk and tell the mgr, “I gotta leak in my sink.” and he says,
“Go ahead.”
Causes of Smell Disorders
(Name some of them)
Age
Decreased smell occurs in the normal elderly
The greatest correlation with olfactory decline
More severe in men than women (Any conjecture on why?)
Multifactorial causes
Upper Respiratory Infections Most Common cause of permanent
smell problems Damage olfactory epithelium &
possibly central structures Common cold, hepatitis, influenza,
HSV, rabies and a bunch I’ve never heard of &
thus don’t care about
Toxins
Herbicides Pesticides Solvents Heavy Metals, esp cadmium, nickel,
chromium & manganese Damage olfactory epithelium Enter brain, esp. cadmium, gold &
manganese
Epilepsy
Right-sided foci > left-sided Anti-seizure meds can correct
problems
Neurodegenerative Diseases Alzheimers & Parkinson’s : Usually ASX, but present (Kevin,
er… Homer)
in 85-90% of pts Doesn’t respond to meds Magnitude not assoc with disease stage
Neurodegenerative Diseases Down’s Syndrome Huntington’s Disease Multiple Sclerosis Jacob-Creutzfeld
Head Trauma
About 20% of all chemosensory disorders Directly related to degree of trauma Also related to strong deceleration
injury Occipital and side injury more than
frontal If recovery, occurs within 1st year of
injury
Other Disorders
Cerebellar Degeneration Schizophrenia Migraine Hyperemesis gravidarum &
hyperosmia A number of systemic diseases Some Medicines Congenital anosmia
References Doty R. The Olfactory System and Its
Disorders. www.medscape.com/viewarticle/588523
Bromley S. Smell & Taste Disorders: A Primary Care Approach. AFP 2000;61:427-36.
Diagnosis of Anosmia. Online Medical Books. www.wrongdiagnosis.com/a/anosmia/diagnosis.htm
Wilson RS, et al. Olfactory identification & incidence of mild cognitive impairment in older age. Arch Gen Psychiatry 2007;64:802-8.
Final 5
Briefly describe one of the possible causes of the lack of smell.