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.