Olfaction PATHWAY

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Achmad Prihadianto

Supervisor : dr. Melati Sudiro, M.Kes, Sp.THT-KL(K)

OLFACTION

Literature ReadingRhinology

Dept of Otorhinolaryngology - Head and Neck SurgeryFaculty of Medicine Universitas Padjadjaran / Hasan Sadikin General

HospitalBandung

2015

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INTRODUCTION

The sense of smell is absolutely crucial for Safety and quality of life .

The sense of smell have variety functionDetermine the flavor of foods and beveragesDetecting dangerous environmental situations exp.

The presence of fire, spoiled food, and leaking natural gas

Bailey,Byron,Johnson,Jonas T, Newlands, Shawn D, Head & Neck Surgery - Otolaryngology, 6th Ed, Lippincott Williams & Wilkins, 2014

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OLFACTORY DISORDERS

• Complete absense of sense of smellAnosmia

• refers to decreased ability to smellHyposmia

• alteration (decrease or distortion ) in smellDysosmias • A smell perceived in the absence of true odor in the

environmentPhantosmia • An alterated perception of an odor in the environment

different from what is usually experienced for that odor parosmia


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EPIDEMIOLOGY

19 % of the population over the age of 20 yo

25 % of the population over the age of 53 yo



ANATOMY

http://1.bp.blogspot.com/-GvJmnMbdRLg/TySINZYBbsI/AAAAAAAADf0/eNbZmZ_S-r0/s1600/New+Picture.png

http://4.bp.blogspot.com/-SDDm3n0eOMY/TySIcPReSFI/AAAAAAAADf8/xNK9OeEZ558/s1600/New+Picture+(1).png

ANATOMY

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• The front and top of the nasal cavity gets sensory innervation of anterior Etmoidalis nerve


ANATOMY


HISTOLOGYNeuroepithelium dan Reseptor Olfaktorius

ANATOMY

9Bailey,Byron,Johnson,Jonas T, Newlands, Shawn D, Head & Neck Surgery - Otolaryngology, 6th Ed, Lippincott

Williams & Wilkins, 2014

ANATOMY

10Bailey,Byron,Johnson,Jonas T, Newlands, Shawn D, Head & Neck Surgery - Otolaryngology, 6th Ed, Lippincott

Williams & Wilkins, 2014

11Bailey,Byron,Johnson,Jonas T, Newlands, Shawn D, Head & Neck Surgery - Otolaryngology, 6th Ed, Lippincott Williams & Wilkins, 2014

PHYSIOLOGY


ANATOMY

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ANATOMY

The bipolar

receptor cells

• as the receptor cell and the first-order neuron,

• project directly from the nasal cavity into the brain

• regenerate from basal cells



PHYSIOLOGY OF OLFACTION

Olfactory Transduction

odorants, most of which are hydrophobic, move

from the air phase of the nasal cavity into the

aqueous phase of the olfactory mucus

transported through the mucus by small water-

soluble proteins (termed odorant binding

proteins)

bind to the proteinaceous olfactory receptors located mainly

on the cilia action potentials 500 to 1,000 genes are

expressed in olfactory receptors Each

receptor cell seems to express only one or, at most, a few receptor

genes

Neurons expressing the same gene to olfactory

bulb

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ETIOLOGI OF OLFACTORY LOSS

• sensorineural factors • Conductive factors• Numerous causes for a decrease in ability to smell and

multipel reports from various smell and taste centers have consistenly recognized similar etiologi.

• The three most common are :a) Head traumab) Upper respiratory infection (URI)c) Cronic Rhinosinusitis


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1. Head Traumaoccurs in 15% of

patients with significant head trauma

Occipital blows > frontal blows.

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2. Upper Respiratory Infectionsthe most common cause of permanent smell loss in

adulthoodFactors that predispose individuals to virus induced smell

dysfunction and the mechanisms underlying it remain unclear


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3. Cronic Rhinosinusitis Not solely caused by decreased

conduction of airflow to the olfactory receptors

Chronic inflammation is, in fact, likely toxic to olfactory neurons

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4. Other causes:a) Congenital anosmia ( associated with Kallmann

syndrome (hypogonadotrophic hypogonadism)b) Neurodegenerative diseases such as Alzheimer

and Parkinson disease.c) Schizophrenia has also been associated with

smell disorders resulting in difficulty with identification of odors

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EVALUATION

• etiology of smell loss is obtaining a detailed history. Clues as to surrounding circumstances can point to a source of the disorder, and timing can also provide prognostic information

• The physical exam in evaluation of smell disorders includes a thorough head and neck examination with assessment of cranial nerve function

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PHISICAL EXAMINATION

otolaryngologic examination : • ant. rhinoscopy and nasal endoscopy the olfactory

cleft, nasal mucus membranes, polyp, masses,adhesions of the turbinates, deviations of the septum, and mucopus of the eustachian tube orifice

neurologic evaluation : • cranial nerve function and intracranial lesions

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OLFACTORY TESTING

Examination of olfactory sensory functions required to :1. Ensure the patient's complaints2. Establish the validity of a patient’s complaint3. Evaluate the efficacy of therapy, and4. Determine the degree of permanent

disturbance.5. Indentify malingering

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OLFACTORY TESTING

TWO TYPES OF OLFACTORY

TESTING

Psychophysical Tests• UPSIT (University of Pennsylvania

Smell Identification Test) • Sniffin Sticks test• CCRS (Connecticut Chemosensory

Clinical Research Center test)

Electrophysiological Tests • OERP (Odor Event-Related Potentials)• The Electro-Olfactogram

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OLFACTORY TESTING

• Psychophysical tests are more common in clinical practice, many of which are easy to use and the results can be compared to known population standards

• Threshold tests measure the ability to detect an odor (such as butyl alcohol) at the lowest concentration compared with a blank

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OLFACTORY TESTINGscratch and sniff

UPSIT (University of Pennsylvanias smell identification test )e 40-item SIT (Sensonics, Inc., Haddon Heights, NJ) consists of 40 scratch-and-sniff samples matchad with the names of four possible odors the patient can choose from. 'The number of correct responses correlates with the degree of oH'actory ability.

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OLFACTORY TEST

• simple measuring devices, • sensitivity 95% and specificity of 88% easily portable and can be

applied in the clinic,• can assess and measure the discrimination threshold of smell. • The aroma contained aroma of citrus fruits, coffee, onions, and

other

How to: open the hood of a pencil tip for 3 seconds and then positioned as far as 2 cm from the nostril, the patient was asked to recognize the scent there and then the examiner noted the results of the examination. The format is designed for three examinations, measurement threshold, discrimination and identification

Sniffin sticks

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OLFACTORY TESTING

The butanol threshold test consists of 8 series of progressively stronger butanol dilutions {outer 10 bottles) and blank controls (center four bottles).Patients asked to Identify the bottle containing butonal after smelling a puff of air squeezed from the dilution and a blank.

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IMAGING

• Because a detailed history provides the underlying etiology of olfactoty disorders in the majority of cases, imaging studies are usually not needed.

• A sinus computed tomography (CT) is helpful for the assessment of CRS and obstruction of the olfactory cleft.

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IMAGING STUDIES

MRI when the olfactory disorder occurs :a) in the absence of a clear etiology, b) with an unusual presentation, c) under suspicion of intracranial lesion based on

history and exam,d) with suspicion of a neurodegenerative processe) In congenital anosmia for assessment of the

olfactory bulbs and gyrus rectus.

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PANTOSMIA/DYSOSMIA CONSIDERATION

• Qualitative olfactory changes related to perceived distortions of inhaled odorants are called parosmia while the perception of smell when there is no odorant in the environment is known as phantosmia or olfactory hallucination.

• survey of 193 patients with olfactory complaints, Landis et al. noted that patients with parosmia frequently have a close temporal history of head trauma or URI.

PANTOSMIA "olfactory hallucination".

• Phenomenon of smelling odors that aren't really present

• Olfactory hallucinations without subsequent myoclonic activity have not been well characterized or understood

• Mechanisms responsible for phantosmia in each group were related to decreased gamma-aminobutyric acid (GABA) activity in specific brain regions.

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PANTOSMIA "olfactory hallucination".

There are a wide range of possible causes of phantosmia, include:• nasal infection • nasal polyps, which are abnormal tissue growths that form

inside the nasal passages and sinuses• migraine with aura – some people smell phantom odours just

before or during a migraine • dental problems • smoking • exposure to certain chemicals such as insecticides• radiation for treatment of head and neck cancer

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PANTOSMIA ‘Olfactory hallucination’

Neurological (nervous system) conditionsLess commonly, the cause of phantosmia is either nerve cells sending abnormal smell signals to the brain, or a problem with the brain itself.

This may be the result of:• a disease affecting the nervous system, such as epilepsy,

Parkinson’s disease or Alzheimer’s disease • a stroke • a head injury • cancer – usually a brain tumour or neuroblastoma (a rare cancer

that may start in the olfactory nerve)

http://www.nhs.uk/conditions/epilepsy/Pages/Introduction.aspx

http://www.nhs.uk/conditions/parkinsons-disease/Pages/Introduction.aspx

http://www.nhs.uk/conditions/Alzheimers-disease/Pages/Introduction.aspx

http://www.nhs.uk/conditions/Stroke/Pages/Introduction.aspx

http://www.nhs.uk/conditions/head-injury-severe-/pages/introduction.aspx

http://www.nhs.uk/conditions/brain-tumour/Pages/Introduction.aspx

http://www.nhs.uk/conditions/brain-tumour/Pages/Introduction.aspx

http://www.nhs.uk/conditions/neuroblastoma/Pages/Introduction.aspx

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PANTOSMIA ‘Olfactory hallucination’

Some people with phantosmia will find that the smell gradually fades over a few months, and no treatment is needed.

treatments may be tried:

A. Rinsing out the nasal passages with saline solution

B. Nasal drops or spray

C. Sedatives, antidepressants or anti-epileptic drugs

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TREATMENTS

• effective treatment for quantitative olfactory losses is only available for the conductive type where odorant molecules cannot physically access the olfactory receptors.

• For neural quantitative losses, there are generally no effective therapies. There is no documented return of smell in patients with complete congenital olfactory loss

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TREATMENT

• For the two most common types of neural losses, post head trauma and URI-related loss, there is no predictably effective therapy

• Olfactory training has been recently touted as an effectivetherapy for those who have some remaining olfactory ability (hyposmia, not anosmia)

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HIGHLIGHTSDisorders of smell are not infrequent and have a significant impact on quality of life for those who are afflicted.

Olfactory receptor neurons are unique in their direct connection to the brain and the regenerative capacity of the olfactory epithelium to replace them throughout the life of the organism.

URis, head trauma, CRS, and aging are the mostcommon identifiable etiologies for smell loss. In many cases, a cause for smell loss is never identified.

Anamnesis and nasal endoscopy are crucial in the evaluation of patients complaining of smell disorders.

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HIGHLIGHTSValidated tests of smell are available for use by all physicians and allow for a subjective assessment of the degree of impairment.

Phantosmia and parosmia commonly occur with olfactory loss, but usually resolve

spontaneously.

Physicians evaluating patients with smell disorders need to discuss hazards associated

with smell loss

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Thank You

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Olfaction PATHWAY