1 Smell aka Olfaction (Latin olfacere)Taste aka Gustation (Latin gustare)

2 Sense of Smell Smell is the least understood of our senses.one of the chemical senses This results partly from the fact that the sense of smell is a subjective phenomenon that cannot be studied with ease in lower animals. Another complicating problem is that the sense of smell is poorly developed in human beings (Microsmatic) in comparison with the sense of smell in many lower animals (Macrosmatic). Important for pleasure and for enjoying the taste of food. Chemical detection without the danger of ingesting poison alert us to potential dangers, e.g. smoke

3 Where does smell figure?In humans Strong link to sense of taste Strong link to emotional states Exploited by commercials/marketing Used for identification of gender Dangers and hazards Pheromones - signal sexual arousal or a readiness for mating

4 Olfactory Membrane lies in the superior part of each nostrilLocated 7 cm inside the nasal cavity In each nostril, the olfactory membrane has a surface area of about 2.4 square centimeters The human olfactory epithelium covers an area of roughly 1 cm2 on each side Olfactory Cells - The receptor cells for the smell sensation - bipolar nerve cells derived originally from the CNS about 10 million of these cells in the olfactory epithelium interspersed among sustentacular cells--rabbit  have approximately 50 million olfactory axons, whereas humans  have only 6 million bilaterally Olfactory mucous membrane is the place in body where NS is closest to external world

5 Olfactory Membrane The mucosal end of the olfactory cell forms a knob from which 4 to 25 olfactory hairs (also called olfactory cilia), project into the mucus that coats the inner surface of the nasal cavity cilia react to odors in the air and stimulate the olfactory cells Spaced among the olfactory cells - Bowman’s glands that secrete mucus onto the surface of the olfactory membrane. Olfactory cells are constantly being replaced with a half-time of a few weeks

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8 The olfactory mucosa

9 -From rods cilia project to the mucous surfaceOlfactory Receptor Cells have cilia Cilia are bathed in mucous Mucous contains Odorant binding proteins (OBP) OBP transmits the odorant molecules from the air to receptor sites on the cilia -Each neuron has a thick dendrite with an expanded end called olfactory knob -From rods cilia project to the mucous surface -Each receptor neuron has cilia -Axons of olfactory receptor neurons pierce cribriform plate of ethmoid bone and enter olfactory bulbs -Olfactory neurons have half-time of few weeks- Live for 5- 8 weeks & then die

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13 Excitation of the Olfactory CellsThe portion of each olfactory cell that responds to the olfactory chemical stimuli is the olfactory cilia. The odorant substance, on coming in contact with the olfactory membrane surface, first diffuses into the mucus that covers the cilia. Then it binds with receptor proteins in the membrane of each cilium - OBP Receptor protein – G protein – cAMP pathway – opening of Na channels – action potential – exciting the olfactory neuron - olfactory nerve – CNS

14 Excitation of the Olfactory CellsOnly volatile substances that can be sniffed into the nostrils can be smelled Substance must be at least slightly water soluble so that it can pass through the mucus to reach the olfactory cilia. substance to be at least slightly lipid soluble, presumably because lipid constituents of the cilium itself are a weak barrier to non-lipid-soluble odorants. Sniffing is a semi-reflex response that usually occurs when a new odor attracts attention.

15 Ever wonder why we sniff?Because only 5% of our nostril is covered with the olfactory epithelium, we sniff to maximize the coverage of the air intake over this portion of our nose as seen in the diagram to the left. Cool huh?

16 Odor pathways ➜ Orthonasal Pathway ➜ Retronasal pathwayThere is a good reason not to talk with one's mouth full: it means a loss of precious smells making their way to the organ of olfaction

17 Adaptation Olfactory fatigueThe olfactory receptors adapt about 50 per cent in the first second or so after stimulation. Thereafter, they adapt very little and very slowly. our own experience that smell sensations adapt almost to extinction within a minute or so after entering a strongly odorous atmosphere.

18 Adaptation cross-adaptationBecause this psychological adaptation is far greater than the degree of adaptation of the receptors themselves most of the additional adaptation occurs within the CNS Large numbers of nerve fibers pass from the olfactory regions of the brain backward along the olfactory tract and terminate on special inhibitory cells in the olfactory bulb, the granule cells. cross-adaptation

19 Primary Smell Sensations1. Camphoraceous 2. Musky 3. Floral 4. Pepperminty 5. Ethereal 6. Pungent 7. Putrid 100 primary sensations of smell

20 Affective Nature of Smellaffective quality of either pleasantness or unpleasantness. smell is probably even more important than taste for the selection of food a person who has previously eaten food that disagreed with him or her is often nauseated by the smell of that same food on a second occasion

21 Neural RepresentationsVery little known No odorotopic map found. All cells fire for all odors but form different patterns different odors => Population code. Other complications: Change in intensity leads to increase in the firing rate of neurons but triggers changes in the perceived quality of the odorant. Rats are 8 to 50 times more sensitive to odors than humans Dogs are 300 to 10,000 times more sensitive The difference lies in the number of receptors they each have Humans have 10 million and dogs have 1 billion olfactory receptors

22 Threshold for Smell the minute quantity of stimulating agent in the air can elicit a smell sensation. the substance methylmercaptan can be smelled when only one 25 trillionth of a gram is present in each milliliter of air. Because of this very low threshold, this substance is mixed with natural gas to give the gas an odor that can be detected when even small amounts of gas leak from a cylinder.

23 Smoking is injurious to odor detection!Odor Perception Odor (as well as taste) are much more phenomenological than vision or audition. Odor Detection Very good: Mercaptan 1 part per 50 billion parts of air. Varies greatly from odor to odor (molecular properties) Varies with a variety of other factors Time of day, Age and Gender Smoking is injurious to odor detection! Odor Identification Much worse Shows context dependence Varies once again with age and gender Humans can discriminate among 100,000 odors but they cannot label them accurately This appears to be caused by an inability to retrieve the name from memory, from a lack of sensitivity

24 Olfactory thresholds and discriminationOlfactory receptors respond only to substances in contact with olfactory epithelium and need to be dissolved in mucus Methyl marcaptan one of the substances in garlic can be smelled at very low concentration showing the remarkable sensitivity of olfactory receptors Humans can recognize more than different odors However determination of intensity of odor is poor Substance mg/L of Air Ethyl ether 5.83 Chloroform 3.30 Pyridine 0.03 Oil of peppermint 0.02 Iodoform Butyric acid 0.009 Propyl mercaptan 0.006 Artificial musk Methyl mercaptan

25 Smoking is injurious to odor identification!Determined by Gender Women vastly superior Can be improved with practice - benefits both genders Stimulus Saliency Infants and mothers can recognize each other by smell alone Infants hedonic reactions to smell develops with age Odor Familiarity - Seen in elderly people Smoking is injurious to odor identification!

26 Some more amazing factsOdor Constancy Natural sniffs lead to constant odor perception but artificial blowing of air does not Common Chemical Sense Odors judged pleasant at moderate concentrations are judged unpleasant at high concentrations Related to the action of free nerve endings – stimulated in an indiscriminate manner Warning system for the organism Adaptation - Adapt to a particular odor Cross Adaptation: Adapt to a different odor Could have led to odor categorization but turns out that cross-adaptation is not symmetric!

27 Researchers have found it difficult to map perceptual experience onto physical attributes of odorants. Linking chemical structure to types of smells Some molecules with similar shapes had very different smells Some similar smells came from molecules with different shapes 1,000 different receptor types - about 1% of your DNA codes for olfactory receptors making it the largest single gene family

28 Perception of Smell We can distinguish between about 10,000 different smells Different threshold levels for different smells Two thresholds for each smell -low threshold for the existence of a chemical, somewhat higher threshold to discriminate one smell from another

29 Smell Pathway Olfactory bulb - olfactory tract – olfactory nerve – 1st cranial nerve both the tract and the bulb are an anterior outgrowth of brain tissue from the base of the brain olfactory bulb lies over the cribriform plate, separating the brain cavity from the upper nasal cavity The cribriform plate has multiple small perforations through which an equal number of small nerves pass upward from the olfactory membrane in the nasal cavity to enter the olfactory bulb in the cranial cavity

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31 Olfactory Bulbs Olfactory bulb - organ which houses all the nerves which receive inputs from the olfactory receptors -Axons of receptors contact the primary dendrites of mitral cells and tufted cells. -Forming complex globular synapses called olfactory glomeruli. -Periglomerular cells are inhibitory neurons connecting one glomerulus to another

32 Olfactory Bulb

33 Olfactory pathway There are approximately 20 olfactory foramina on either side of the nose in the cribiform plate of the ethmoid bone passes 40 or so bundles of axons form right and left olfactory nerves They terminate in the olfactory bulbs – below the frontal lobes of the cerebrum Axons of the olfactory bulbs form the olfactory tract which projects to the primary olfactory area of the cerebral cortex. Some project into the limbic system and hypothalamus (emotional and memory evoked responses). Olfactory sensations are the only sensations that reach the cerebral cortex without first synapsing in the thalamus. The primary olfactory area has axons that extend to the orbit frontal area (frontal lobe) – region for odor identification.

34 Olfactory pathway

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36 -Granule cells have no axons and make reciprocal synapses with lateral dendrites of tufted and mitral cells -Mitral and Tufted – excite granule releasing glutamate and granule cell in turn inhibits both by releasing GABA Olfactory Bulbs

37 Stimulation of Olfactory cells

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39 Smell Pathway short axons from the olfactory cells terminating in multiple globular structures within the olfactory bulb called glomeruli Each glomerulus is the terminus for dendrites from about 25 large mitral cells and about 60 smaller tufted cells, the cell bodies of which lie in the olfactory bulb superior to the glomeruli – granule cells - Periglomerular cells mitral and tufted cells send axons through the olfactory tract to transmit olfactory signals to higher levels in the CNS Mucus – cilia - Axons of olfactory cells – glomeruli in bulb – dendrites of mitral, tufted cells in bulb – axons of mitral, tufted cells in tract - CNS

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41 Smell CNS Pathway Olfactory tract divides intomedially into the medial olfactory area (stria) of the brain stem – very old olfactory system other passing laterally into the lateral olfactory area (stria) - a newer & less old system The Medial Olfactory Area (very old) – septal nuclei – hypothalamus – limbic system – removal – not much effect The Less Old Lateral Olfactory Area - prepyriform and pyriform cortex plus portion of the amygdaloid nuclei – limbic system (hippocampus) – learning & aversion

42 Smell CNS Pathway lateral olfactory area - anteromedial portion of the temporal lobe (cerebral cortex) *This is the only area of the entire cerebral cortex where sensory signals pass directly to the cortex without passing first through the thalamus The Newer Pathway - passes through the thalamus, passing to the dorsomedial thalamic nucleus - orbitofrontal cortex conscious analysis of odor Granule cells, Periglomerular cells – lateral inhibition

43 Mitral cell projectionsMitral cell axons form the lateral olfactory tract. Projects to accessory olfactory nuclei, olfactory tubercule, entorhinal cortex, amygdala, pyriform cortex Pyriform cortex axons project to thalamus, hippothalamus, hippocampus, amygdala.

44 Central olfactory pathwaysLateral olfactory tract projects directly to the piriform cortex (= primary olfactory cortex = paleocortex) adjacent to lateral olfactory tract in temporal lobe. This is only sense that does not have relay in thalamus on way from receptors to cerebral cortex. From piriform cortex there are projections to hypothalamus, the thalamus, amygdala, entorhinal cortex. From thalamus there is a projection to orbitofrontal cortex where odor perception and discrimination takes place. Electrical stimulation of piriform cortex causes olfactory sensations. People with lesions of orbitofrontal cortex are unable to discriminate odors. Pathways through amygdala and hypothalamus mediate emotional, motivational and many physiological effects of odors.

45 Transmission of smell signals to CNS

46 Structure of the Olfactory SystemSignals are sent to Primary olfactory (piriform) cortex in the temporal lobe Secondary olfactory (orbitofrontal ) cortex in the frontal lobe Amygdala deep in the cortex ch 15

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50 Central Olfactory PathwaysAnthony J Greene

51 Central Olfactory PathwaysAnthony J Greene

52 Central Olefactory PathwaysAnthony J Greene

53 Central Olefactory PathwaysAnthony J Greene

54 Central Olefactory PathwaysAnthony J Greene

55 Central Olefactory PathwaysAnthony J Greene

56 Vomeronasal Organ In rodents and various other mammals, the nasal cavity contains another patch of olfactory mucous membrane located along the nasal septum in a well- developed vomeronasal organ. This structure is concerned with the perception of odors that act as pheromones. Its receptors project to the accessory olfactory bulb and from there primarily to areas in the amygdala and hypothalamus that are concerned with reproduction The organ is not well developed in humans.

57 Vomeronasal Organ Organ is not well developed in humans very well developed in rodents This organ is concerned with perception of odors that act as pheromones There is evidence of pheromones in humans and a close relationship between smell and sexual function

58 Evidence for the existence of pheromones in humans ???close relationship between smell and sexual function - The perfume ads The sense of smell is said to be more acute in women than in men, and in women it is most acute at the time of ovulation. Smell and, to a lesser extent, taste have a unique ability to trigger long-term memories Vomeronasal Organ

59 Pheromones Species specific odorants.Some pheromones stimulate the vomeronasal organ VNO--> accessory olfactory bulb-->hypothalamus. (Found in 8% of human adults), VNO receptors are pseudogenes in humans ➜ Kairomone Attracts individuals of other species ➜ Allomone Repels individuals of other species ➜ Pheromone Affects individuals of the same species ➜ Primer pheromone Triggers a long-lasting physiological change in the target animal ➜ Releaser pheromone Triggers an immediate behavioral response in the target animal Mammals and pheromones ➜ Primer effect Male mice produce chemosignals that accelerate puberty in immature females. Female mice housed in groups produce a urinary chemosignal that supresses estrus in other females. If a just-mated female mouse is exposed to the smell of a strange male (i.e. different from the mating male), this smell prevents the female from becoming pregnant. Releaser effect A vaginal discharge of the female golden hamster causes males to mate. When a sow in estrus smells the boar odor, she become motionless, rounds her back and pricks up her ears (lordosis).

60 Pheromones: Mammals Powerful effects on behavior, specifically sexual behavior, territorial behavior and identification of kin Mammals Most mammals only become sexually aroused in the presence of pheromones Increased likelihood of pregnancy Synchronization of estrus cycles Mutual recognition of mother and offspring Territory marking (e.g. dogs) Releasers - trigger a specific behavioral response Primers - trigger a hormone response which increases the likelihood of certain types of behaviors

61 Pheromones: Humans Humans infants can correctly identify their own mother's milk and are much more likely to nurse when its their own mother female menstrual cycles can be altered by pheromones - the sorority effect male and female behavior is highly influenced by pheromones t-shirt experiment - musky versus sweet - the musky odor is rated by males and females as unpleasant and is thought to serve as a territorial marker among males

62 Pheromones: Alpha Androstenolalpha androstenol (predominantly secreted by females) Increase sexual arousal in males Increases male perception of female attractiveness women in photographs were rated as significantly more sexually attractive when judges were first exposed to alpha androstenol Increases willingness of females to initiate social contact with males females exposed to alpha androstenol were much more receptive to male-initiated contact more likely to seek out male company less likely to seek female company Anthony J Greene

63 Applied Pain Fibers in the Nose - Naked endings of many trigeminal pain fibers are found in the olfactory mucous membrane - stimulated by irritating substances peppermint, menthol and chlorine - sneezing, lacrimation, respiratory inhibition anosmia (absence of the sense of smell), hyposmia (diminished olfactory sensitivity), and dysosmia (distorted sense of smell). Olfactory thresholds increase with advancing age, and more than 75% of humans over the age of 80 have an impaired ability to identify smells. Anosmia + Hypogonadism (Kallmann's syndrome)

64 Role of Pain Fibers in the NoseMany trigeminal pain fibers are found in olfactory membrane They are stimulated by irritating substances Are responsible for initiating sneezing, lacrimation and other reflex responses.

65 Measuring the detection thresholdDetecting Odors Measuring the detection threshold Yes/no procedure - participants are given trials with odors along with “blank” trials They respond by saying yes or no Forced-choice - two trials are given, one with odorant and one without Participant indicates which smells strongest Measuring the difference threshold Measure the smallest difference that can be detected between two samples ch 15

66 Olfactory Testing  Essential for multiple factors: Validate patient’s complaint  Characterize specific nature of the problem  Monitor changes in function over time  Detect malingering  Establish compensation for permanent disability  Many patients complaining of anosmia or hyposmia have normal function relative to age and gender  90% of patients with idiopathic Parkinson’s Disease have demonstrable smell loss, yet less than 15% are aware of their problem

67 Olfactory Testing  Asking a patient to sniff odors is like testing vision by shining a light in each eye and asking whether the patient can see the light  No current testing that can distinguish central and peripheral deficits  Unilateral testing is often warranted  Sealing contralateral naris using Microfoam tape and having the patient sniff naturally and exhale through the mouth to prevent retronasal stimulation

68 Medical/Legal Considerations with Ansomia Common in head injury and often the only residual neurologic impairment  Claims of accidental and iatrogenic smell disturbance often results in substantial financial awards  Veterans Administration awards a 10% whole-body disability for total anosmia  Occupation should be taken into account in disability issues

69 Olfactory Testing  Psychophysical Testing Electrophysiologic Testing  Neuropsychologic Testing

70 Psychophysical Testing UPSIT or Smell Identificiation Test  Can be administered in 10 to 15 minutes by most patients  4 booklets of 10 odorants apiece  Stimuli embedded into 10- to 50-μm diameter microencapsulated crystals  Multiple choice questions with four response alternatives  Test is forced-choice, required to choose an answer even if none seems appropriate  Chance performance is 10 out of 40 , lower scores can represent avoidance  Norms available based on administration to 4,000 people  Individuals are ranked relative to age and gender

71 UPSIT (continued)  Test can classify individual’s function into 6 categories:  Normosmia  Mild microsmia  Moderate microsmia  Severe microsmia  Anosmia  Probable malingering  Very high reliability, test-retest Pearson r = 0.94

72 Medical/Legal Considerations with Anosmia UPSIT score sensitive to malingering  Theoretical probability of true anosmic to score UPSIT 5 or less: 0.05%  Theoretical probability of true anosmic scoring 0 on UPSIT:

73 Electrophysiologic Testing 2 procedures are available but application largely experimental  Odor event-related potentials(OERPs)  Electro-olfactogram (EOG)

74 Odor Event-Related Potentials(OERPs)  Discerning synchronized brain EEG activity recorded on the scalp from overall EEG activity following presentations of odorants  Stimuli presented in precise manner using equipment that produces stimuli embedded in warm, humidified air stream  Unable to perform necessary trials and test reliability is suspect  No inference can be made regarding location of a lesion or deficit  Can be usefully in detecting malingering

75 OERP

76 Electro-olfactogram (EOG) Measures electrode placed on the surface of the olfactory epithelium  Few patients amenable to recordings  Must place electrode under endoscopic guidance without local anesthesia  Can be quite unpleasant and sneezing/mucous discharge common  Cannot reliably record in many subjects  Presence of robust EOG does not always represent olfactory functioning  Anosmic patients with Kallmann syndrome and hyposmic patients with schizophrenia have large EOG responses

77 Neuropsychologic Testing Strong association between Alzheimer’s, Parkinson’s, and olfactory dysfunction  Brief neuropsychologic testing warranted in some cases to determine presence of dementia  Mini-Mental State Examination- brief screening tool for dementia and can be quickly administered in a few minutes for further referral as necessary

78 Neuroimaging Olfactory Biopsy Olfactory dysfunction of idiopathic etiology warrants CT imaging  High-resolution CT is most useful and cost-effective screening tool  MRI: useful in evaluating olfactory bulbs, olfactory tract, and intracranial structures  MRI can detect decrements associated with anosmia and patients with schizophrenia Olfactory Biopsy  Small amount of superior septal tissue removed by experienced rhinologist  Multiple biopsies needed to obtain true neuroepithelium

79 The tools of the psychophysical trade: an informed, consenting human subject and an odor source. Odorants are supplied by a variety of means: squeeze bottles, ‘rip-and-sniff’ packets, glass vials (as depicted here), or sophisticated computer-controlled olfactometers that deliver odors in a stream of warm and humidified air directly into the nose

80 Threshold olfactory testsA dilutional series of a stimulus odor Uses an ascending concentration trial Must answer ‘yes’ or ‘no’

81 The UPSIT Commercial Most used Self-administered in 10-15 minutesScored 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

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83 چرخ و فلک بوها یک تست بویایی بسیار ساده است که به صورت بازی طراحی شده است. در این تست 9 بوی استاندارد قرار داده شده‌اند و در کنار هر یک از آنها، چهار گزینه به صورت مصور وجود دارد. از کودک خواسته می‌شود که پس از بو کشیدن هر یک از بوها، بر اساس بویی که تشخیص داده، یکی از چهار گزینه‌ی مجاور آن را انتخاب نماید. بر اساس تعداد پاسخ­‌های صحیح، مشخص می‌شود که حس بویایی کودک نرمال است یا اینکه دچار اختلال بویایی می‌باشد. کودکان از مشکلات بویایی خود خبر ندارند. وجود اختلالات بویایی در کودکان بسیار خطرناک است، زیرا تشخیص بسیاری از مخاطرات مانند آتش‌سوزی، نشت گاز و غذای فاسد، تنها از بوی آنها امکان‌پذیر است. از طرفی، کودکان دچار اختلالات بویایی عموماً مشکلات تغذیه‌­ای نیز دارند.  چرخ و فلک بوها، در وحله‌ی اول یک تست پزشکی برای تشخیص اختلال بویایی در کودکان 3 تا 11 سال است. با انجام این تست می‌توان از سلامت بویایی کودک اطمینان حاصل نمود. انجام این تست مزایایی دیگری نیز دارد که عبارتند از: -   تجربه بوهای مختلف و شناخت بهتر دنیای پیرامون -   تقویت ادراک حسی کودک -   آشنایی کودک با توانمندی­‌های جسمی خود و افزایش اعتماد به نفس -   سنجش و تقویت تمرکز در کودکان چرخ و فلک بوها برای استفاده در منازل، مهد کودک‌­ها، پیش دبستانی‌­ها، دبستان­‌ها، مراکز درمانی، تحقیقاتی، آموزشی و توان‌بخشی مناسب است.

84 «آزمون تشخیص بویایی ایران» اولین روش استاندارد ارزیابی حس بویایی به صورت کمّی در ایران است. این تست، نسخه‌ی ایرانی تست تشخیص بویایی دانشگاه پنسیلوانیا  (UPSIT)است که در آن از بوهای آشنا با فرهنگ مردم ایران استفاده شده است. «آزمون تشخیص بویایی ایران» به صورت یک کیت حاوی 24 نوع بوی مختلف در هشت دسته­‌ی عطری، میوه‌­ای، نعنایی، تند، شیرین، ترش، چوبی و زننده می‌باشد و با استفاده از آن می‌­توان توانایی افراد در افتراق بوهای مختلف را ارزیابی نمود. نتیجه‌ی تست به صورت یک عدد از صفر تا 24 گزارش می­‌شود و عملکرد حس بویایی را در محدوده نرموسمی، آنوسمی، هیپوسمی (میکروسمی) شدید و خفیف مشخص می­‌نماید. «آزمون تشخیص بویایی ایران» برای مردم ایران استاندارد‌سازی شده است و محدوده‌ی نرمال آن برای سنین 20 تا 50 سال، 24-19 می‌باشد. این محدوده برای افراد با رنج سنی کمتر از 20 و  بیشتر از 50 سال کمی افت دارد. انجام این تست بسیار ساده است و به صورت خودآزمون نیز قابل انجام است. مدت زمان انجام تست برای کاربر غیرحرفه‌­ای کمتر از 12 دقیقه است. 

85 آزمون تشخیص بویایی ایران ویژه‌ی پزشکی قانونی Iran smell Identification Test (Iran-SIT) For forensics medicine ·         شامل کیت و نرم‌افزار ویژه‌ی تشخیص تمارض ·         تشخیص تمارض به از دست دادن حس بویایی (Malingering) به روش کلامی (Subjective) ·         بررسی 6 معیار تشخیص تمارض ·         دقت تشخیص بیش از 90% ·         مدت زمان انجام تست کم‌تر از 20 دقیقه ·         مناسب برای استفاده در مراکز معتمد پزشکی قانونی

86 آزمون تشخیص بویایی ایران «تست سریع»    روش ساده، سریع و کم‌ هزینه برای ارزیابی اولیه‌ی عملکرد حس بویایی طراحی‌شده به صورت یک کیت با 6 بوی مختلف تشخیص نرموسمی، آنوسمی و یا وجود اختلال بویایی مدت زمان انجام تست کمتر از 3 دقیقه مناسب برای استفاده در مطب­‌ها و کلینیک‌های گوش و حلق و بینی تست کاربردی در تحقیقات پزشکی با حجم نمونه بالا و غربالگری­‌ها

87 تست آستانه بویایی Smell Threshold Testشامل یک سری محلول فنیل بوتیل الکل با غلظت­‌های مختلف از 2-10 تا 9-10 تعیین حد آستانه‌ی بویایی افراد (کم‌ترین غلظتی از بو که فرد می‌تواند شناسایی کند) تشخیص اختلالات هایپوسمی و هایپروسمی مناسب برای کاربردهای تحقیقاتی و کلینیکی ·        

88 تست حجم بویایی  SMT Sniff Magnitude Test

89 دستگاه SMT (Sniff Magnitude Test) وسیله‌ای برای ارزیابی عملکرد کمّی بویایی به صورت غیرکلامی است. این دستگاه شامل سنسورهای حساس و دقیقی است که توانایی بویایی افراد را ارزیابی می‌کنند و هم‌چنین با بهره‌گیری از یک نرم‌افزار، داده‌ها را تحلیل کرده و نتیجه را با دقت بالایی ارائه می‌نماید.  ویژگی‌های کلّی SMT: دارای کم‌ترین وابستگی به زبان، توانایی‌های شناختی، حافظه و توانایی نام بردن بوها قابلیت تشخیص اختلالاتی که به علت نقص در ورودی حسی اولیه ایجاد می‌شوند را از اختلالاتی که به علت نقص در ورودی حسی اولیه ایجاد می‌شوند را از اختلالاتی که به علت پردازش در سطح بالاتر در اثر بیماری‌هایی مانند تروپوسمی، فانتوسمی و اگنوزی بویایی عدم تأثیر کم شدن حافظه یا دقت افراد کهنسال روی نتیجه‌ی تست اندازه‌گیری عملکرد حس بویایی به صورت کمّی مشخصات فنّی SMT: این دستگاه دارای یک یونیت کنترل، یک کانولا، 4 قوطی فلزی حاوی بوهای مختلف، نرم افزار مخصوص و سیم‌های اتصال است. استفاده از این دستگاه مستلزم به‌کارگیری هم زمان یک کامپیوتر و پرینتر می‌باشد. دستگاه دارای استاندارد ISO 9001:2000 و ISO 13485:2003 است.

90 روش کار SMT: ابتدا کانولا به بینی بیمار متصل می‌شود، سپس با قرار گرفتن قوطی‌های مخصوص در مقابل بینی، از وی خواسته می‌شود که محتویات قوطی را بو بکشد. در این حالت، نرم افزار مخصوص دستگاه به طور هم زمان نمودار بویایی فرد را رسم‌کرده و وضعیت اختلال وی را مشخص می‌نماید. موارد استفاده از SMT: برای تشخیص تمارض به از دست دادن حس بویایی در کاربردهای پزشکی قانونی  تشخیص بیماری های آلزایمر، پارکینسون، ام اس و بسیاری از بیماری های اعصاب مرکزی تشخیص آسیب مغزی در اثر تروما تشخیص هر بیماری یا وضعیتی که به عصب یکم جمجمه ای آسیب وارد کند.

91 درمان اختلالات بویایی، وابستگی زیادی به علّت زمینه‌ای ایجاد اختلال دارد. اختلالات مرتبط با انسداد مسیر بویایی معمولاً با درمان‌های متداول برطرف می‌شوند، در حالی که درمان اختلالات حسّی در بسیاری از موارد بی‌نتیجه می‌ماند. در شماری از آسیب‌های سیستم بویایی، نورون‌های گیرنده‌ی بویایی با گذشت زمان ترمیم و بازسازی می‌شوند، اما به دلیل نداشتن نظم و جهت‌گیری صحیح، توانایی بویایی فرد بهبود نمی‌یابد. تمرین بویایی (Olfactory Training) یک روش جدید برای توانبخشی حس بویایی است که در آن نورون‌های بازسازی شده با قرارگیری در معرض بوهای خاص جهت‌گیری می‌نمایند. تحقیقات نشان می­‌دهند که نورون­‌های گیرنده­‌ی بویایی انسان توانایی ترمیم و بهبود دارند و قرارگیری در معرض برخی بوها به صورت مداوم می‌­تواند به بازیابی حس بویایی کمک کند. در این روش فرد به صورت مداوم و کوتاه مدت در معرض بوهای خاص در یک دوره زمانی قرار می­‌گیرد. به این ترتیب وقتی که نورون­‌های گیرنده­‌ی بویایی ترمیم و بازسازی می­‌شوند، بوها می­‌توانند جهت گیری مناسب را در آنها ایجاد نمایند. اولفکتِرین، یک کیت درمان اختلالات بویایی به روش تمرین بویایی (Olfactory Training) است که در آن چهار ماده معطر که سررده­ هرم بویایی می­‌باشند، قرار داده شده‌­اند. تحقیقات نشان داده­‌اند که استفاده ار این کیت دوبار در روز و به مدت 12 هفته باعث بهبود عملکرد بویایی در افراد دچار اختلال پس از عفونت (Postinfection) یا ضربه به سر (Post Trauma) و یا کسانی که حس بویایی خود را به دلایل نانشاخته ( ایدیوپاتیک) از دست داده‌اند، می‌­گردد. توصیه می­‌شود قبل از شروع درمان، حس بویایی بیمار با استفاده از «تست بویایی کامل» مورد ارزیابی قرار گیرد و پس از اتمام دوره درمان (12 هفته)، مجدداً تست بویایی انجام شود تا میزان بهبود بویایی بیمار مشخص شود.

92  Central olfactory neural lossDisorders of Smell Classification  Conductive loss  Obstruction of nasal passages  E.g., chronic nasal inflammation, polyposis  Sensorineural loss  Damage to neuroepithelium  E.g., viral infection, airborne toxin  Central olfactory neural loss  CNS damage  E.g., tumors, neurodegenerative disorders Anosmia or “Odor Blindness” can be Temporary since ORCs can regenerate Sometimes can be total but in that case is specific to certain odors, e.g. sweat,urine Anosmia can have serious consequences such as loss of apetite and weight

93 Disorders of Olfaction Obstructive Nasal and Sinus Disease  Upper Respiratory Infection  Head Trauma  Aging  Congenital Dysfunction  Toxic Exposure  Neoplasms  HIV  Epilepsy and Psychiatric Disorders  Medications  Surgery  Idiopathic Loss

94 Causes of Smell Disorders

95 Age Decreased smell occurs in the normal elderlyThe greatest correlation with olfactory decline More severe in men than women (Any conjecture on why?) Multifactorial causes

96 Upper Respiratory InfectionsMost 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

97 Toxins Herbicides Pesticides SolventsHeavy Metals, esp cadmium, nickel, chromium & manganese Damage olfactory epithelium Enter brain, esp. cadmium, gold & manganese

98 Epilepsy Right-sided foci > left-sidedAnti-seizure meds can correct problems

99 Neurodegenerative DiseasesAlzheimers & Parkinson’s : Usually ASX, but present in 85-90% of pts Doesn’t respond to meds Magnitude not assoc with disease stage

100 Neurodegenerative DiseasesDown’s Syndrome Huntington’s Disease Multiple Sclerosis Jacob-Creutzfeld

101 Head Trauma About 20% of all chemosensory disordersDirectly 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

102 Other Disorders Cerebellar Degeneration Schizophrenia MigraineHyperemesis gravidarum & hyperosmia A number of systemic diseases Some Medicines Congenital anosmia