Anosmia. Mohammed alqabasani R 5 Rhinology research chair academic activity King saud university. Rhinology research Chair Weekly Activity

Transcription

1 Rhinology research Chair Weekly Activity Anosmia Mohammed alqabasani R 5 Rhinology research chair academic activity King saud university conference@rhinologychair.org Rhinology Chair

2 The chemo senses of smell and taste contribute to quality of life and environmental appreciation they also play significant role nutrition and safety. Disorders of olfaction are common worldwide and may involve as many as 2 to 4 million people in the United States

3 the nasal passages contain the structures of olfaction which include: the upper nasal septum, middle and superiorturbinates. These structures facilitate airflow and contain the primary olfactory neurons anatomy

4 anatomy In the olfactory mucosa, the axons from the bipolar olfactory neurons coalesce into bundles to form cranial nerve I This nerve traverses upward through the cribriform plate and skull base to the olfactory bulb to cortex

5 histology The olfactory epithelium is primarily composed of pseudostratified columnar-type epithelium situated with a vascular lamina propria, and lack a submucosa. It is derived from ectoderm It can regenerate after damage but it rarely complete also it depend on degree of damage

6 histology

7 Histology The human olfactory epithelium covers an area of roughly 1 cm2 on each side Humans have approximately 6 million olfactory neurons each cell express single odorant receptor

8 histology The cells that facilitate olfaction are divided into 4 main cell types: 1-ciliated olfactory receptors. 2-microvillar cells. 3-sustentacular cells. 4- basal cells.

9 Nerves involve in smell Cranial nerve I mediates the olfactory response The trigeminal nerve relays irritating odors such as carbon dioxide and ammonia Cranial nerves IX and X assist in retronasal olfaction

10 Most patient-described losses or disturbances of taste are olfactory losses. True solitary taste loss is less common

11 Taste Grossly, the tongue is composed of multiple taste papillae geographically distributed: Fungiform, circumvallate and foliate papillae which contain taste buds that facilitate gustatory sensation The filiform papillas do not contribute to taste

12 PHYSIOLOGY OF SMELL Nasal airflow plays an integral part of smell detection. As airflow distributes itself in the nasal cavity, about 15% flows to the olfactory cleft

13 PHYSIOLOGY OF SMELL key to this process is that odorant molecules must dissolve in or pass through the mucous overlying the olfactory epithelium to be detected. Once the odorants bind to the receptor neurons, a complex enzyme-mediated pathway Will start

14 PHYSIOLOGY OF SMELL

15 PHYSIOLOGY OF TASTE In the taste buds, the chemical molecules are transformed into electrical signals that travel to the nucleus solitarius (medulla), to the ventricular posterior medial nucleus in the thalamus then to the parietal lobe, and give the perception of gustation

16 PHYSIOLOGY OF TASTE olfaction and food flavor perception is retronasal olfaction, which occurs during ingestion of substances with airflow of odorant molecules generated by exhalation or mouth and pharynx contraction.

17 DIAGNOSIS AND WORKUP OF OLFACTORY loss Hyposmia describes a decreased ability to perceive smell Anosmia describes the absence of useful smelling ability Parosmia is the distorted perception of odor following a stimulus Phantosmia is perception of odor in the absence of an odorant stimulus.

18 DIAGNOSIS AND WORKUP OF OLFACTORY loss History: age the onset, sudden vs gradual, Side and duration of smell and taste changes. The patient may not disclose an olfactory disturbance unless directly asked.

19 DIAGNOSIS AND WORKUP OF OLFACTORY loss Any nasal symptoms should be addressed in details Associated clinical clues such as preceding trauma or viral infection,exposure to toxin smoking Taste loss vs flavor

20 DIAGNOSIS AND WORKUP OF OLFACTORY loss Past surgical history: Any nasal surgery Past medical: radiation,delayed puberty,dementia and neurological disease Detailed medication history Family history of anosmia

21 Physical Examination for Olfaction Complete head and neck examination with specific concentration on: anterior rhinoscopy may reveal gross disease such as septal perforation, polyps, and epistaxis, tumors, or allergic edematous nasal mucosa nasal endoscopy, a view of the olfactory cleft and assessment of blockage Neurologic status and cranial nerve function should be assessed Documentation of the physical examination is vital before surgery.

22 Olfactory testing Is it important? why? 1-to establish validity &nature of patient complaint 2-to monitor the changes over time 3-to detect malingering 4-establish compensation for permanent disability

23 Investigation of anosmia Two classes of testing are available: electro physical and psychophysical tests however psychophysical tests are more useful in the interoffice setting, more widely used. Olfactory testing generally measures either threshold of smell or identification of various smells

24 psychophysical tests

25 psychophysical tests Mostly common used test is UOPSIT (smell identification test ): Easy test can be finished in 15 minutes multiple language It has four booklets contain 10 odorant Stimuli are embedded micro m diameter encapsulated crystals located on scratch and sniff strip

26 psychophysical tests UOPSIT (smell identification test ): Over each strip mcq with four choices patient should choose answer even if none seems appropriate or no odor perceived Then patient classified according their score to six groups :normosmia,mild,moderet, sever micosmia,anosmia and malingering because chance performance is 10 out of 40 reflect avoidance which detect malingering patient

27 Investigation of anosmia Electrophysiological test 1-odor event-related potential (OERPs): Which measure EEG from scalp electrode following presentation of odorant It is good to detect malingering patient but can not be standardized Electro-olfactogram (EOG): Electrode inserted in olfactory cleft which measure the action potential it is no good because of the difficulty in doing the test and its not reliable

28 Investigation of anosmia

29 Investigation Neuropsychological tests : There is association between anosmia and neurodegenerative disease like Alzheimer's, dementia and Parkinson So mini-mental state examination is easy screening tool if abnormal better to send the patient to neurologist for further assessment

30 Investigation of anosmia the history, physical examination, or olfactory tests suggest polypoid or obstructive disease or malignant potential, then sinonasal imaging is Computed tomography (CT) scans of pns is needed Magnetic resonance imaging (MRI): may visualize the olfactory sulci and brain structure

31 Common Causes of Olfactory Loss Olfactory disturbances can be better separated into those with a conductive component (anatomic blockage of the olfactory cleft or surrounding structures) and a sensorineural component (a nerve loss or damage to receptor or higher cortical processing).

32 Common Causes of Olfactory Loss Nasal inflammatory disease: nasal disorders from chronic rhinosinusitis to polyps or allergic edema. This group of disorders is thought to primarily alter nasal airflow to the olfactory cleft

33 Common Causes of Olfactory Loss After Upper Respiratory Infection: Many patients report temporary decreased smell during upper respiratory infection (URTI) The nasal membrane edema commonly abates within a few days and smell returns to baseline. However in a subset of patients, there is permanent loss and the prognosis is principally poor, with only one-third recovering In these patients a sensorineural insult occurs to the primary olfactory neurons more in female

34 Causes of Olfactory Loss Head Trauma and Loss of Smell About 5% to 10% of patients with head trauma suffer from smell loss, often from occipital or frontal blows of the cribriform plate injury to the olfactory bulb,or supraorbital and frontal brain contusions that result in axonal injury.

35 Causes of Olfactory Loss Aging and Loss of Smell sense of smell has been studied and defined with age-related norms and known decreases especially in individuals more than 65 years of age.

36 Causes of Olfactory Loss Congenital Loss of Smell The cause is secondary to degeneration or failure of formation of the olfactory bulb and/or epithelium during development These patients often present around 8 years Kallman syndrome or hypogonadotropic Hypogonadism the most common one

37 Causes of Olfactory Loss Toxins and Loss of Smell is best described as a sensorineuralinjury It representbetween 1% and 5% of olfactory Disorders The diagnosis is largely based o history and known environmental exposure to the toxin.

38 Causes of Olfactory Loss Neoplasm and Loss of Smell intracranial meningiomas, gliomas, and other tumors may cause confined destruction of the central olfactory neurons. The intranasal tumors most frequently encountered are inverting papillomas, adenomas, squamous cell carcinomasand esthesioneuroblastomas.

39 Causes of Olfactory Loss Postsurgery Loss of Smell: If surgeons do not test and document olfactory loss at baseline they can miss a loss before surgery Mechanism for loss post surgical intervention: 1. Scar tissue 2. Granulation tissue 3. Persistent mucosal edema 4. Inflammation and olfactory neuroepithelialdamage

40 Postsurgery Loss of Smell Middle turbinate resection Kimmelman1 suggested that a resection of the lower half of the middle turbinate likely does not result in anosmia or hyposmia study completed by Biedlingmaier and colleagues82 reviewed patients with partial middle turbinate resections during routine sinus surgery. They found that only 1 patient out of 198 (0.9%) complained of anosmia

41 Postsurgery Loss of Smell Septoplasty complications: Overall, olfactory dysfunction after surgery is rare after septoplasty One study found that total anosmia following septoplasty in the long term was found in 0.3% to 2.9% and hyposmia 1%. However, olfactory disturbance may be present in up to 8% of patients before septoplasty, and both the surgeon and patient may be unaware without preoperative testing.

42 Postsurgery Loss of Smell Rhinoplasty complications: Smell dysfunction following rhinoplasty has been reported and studied This suggests a low risk overall (3%), but that it is nonetheless a risk that needs to be addressed with patients.

43 Postsurgery Loss of Smell Skull base surgery and loss of smell: Complex anterior and middle fossa skull base surgery and many cranial surgeries near the olfactory bulbs may cause olfactory loss

44 Causes of Olfactory Loss Neurodegenerative Disorders and Loss of Smell: Much research has recently been devoted to the link between olfactory loss and neurodegenerative disorders such as Alzheimer disease and Parkinson Disease Psychiatric Disorders (Depression or Anxiety) and Loss of Smell

45 TREATMENT OF OLFACTORY LOSS A patient s quality of life is affected after an olfactory loss, from enjoying a meal to safety around toxic chemicals Determining the cause of the olfactory deficit is imperative in counseling the patient and predicting the likelihood of improvement

46 TREATMENT OF OLFACTORY LOSS Sensorineural losses are less likely to recover, Whereas conductive losses, for example obstructive nasal polyps, are more easily treatable

47 TREATMENT OF OLFACTORY LOSS Conductive smell losses resulting in hyposmia or anosmia after nasal surgery or obstructing URIs have treatments available Nasal treatments: including saline irrigations and a nasal steroid spray, may decrease nasal membrane edema, increase nasal airflow, and improve olfaction

48 TREATMENT OF OLFACTORY LOSS Medicines such as high dose oral steroid boluses tapered over 3 weeks have been studied with promising results. recent study noted that a systemic steroid administration is useful in distinguishing betweena conductive loss that will improve and a sensorineuralloss that will not respond

49 TREATMENT OF OLFACTORY LOSS training the hyposmic or anosmic patient to appreciate remaining sensory modalities such as texture of food, residual taste,and mouth feel is beneficial.

50 TREATMENT OF OLFACTORY LOSS Protection remains a critical aspect of smell Loss Educating patients family members Patients with olfactory loss must use smoke and natural gas detectors in their homes and offices. Converting to an electric powered system may be safer.

51 Any question? Thank you