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==Overview==
==Overview==
The pathophysiology for both acute and chronic rhinosinusitis involves blockage of the nasal sinuses and inflammation of the nasal sinuses. However, biofilms play a role in the pathogenesis of chronic rhinosinusitis. There are many associated conditions with rhinosinusitis, but most notably are those related to allergy and immunodeficiency.  
The pathophysiology for both acute and chronic rhinosinusitis involves blockage of the [[nasal sinuses]] and [[inflammation]] of the [[nasal sinuses]]. However, [[biofilms]] play a role in the pathogenesis of chronic rhinosinusitis. There are many associated conditions with rhinosinusitis, but most notably are those related to [[allergy]] and [[immunodeficiency]].
 
==Pathophysiology==
==Pathophysiology==
===Physiology===
Sinuses are made up of frontal, maxillary and anterior ethmoid bones of the face. They are lined with ciliated pseudostratified columnar epithelium with a protective layer of mucosa. The cilia by propelling the inhaled particles into the nose for disposal and the mucosa by trapping the particles, together protect the sinuses from irritants and potential immune reactions.<ref name="pmid26889651">{{cite journal| author=Orlandi RR, Kingdom TT, Hwang PH, Smith TL, Alt JA, Baroody FM | display-authors=etal| title=International Consensus Statement on Allergy and Rhinology: Rhinosinusitis. | journal=Int Forum Allergy Rhinol | year= 2016 | volume= 6 Suppl 1 | issue=  | pages= S22-209 | pmid=26889651 | doi=10.1002/alr.21695 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=26889651  }} </ref>
===Pathogenesis===
===Pathogenesis===
====Acute Rhinosinusitis====
====Acute Rhinosinusitis====
Allergens, infections and other disease processes can cause inflammation and swelling of the nasal mucosa. When the [[sinus]] opening becomes blocked due to swelling of the nasal mucosa, it provides a medium for an inflammatory response to ensue and prevents the clearing of pathogens. Inflammation is mediated by protease in granulocytes and if the amount of protease overwhelms the amount of protease inhibitors available, tissue destruction will take place.<ref name="pmid6580734">{{cite journal| author=Lundberg C, Engquist S| title=Pathogenesis of maxillary sinusitis. | journal=Scand J Infect Dis Suppl | year= 1983 | volume= 39 | issue=  | pages= 53-5 | pmid=6580734 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=6580734 }} </ref>
Pathophysiology of acute rhinosinusitis could be explained by several mechanisms <ref name="pmid26889651">{{cite journal| author=Orlandi RR, Kingdom TT, Hwang PH, Smith TL, Alt JA, Baroody FM | display-authors=etal| title=International Consensus Statement on Allergy and Rhinology: Rhinosinusitis. | journal=Int Forum Allergy Rhinol | year= 2016 | volume= 6 Suppl 1 | issue=  | pages= S22-209 | pmid=26889651 | doi=10.1002/alr.21695 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=26889651 }} </ref>:
*Anatomic variants: Since imaging modalities are not necessary for uncomplicated ARS, there aren’t enough evident regarding the contribution of anatomy to the pathogenesis of ARS. However, several contributing factors have been proposed:
**Anomalies of the unicate and middle turbinate
**Stenosis of the infundibulum
**Recirculation phenomenon
**Infraorbital ethmoid cells
**Nasoseptal deviation
*Allergy: Allergens trigger the recruitment of eosinophils into the maxillary sinus causing inflammation. 
*Viruses: Viruses (e.g. Rhinovirus, H1N1), inhibit the mucociliary clearance and local swelling which in turn leads to the blockade of the sinus ostea and subsequent bacterial infection.
*Odontogenic infection: The proximity of maxillary sinus to the teeth roots causes rhinosinusitis in patients with dental maxillary pathology.


====Chronic Rhinosinusitis====
====Chronic Rhinosinusitis====
Biofilms are complex aggregates of extracellular matrix and inter-dependant [[microorganism]]s from multiple species, many of which may be difficult or impossible to isolate using standard [[medical microbiology|clinical laboratory]] techniques. [[Bacteria]] found in biofilms may show increased [[antibiotic resistance]] when compared to free-living bacteria of the same species. It has been hypothesized that biofilm-type [[infection]]s may account for many cases of [[antibiotic]]-refractory chronic sinusitis. While biofilms have been implicated in the pathogenesis of chronic sinusitis, their role in causing inflammation and disease is not fully understood. <ref name="pmid17432062">{{cite journal| author=Harvey RJ, Lund VJ| title=Biofilms and chronic rhinosinusitis: systematic review of evidence, current concepts and directions for research. | journal=Rhinology | year= 2007 | volume= 45 | issue= 1 | pages= 3-13 | pmid=17432062 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=17432062 }} </ref><ref>{{cite journal |author=Palmer JN |title=Bacterial biofilms: do they play a role in chronic sinusitis? |journal=Otolaryngol. Clin. North Am. |volume=38 |issue=6 |pages=1193-201, viii |year=2005 |pmid=16326178}}</ref><ref>{{cite journal | author = Sanclement J, Webster P, Thomas J, Ramadan H | title = Bacterial biofilms in surgical specimens of patients with chronic rhinosinusitis. | journal = Laryngoscope | volume = 115 | issue = 4 | pages = 578-82 | year = 2005 | id = PMID 15805862}}</ref>
There are several proposed mechanisms for the pathophysiology of chronic rhinosinusitis <ref name="pmid26889651">{{cite journal| author=Orlandi RR, Kingdom TT, Hwang PH, Smith TL, Alt JA, Baroody FM | display-authors=etal| title=International Consensus Statement on Allergy and Rhinology: Rhinosinusitis. | journal=Int Forum Allergy Rhinol | year= 2016 | volume= 6 Suppl 1 | issue= | pages= S22-209 | pmid=26889651 | doi=10.1002/alr.21695 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=26889651 }} </ref><ref name="pmid26143392">{{cite journal| author=Lam K, Schleimer R, Kern RC| title=The Etiology and Pathogenesis of Chronic Rhinosinusitis: a Review of Current Hypotheses. | journal=Curr Allergy Asthma Rep | year= 2015 | volume= 15 | issue= 7 | pages= 41 | pmid=26143392 | doi=10.1007/s11882-015-0540-2 | pmc=4874491 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=26143392  }} </ref>:
*Fungus: Proteins of the fungus trigger T cell response, causing cytokine storm which in turn leads to recruitment of the eosinophils to mucus. Degranulated eosinophils target the fungi causing collateral tissue damage.
*Bacteria, mostly contribute to the pathogenesis of chronic rhinosinusitis without nasal polyps and are composed of three hypotheses:
**Super antigen: Staphylococcus aureus superantigenic exotoxins bind T cells outside their antigen binding site, bypassing the antigen recognition pathway, thus provoking polyclonal T cell response which in turn leads to cytokine storm. 
**Biofilm: Biofilms are composed of bacteria embedded in an extracellular matrix, protecting them from antibiotics.
**Microbiome: It is suggested that external factors could change the normal microbiome of the nasal and sinus mucosa facilitating the growth of pathogens that were normally suppressed by the commensals.
*Host related factors:
**Immune barrier:
***Mechanical barrier: Defect in mucociliary clearance, increased susceptibility to exogenous protease and decreased tight junction proteins of the epithelium causing the formation of a porous barrier contribute to the increased access and transmit time of the foreign materials.   
***Innate immune response: Abnormal secretion of the antimicrobials of the mucosa (i.e. defensins, lysozyme, cathelicidins, collectins, lactoferrin, S100s and PLUNC) in response to pathogen recognition receptors (PRR), results in abnormal microbiome, increased exposure to foreign materials and increased compensatory response of the innate and adaptive immune system.
**Anatomic variations: Variations that affect the ostio-meatal complex (i.e. anomalies in the middle turbinate, concha, cells of the infraorbital ethmoid and nasoseptal deviation) or the drainage of the frontal sinus contribute to chronic rhinosinusitis with polyps.
There are limited evidence proposing some other mechanisms involved in the pathogenesis of chronic rhinosinusitis:
**Eicosanoids: Eicosanoids are the product of Arachidonic acid metabolism which function as signaling molecules. Defects in the Eicosanoid pathway causes an increased pro-inflammatory leukotriene and decreased anti-inflammatory prostaglandin resulting in the mucosal inflammation.
**Vitamin D deficiency: Vitamin D has anti-microbial and anti-inflammatory effects. Thus, its deficiency results in increased Th2 and eosinophilic response resulting mostly in chronic rhinosinusitis without polyps. 
**Osteitis and neo-osteogenesis: Histopathological changes of the bone including inflammation, fibrosis and new bone formation were observed in harvested ethmoid bones of patients with chronic rhinosinusitis.
**Reflux: Laryngopharyngeal reflux exposes the nasal cavity and sinuses to gastric acid and possible H. Pylori infection causing inflammatory response and defective mucociliary clearance. Also, the reflux triggers the esophagus resulting in stimulation of vagus nerve.


===Genetics===
===Genetics===
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===Gross Pathology===
===Gross Pathology===
On gross examination of the sinuses, polyps may appear as transparent and pedunculated masses. In sinusitis, changes include minimal edema and thickening of the mucosa.<ref name="headandneck">{{cite book |last=Thompson |first=Lester D. R. |date= |title=Head and Neck Pathology |url=https://books.google.com/books?id=zn_cP3nP19gC&pg=PA3&lpg=PA3&dq=rhinosinusitis+gross+and+microscopic+pathology&source=bl&ots=-3k8UvRalI&sig=qKiIbizx9n55YoBw7kHoOsxUiLY&hl=en&sa=X&ved=0ahUKEwijwOquiK7PAhWh6IMKHRf3AYIQ6AEIITAA#v=onepage&q=rhinosinusitis%20gross%20and%20microscopic%20pathology&f=false |location= |publisher=Elsevier Health Sciences |page=3 |isbn=9781437726077}}</ref>  
On gross examination of the [[sinuses]], [[polyps]] may appear as transparent and [[pedunculated]] masses. In sinusitis, changes include minimal [[edema]] and thickening of the [[mucosa]].<ref name="headandneck">{{cite book |last=Thompson |first=Lester D. R. |date= |title=Head and Neck Pathology |url=https://books.google.com/books?id=zn_cP3nP19gC&pg=PA3&lpg=PA3&dq=rhinosinusitis+gross+and+microscopic+pathology&source=bl&ots=-3k8UvRalI&sig=qKiIbizx9n55YoBw7kHoOsxUiLY&hl=en&sa=X&ved=0ahUKEwijwOquiK7PAhWh6IMKHRf3AYIQ6AEIITAA#v=onepage&q=rhinosinusitis%20gross%20and%20microscopic%20pathology&f=false |location= |publisher=Elsevier Health Sciences |page=3 |isbn=9781437726077}}</ref>


===Microscopic Pathology===
===Microscopic Pathology===
Rhinosinusitis can present with the following microscopic findings;<ref name="headandneck">{{cite book |last=Thompson |first=Lester D. R. |date= |title=Head and Neck Pathology |url=https://books.google.com/books?id=zn_cP3nP19gC&pg=PA3&lpg=PA3&dq=rhinosinusitis+gross+and+microscopic+pathology&source=bl&ots=-3k8UvRalI&sig=qKiIbizx9n55YoBw7kHoOsxUiLY&hl=en&sa=X&ved=0ahUKEwijwOquiK7PAhWh6IMKHRf3AYIQ6AEIITAA#v=onepage&q=rhinosinusitis%20gross%20and%20microscopic%20pathology&f=false |location= |publisher=Elsevier Health Sciences |page=3 |isbn=9781437726077}}</ref>
Rhinosinusitis can present with the following microscopic findings;<ref name="headandneck">{{cite book |last=Thompson |first=Lester D. R. |date= |title=Head and Neck Pathology |url=https://books.google.com/books?id=zn_cP3nP19gC&pg=PA3&lpg=PA3&dq=rhinosinusitis+gross+and+microscopic+pathology&source=bl&ots=-3k8UvRalI&sig=qKiIbizx9n55YoBw7kHoOsxUiLY&hl=en&sa=X&ved=0ahUKEwijwOquiK7PAhWh6IMKHRf3AYIQ6AEIITAA#v=onepage&q=rhinosinusitis%20gross%20and%20microscopic%20pathology&f=false |location= |publisher=Elsevier Health Sciences |page=3 |isbn=9781437726077}}</ref>
*Acute Bacterial Sinusitis: Inflammatory infiltrate is dominated by neutrophils.  
*Acute Bacterial Sinusitis: Inflammatory infiltrate is dominated by [[neutrophils]].  
*Allergic Rhinosinusitis: Inflammatory infiltrate is dominated by eosinophils.  
*Allergic Rhinosinusitis: Inflammatory infiltrate is dominated by [[eosinophils]].  
*Chronic Rhinosinusitis: Mixed inflammatory infiltrate of lymphocytes, plasma cells, eosinophils, neutrophils and macrophages.  
*Chronic Rhinosinusitis: Mixed inflammatory infiltrate of [[lymphocytes]], [[plasma cells]], [[eosinophils]], [[neutrophils]], and [[macrophages]].


==References==  
==References==  
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[[Category:Otolaryngology]]
[[Category:Emergency mdicine]]
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[[Category:Infectious disease]]
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[[Category:Primary care]]
[[Category:Immunology]]
[[Category:Otolaryngology]]

Latest revision as of 14:10, 3 December 2020

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Dima Nimri, M.D. [2]

Overview

The pathophysiology for both acute and chronic rhinosinusitis involves blockage of the nasal sinuses and inflammation of the nasal sinuses. However, biofilms play a role in the pathogenesis of chronic rhinosinusitis. There are many associated conditions with rhinosinusitis, but most notably are those related to allergy and immunodeficiency.

Pathophysiology

Physiology

Sinuses are made up of frontal, maxillary and anterior ethmoid bones of the face. They are lined with ciliated pseudostratified columnar epithelium with a protective layer of mucosa. The cilia by propelling the inhaled particles into the nose for disposal and the mucosa by trapping the particles, together protect the sinuses from irritants and potential immune reactions.[1]

Pathogenesis

Acute Rhinosinusitis

Pathophysiology of acute rhinosinusitis could be explained by several mechanisms [1]:

  • Anatomic variants: Since imaging modalities are not necessary for uncomplicated ARS, there aren’t enough evident regarding the contribution of anatomy to the pathogenesis of ARS. However, several contributing factors have been proposed:
    • Anomalies of the unicate and middle turbinate
    • Stenosis of the infundibulum
    • Recirculation phenomenon
    • Infraorbital ethmoid cells
    • Nasoseptal deviation
  • Allergy: Allergens trigger the recruitment of eosinophils into the maxillary sinus causing inflammation.
  • Viruses: Viruses (e.g. Rhinovirus, H1N1), inhibit the mucociliary clearance and local swelling which in turn leads to the blockade of the sinus ostea and subsequent bacterial infection.
  • Odontogenic infection: The proximity of maxillary sinus to the teeth roots causes rhinosinusitis in patients with dental maxillary pathology.

Chronic Rhinosinusitis

There are several proposed mechanisms for the pathophysiology of chronic rhinosinusitis [1][2]:

  • Fungus: Proteins of the fungus trigger T cell response, causing cytokine storm which in turn leads to recruitment of the eosinophils to mucus. Degranulated eosinophils target the fungi causing collateral tissue damage.
  • Bacteria, mostly contribute to the pathogenesis of chronic rhinosinusitis without nasal polyps and are composed of three hypotheses:
    • Super antigen: Staphylococcus aureus superantigenic exotoxins bind T cells outside their antigen binding site, bypassing the antigen recognition pathway, thus provoking polyclonal T cell response which in turn leads to cytokine storm.
    • Biofilm: Biofilms are composed of bacteria embedded in an extracellular matrix, protecting them from antibiotics.
    • Microbiome: It is suggested that external factors could change the normal microbiome of the nasal and sinus mucosa facilitating the growth of pathogens that were normally suppressed by the commensals.
  • Host related factors:
    • Immune barrier:
      • Mechanical barrier: Defect in mucociliary clearance, increased susceptibility to exogenous protease and decreased tight junction proteins of the epithelium causing the formation of a porous barrier contribute to the increased access and transmit time of the foreign materials.
      • Innate immune response: Abnormal secretion of the antimicrobials of the mucosa (i.e. defensins, lysozyme, cathelicidins, collectins, lactoferrin, S100s and PLUNC) in response to pathogen recognition receptors (PRR), results in abnormal microbiome, increased exposure to foreign materials and increased compensatory response of the innate and adaptive immune system.
    • Anatomic variations: Variations that affect the ostio-meatal complex (i.e. anomalies in the middle turbinate, concha, cells of the infraorbital ethmoid and nasoseptal deviation) or the drainage of the frontal sinus contribute to chronic rhinosinusitis with polyps.

There are limited evidence proposing some other mechanisms involved in the pathogenesis of chronic rhinosinusitis:

    • Eicosanoids: Eicosanoids are the product of Arachidonic acid metabolism which function as signaling molecules. Defects in the Eicosanoid pathway causes an increased pro-inflammatory leukotriene and decreased anti-inflammatory prostaglandin resulting in the mucosal inflammation.
    • Vitamin D deficiency: Vitamin D has anti-microbial and anti-inflammatory effects. Thus, its deficiency results in increased Th2 and eosinophilic response resulting mostly in chronic rhinosinusitis without polyps.
    • Osteitis and neo-osteogenesis: Histopathological changes of the bone including inflammation, fibrosis and new bone formation were observed in harvested ethmoid bones of patients with chronic rhinosinusitis.
    • Reflux: Laryngopharyngeal reflux exposes the nasal cavity and sinuses to gastric acid and possible H. Pylori infection causing inflammatory response and defective mucociliary clearance. Also, the reflux triggers the esophagus resulting in stimulation of vagus nerve.

Genetics

Chronic rhinosinusitis is believed to be the result of environmental and genetic factors combined. The role of genetic factors in chronic rhinosinusitis is not yet fully understood.[3] However, in chronic rhinosinusitis with and without nasal polyposis, first and second degree relatives conferred an increased risk to receiving the same diagnosis.[4]

Associated Conditions

Gross Pathology

On gross examination of the sinuses, polyps may appear as transparent and pedunculated masses. In sinusitis, changes include minimal edema and thickening of the mucosa.[10]

Microscopic Pathology

Rhinosinusitis can present with the following microscopic findings;[10]

References

  1. 1.0 1.1 1.2 Orlandi RR, Kingdom TT, Hwang PH, Smith TL, Alt JA, Baroody FM; et al. (2016). "International Consensus Statement on Allergy and Rhinology: Rhinosinusitis". Int Forum Allergy Rhinol. 6 Suppl 1: S22–209. doi:10.1002/alr.21695. PMID 26889651.
  2. Lam K, Schleimer R, Kern RC (2015). "The Etiology and Pathogenesis of Chronic Rhinosinusitis: a Review of Current Hypotheses". Curr Allergy Asthma Rep. 15 (7): 41. doi:10.1007/s11882-015-0540-2. PMC 4874491. PMID 26143392.
  3. Al-Shemari H, Bossé Y, Hudson TJ, Cabaluna M, Duval M, Lemire M, Vallee-Smedja S, Frenkiel S, Desrosiers M (2008). "Influence of leukotriene gene polymorphisms on chronic rhinosinusitis". BMC Med. Genet. 9: 21. doi:10.1186/1471-2350-9-21. PMC 2292155. PMID 18366797.
  4. Oakley GM, Curtin K, Orb Q, Schaefer C, Orlandi RR, Alt JA (2015). "Familial risk of chronic rhinosinusitis with and without nasal polyposis: genetics or environment". Int Forum Allergy Rhinol. 5 (4): 276–82. doi:10.1002/alr.21469. PMID 25677865.
  5. Christodoulopoulos P, Cameron L, Durham S, Hamid Q (2000). "Molecular pathology of allergic disease. II: Upper airway disease". J. Allergy Clin. Immunol. 105 (2 Pt 1): 211–23. PMID 10669839.
  6. Slavin RG (2008). "The upper and lower airways: the epidemiological and pathophysiological connection". Allergy Asthma Proc. 29 (6): 553–6. doi:10.2500/aap.2008.29.3169. PMID 19173781.
  7. Meltzer EO, Hamilos DL (2011). "Rhinosinusitis diagnosis and management for the clinician: a synopsis of recent consensus guidelines". Mayo Clin. Proc. 86 (5): 427–43. doi:10.4065/mcp.2010.0392. PMC 3084646. PMID 21490181.
  8. Le C, McCrary HC, Chang E (2016). "Cystic Fibrosis Sinusitis". Adv. Otorhinolaryngol. 79: 29–37. doi:10.1159/000444959. PMID 27466844.
  9. 9.0 9.1 Ryan MW (2008). "Diseases associated with chronic rhinosinusitis: what is the significance?". Curr Opin Otolaryngol Head Neck Surg. 16 (3): 231–6. doi:10.1097/MOO.0b013e3282fdc3c5. PMID 18475077.
  10. 10.0 10.1 Thompson, Lester D. R. Head and Neck Pathology. Elsevier Health Sciences. p. 3. ISBN 9781437726077.

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