Sinusitis
Classification
- Infectious
- community or hospital setting
- the immune status of the patient
- viral, bacterial,
or fungal cause
- Non infectious
Predispoing factors
- Allergy
- Swimming
- Nasal obstruction due to
polyps, foreign bodies, and tumors
- Other less common risk factors are immune deficiencies such as
- agammaglobulinemia
- acquired immunodeficiency syndrome
-
abnormalities of white cell function as found in chronic granulomatous disease
- structural
defects, especially cleft palate
- disorders of mucociliary clearance including
- cilial
dysfunction
- cystic fibrosis.
Etiologic agents
-
Acute Community-Acquired.
- The most common causes of sinusitis are the same as for
otitis media:
- Streptococcus pneumoniae (40%)
- Hemophilus influenzae (30%)
- Moraxella catarrhalis (15%)
- Other streptococcal species including Streptococcus intermedius, Streptococcus
pyogenes, and other alpha-hemolytic streptococci; M. catarrhalis; Staphylococcus
aureus; and anaerobic bacteria each account for an additional proportion of cases.
- Most sinusitis due to anaerobic bacteria
arises from infection of the roots of the premolar
teeth, thus representing a pure bacterial infection.
- Staphylococcus aureus and anaerobes are
seen in chronic sinusitis and are often the pathogens seen in intracranial
extension of infection.
- Chlamydia pneumoniae has been identified in patients with respiratory illness
that includes features of sinusitis.
- Only approximately 60% of sinus aspirates in suspected cases of
sinusitis yield bacteria.
- The cause of the culture-negative cases is not clear, but undoubtedly, many have a
viral cause.
-
Nosocomial
- Nosocomial sinusitis has been most often associated with
Staph. aureus, Pseudomonas
Proteus mirabilis and is often polymicrobic.
- Pseudomonas aeruginosa is the most frequent isolate in sinus aspirates from patients with cystic
fibrosis.
- Legionella pneumophila was identified in sinus tissue from a patient with
acquired immunodeficiency syndrome
-
Fungi
-
Fungi are a well-established cause of occasional cases of acute community-acquired
sinusitis.
- Also, fungal infections occur in hospitalized patients and those with other
diseases such as diabetes mellitus.
Noninfectious
- chemical irritation
- nasal and sinus tumors
- foreign bodies
- Wegener's granulomatosis
- midline granuloma.
Physiology/Normal function
- reduce the bony mass and weight of the skull
- participate in warming and humidification of inspired air
- add resonance to the voice.
The paranasal sinuses, although directly connected to the nasal passages, which are
colonized with bacteria, are themselves sterile under normal conditions.
Anatomy of the sinuses
- Ethmoid and maxillary sinuses are formed in utero and are present at
birth.
- Frontal sinuses are not present until age 5-6 years.
- The ostia or outflow tract of the maxillary sinus is high on its
medial wall; this positioning creates a situation where drainage is against
gravity-this explains part of the reason why maxillary sinuses are so
commonly infected.
- The ethmoid sinus is separated from the orbit by the paper-thin,
fenestrated lamina paprycea bone.
- It is very easy for pus to get from the
ethmoid sinus into the orbit.
- Therefore, sinusitis in the ethmoid is most
likely to lead to orbital cellulitis and abscess.
- The anterior ethmoid and frontal sinuses also empty into the middle
meatus.
- The sinus is lined with ciliated pseudostratified epithelium and is covered with a mucous blanket.
- The epithelium is well supplied with goblet cells
Pathogenesis
-
The nasal passages and nasopharynx are colonized with the same bacterial species that
cause sinusitis, and, undoubtedly, the bacteria in these areas serve as the reservoir for
this infection.
- Three factors are important in the normal functioning of the sinuses,
to keep these cavities sterile:
- the ostia (through which the sinus drains into
the nose) must be patent
- the cilia must be functioning properly
- the
secretions of the mucosa must be thin and not very copious
- An upper respiratory
infection or a allergy may alter all of these factors: ostia may become occluded
by mucosal inflammation and swelling, cilia may not function properly in the
presence of inflamed mucosal tissue, and the secretions may become thick and
copious, overpowering the ability of the cilia to direct the secretions toward
the ostia and into the nose.
- It has been estimated that 5- 10 % of upper respiratory infections in early
childhood are complicated by acute sinusitis.
- Since children average 6-8 colds
per year, sinusitis is a very common problem in pediatrics.
- Sneezing, coughing, and nose blowing may create pressure differentials that
deposit these bacteria into the sinuses.
-
Once bacteria are deposited into the cavity of an obstructed sinus, growth conditions are
favorable.
- However, granulocyte phagocytosis may be impaired by the reduced oxygen tension present in an obstructed sinus.
Clinical Features
- Following Viral bacterial/Acute sinusitis
- Following Dental infection
- When the sinusitis follows dental infection, molar pain and a foul odor to the breath are
characteristic features.
- With complications
-
Lethargy and the clinical findings of cavernous sinus or cortical vein thrombosis may also
be present as well as signs of orbital cellulitis and abscess.
- With severe frontal sinusitis,
pus may collect under the periosteum of the frontal bone causing swelling and edema of
the forehead, which is known as Pott puffy tumor.
- Nosocomial.
- Nosocomial sinusitis of bacterial origin has features that are similar to those of
Sinusitis, but because many patients with this condition are severely ill or unconscious, typical
clinical features may not be obvious.
- Nosocomial sinusitis should be suspected when fever of undetermined origin occurs in patients with risk factors such as
nasal intubation.
- Chronic sinusitis
- Signs of chronic infection
- Refractory productive cough
- Post nasal drip
- Worsening cough in supine position
- Acute exacerbations
-
Fungal.
-
Patients with community-acquired fungal sinusitis usually present with masses,
proptosis, and bony erosion due to pressure effects.
- The invasive form of fungal sinusitis typically presents as a rapidly progressive infection.
-
Fungal.
- .Acute fungal sinusitis can resemble bacterial sinusitis but occurs in patients with
serious underlying diseases and has a marked propensity for invading through contiguous
bone into the orbit, brain, and hard palate
- Chronic fungal sinusitis has three forms:
- invasive sinusitis,
- fungus ball of the sinus
- allergic fungal sinusitis
- Invasive infection resembles squamous carcinoma, Wegener's granulomatosis,
midline granuloma, and rhinoscleroma.
- Fungus ball of the sinus is a benign mass of hyphae, usually
Aspergillus.
- Allergic fungal sinusitis presents as chronic sinus pain and an expansile mass of inspissated mucus, eosinophils, and hyphae that can deform outward
the bony wall between the ethmoid sinus and the orbit or between the maxillary sinus and
the nasal cavity.
- Patients usually have a history of allergic rhinitis and nasal polyps.
Complications and long-term consequences
- Intracranial
- meningitis
- brain abscess
- subdural empyema
- cavernous sinus
- cortical vein thrombosis
- Orbital complications are most common in young children and include
- orbital cellulitis
- subperiosteal abscess
- orbital abscess
- Respiratory
- Sinusitis is also associated with the onset or exacerbation of asthma and bronchitis.
- Sinopulmonary disease is a well-recognized combination, especially when the condition has become
chronic
Diagnosis
- Paranasal sinuses are not accessible to direct
examination and to noninvasive sampling for microbial culture.
- Physicians have to rely on clinical findings that are either insensitive or nonspecific.
-
Diagnostic evaluation should include a history and an examination of the pharynx, nose,
ears, sinuses, teeth, and chest. Information should be obtained about coryzal and influenzal
illnesses, respiratory allergies, toothache, and other dental complaints.
-
Because of its superior sensitivity, CT scanning of the sinuses has largely supplanted
conventional radiography as the imaging method of choice.
- Imaging studies are not recommended for the routine diagnosis of
community-acquired sinusitis because of their lack of specificity.
- Nasal cultures are of no use in determining the bacterial agent
because of the large number of bacteria which colonize the nose
- Sinus
aspiration is occasionally performed, but generally therapy is aimed at covering
the most likely pathogens, similar to otitis media.
-
Sinus puncture is a relatively painless and safe procedure when performed by an experienced operator, although it is not appropriate for routine clinical use.
- Immunocompromised patients
may require a diagnostic procedure, as they may develop sinusitis with a variety
of unusual organisms including fungi.
-
It is not possible to enter the sinus cavities with an endoscope by way of the natural
ostia and avoid nasal flora contamination..
Therapy
- Since the pathogens of acute otitis media and sinusitis are similar,
the antimicrobial agent used are also similar.
-
Antimicrobial therapy is usually selected on an empirical basis because sinus aspirate
culture results are not available in the usual clinical setting.
- Amoxicillin remains the drug of
choice for uncomplicated sinusitis.
- With a 10-day course of an antimicrobial with an appropriate spectrum used at the correct dose,
the symptoms of acute community-acquired sinusitis usually improve after 2 or 3 days
of treatment and are generally resolved by 7 to 14 days with bacteriologic cure rates of 90% or higher
- The beta-lactam antimicrobials that continue to show the best activity against intermediately resistant strains of pneumococci
and are also effective against beta-lactamase-producing H. influenzae and M. catarrhalis are
amoxicillin-clavulanate, cefpodoxime, cefdinir, and cefuroxime.
- Also, the new quinolones provide excellent activity against pneumococci and other sinusitis
pathogens. Of these drugs, amoxicillin-clavulanate, cefdinir, cefuroxime, and levofloxacin
have been shown to be effective in pre- and post-therapy sinus puncture clinical trials in
patients with Sinusitis.
- There are no pre- and postsinus aspirate culture data on the effectiveness of longer or shorter courses
of treatment for Sinusitis.
- However, it is important to be aware that patients with acute sinusitis may have substantial symptomatic
improvement despite the persistence in the sinus of purulent material containing
high titers of bacteria.
- Severe infection or in whom intracranial or orbital extension of infection
- intravenous
therapy should be started with vancomycin and ceftriaxone or cefotaxime until the results
of culture and sensitivity testing are available for directing treatment.
- Nosocomial sinusitis
- Antimicrobial treatment of patients should be directed by culture and
sensitivity information when available, or when empirical, should cover the usual
pathogens responsible for these infections.
- Fungal
- Community-acquired fungal sinusitis in persons with normal immunity i: surgical debridement
- Complicated cases and patients with immunodeficiencies suspected of having invasive infection
: appropriate surgical and antifungal therapy.
Symptomatic therapy
Decongestants, Topical steroids and mucoevacuants are of no
proven value.
Prevention
-
Preventing colds
- The promotion of decongestion and drainage is of limited
value
- Prophylactic antimicrobial administration to prevent recurrent
Sinusitis is not recommended
-
Avoiding nasal intubation has been shown to be effective in reducing the incidence of
nosocomial sinusitis.