TITLE: Acute Sinusitis
SOURCE: Grand Rounds Presentation, UTMB, Dept. of Otolaryngology
DATE: March 19, 1997
RESIDENT PHYSICIAN: , Michael E. Prater, M.D.
FACULTY: Francis B. Quinn, Jr., M.D.
SERIES EDITOR: Francis B. Quinn, Jr., M.D.

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"This material was prepared by resident physicians in partial fulfillment of educational requirements established for the Postgraduate Training Program of the UTMB Department of Otolaryngology/Head and Neck Surgery and was not intended for clinical use in its present form. It was prepared for the purpose of stimulating group discussion in a conference setting. No warranties, either express or implied, are made with respect to its accuracy, completeness, or timeliness. The material does not necessarily reflect the current or past opinions of members of the UTMB faculty and should not be used for purposes of diagnosis or treatment without consulting appropriate literature sources and informed professional opinion."


ANATOMY:

There are eight paranasal sinuses, four on each side of the midline. They are the paired frontal, ethmoidal (anterior and posterior), maxillary and sphenoidal sinuses. They are lined with a pseudostratisfied columnar (respiratory) epithelium which is continuous with the nasal mucosa. The lining provides a mucous secretion which traps bacteria and subsequently extrudes the mucous and bacteria through the sinus ostia to be swallowed or expectorated. Under normal conditions, the sinuses are air filled and communicate directly with the nasal passages through patent ostia.

The sinuses are divided into two groups, the anterior and posterior sinuses, which drain into the middle meatus and above the middle meatus, respectively. The posterior group is comprised of the sphenoid sinuses and the posterior ethmoid sinuses, whereas the anterior group are the frontal, maxillary and anterior ethmoidal sinsuses. The drainage site into the middle meatus of the anterior sinuses is the infundibulum.

Ethmoid:

The ethmoidal labyrinth appears during the third month of fetal development as evaginations of the lateral nasal wall. The anterior ethmoids arise near the middle meatus and the posterior ethmoids arise near the superior meatus. Along with the maxillary sinus, the ethmoids are the only sinuses usually present of birth. They reach adult size by age 12. Anatomically, the ethmoids lie medial to the orbit in the superior nasal vault. There are vertical and horizontal plates, with the vertical plate known as the perpendicular plate of the ethmoid inferiorly and the crista galli superiorly. Horizontally, the lateral aspect is called the fovea ethmoidalis and the medial portion the cribriform plate. The most medial and also the thinnest portion of the ethmoid bone abuts the orbit, and is the lamina papyracea. The anterior and posterior ethmoids are separated by a bony plate, known as the ground lamella. Additional findings include an aerated portion of the middle turbinate, the concha bullosa, as well as anteriorly located cells which frequently extend into the uncinate process.

The blood supply to the ethmoids is from both the external and internal carotid arteries. The external carotid supply is from the sphenopalatine artery, and the internal carotid artery derivatives are the anterior and posterior ethmoidal arteries. Innervation is from V2 and V3, with the contributions from V2 being the anterior and posterior ethmoidal nerves and V3 being the sphenopalatine nerve.

Maxillary Sinuses:

The maxillary sinus occupies the body of the maxilla and is the largest of the paranasal sinuses. Although present at birth, they are usually not visible on plain x-rays until about 3 or 4 months of age. They are pyramidal shaped, with the apex near the zygomatic arch and the base at the lateral nasal wall. In the child, the inferior border is usually at the nasal floor, whereas in the adult the sinuses may extend a full centimeter below the nasal floor. The anterior wall is the canine fossa, and the posterior wall is the infratemporal fossa. The floor consists of the premolars and molars, and often there is only a thin mucous covering, leaving easy extension of infection from a tooth root into the sinuses, or the possibility of an oroantral communication with tooth extraction. The roof of the sinus is the orbital floor, with the infraorbital nerve usually lying in a midline groove. This nerve is often dehiscent, making it at risk during antral procedures. The sinus communicates with the nose at the infundibulum of the middle meatus through the sinus ostium. These true ostia are located anteriorly and superiorly, although with chronic infection there is sometimes accessory ostia located more posterioly. The accessory ostia are not felt to be congenital. In general, the ostia are surrounded by a membranous portion, with the bony portion being larger than the actual opening. Most nerves and vessels enter through the membranous portion.

Drainage of mucous from the maxillary sinus is now believed to be dependent on the natural ostia, with mucociliary clearance patterns directed in a circular pattern towards these ostia, even in the presence of accessory drainage sites.

Blood supply to the maxillary sinus is predominantly from the divisions of the maxillary artery, including greater palatine, posterosuperior and anterosuperior alveolar arteries and the lateral nasal branches of the sphenopalatine artery. Innervation is via the maxillary nerve, including the greater palatine, posterolateral nasal and the alveolar branches of the infraorbital nerve. CN VII, through the greater superficial petrosal nerve, supplies postganglionic parasympathetic innervation.

Frontal Sinuses:

The frontal sinus begins as an evagination of the anterior nasal capsule around the fourth month of fetal development, but it is rarely radiographically visible until around the second year of life and does not reach adult size until the teenage years. Great variability in size exists, and approximately 5% of people have absent frontal sinuses. The sinus connects with the middle meatus via the frontal recess near the upper portion of the infundibulum. The anterior plate of the frontal sinus is diploic bone, whereas the posterior plate is compact bone. Like the maxillary sinuses, the frontal sinuses have circular mucociliary clearance.

Blood supply is from the supraorbital and supratrochlear arteries derived from the ophthalmic artery, a branch of the internal carotid artery. Innervation is from the supraorbital and supratrochlear branches of the frontal nerve.

Sphenoidal Sinuses:

The sphenoidal sinuses begin as outpouchings of the superior nasal vault around the fourth month of gestation. The sinuses are not radiographically present at birth, with pneumatization beginning around the fourth year and ending around age 15. The sinuses are usually asymmetric, being separated by a septum, and each drains into the superior meatus in the sphenoethmoidal recess through variable sized ostia. Once again, these ostia are primarily membranous, with the bony portion being much larger.

Structures of great importance surround the sphenoids. The optic nerve lies superiorly and the pons posteriorly. Lateral are the cavernous sinuses and their associated structures, along with the superior orbital fissure and the carotid artery. The carotid artery forms a indentation in over 50% of specimens, and in many the wall of the sinus is dehiscent, leaving this vital structure exposed during surgical procedures.

Both the external and internal carotids are responsible for the blood supply. The posterior ethmoidal branch of the ophthalmic artery contributes vessels to the roof whereas the sphenopalatine artery supplies the floor. Innervation is from both V2 and V3 via the posterior ethmoid nerve and the sphenopalatine nerve.

PHYSIOLOGY:

The linings of the paranasal sinuses are composed of respiratory epithelium, ie, pseudostratified columnar epithelium, with interspersed goblet cells. There is a double layer of mucous with a superficial viscid layer and an underlying serous layer. The cilia of the respiratory epithelium beat predominantly in the serous layer, and move the mucous toward the natural ostia. It is now believed the primary factors of normal physiology are the patency of the ostia, the function of the cilia, and the quality of the mucous blanket.

The most important pathologic process in sinus disease is obstruction of the natural ostium. The obstruction leads to hypooxygenation which in turn leads to ciliary dysmotility. When ciliary motility is compromised, the mucous blanket does not function properly, leading to retention of secretions and intranasal pressure. Thus, an ideal environment for bacterial invasion is created.

Both local and systemic factors can contribute to sinusitis. Local causes predominantly result in impaired mucociliary clearance. Cold air is believed to "stun" the epithelium which leads to decreased ciliary action. Dry air is believed to dessicate the mucous blanket. Anatomical blockage of the ostia by polyps, tumors, and foreign bodies also predispose to sinus disease. Kartagener's Syndrome (immotile cilia syndrome) leads to sinus disease and bronchitis by similar methods. Systemic factors leading to sinus disease include malnourished or immunocompromised states.

There are three classifications of sinus disease, acute, subacute and chronic. Acute sinusitis is defined as disease lasting less than one month. Subacute is defined as one month to three months, and chronic is longer than three months duration. Chronic sinusitis usually results from acute sinusitis that has been inadequately treated, and the pathophysiologic process is considered irreversible by medical therapy. Surgical therapy, i.e., opening of the sinus ostia to oxygenate the sinuses is the primary therapy for chronic sinusitis, whereas acute and subacute sinusitis are generally treated medically.

HISTORY and PHYSICAL FINDINGS:

The symptoms of bacterial sinusitis relate to the duration of symptoms and the location of disease. Acute sinusitis primarily presents as pain over the infected area with or without headache and associated facial pain. The patient may complain of a "cold." Pain over the infected sinus is possible to elicit with the anterior sinuses, but the usual presenting symptom of posterior sinusitis is bitemporal or vertex headaches. There is usually a mucopurulent greenish or yellow discharge from the nose, which may be bilateral. There is often associated fever and malaise. In chronic sinusitis, there is usually a discharge but pain and fever are more often than not absent. Acute sinusitis can be superimposed on chronic sinusitis, and it is sometimes found these patients have pansinusitis.

The diagnosis of sinusitis is primarily clinical, but radiographs and cultures can be helpful. Any facial edema should be noted, particularly around the orbit. Any tenderness should then be assessed. Palpate and percuss the sinuses, including the medial orbital regions to assess the ethmoids. Intranasally, any mucosal edema should be noted, as should any purulence, masses or septal deviation. The nasopharynx should be examined for evidence of obstruction, including choanal atresia, adenoidal hypertrophy and unusual masses. An otoscopic exam should be performed to rule out concommitant otitis media. Transillumination of the maxillary and frontal sinuses can be performed, but as these sinuses are sometimes hypoplastic, decreased illumination is not always indicative of sinus disease.

The most significant advances have occurred in the area of diagnois. With nasal endoscopy, the sinuses involved and any local pathology can be determined with a high degree of certainty. This exam should be performed both pre and post nasal decongestion.

Antral lavage can be performed in select cases through an anterior maxillary puncture or by an inferior meatal window. These procedures are simply performed using topical anesthetics followed by puncture of the sinus wall using a trochar. Cultures can be obtained as necessary. The main indications for this procedure are the presence of mucopurulent material in an immunosuppressed patient or with known sinusitis that has failed medical management.

ACUTE BACTERIAL SINUSITIS:

Acute sinusitis can be thought of as an abscess or empyema, and like all abscesses the cornerstone of treatment is drainage and antibiotics. The drainage in most cases can be accomplished medically with topical decongestants and sometimes systemic antihistamines. In those rare cases where the sinus is insufficiently drained medically, surgical drainage may be necessary.

Antibiotic coverage is aimed at the most common pathogens, including s. pneumoniae, H. influenzae and M. catarrhalis. As a first line antibiotic, amoxicillin is adequate. If a patient fails to improve in 3-5 days or has symptoms beyond 10 to 14 days, either the drainage has been inadequate or resistant organisms have developed. Under these circumstances, proper antibiotic coverage is essential, and fluid should be obtained for culture and gram stain, and coverage broadened, usually with the addition of clavulonic acid. If the infection continues to worsen, surgical drainage of the sinuses is required.

Different techniques are available for surgical drainage of the sinuses. The maxillary sinuses can be irrigated using the above methods for antral lavage or middle meatal antrostomy. In refractory cases, endoscopic enlargement of the osteomeatal complex can be undertaken. The traditional approach tot he frontal sinus is to trephinate the sinus. This is done through an incision in the medial aspect of the upper eyelid, exposing the floor of the frontal sinus. The bone is removed with a drill, and a drain placed. The sinus must be irrigated twice a day until free drainage is noted through the nasofrontal duct. Oftentimes, this takes a week or more. The traditional approach to the ethmoid sinuses is an external ethmoidectomy, but more common today is the endoscopic approach.

ACUTE FUNGAL SINUSITIS:

Fungal infections of the paranasal sinuses are uncommon. Aspergillosis, mucormycosis, candidiasis, histoplasmosis and coccidiomycosis occur. Aspergillosis is the most common pathogen seen, and usually occurs in the maxillary sinuses. Recognition of acute fungal sinusitis requires a high index of suspscion. Immunosuppressed patients are at highest risk. The final diagnosis is usually made by antrostomy and biopsy or culture.

Aspergillus is common pathogen of soil, decaying fruits and vegetables and grains, as is pathogenic in humans, birds and other animals. An infection should be suspected if dark, thick greasy material is seen in the sinuses. Of note, a culture of the nose or even an aspirate of the sinus is usually not diagnostic. An antrostomy with a biopsy is usually required. The diagnosis is usually made using a fungal stain such as Gridley's or PAS. The hyphae are septate with 45 degree branching angles. The infections may be invasive, noninvasive, or fulminant. The noninvasive form results in a fungus ball within the sinus, and this is usually surgically removed. Invasive aspergillosis may behave much like a malignant neoplasm, with destruction of bone. Treatment involves wide surgical debridement and amphotericin. Fulminant aspergillosis most commonly occurs in immunocompromised patients and is characterized by the spread of organisms beyond the sinuses and into surrounding structures. Again, therapy is wide excision and amphotericin.

Mucormycosis is a fungi of the Phycomycetes class. They are encountered in dust and soil and enter the host through the respiratory tract. The fungus directly invades vascular channels and causes hemorrhagic ischemia and thrombosis. The disease is frequently fatal, with even normal hosts having up to a 40% mortality rate. Immunocompromised hosts have an approximately 90% mortality rate.

Ketoacidosis predisposes to severe mucormycosis as the fungus thrives in acidic, glucose rich areas. Other patients at risk are any immunocompromised patient, including those on steroids, chemotherapy or receiving broad spectrum antibiotics.

The initial signs of infection include engorgement of the turbinates and obstruction, followed by ischemia and thrombosis leading to necrosis of the turbinates and a bloody discharge. The area typically appears black. Progession to invasive disease is the usual course, heralded by proptosis, ptosis, ophthalmoplegia and facial palsy. The diagnosis is made by fungal stains, including PAS and methenamine-silver. In fulminant cases, the characteristic non-septate hyphae can be seen on frozen section.

Management of mucormycosis involves radical surgical debridement with aggressive correction of underlying immunocompromised states as well as high doses of amphotericin. Amphotericin alone is ineffective.

COMPLICATIONS:

Mucoceles:

A mucocele is a chronic, cystic lesion of the sinuses which is lined by pseudostratified or columnar epithelium. These lesions expand slowly, often requiring more than ten years to become symptomatic. Symptoms include bony erosion of adjacent structures.

The etiology of mucoceles is debated, but two general theories exist. The first suggests obstruction of the ostium results in the retained mucocele, while the other postulates obstruction of a minor salivary gland is all that is required. Regardless, nearly half of all patients have chronic obstruction of the ostia or have an antecedent trauma to one of the sinuses. In nearly 30%, no prior nasal symptoms can be elicited.

Maxillary mucoceles are frequently noted on routine CT scans. In general, these cysts are asymptomatic and do not require treatment, unless they are blocking a natural ostium. If therapy is warranted, these cysts can often be aspirated through an antral puncture.

Frontal sinus mucoceles are the most clinically significant mucoceles. They often cause proptosis and double vision. Therapy involves complete removal and obliteration of the frontal sinus.

Sphenodoethmoidal mucoceles are more subtle. Vertex headaches and deep nasal headaches are common complaints. These must be widely drained into the nasal vault.

Orbital Complications:

The orbit is separated from the ethmoidal sinuses by the thin lamina papyracea, making orbital involvement the most common complication of sinusitis. The first indication is inflammatory edema of the eyelids which progresses to cellulitis, proptosis, chemosis and ophthalmoplegia. There are five classifications of orbital involvement:

Of note, purulent frontal sinusitis may also result in orbital complications. The floor of the sinus is thin, leading to easy transmission to the orbit. An abscess in this area leads to osteomyelitis of the frontal bone and an abscess and is known as Pott's puffy tumor.

Orbital inflammation and cellulitis is treated with IV antibiotics with or without sinus drainage, depending upon the severity of symptoms, and patients should be hospitalized for close evaluation. If an abscess develops, immediate surgical drainage is necessary to avoid possible permanent sequelae. Indications for surgical drainage include:

Cavernous Sinus Thrombosis:

Most cases of cavernous sinus thrombosis are caused by infections of the middle one third of the face as the ophthalmic veins are valveless and lead directly to the cavernous sinus. Sinus disease is also a common finding.

Clinical findings include palsies of cranial nerves 3, 4, V1, V2 and 6 as these are located in or near the cavernous sinus. Severe frontal and ethmoid headaches are seen, as are fever, and progressive unilateral or bilateral orbital findings. Initially, the eye becomes proptotic and chemotic with subsequent 6th and 3rd nerve palsies. As there are no ophthalmic valves, the other eye is subsequently affected.

Although the diagnosis is primarily clinical, CT scans show a filling defect of the involved sinus with a dilated ophthalmic vein. Treatment is intravenous antibiotics and surgical drainage of the affected sinuses. Heparinization, although controversial, is sometimes performed. Mortality rates are 30%, but less than half survivors are neurologically intact.

Brain Abscess:

Nearly one in seven brain abscesses are from sinususitis, and the mortality rate is 20%. Clinically, the most important prognostic sign is the degree of neurological deficit, with those alert and oriented at presentation having minimal mortality.

Treatment includes drainage of the affected sinus and the abscess along with intravenous antibiotics. The frontal, ethmoidal and sphenoid sinuses are commonly involved.

Meningitis:

Since sustained bacteremia is primarily seen in the young, menigitis is more often found in children. Sinusitis accounts for nearly one in nine cases. The clinical findings of nuchal rigidity and fever are well known. Focal neurological deficits are uncommon. The mortality for adults is nearly 20%, but much lower for children. Therapy is intravenous antibiotics and surgical drainage of the affected sinus.

Subdural/Epidural Abscesses:

Most cases of subdural abscesses result from sinusitis. The clinical presentation is characterized by swift neurological deterioration, with hemiparesis, seizures and aphasia commonly found. The mortality rate is 20%, with 1/3 of survivors remaining neurologically impaired. Treatment is intravenous antibiotics and surgical drainage.

Radiology:

There are generally two commonly performed radiographic studies of the paranasal sinuses, plain films and computed tomography. Customarily, plain films include the Waters', Caldwell's and lateral views of the sinuses. They are useful in evaluating the transparency, size and integrity of these structures, but are limited in their evaluation of the sphenoids and ethmoids due to overlapping structures. In general, bony structures are seen with far more detail than soft tissue. Computed tomography has largely replaced plain films, as it simultaneously displays bone, soft tissue and air, and their evaluations of the sinuses is in much greater detail and at an increasingly competitive cost.

The Waters view is a posteroanterior projection performed with the patient's nose and chin on the film. This view is useful for evaluating the maxillary sinuses. The Caldwell view is taken with the nose and forehead on the film, and is useful in evaluation the frontal and ethmoid sinuses. The lateral view is most useful for evaluating the sphenoid sinuses. The basal view can evaluate the sphenoid and ethmoid sinuses.

Viral sinusitis is classically seen as slight mucoperiosteal thickening. Bacterial sinusitis usually has an air fluid level, with one sinus affected greater than the others. In allergic rhinitis, bilateral mucoperiosteal thickening is seen, thus helping differentiating it from bacterial sinusitis.

Computed Tomography Since CT can simultaneously display bone and soft tissue and has the additional property of displaying selected anatomical areas, it has largely made plain films obsolete.

In normal sinuses, mucosa is usually barely perceptible and the air appears to nearly abut against the bone. With chronic disease, the mucosa becomes more clearly defined. Care must be taken to not construe the normal nasal cycle as sinusitis. Allergic fungal sinusitis is seen as the characteristic double density.

Two series of views are obtained, the coronal and the axial. The coronal cuts are much more useful as the ostiomeatal complex is more clearly seen. In some instances, the coronal cuts are adequate for diagnosis, while the axial views must be obtained if one contemplates surgery upon the sinuses.

Discussion (Dr. Quinn):

In the matter of surgical drainage of the acute frontal sinus empyema, it was the discussant's view, shared by the faculty then present, that the standard external trephine is superior to the intranasal endoscopic approach and is to be preferred.

Drs. Quinn and Deskin remarked upon the severity of acute frontal sinusitis when its onset is immediately preceded by swimming or diving, and comments were offered regarding the suitability of various local bodies of water for recreational bathing.

Dr. Quinn suggested that an acute viral rhinosinusitis might be distinguished from a bacterial sinusitis by the simple expedient of a "snot smear" stained with Gram's method. In viral sinusitis, bacteria may be seen in assocation with clusters of epithelial cells as from the nasal vestibule, while in bacterial sinusitis bacteria are seen generously admixed with and occasionally within the overwhelming number of polymorphonuclear leucocytes in the nasal discharge. While current doctrine espouses (and patients expect) antibiotic treatment when a diagnosis of sinusitis has been made, the recent emergence of resistant strains of common pathogens may cause us to reconsider this practice.

It cannot be denied that when a patient observes his physician obtaining a sample of nasal discharge, then studying it intently through a microscope (in the same room as the patient, of course) that patient leaves with the conviction that his doctor regards his complaint of "a terrible sinus problem" with serious concern as well as with sympathy.

Finally, the assemblage failed to resolve the question of why the nose runs in cold weather. One faction contends that the phenomenon is a response of the nasal mucosal secretory apparatus, while a minority claimed that the fluid represents excessive lacrimal secretion (in response to cold wind striking the conjunctiva and cornea) issuing though the nasolacrimal duct, emerging from the nostrils. The question clearly offers a sound basis for external funding of studies to determine the effectiveness of Atrovent nasal spray in conditions experienced by cross-country and downhill skiers. A number of individuals immediately volunteered to act as subjects, contingent upon suitable grant support.

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