The most common radiographic sign for secondary osteomyelitis of the paranasal sinuses is:

Paranasal Sinus Mucocele

Paranasal sinus mucocele is a chronic, cystic lesion of the paranasal sinuses that results from obstruction of the draining ostia.519 Paranasal sinus mucocele occurs most commonly in the frontal and ethmoidal sinuses. Symptoms, which depend on the site of involvement and the direction and extent of expansion, include pain, facial swelling or deformity, proptosis, enophthalmos, diplopia, rhinorrhea, and nasal obstruction. The clinical picture may lead to the search for a neoplasm. Radiographic findings include opacification of the involved sinus; erosion or destruction of the sinus walls, with loss of the typical scalloped outline along the mucoperiosteum; and abnormal radiolucency due to loss of bone.

There are two types of mucoceles. Herniation of the cyst into submucosal tissue adjacent to the bony wall of the sinus is referred to as an internal mucocele. Herniation of the cyst through the bony wall of the sinus with extension into subcutaneous tissue or into the cranial cavity is an external mucocele. Expansion of a mucocele occurs in the direction of least resistance. Regardless of the sinus involved, the pathogenesis of mucoceles is thought to be an increase in pressure within a given sinus secondary to blockage of the sinus outlet (ostium). Most often, this is the result of an inflammatory or allergic process. Other factors implicated in the development of mucoceles include trauma, surgery, and neoplasia.

Histologic features are not as impressive as the clinical appearance. There is a cyst lined by a flattened, pseudostratified, ciliated columnar epithelium. Reactive bone formation may be present in proximity to the cyst epithelium. In long-standing cases, the cyst epithelium may demonstrate squamous metaplasia.

The prognosis is excellent after complete surgical excision. Complications include superimposed infection (pyocele), meningitis, and brain abscess. The diagnosis of paranasal sinus mucocele is a correlation of clinical, radiographic, and pathologic findings. Diagnosis by histopathologic examination alone may be extremely difficult, given the nonspecific histologic features; the lining of paranasal sinus mucoceles is the same as that of the normal paranasal sinus or the lining associated with nonspecific sinusitis.

Pain of Sinus and/or Nasal Mucosal Origin

Sinus/nasal mucosal pain is another source of pain that can mimic toothache.2,3,25,114 Sinus pain can exhibit symptoms of fullness or pressure below the eyes, but is generally not particularly painful unless the nasal mucosa is also affected.32 Pain from the nasal mucosa tends to be dull and aching and can also have a burning quality typical of visceral mucosal pain. In general, these pains are of viral, bacterial, or allergic etiology. Other symptoms consistent with these types of disease (e.g., congestion and/or nasal drainage) should be noted in the patient history.

Typical of deep visceral tissues, sinus/nasal mucosal pain can induce central excitatory effects such as secondary hyperalgesia, referral of pain, and autonomic changes. It is this tendency that gives sinus/nasal pain the ability to masquerade as toothache. Secondary hyperalgesia, seen clinically as a concentric spread of pain beyond the area of tissue injury, will result in tenderness of the mucosa in the area of the maxillary sinuses as well as tenderness to percussion of several maxillary teeth. Teeth tender to percussion and palpation suggest periradicular inflammation. Autonomic sequelae might present as edema and/or erythema in the area, which could be suggestive of a dental abscess. However, when an etiology for pulpal and therefore periradicular pathosis is absent, sinus/nasal mucosal disease should be suspected. Other symptoms of sinus disease include sensitivity to palpation of structures overlying sinuses (i.e., paranasal tenderness) and a throbbing or increased pain sensation when the head is placed lower than the heart. Dental local anesthetic blockade will not abate sinus/nasal mucosa pain although topical nasal anesthetic will.

Patients with suspected sinus/nasal mucosal disease should be referred to an otolaryngologist for further diagnosis and treatment. Physical examination as well as adjunctive tests may be necessary for definitive diagnosis. Tests may include nasal cytologic and ultrasound studies and the use of nasal endoscopes, in addition to imaging tests such as radiology and computed tomographic imaging.31 Treatment of sinus/nasal mucosa pain is dependent on the etiology (e.g., bacterial, viral, allergic, or obstructive),

Prevention

The prevention of acute rhinosinusitis after sinus graft surgery includes:

Paranasal Sinuses and Nasal Lymphoma

Paranasal sinus lymphoma includes several distinct diseases. Important differences in clinical features, phenotypic and genotypic characteristics, and prognosis are apparent between disease occurring in Western275,276 and Asian populations.277,278 Common presenting features include painless nasal obstruction, nasal discharge or bleeding, facial swelling, or palatal lesions with dental impacts. Involvement of the orbit can cause epiphora, proptosis, or diplopia. Tumors are most commonly of DLBCL type in North America and Europe. In Asia, a destructive, erosive lesion is a characteristic presentation and T-cell/NK-cell tumors predominate and show the characteristic features of angioinvasion, necrosis, and epitheliotropism. Indolent lymphomas are less common. The nasal type of CD56-positive T-cell/NK-cell lymphoma is a distinct clinicopathologic entity associated with Epstein-Barr virus.28,41 T-cell/NK-cell tumors with an identical phenotype and genotype can occur rarely in other extranodal sites, usually in the skin, subcutis, gastrointestinal tract, and testis.28,279 For DLBCL, the current practice of combined-modality therapy yields overall 5-year survival rates of 60% to 75%.276,277,280 In T-cell/NK-cell disease, the Asian experience with stage I and II presentations is disappointing, with a response rate to doxorubicin-containing chemotherapy of less than 50% and 5-year survival of 30% to 70%.278,279,281-283 The early use of RT to a higher dose of 45 to 50 Gy appears to be important for optimal local control.278,279,284,285 For patients who responded favorably to initial treatment, the use of consolidation therapy with high-dose chemotherapy and autologous stem cell transplantation appears to result in prolonged remissions.42

Staging, Treatment, and Outcome

Approximately 75% of cases are localized at presentation (Ann Arbor stage I or II).59,81 Patients with stage IV disease may have involvement of the CNS, lung, bone, kidney, or gastrointestinal tract.81,82 In earlier times patients usually were treated with radiation alone; however, that approach was associated with a high proportion of treatment failures.94 Currently, most patients receive radiation and chemotherapy. Some authorities recommend prophylactic treatment of the CNS to improve long-term, disease-free survival.60,81

When paranasal sinus lymphomas relapse or progress, they frequently involve lymph nodes and may also involve a variety of extranodal sites, including the CNS, lung, bone, ovary, testis, marrow, liver, spleen and skin.∗ Local failures are uncommon when optimal radiation is included in the therapeutic regimen.95 The results of follow-up have varied widely, with 5-year survival rates ranging from 29%87 to 80%89 in different series of patients with paranasal sinus lymphoma treated with combined modality therapy. In one large series of patients, most of whom received chemotherapy, radiation, and prophylactic intrathecal chemotherapy, the 5-year overall survival rate was 54%, and the 5-year disease-specific survival rate was 67%.60

Anatomy and Physiology of the Paranasal Sinuses

The paranasal sinuses are a complex system of air-filled bony cavities, which extend from the skull base down to the alveolar and zygomatic processes (Fig. 8-1). They are composed of four groups of sinuses, being named for the bone in which they are found. The maxillary and ethmoid sinuses are usually present radiologically at birth and continue to develop until early adulthood, whereas the sphenoid sinus usually becomes apparent at about 3 to 7 years of life and the frontal sinus by 6 to 8 years.5,6 The sinuses share a number of common borders with the orbit, as well as the anterior and middle cranial fossae. These anatomic relationships are important in terms of the pathophysiology of the various pyogenic complications that can arise from acute sinusitis.

The focal point of sinus drainage is through the ostiomeatal complex, located in the middle meatus. The maxillary, frontal, and anterior ethmoid ostia all drain into this anatomic structure.5 The posterior ethmoids empty into the superior meatus and the sphenoid sinuses into the sphenoethmoidal recess. The paranasal sinuses are lined with pseudostratified, ciliated, columnar epithelium that is continuous via their ostia with the lining of the nasal cavity. Cilia are concentrated near and beat in the direction of the natural sinus ostia. Inflammation of the mucosa in the region of the ostia can cause obstruction and ciliary dysfunction, resulting in stasis and accumulation of purulent secretions, with the development of acute sinusitis.

The arterial supply of the paranasal sinuses is from branches of the internal and external carotid arteries, whereas the venous and lymphatic drainage are through the sinus ostia into the venous drainage of the nasal cavity.7 In addition, venous drainage occurs through valveless vessels corresponding to the arterial supply.7 Infection of the sinuses may result in retrograde thrombophlebitis of these vessels, resulting in pyogenic intracranial and orbital complications.

The exact function of the paranasal sinuses is not well understood. The possible roles of the sinuses may be to reduce the weight of the skull, act as a pressure dampener, provide humidification and warming of inspired air, serve to cushion trauma, and act to insulate the brain from heat. Other postulated roles have included providing resonance of sound, giving mechanical rigidity to the face, or increasing the olfactory surface area.8

20 Do paranasal sinuses form during fetal or postnatal development?

The paranasal sinuses consist of four pairs of structures: the maxillary, sphenoidal, frontal, and ethmoidal sinuses. Two of these sinuses appear during fetal life; the other two appear after birth. The first of these structures to form are the maxillary sinuses during the third month of gestation, followed by the ethmoid sinuses during the fifth month of gestation. The sphenoid sinuses, which represent extensions of the ethmoid sinuses into the sphenoid bone, appear during the fifth month of postnatal life. The development of the frontal sinus does not begin until 2 years of age and is not evident radiographically until age 6 years.

SK8 Mass in the Paranasal Sinuses

The paranasal sinuses comprise the paired frontal, ethmoid, sphenoid, and maxillary sinuses. Alteration in the normally radiolucent appearance of the sinus suggests pathology. Aggressive pathology within the sinuses may have serious complications because of the sinuses' anatomic proximity to the brain and eyes. Multiple radiographic projections as well as CT are needed to evaluate all of the paranasal sinuses.

Anatomy, Histology, and Physiology

The paranasal sinuses are aerated cavities within the skull that connect to the nasal cavity. There are four sets of paired sinuses: the maxillary, ethmoid, frontal, and sphenoid sinuses. The sinuses are lined with a pseudostratified, ciliated epithelium. Goblet cells within the epithelium produce mucus, and the coordinated action of the cilia moves this mucus through the sinus cavities and into the nose. Once thought to be sterile, it is now known that bacterial communities inhabit the mucosal surfaces of the paranasal sinuses in both health and disease.22

The function of the sinuses has not been clearly established. They may serve a protective role in force dissipation with blunt trauma to the head or face. The paranasal sinuses can impact vocal resonance, which may have aided their evolution. The sinuses may allow for enhanced facial aesthetics. They may play a role in mucus production and immune surveillance in the nasal cavity.

The four paired sinuses are named after the bones that they aerate. The maxillary and ethmoid sinuses are the first to develop and are present at birth. The frontal and sphenoid sinuses develop more slowly. A visible frontal sinus is often not present until age 4 or 5, and continued aeration and development persist throughout the teenage years.60 Asymmetric aeration of the sinuses is common, particularly in the later-developing frontal and sphenoid sinuses. The frontal sinus may be absent in up to 10% of normal patients.61,62 An increased incidence of frontal sinus aplasia and diminished overall paranasal sinus aeration is seen in patients with congenital disorders that impact the sinuses such as cystic fibrosis.63

Mucus produced in the sinuses is propelled into the nasal cavity by coordinated ciliary motion. The maxillary (Fig. 49-4) and sphenoid sinuses are connected to the nasal cavity by discrete ostia, which often have a diameter of no more than 4 mm. The ethmoid sinuses are made up of a labyrinth of small cavities called air cells that sit between the orbit and the nasal septum. The ethmoid sinus typically drains through clefts between air cells rather than discrete ostia. The anterior ethmoid air cells drain through the middle meatus, between the middle turbinate and the lateral nasal wall. The posterior ethmoid cells drain through the superior meatus, between the superior turbinate and lateral nasal wall. The frontal sinus drainage tract is determined by the variable anatomy of the underlying anterior ethmoid air cells and eventually leads to the middle meatus.

Blood supply to the paranasal sinuses is provided through both the internal and external carotid systems. The sphenopalatine artery (SPA) is the terminal branch of the internal maxillary artery, which originates from the external carotid artery. The SPA enters the nasal cavity through the sphenopalatine foramen just behind the posterior wall of the maxillary sinus. The majority of the blood supply to the nasal cavity is provided by the SPA. The blood supply to the superior nasal cavity, and much of the ethmoid system, arises from the anterior and posterior ethmoid arteries. These vessels are branches from the ophthalmic artery of the internal carotid system and typically run within the skull base along the roof of the ethmoid sinuses. All of these vessels may contribute to refractory or “posterior” nosebleeds. Epistaxis originating from the SPA is amenable to embolization or surgical ligation of the SPA. The anterior and posterior ethmoid arteries are not amenable to embolization due to their origin from the ophthalmic artery and the associated risk for blindness. These vessels are amenable to surgical ligation in cases of refractory epistaxis.64

Face and Sinuses.

The paranasal sinuses are characteristically absent or hypoplastic, consistent with an abnormality predominating in bones formed through intramembranous ossification. The sella turcica often is hypoplastic, and the dorsum sellae often is bulbous. Nasal bones almost always are hypoplastic or agenetic. Likewise the zygomatic arches are hypoplastic or absent.119 All craniofacial regions are affected in cleidocranial dysplasia.117 Even the hyoid bone may demonstrate decreased ossification.210 The height and width of the mandible and maxilla are decreased, with anterior inclination of the mandible.117 The coronoid process of the mandible is slender and obliquely oriented in a posterosuperior direction. Persistence of a midline suture at the mandibular symphysis is classic for cleidocranial dysplasia.65 Facial abnormalities appear to progress with increasing age and may not be readily apparent in younger children.119,120