ComplicationsORBITAL INFECTIONThe lamina papyracea of the ethmoid bone forms a large part of the medial wall of the orbit. The orbit, therefore, is separated from the ethmoid sinuses by the paper-thin and often dehiscent lamina. Because of the weakness of this barrier, the spread of infection to the orbit is the most common complication of acute sinusitis. In addition, the ophthalmic venous system is devoid of valves and communicates with the ethmoid veins, providing a path for infection to enter the orbit. Infection of the orbital structures usually follows a stepwise sequence as described in Table 14–3. Inflammatory edema of the lid may be treated in an outpatient setting with oral antibiotics, provided that close follow-up can be achieved. Orbital cellulitis usually responds to intravenous antibiotics, whereas subperiosteal and orbital abscesses require operative drainage and drainage of the offending sinus. Cavernous sinus thrombosis is truly life threatening and is associated with a poor prognosis even with aggressive medical and surgical management. The incidence of all orbital complications is higher in the pediatric population than in adults.

Table 14–3. Orbital complications of sinusitis.

Lid EdemaNo limitation of extraocular movements and vision is nor-

mal.Infection is anterior to the orbital septum.

Orbital CellulitisInfection of the soft tissue posterior to the orbital septum.

Subperiosteal AbscessPus collection beneath the periosteum of the lamina papy-

racea.Orbital Abscess

Pus collection in the orbit.Associated with limitation of extraocular movements, ex-

ophthalmos, and visual changes.Cavernous Sinus Thrombosis

Bilateral eve involvement, meningeal signs, and other intra-

A.. LOCAL COMPLICATIONSMucocele of Paranasal Sinuses andMucous Retention Cysts The sin uses commonly affected by mucocele in the order of frequency, are the frontal, ethmoidal, maxi llary and sphenoidal. There are two views in the genesis of amucocele:(i) Chron ic obstruction to sinus ostium resu lting inaccumulation of secretions which slowly expand the sinus and destroy its bony walls.(ii) Cystic dilatation of mucous gland of the sinus mucosa due to obstruction of its duct. In this case, wall of mucocele is surrounded by normal sinus mucosa. The contents of mucocele are sterile.

Mucocele of the frontal sinus (Fig. 38.2).It usually pres. ents in the superomedial quadrant of the orbit (90%) and displaces the eyeball forward, downward and laterally. The swelling is cystic and non-tender; egg-shell crackling may be elicited. Sometimes, it presents as a cystic swelling in the forehead (10%). Patient's complaints are usually mild and may include headache, diplopia and proptosis. Radiographs of the frontal sinus usually reveal clouding of the sinus with loss of scalloped outline which is so typical of the normal frontal sinus. Treatment is frontoethmoidectomy with free drainage of frontal sinus into the middle meatus. Mucocele of ethmoid sinuses causes expansion of the medial wall of the orbit, displacing the eyeball orward and laterally. In addition, it may cause a bulge in the middle meatus of nose. A mucocele of the ethmoid c<'ln be dra ined by an intranasal operation, uncapping the ethmoidal bulge and establishing free drainage. Sometimes, it may require external ethmoid operation. Mucous retention cyst of the maxillary sinus presents as a retention cyst due to obstruction of the duct of seromucinous gland and usually does not cause bone erosion. It is asymptomatic and is observed as an incidental finding on radiographs. No treatment is generally required for asymptomatic retention cysts as most of them regress spontaneously over a period of time. Mucocele of the maxillary sinus can occur as a complication of chronic sinus inflammation when its ostium is blocked. The sinus fills with mucus and its bony walls get expanded due to expansile process. CT scan and MRI can help in the diagnosis. A polyp, tumour or trauma in the middle meatus may also obstruct the sinus ostium to cause a mucocele. Mucocele of sphenoid sinus or sphenoethmoidal mucocele arises from slow expansion and destruction of sphenoid and posterior ethmoid sinuses. C linical features are those of superior orbital fissure synJrome (involvement of CN III, IV, VI and ophthalmic division of V) or orbital apex syndrome which is superior orbital fissure syndrome with additional involvement of optic and maxillary division of trigeminal nerve. Exophthalmos is always present and the pain is localised to the orbit or forehead. Some may complain of headache in the occipu t or vertex. Treatment is extemal ethmoidectomy with sphenoido tomy. Anterior wall of the sphenoid sinus is removed, cyst wall uncapped and its fluid contents evacuated. Pyocele or mucopyocele is similar to mucocele but its contents are purulent. It can result from infection of a mucocele of any of the sinuses. Endoscopic surgery has replaced external operation of the sinuses for treatment of all mucocele or mucopyoceles of various sinuses.

Fig. 38.2 Mucocele of frontal sinus. Note swelling above the medial canthus of left eye (a rrow).

Tabel 38.1 Complications of pa ranasal sinus infection

A. Local (i) Mucocele/Mucopyocele (i i) Mucous retention cyst (iii) Osteomyel i tis- Frontal bone(more common)- Maxil la

B. Orbital(i) Preseptol inflammatory oedema of l ids(ii) Subperiosteal abscess(iii) Orbital cell u lit is(iv) Orbital abscess

(v) Superior orbital fissure syndrome(vi) Orbi tal apex syndrome