MAXILLARY SINUSITIS

Anatomy and physiology

The maxillary antrum is pyramidal and has a capacity in the adult of ap- proximately 15mL. Above it lies the orbit. Behind it is the pterygo-palatine fossa containing the maxillary artery. Inferiorly hard palate forms the floor and lies close to the roots of the second premolar and the first two molar teeth. Medially the antrum is separated from the nose by the lateral nasal wall made up of the middle and inferior turbinate bones, each with a corresponding recess or meatus below it. The ethmoidal sinuses form a honey-comb of air cells between the lamina papyracea of the orbit and the upper part of the nose. An upward extension forms the fronto-nasal duct draining the frontal sinus. The openings of the sinuses under the middle turbinate form the ostio- meatal complex and it is now recognized that abnormality of this area leads to failure of sinus drainage and thence to sinusitis. Abnormalities may be structural, as with a large aerated cell blocking the ostial openings, or may be functional such as oedema, allergy or polyp formation.The key to treatment of sinusitis lies in recognition of the abnor- mality and its correction by surgery or medication.

ACUTE INFECTION

AETIOLOGY

Most cases of acute sinusitis are secondary to:

1 common cold;

2 influenza;

3 measles,

whooping cough, etc.

In about 10% of cases the infection is dental in origin, as in:

1 apical abscess;

2 dental extraction.

Occasionally, infection follows the entry of infected material, as in:

1 diving —water is forced through the ostium, into the sinus;

2 fractures;

3 gunshot wounds.

SYMPTOMS

1 The patient usually has an upper respiratory tract infection, or gives a history of dental infection or recent extraction.

2 Pain over the maxillary antrum, often referred to the supra-orbital region.The pain is usually throbbing and is aggravated by bending, coughing or walking.

3 Nasal obstruction —may be unilateral if unilateral sinusitis is present.

PATHOLOGY

The causative organisms are usually streptococcus pneumoniae, Haemophilus influenzae or Staphylococcus pyogenes. In dental infections, anaerobes may be present. The mucous membrane of the sinuses becomes inflamed and oedema- tous and pus forms. If the ostia are obstructed by oedema, the antrum becomes filled with pus under pressure —empyema of the antrum

. SIGNS

1 Pyrexia is usually present.

2 Tenderness over the antrum and on percussion of the upper teeth.

3 Mucopus in the nose or in the nasopharynx.

4 There may be dental caries or an oro-antral fistula.

5 X-ray shows opacity or a fluid level in the antrum.

Three important rules 1 Swelling of the cheek is very rare in maxillary sinusitis.

2 Swelling of the cheek is most commonly of dental origin.

3 Swelling of the cheek as a result of antral disease usually indicates carci- noma of the maxillary antrum.

TREATMENT

1 The patient should be off work and should rest.

2 An appropriate antibiotic should be started after taking a nasal swab. Amoxycillin (to take account of Haemophilus) is a good first-time treatment.

3 Vasoconstrictor nose drops, such as 1% ephedrine or 0.05% oxymeta- zoline, will aid drainage of the sinus.

4 Analgesics. In most cases, resolution of acute maxillary sinusitis will occur, but on occa- sion antral wash-out will be necessary to drain pus. Chronic sinusitis Most cases of acute sinusitis resolve but some progress to chronicity.This is particularly likely to happen if there is an abnormality of the anatomy, allergy, polyps or immune deficit.

SYMPTOMS

1 Patients with chronic maxillary sinusitis usually have very few symptoms.

2 There is usually nasal obstruction and anosmia.

3 There is usually nasal or postnasal discharge of mucopus. 4 Cacosmia may occur in infections of dental origin.

SIGNS

1 Mucopus in the middle meatus under the middle turbinate.

2 Nasal mucosa congested.

3 Imaging shows fluid level or opacity, or mucosal thickening within the sinus.

TREATMENT

Medical

A further course of treatment with antibiotics, vasoconstrictor nose drops and steam inhalations is worthwhile, as it may produce resolution.

Functional endoscopic surgery Developments in endoscopic instruments allow inspection of the sinus ostia and interior of the antrum. Ostial enlargement and removal of polyps and cysts can be performed. The ostio-meatal complex under the middle turbinate is opened up and allows more physiological drainage of the antrum.

ACUTE FRONTAL SINUSITIS

This may occur as an isolated condition but more usually forms part of more widespread sinus infection.

TREATMENT:

1 Bed rest.

2 Antibiotics —amoxycillin plus metronidazole will cover the most likely organisms.

3 Nasal decongestants —0.5% ephedrine or 0.05% oxymetazoline.

4 Analgesics.

5 In severe cases where, despite intensive therapy, there is increasing oedema and redness of the eyelid, the frontal sinus must be drained. An in- cision is made below the medial one-third of the eyebrow and a trephine opening made into the sinus. A drainage tube is inserted, through which the sinus can be irrigated.

Acute and Chronic Sinusitis

CLINICAL FEATURES OF FRONTAL SINUSITIS

The symptoms and signs are similar to those of acute maxillary sinusitis, with the following additional features:

1 the pain is mainly supra-orbital;

2 the pain may be periodic (present in the morning; very severe at midday; subsides during the afternoon);

3 acute tenderness is elicited by upward pressure under the floor of the sinus or by percussion of its anterior wall;

4 oedema of the upper eyelid may be present;

5 X-rays show opacity or fluid level in frontal sinus, and usually opacity of ethmoids and maxillary sinus.

COMPLICATIONS

 1 Orbital complication (cellulitis or abscess) are characterized by diplopia, marked oedema of the eyelids, chemosis of the conjunctiva and sometimes proptosis. Resolution usually follows intensive antibiotic ther- apy and local drainage but surgical drainage is required urgently if there is any change in vision. Loss of colour discrimination is an early sign of im- pending visual loss.

2 Meningitis, extradural and subdural abscesses may occur and should be treated as neurosurgical emergencies.

3 Cerebral abscess (frontal lobe) deserves special mention in view of the insidious nature of its development. Any patient who has a history of recent frontal sinus infection and complains of headaches, is apathetic or exhibits any abnormality of behaviour should be suspected of harbouring a frontal lobe abscess.

4 Osteomyelitis of the frontal bone is characterized by persistent headache and oedema of the scalp in the vicinity of the frontal sinus. X-ray signs are late, and by the time they become apparent osteomyelitis is well established. Sequestration may occur, and intensive antibiotic therapy combined with removal of diseased bone is necessary.

5 Cavernous sinus thrombosis is very rare. Proptosis, chemosis and ophthalmoplegia characterize this dangerous complication.

Recurrent and chronic infection

Recurring acute or persisting chronic infection may become established. Treatment is by antibiotics and topical steroids. If surgery is necessary, it is now usual to establish drainage by endoscopic surgery of the ostio- Sinusitis.

ETHMOIDAL SINUSITIS

Acute infection of the ethmoidal complex usually follows a coryzal cold. The area becomes swollen and inflamed.There may be gross oedema of the eyelids and rupture into the orbit may occur. Pressure on the optic nerve endangers the sight in the affected eye (see above under frontal sinusitis).

TREATMENT:

In the early stages antibiotics should prove curative but if abscess formation is suspected, it may be confirmed by CT or MR scan. Either external drainage by external ethmoidectomy, or intranasal drainage by endoscopic surgery is performed to drain pus and relieve pressure on the orbit.