Sinus polyps

Sinus polyps

Polyps of the sinonasal mucosa are a common cause of intractable nasal obstruction. This is a distinct entity and may not be associated with an allergy. Swollen inferior turbinates are often mistaken for nasal polyps as they may be dramatically enlarged and occlude the nares.

Epidemiology

The prevalence of sinus polyps is between 0.2% and 4.3% of the population. Incidence appears to rise with age, and there is a clear male predominance (2-4-fold increase). At autopsy, up to 42% of individuals have evidence of nasal polyposis. There is a higher prevalence of sinus polyps in patients with aspirin sensitivity (36%), cystic fibrosis (20%) and asthma (10%). Amongst patients with polyps, 45% are asthmatic. The association of asthma, aspirin sensitivity and sinus polyps was described by Widal, but is now widely known as Samter's triad.

Pathology

The factors that initiate polyp formation are unknown. However, increasing oedema of the connective tissue stroma of the nasal mucosa eventually causes herniation through the basement membrane to form a sinus polyp. This stroma contains a variety of inflammatory mediators and cells, with eosinophils predominating. The epithelium of the polyp remains respiratory, with an increase in the goblet cell population. There are often areas of squamous metaplasia.

Polyps appear to arise from the middle meatus and lining of the ethmoid sinuses. They are frequently found in the maxillary antrum. A distinct entity is the large antrochoanal polyp which arises in the maxillary antrum, protrudes into the nasal cavity through the middle meatus and then passes posteriorly towards the choana.

There is no evidence to link general allergy to sinus polyposis. Indeed, skin-prick testing does not show a higher incidence of atopy in polyp patients, and the incidence of polyps in allergic patients is no higher than in normal controls (1.5% vs 1%). The incidence of polyposis is higher in non-allergic asthmatics (12%) than in atopic asthmatics (5%).

There is, however, evidence of 'local' allergy in the nasal mucosa with mast cell degranulation, raised IgE levels and eosinophilia. Recent research has suggested a role for fungi in the pathogenesis of polyps. The ubiquitous nature of fungal spores in the paranasal sinuses of all individuals makes proving causation immensely difficult.

Scope of disease

Sinus polyps predispose individuals to chronic rhinosinusitis and infective exacerbations. Indeed, any of the complications of sinusitis may be seen in these patients. Gross sinus polyposis may cause facial deformity, with widening of the nasal bridge and even displacement of the globes.

Clinical features

Sinus polyps may be asymptomatic but characteristically cause nasal obstruction. The patient may also complain of a post-nasal drip, rhinorrhoea and hyponasal speech. Thereis a profound loss of smell and therefore reduced taste. Symptoms of sinusitis, such as facial pressure and headache, may occur but are not as common as one might expect.

In severe cases, sinus polyps may protrude from the patient's nostrils and prove an embarrassment. Polyps are insensate and therefore amenable to removal using snares in the clinic. A unilateral sinus polyp and a history of bleeding should raise the suspicion of malignancy and warrants urgent biopsy.

Initial investigations

Skin-prick testing/RAST

Few investigations are mandatory, but the exclusion of allergy by skin-prick testing or RAST is advisable.

Peak expiratory flow

Assessment of peak expiratory flow rates (PEFR) will identify mild asthmatics who may have no overt respiratory symptoms.

Sweat test

All children with sinus polyposis should have a sweat test to exclude cystic fibrosis.

Further investigations

CT of the paranasal sinuses

For patients in whom medical management has failed, CT scanning provides important anatomical information for endoscopic sinus surgery and polypectomy. Simple plain sinus radiographs are of no value.

Medical management

Nasal topical steroids

All patients should have a trial of optimal medical therapy before surgical polypectomy is contemplated. Nasal steroid drops instilled in the head-dependent position offer better drug delivery to the sinonasal mucosa than sprays.

Oral steroids

In severe cases, a short course of oral steroids (e.g. prednisolone at 1 mg/kg body weight daily for 5 days) will offer spontaneous short-term benefit.

RECENT ADVANCES

There is some evidence that leukotriene receptor antagonists (e.g. montelukast, zafirlukast) may be beneficial in reducing congestion in aspirin-sensitive asthmatics with sinus polyps.

Surgical management

Endoscopic polypectomy

When medical measures have failed, surgical endoscopic polypectomy is indicated. This is often combined with sinus surgery to lay open the paranasal sinuses. The purpose of surgery is to allow topical steroids to access the sinonasal mucosa. It is an adjunct to medical treatment and not an alternative.

Powered instrumentation in the form of a suction debrider with its own irrigation system has allowed surgeons to perform polypectomy swiftly, effectively and safely.

Caldwell-Luc procedure

Occasionally, complete removal of large antrochoanal polyps arising from the maxillary sinus is not possible endoscopically. A fenestration is made in the front wall of the maxillary sinus through a sublabial incision. This was, in fact, a common procedure before the advent of endoscopes and is known as the Caldwell-Luc procedure.

Prognosis

Polyps invariably recur to some extent: 5-10% of sufferers have severe intractable disease that necessitates repeated surgery. Overall, 60% of those undergoing polypectomy will have a repeat procedure in the first 5 years following surgery.






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