Anatomy

It is useful to consider the anatomy of the nose by dividing it into:

External nose

The upper third of the external nose (Fig. 2.1) is bony, consisting of nasal bones which connect with the nasion at the forehead. The inferior two-thirds are cartilaginous, consisting of the upper lateral and lower lateral (alar) cartilages. The tip laterally contains resilient but pliable fibrocartilage. This allows maintenance of nasal shape after minor trauma. The skin over the cartilaginous portion is closely adherent and contains multiple sebaceous glands; these latter structures may hypertrophy to form a rhinophyma.

Fig. 2.1 Constituent elements of the external nose.

Nasal cavity

The nasal cavity stretches from the vestibule anteriorly to the nasopharynx posteriorly and is divided by a midline osteocartilaginous septum. The lateral wall of the cavity supports a series of ridges called turbinates (Fig. 2.2). These structures are lined by ciliated columnar epithelium and contain erectile tissue. The paranasal sinuses – maxillary, frontal, ethmoid and sphenoid – drain into the nasal cavity around the middle turbinate.

Fig. 2.2 Structure of the lateral wall of the nasal cavity.

The nasal septum comprises bony and cartilaginous elements. Inferiorly, it is inserted into a groove in the maxillary crest (Fig. 2.3). It is lined with mucoperichondrium and mucoperiosteum over the cartilage and bone, respectively. The nasal septum is rarely straight; marked displacement causes nasal airway blockage and an external cosmetic deformity.

Fig. 2.3 The nasal septum.

Vascular and nerve supply

Both the external and internal carotid arteries supply the nose via their terminal branches. As a guideline, the region above the root of the middle turbinate is supplied by the anterior and posterior ethmoidal arteries, with the remaining areas being supplied by the sphenopalatine, palatine and labial arteries. The carotid system anastomoses at the anteroinferior region of the septum are called Little’s area or Kiesselbach’s plexus.

Venous drainage of the external nose is of importance, as blood can drain via the facial and ophthalmic veins to the cavernous sinus. Therefore, a superficial infection of the nasal lining may involve the cavernous sinus.

The main sensory supply is via the maxillary division of the trigeminal nerve. Secretory glands are under the control of the autonomic nervous system in the vidian nerve. The nasal vascular supply is constricted by sympathetic nerve stimulation and dilated by parasympathetic.

Physiology

Anatomy

The paranasal sinuses (Fig. 2.4) are really extensions of the nasal cavity as air-filled spaces into the skull bones. Although paired anatomically, from a pathophysiological view they should be grouped as anterior and posterior. The frontal, anterior ethmoidal and maxillary sinuses (anterior group) drain into the middle meatus, and the posterior ethmoidal and sphenoid (posterior group) drain into the superior meatus and sphenoethmoidal recess. The crucial drainage area of the anterior group of paranasal sinuses is called the ostiomeatal complex (Fig. 2.4). The nasolacrimal duct opens into the anterior part of the inferior meatus.

Fig. 2.4 The paranasal sinuses.

Physiology

No specific function has been attributed to the paranasal sinuses. The following have been considered:

Nasal obstruction

Nasal obstruction is the most common symptom, and may be due to anatomical abnormalities, disorders of the mucous membrane lining or stimulation of the autonomic nervous system (Table 2.1). An allergic aetiology is likely where the symptoms manifest after contact with allergens such as grass pollen, feathers or animal dander. Viral infections, e.g. acute coryza and influenza, cause severe nasal obstruction but generally resolve rapidly over days. An overactivity of the parasympathetic as compared to the sympathetic nerve supply will cause dilatation of the vascular tree and hence engorgement. This is particularly noted by some patients in stress situations and with alterations in ambient temperature and humidity. Neoplasia produces a progressive unilateral obstruction.

Table 2.1 Causes of nasal obstruction

Nasal discharge

The specific character of the discharge is helpful in deciding aetiology (Table 2.2). Many patients describe this as ‘catarrh’. However, if it produces a runny nose, the discharge should be described as rhinorrhoea and the term ‘catarrh’ (or postnasal drip) reserved for nasal discharge passing backwards into the nasopharynx. Epistaxis is nasal haemorrhage and is most commonly due to spontaneous rupture of a blood vessel in the nasal mucous membrane. However, it is vital to exclude any bleeding disorders and neoplasms. If the discharge is offensive, it may indicate a bacterial infection, the presence of a foreign body or neoplasia.

Table 2.2 Nasal discharge: its characteristics and significance

Sneezing

Sneezing is a frequent accompaniment of allergic and infective rhinitis. Patients with allergies to household dust and dust mite sneeze on awakening, as the bed mattress forms a huge reservoir of allergens.

Facial pressure/pain

It is uncommon to see facial pain due to a local cause such as nasal vestibulitis or herpes eruption. More frequently it is related to disease in the distribution of the trigeminal nerve, which supplies the sensory component to the face and the interior of the nose and paranasal sinus via the ophthalmic and maxillary nerves.

Otological

Any pathological process that disrupts the function of the Eustachian tube may give rise to aural symptoms. Nasal polyps, particularly of the antrochoanal variety, can physically block the pharyngeal end of the tube. Allergic diseases result in a similar problem by provoking oedema, and neoplasms may directly invade the Eustachian tube. The most frequent otological symptom is hearing loss caused by a middle ear effusion secondary to Eustachian tube dysfunction.

Disorders of smell

Anosmia, a total loss of sense of smell, is rare. Hyposmia, a reduced sense of smell, is more common.

Cacosmia, which is an unpleasant smell detected mainly by others, may be caused by chronic nasal sepsis. Ozaena, a foul smell, is a common complaint in anaerobic infections seen in cases of atrophic rhinitis, but the presence of a foreign body and tumour must be excluded.

Halitosis

Poor dental hygiene and diet are the most common causes of halitosis. However, chronic sinusitis with purulent postnasal drip can produce this symptom (p. 51).

External

Certain cosmetic deformities such as angulation of the bony nasal pyramid or a nasal hump may be obvious. A saddle deformity due to previous injury or infection is readily identified. It is not unusual to find the septal cartilage dislocated into the nasal vestibule (Fig. 2.6).

Fig. 2.6 Functional and cosmetic deformities of the nose. (a) The caudal end of the nasal septum is dislocated into the right nostril. (b) Saddle deformity caused by excessive removal of septal cartilage.

Internal

A systematic examination is essential. The inferior turbinate is very prominent and often mistaken for a polyp. Common benign nasal polyps are white/grey in colour and painless on palpation (Fig. 2.7).

Fig. 2.7 Enlarged left inferior turbinate (arrow) in a patient with rhinitis (a), compared to a patient with characteristic nasal polyps (arrow) (b).

Mucopus in the middle meatus may indicate infection in the anterior group of sinuses.

The postnasal space or nasopharynx is difficult to view with a head light and mirror. Modern flexible instruments and rigid endoscopes are ideal. The sites to visualize include the Eustachian tube cushions, the posterior choanae, the roof of the nasopharynx and the fossa of Rosenmüller, which is a recess situated immediately posterior to the Eustachian tube.

Examination of the paranasal sinuses is limited to palpation. In an acute frontal sinusitis, there is localized tenderness in the floor of the sinus. Maxillary tumours may cause expansion of the malar and deformities of the teeth-bearing alveolus.

Allergy testing

The simplest allergy test is a skin-prick performed on the volar aspect of the forearm. A wide variety of allergens may be tested, but the common ones include pollens, animal dander, and house and dust mite. Controls such as a negative control (saline) and positive control (histamine) should be employed. A positive response produces a wheal and flare (in about 20 minutes) which can be graded. A negative response does not exclude allergy, and a positive response is not absolute proof that the specific allergen is causing symptoms (Fig. 2.8). The radioallergosorbent test (RAST) measures allergen-specific serum immunoglobulin E, but is expensive.

Fig. 2.8 A skin-prick test illustrating allergy to house dust mite and grass.

Radiology

Plain X-rays of the sinuses have limited value. Computed tomography (CT) is the imaging of choice for the majority of nasal and sinus disease (Fig. 2.9). Soft tissue abnormalities and tumours require magnetic resonance imaging (MRI) (Fig. 2.10).

Fig. 2.9 CT scan showing a malignant tumour of the maxillary sinus with bone erosion in the nasal cavity and cheek.

Fig. 2.10 MRI scan (T1) complementary to Figure 2.9: soft tissue detail is enhanced.

Mucociliary clearance

Mucociliary clearance can be assessed in cases of suspected ciliary motility disorder, e.g. Kartagener’s syndrome. A pellet of saccharin placed on the anterior end of the inferior turbinate should be tasted by the patient in about 20 minutes. Prolongation of this time occurs in some normals after nasal infections and in primary ciliary dyskinesia.

Miscellaneous

Rhinomanometry and acoustic rhinometry, which measure nasal air flow/resistance and cross-sectional area, respectively, are highly specialized research tools. Nasal provocation tests are more accurate than skin tests, but are time consuming as only a single allergen can be tested at a time. Eosinophilia in nasal smears and blood is supportive of a diagnosis of allergic rhinitis.

Clinical features

The clinical features of allergic rhinitis include the classic triad of:

The symptom complex is produced by allergen binding to immunoglobulin E (IgE), which in turn is bound to mast cells. This causes degranulation of mast cells and the release of mediator substances such as histamine, leukotrienes and slow-reacting substance of anaphylaxis (SRSA).

Many patients have associated evidence of atopy such as asthma, eczema, allergic dermatitis and drug allergies. Aspirin sensitivity is not infrequent. Taking a detailed clinical history may identify the allergens involved.

Typically, the nasal mucosa has a boggy, oedematous appearance (Fig. 2.13); it is covered by a thin layer of watery secretion. Application of a vasoconstrictor produces marked mucosal shrinking with improvement in the nasal airway. Skin-prick tests should be interpreted only in relation to the history. Negative skin tests in the face of obvious allergens are not infrequent.

Fig. 2.13 Oedematous inferior turbinates narrowing the nasal airway in a patient with hay fever.

Management

The simplest treatment is avoidance of known allergens. In perennial allergic rhinitis, the quantity of dust and dust mite may be reduced in the bedclothes by:

Suspected food allergens may be excluded from the diet or replaced with suitable alternatives. Removing animal dander by giving up a pet may be emotionally upsetting but necessary.

Desensitization injections may be offered. These work on the principle of producing a blocking IgG antibody that prevents antigen binding to IgE. Obviously, the treatment is only of value if specific allergens can be identified, and it is essential to commence the series of necessary injections well in advance of the exposure. Because of the risk of anaphylaxis, desensitization must be done in a controlled environment with adequate resuscitation available. Sublingual desensitization for grass pollen allergy is also available and carries less risk.

Surgery

Surgical treatment (Fig. 2.14) is only infrequently indicated, as most patients’ symptoms are controlled by conservative therapy. Turbinate resection, cautery or outfracture may improve nasal obstruction, but rhinorrhoea and sneezing are unaffected by surgical manipulations.

Fig. 2.14 (a) Endoscopic photograph of turbinate after laser reduction; (b) resection and submucosal diathermy of inferior turbinates to relieve obstruction.

Clinical features

The main clinical features include nasal obstruction, rhinorrhoea and sneezing as in allergic rhinitis. The nasal mucosa over the inferior turbinate is congested, swollen and red, occasionally completely blocking the airway. Some patients may complain that symptoms occur on exposure to sunlight, gaseous irritants such as tobacco or with ingestion of alcohol.

Management

In all but the mildest of cases, medical treatment in the form of local and systemic decongestants should be tried. Severe cases may require submucosal diathermy, laser treatment or partial turbinectomy to clear the nasal airway (Fig. 2.14).

Management

Treatment should be prophylactic, i.e. certain preparations should only be employed as ‘short, sharp’ therapies. Established rhinitis medicamentosa requires substitution of the offending drug by one containing a steroid, or use of a systemic decongestant. In severe cases, the mucosal swelling becomes irreversible. Such cases require surgical treatment, usually partial turbinate resection (Fig. 2.14).

Antrochoanal polyp

The antrochoanal polyp is uncommon. It is usually unilateral and commences as oedematous lining in the maxillary sinus. This prolapses, usually via a posterior accessory ostium, into the nasal cavity and enlarges towards the posterior choana and nasopharynx. The patient, commonly a young adult, complains of unilateral nasal obstruction, which is worse on expiration due to the ball valve effect of the polyp in the posterior choana. If significantly large it may block both choanae and cause otological symptoms due to obstruction of the Eustachian tube (Fig. 2.16). Patients occasionally present so late that the polyp has enlarged behind the soft palate and hangs visibly in the oropharynx.

Fig. 2.16 Antrochoanal polyp. A surgical specimen showing the classic dumbbell appearance. This caused total unilateral nasal blockage.

Treatment is surgical by pernasal excision with removal of the cystic antral portion endoscopically via an antrostomy. Recurrences may require a more radical approach to the antrum to remove the roots of the cyst.

Neoplastic polyps

Neoplastic polyps (p. 110) are invariably unilateral and cause progressive symptoms: nasal obstruction, epiphora (blocking of the vasolacrimal duct), epistaxis and foul-smelling nasal discharge. They are frequently fleshy in appearance and bleed on palpation. Biopsy is mandatory.

Miscellaneous polyps

Nasal polyps are extremely rare in children. In this age group, careful consideration should be given to any evidence of cystic fibrosis, and a sweat test should be performed.

Prolapse of the meninges (meningocele) or cerebrum (encephalocele) can occur through an anterior cranial fossa defect. This should be excluded radiologically before excision or biopsy.