The external ear

The external ear includes the pinna, external auditory meatus and tympanic membrane. The outer third has a cartilage skeleton, and the rest is bony. Both are covered by skin. The skin on the outer part contains hair follicles and wax glands, but these elements are absent in the bony meatus. Canal skin migrates outwards from the deep meatus, but does not desquamate until it reaches the junction with the cartilaginous meatus. This normal mechanism may be disturbed by injudicious use of cotton buds.

The eardrum is the window of the middle ear and is divided into the pars tensa and pars flaccida. The main landmark on the drum is the malleus handle (Fig. 1.2).

Fig. 1.2 A normal right eardrum.

The middle ear

The middle ear is an air-containing space connected to the nasopharynx via the Eustachian tube. It acts as an impedance matching device to transfer sound energy efficiently from air to a fluid medium in the cochlea (Fig. 1.3). The middle ear space, including the mastoid air cells, is closely related to the temporal lobe, cerebellum, jugular bulb and labyrinth of the inner ear. The space contains three ossicles (the malleus, incus and stapes) which transmit sound vibrations from the eardrum to the cochlea. The middle ear also contains two small muscles and is traversed by the facial nerve before it exits the skull.

Fig. 1.3 Section through the cochlea. Hair cells in the organ of Corti transform mechanical energy (vibration) into electrical impulses.

The inner ear

The inner ear comprises a dense bony capsule containing a membranous labyrinth which forms the cochlea, vestibule and semicircular canals.

The membranous part is surrounded by fluid, called perilymph, and is sealed from the middle ear by the stapes footplate and round window membrane.

The membranous part itself contains fluid called endolymph. The cochlea contains the organ of hearing which is connected by the auditory nerve to the brainstem (Fig. 1.3).

Normal hearing depends on transmission of sound via a vibrating tympanic membrane through a mobile ossicular chain to the cochlea. Displacement of the basilar membrane and movement of the hair cells cause an organized volley of electrical discharge in the eighth nerve, perceived as sound in the cerebral cortex.

The vestibule and semicircular canals form the peripheral balance organ. These have connections to the cerebellum and the eyes, and are important in the maintenance of posture and the ability to keep the eyes fixed when the head is moving.

Symptoms

History taking in ear complaints should be brief but thorough. Table 1.1 provides a reference guide of the major points that should be covered. The otological symptoms are discussed in greater detail later in this section, but it is important to establish the predominant complaint and whether it affects one or both ears.

Table 1.1 Major points in history taking in patients with an otological complaint

Signs

Satisfactory examination cannot be undertaken without adequate lighting. Battery auriscopes with a fibre or glass ring light give a coaxial beam with bright uniform illumination. A pneumatic attachment tests the mobility of the eardrum (Fig. 1.4).

Fig. 1.4 Inserting the auriscope. The pinna is elevated upwards and backwards. The instrument should be gripped like a pencil.

The pinna should be examined for scars and signs of crusting or weeping. Before introducing the auriscope, the ear canal must be straightened by elevating the pinna upwards and backwards (Fig. 1.4). The condition of the ear canal should be noted before the eardrum is examined. If an adequate seal of the canal is achieved by the speculum, gentle pressure on the pneumatic bulb will move the eardrum if the middle ear contains air. This is helpful in distinguishing perforations from thin or translucent segments.

A complete examination also involves viewing the Eustachian tube orifice in the nasopharynx.

Tuning fork tests

Tuning fork tests distinguish between conductive and sensorineural hearing loss, but are of limited value in children. Two tests are usually employed using a 512 Hz fork. The fork is sounded by striking the tines against the patella or elbow.

Rinne test

The Rinne test compares air conduction (AC – hearing via ear canal and middle ear) with bone conduction (BC – direct transmission to the inner ear via the mastoid process). The examiner holds the fork by the ear canal and then places it on the mastoid process using gentle counterpressure with the other hand. The patient is asked which position of the fork sounds louder: in front of the ear or touching the mastoid (Fig. 1.5).

Fig. 1.5 Interpretation of tuning fork tests. These tests are invalidated if the ear canals are not free of wax debris.

Sound is normally heard better by air conduction than by bone conduction (Rinne-positive). Disease in the external or middle ear, producing a conductive deafness, will reverse the test result (Rinne-negative).

Subjective tests

Pure tone audiograms are a standard means of recording hearing levels. Using headphones, each ear is tested individually for air conduction and, if necessary, bone conduction thresholds. The results are usually plotted as a graph. A result of 0 dB (decibels) is the average normal threshold for hearing in young adults (Fig. 1.6).

Fig. 1.6 A series of typical pure tone audiograms of the right ear. Hearing level (dBISO) is plotted on the vertical axis; frequency (Hz) is plotted on the horizontal axis. Air conduction (AC) signals are fed through headphones. Bone conduction (BC) signals are transmitted via a vibrator placed on the mastoid process.

Speech audiometry is a more sophisticated test. Phonetically balanced words are presented at different sound intensities and the number of correct answers is expressed as a percentage score. This is a useful test for evaluating hearing aids.

Objective tests

Impedance audiometry is an extremely useful test in the diagnosis of middle ear disease and some types of sensorineural hearing loss. By varying the pressure in the external ear canal, the compliance (i.e. mobility) of the eardrum may be calculated by the degree of sound reflected from a probe tone. This is very useful when screening for middle ear effusions, particularly in children, and for assessing Eustachian tube function (p. 7). It can also test the integrity of the middle ear mechanism and the auditory reflex arc (stapedius reflex).

Electric response audiometry (ERA) (Fig. 1.7) is another objective test. An evoked potential in the eighth nerve, brainstem or auditory cortex may be recorded using skin electrodes following acoustic stimulation of the cochlea. This principle is used to objectively assess hearing thresholds where the standard tests are not applicable, e.g. babies, disabled people and suspected malingerers.

Fig. 1.7 Evoked response audiometry. The response evoked by a sound stimulus can be recorded at a specific site along the auditory pathway, e.g. eighth nerve, brainstem or cortex.

Otoacoustic emissions testing is a useful screening test for neonatal sensorineural loss where the middle ear function is normal.

Hearing assessment in young children

From birth to about 6 months, the ‘gold standard’ method of testing is by electric response audiometry (see above). From 6 months to about 18 months, a child will turn to a noise, e.g. a rattle. This distraction test is performed by two observers and is a basic screening test performed on all children. From 2 years, various conditioning or cooperation tests are employed using free field noises, e.g. placing a peg in a basket after hearing the noise. It is not until the age of 3–4 years that headphones can be used to test each ear independently.

Tests

The functional status of the peripheral vestibular system can be tested in a variety of ways. These include:

Positional test

From an erect sitting position on a couch, the patient lies flat with the head turned to one side and below horizontal (Fig. 1.8). The onset of any vertigo is noted and the eyes are observed for nystagmus. The feeling of movement and the nystagmus, if present, are allowed to settle before the patient sits upright. The manoeuvre is repeated with the head to the opposite side. This test may help to distinguish vertigo caused by peripheral (otological) as opposed to central pathologies.

Fig. 1.8 ‘Positional testing’ in cases of vertigo.

Otitis media with effusion (glue ear)

Otitis media with effusion (OME) is the most common cause of acquired conductive hearing loss in children. The true incidence is unknown, but up to 60% of children in their first year may have middle ear effusions which are clinically asymptomatic. The peak clinical age group is 2–6 years, where about 30% of children suffer effusions. By the age of 11 the incidence has dropped to about 2%. There is a seasonal variation in the disease, associated with upper respiratory tract infections which are more common in October to March in the northern hemisphere.

The effusion in the middle ear may be serous, mucoid or thick (glue). The aetiology is usually Eustachian tube dysfunction, where normal ventilation of the middle ear is disturbed (Fig. 1.12). A diagnosis of chronic otitis media with effusion is made when fluid is present behind the eardrum for 12 weeks or more.

Fig. 1.12 Eustachian tube dysfunction resulting in defective middle ear ventilation. This can be due to a variety of causes and results in a middle ear effusion.

Clinical features

Children with OME usually present with hearing loss or recurrent otalgia. Children with a cleft palate or Down’s syndrome have a higher incidence of middle ear effusions. The otoscopic features of OME are characteristic (Fig. 1.13).

Fig. 1.13 Otoscopic appearance in otitis media with effusion (OME). The handle and short process of the malleus are brought into relief due to retraction of the eardrum. There is a slightly yellow appearance to the eardrum due to the middle ear effusion.

The hearing loss is conductive and may fluctuate down to as much as 40 dB. Tympanometry produces a flat trace, indicating an immobile drum (Fig. 1.14).

Fig. 1.14 Impedance tympanometry. This is an excellent method for detecting the presence of middle ear effusions. A flat compliance is seen in cases of otitis media with effusion.

Treatment

There is as yet no effective long-term medical treatment for established OME. Short-term improvements with antibiotics are not sustained. Decongestant mixtures are ineffective. If the effusion persists, surgery may be required to restore hearing. Removal of the adenoids reduces the incidence of recurrent effusions. Myringotomy, aspiration of fluid and insertion of a ventilation tube (grommet) immediately restores the hearing (Fig. 1.15). Grommets may remain in the drum for up to 12 months before being extruded. After grommet extrusion some children require reinsertion due to recurrent or persisting middle ear effusions.

Fig. 1.15 Types of grommets (middle ear ventilation tubes). The designs are numerous in variety in an attempt to prevent too rapid an extrusion from the eardrum and to assist in insertion.

Following grommet extrusion, it is common to see tympanosclerosis (white patches) in the eardrum. This type of white patch does not impair hearing.

Chronic failure of the Eustachian tube to function normally results in persisting middle ear effusion and thinning of the tympanic membrane. The eardrum may collapse onto the ossicles, producing a retraction pocket. Long-term ventilation may be necessary to prevent progressive retraction from the low middle ear pressure and subsequent development of chronic suppurative otitis media with cholesteatoma.

Otorrhoea after grommets

Grommets may become infected, producing a mucoid discharge. This should be mopped away and anti-inflammatory drops instilled. Massaging the tragus will allow the drops to penetrate the grommet lumen. Antibiotic eardrops are not recommended except under specialist supervision. Oral antibiotics may also be necessary if the discharge follows an upper respiratory tract infection. Persistent otorrhoea will necessitate removal of the grommet.

Children with grommets should not be prevented from participating in swimming activities. Infection is uncommon and usually readily treated.

Ear canal

Wax production varies between individuals and races. Blind attempts to remove wax with cotton buds usually result in impaction. Wax may be properly removed by syringing the ear or with a blunt hook (p. 25). Preliminary softening can be achieved with sodium bicarbonate eardrops three times a day, or hydrogen peroxide. Rarely, excessive accumulations of desquamated skin and wax in the deepest part of the external meatus can expand and erode the ear canal. This is termed keratosis obturans, and an anaesthetic may be required to remove it.

The external canal may be narrowed by bony exostoses predisposing to keratin accumulation (Fig. 1.16). These exostoses often occur in swimmers and require no treatment unless they cause external otitis or hearing deficits.

Fig. 1.16 Multiple exostoses may lead to narrowing of the external meati. They are sited at the osseocartilaginous junction of the ear canal.

Eardrum and middle ear

Perforations of the eardrum can occur from trauma and acute or chronic otitis media (Fig. 1.17). The degree of hearing loss depends on the site of the perforation and the extent of middle ear disease.

Fig. 1.17 A subtotal perforation of the left eardrum. The round window niche (RWN), the inudostapedial joint (ISJ) and promontory (P) are clearly visible.

Perforations from simple chronic otitis media where the mastoid is not diseased may be repaired by a tympanoplasty procedure using a graft (temporalis fascia). Ossicular discontinuity may also be treated surgically. Traumatic perforations, e.g. blow to the ear, invariably heal spontaneously if the ear is kept dry.

Adults may suffer with middle ear effusions, although less commonly than children. Investigations should rule out sinusitis, or nasopharyngeal tumours blocking the Eustachian tube (see Fig. 1.12, p. 7).

Otosclerosis is a disease where new bone growth occurs in the capsule of the inner ear. This may fix the footplate of the stapes. Hearing loss characteristically develops in the young adult and is usually conductive (p. 3), although the otoscopic appearance of the eardrum is normal. Pregnancy can accelerate the symptoms, suggesting a hormonal association with the disease. A family history is frequently elicited. Tinnitus may also be present.

Surgery for otosclerosis may restore normal hearing but also carries a small risk of total hearing loss. Use of a hearing aid has no complications, but is often refused (Fig. 1.18).

Fig. 1.18 The pathology and management of otosclerosis.

Presbyacusis (common)

Presbyacusis is a progressive loss of hair cells in the cochlea with age. Roughly 1% of cells are lost each year, and this affects the high-frequency part of the inner ear first (Fig. 1.19). It becomes clinically noticeable from the age of about 60–65 years. The degree of loss varies, as does the age of onset. Some patients with presbyacusis have recruitment (reduced dynamic range of hearing) which reduces effective amplification. The threshold for hearing and the uncomfortable level of sound are abnormally close (e.g. ‘Speak up, I can’t hear you … don’t shout so loud!’). Discrimination may also be affected (‘I hear you but can’t understand you’). There is no treatment to prevent this loss. When a significant social or work handicap is present, a hearing aid may be prescribed. This should be digital so that the pattern of amplification is tailored to the pattern of the individual’s hearing loss. Two hearing aids are better than one, because of binaural hearing.

Fig. 1.19 A typical audiogram seen in a patient with presbyacusis. There is a ski-slope-type high-frequency loss. The low frequencies may remain within the normal range.

Sudden (idiopathic) hearing loss (rare)

Cochlear failure may occur in a previously normal ear. The patient is suddenly aware of a blockage or rapid deterioration in hearing. Tinnitus or vertigo may be present. The aetiology is thought to be either a virus infection or vascular ischaemia. Treatment is largely empirical, and changes from decade to decade. Currently there is a great deal of interest in the role of steroids and antiviral agents. Preservation of high-frequency hearing on serial audiograms indicates a good prognosis.

Noise exposure (common)

Acoustic trauma occurs from sudden exposure (impact or blast), or from prolonged exposure, e.g. noise of heavy industrial machinery. Levels of 90 dB or greater require ear protection with properly fitted ear defenders. After exposure there may be a temporary threshold shift, perceived as ‘woolly hearing’ and associated with tinnitus. Continued noise exposure will lead to permanent threshold shifts, usually affecting the higher frequencies starting at 4 kHz.

Treatment is by avoidance or employing adequate ear protection in the form of ear defenders. An established hearing loss may benefit from a hearing aid. A system of compensation is available for occupational hearing loss.

Perilymph fistula (rare)

A rupture of the labyrinthine windows (round or oval) will result in leakage of perilymph fluid and a sensorineural type hearing loss. Mild features of imbalance or even frank vertigo may also occur. The rupture is usually preceded by an event that raises the intracranial pressure, e.g. straining to lift. It may also follow a stapedectomy operation where an iatrogenic fistula is sealed but the leak persists. The middle ear should be explored in cases where the hearing is deteriorating; otherwise, there is a risk of total hearing loss. The offending rupture is then sealed with a fat plug.

Inflammatory diseases (rare)

Measles, mumps, meningitis or syphilis may cause cochlear damage and can result in permanent sensorineural hearing loss. Chronic middle ear disease is also often associated with some degree of sensorineural loss.

Ototoxicity

The inner ear has many active metabolic processes which are susceptible to drugs. The cochlea or labyrinth may be affected in isolation or in combination, and this can result in hearing loss and symptoms of imbalance. Agents that are toxic to the renal system commonly affect the ear, e.g. systemic aminoglycosides and cytotoxic agents. Salicylates and quinine have reversible toxicity.

Acoustic tumours

Acoustic tumours are rare, but treatable, tumours of the vestibular element of the eighth cranial nerve. The most common presentation is a progressive unilateral hearing loss with tinnitus. MRI scanning with gadolinium is the investigation of choice and can demonstrate small tumours (Fig. 1.20). Current treatment options include serial scanning (for small tumours), surgical excision or stereotactic radiosurgery.

Fig. 1.20 An axial view of an acoustic neuroma seen on MRI after injection of gadolinium contrast. The tumour stands out clearly.

Dysacusis

Despite having normal hearing thresholds, some patients are still unable to hear well, particularly in noisy environments. This is termed dysacusis. The aetiology is presumed to be a cochlear abnormality.

Problems with electronic hearing aids

To gain the maximum benefit from the aid, it is important to provide patients with training. It is a shock to many to learn that an aid cannot produce normal hearing. Patients with conductive hearing losses have better results with aids than those with sensorineural losses. This is due to the fact that many of the latter losses are associated with a phenomenon called ‘recruitment’, where loud sounds are heard exceptionally loudly so that the amplification from a hearing aid merely adds to the patient’s difficulties.

The common problems encountered with electronic aids are listed in Table 1.7. Probably the most frequent difficulty is with acoustic feedback. This produces the familiar high-pitched whistle and is particularly seen in patients who require high amplification, and in whom the ear mould allows sound to escape into the microphone. A similar event will occur if the mould is incorrectly inserted, as is frequently seen in elderly people suffering from arthritic joints.

Table 1.7 Common problems with electronic hearing aids

A persistent otorrhoea may occur due to allergy to the mould. Alternative non-allergenic material can be employed. In some patients this manoeuvre is simply ineffective and, in others, continued insertion of a mould produces otitis externa or a discharge from a mastoid cavity. Such cases may benefit from a bone conducting aid worn as a headband with the microphone abutting firmly onto the mastoid. However, these are cosmetically unsightly.

More recent alternatives are bone conduction aids that are anchored in the temporal bone. The external stimulator sets the aid in vibration either across the intervening skin or by a direct percutaneous attachment facility (Fig. 1.22; Fig. 1.53, p. 24). Such aids do not suffer the feedback problems of conventional air conduction aids and also have the advantage of greatly reduced background noise.

Fig. 1.22 Osseointegrated aid. This avoids many of the problems of traditional aids.

Acute otitis externa

Acute otitis externa is common in patients with eczematous ear canal skin, and in those who produce trauma with cotton buds. Moist, humid environments predispose to ear canal infections. Symptoms may vary from itching and irritation to excruciating pain. Streptococci, staphylococci, Pseudomonas and fungi are the usual infecting agents. Pressure on the tragus or manipulation of the pinna at its root will cause discomfort. In the early stages the canal is red and tender and there may be a thin discharge. Hearing loss occurs later with oedema of the canal and accumulation of debris.

Treatment is outlined in Figure 1.25. A very convenient ear dressing is the otowick, which after insertion into the ear canal will expand if topical drops are applied. Discharge should be sent for culture. Relapse is often due to residual debris in the meatus. Prolonged use of antibiotic/steroid drops promotes secondary fungal otitis, e.g. Aspergillus (see Fig. 1.30, p. 14). Itching may be controlled by 1% hydrocortisone cream applied with a cotton bud, but only after the infection has been treated.

Fig. 1.25 Treatment of acute otitis externa. Systemic treatment involves the use of oral analgesics and antibiotics.

Furunculosis

Furunculosis is an infection of a hair follicle in the outer ear canal. Severe throbbing pain with pyrexia precedes rupture of the abscess. Examination and drainage under anaesthetic may be required.

Malignant otitis externa

Malignant otitis externa is an aggressive form of otitis externa; the term malignant is a misnomer. The pathophysiology is a spreading osteomyelitis of the temporal bone caused by the organism Pseudomonas pyocyaneus. It tends to occur in immunocompromised patients, such as elderly diabetics. Marked granulations are formed in the ear canal. The infection spreads to involve the middle ear and the lower cranial nerves.

CT and isotope scanning provide information on the extent of the osteomyelitis (Fig. 1.26). Treatment comprises local aural toilet and insertion of wicks impregnated with an antipseudomonal accompanied by high-dose antibiotics. Surgery for debridement may be necessary in patients in whom the disease progresses despite conservative treatment.

Fig. 1.26 A case of malignant otitis externa showing extensive destruction of the temporal bone. The facial nerve is frequently affected, but the other lower cranial nerves (glossopharyngeal, vagus and hypoglossal) become involved as the osteomyelitis spreads.

Myringitis bullosa

Myringitis bullosa is a localized form of otitis externa where blisters form on the eardrum and deep meatus. It presents as an excruciating earache and is presumed to be a viral infection. Treatment is symptomatic.

Perichondritis

Perichondritis can follow severe otitis externa, or be subsequent to trauma. The infected cartilage produces a swollen red and tender pinna. Oedema may spread onto the face and the pretragal lymph nodes are enlarged. Local astringents (e.g. magnesium sulphate) and systemic antibiotics are required to prevent permanent damage to the cartilage and an ugly cosmetic appendage.

Acute otitis media

Acute otitis media is a common cause of severe otalgia in children. Inflammation of the middle ear cleft usually follows an upper respiratory tract infection which ascends via the Eustachian tube. The eardrum becomes retracted as the tube is blocked, and an inflammatory middle ear exudate develops. Pressure in the middle ear produces severe pain, and the eardrum becomes congested and bulging (Fig. 1.27). At this stage the patient is quite unwell, with fever and tachycardia. Eardrum rupture may then occur, producing a bloodstained discharge with relief of the pain.

Fig. 1.27 Acute otitis media is a common cause of otalgia in children. If allowed to progress, the initial infection of the eardrum leads to bulging as the middle ear pressure increases due to pus formation, with the ultimate rupture of the drum.

Antibiotic treatment of acute otitis media is somewhat controversial as many cases are of viral origin. After 24–48 hours, if spontaneous resolution has not occurred, a broad-spectrum antibiotic to cover Haemophilus and streptococci is indicated. Before this, analgesics and nasal decongestants may be employed. The discharging ear should be swabbed, mopped and kept dry. Resolution is usual, but a middle ear effusion may persist. It is not uncommon for hearing to remain muffled for up to 1 month or more in adults. Children frequently suffer more than one attack of acute otitis media. If this is associated with persisting middle ear effusions, then myringotomy and grommet insertion, possibly with adenoidectomy, may be indicated. An alternative is to give a low dose of antibiotic, e.g. 125 mg penicillin, at night for 6 weeks. Acute otitis media accompanying childhood infections, e.g. measles, may be so severe that the eardrum fails to heal, leaving a large central perforation.

The complications of otitis media usually arise from inadequate treatment or non-compliance. Inflammation of the mastoid air cell system often occurs with acute otitis media, and is controlled with antibiotics. However, suppuration in the mastoid (acute mastoiditis) is serious and potentially life threatening (see Fig. 1.36, p. 16).

Acute otitic barotrauma

Acute otitic barotrauma may occur during descent in aircraft. It leads to severe otalgia and occasionally rupture of the eardrum with a bloody otorrhoea.

Herpes zoster oticus (Ramsay Hunt syndrome)

The facial nerve ganglion may be affected by shingles. This produces severe pain, with vesicles in the ear canal and on the concha, and is frequently accompanied by facial palsy (see Fig. 1.44, p. 19). Administration of antivirals such as famciclovir or aciclovir, if the vesicles are recognized early, may prevent permanent damage to the facial nerve.

Neoplasia of the ear

Otalgia in these patients is caused by perichondritis or nerve involvement by tumour (p. 114).

Referred otalgia in children

Tonsillitis with otalgia is frequently seen in young children. Referred otalgia is common 5–7 days after tonsillectomy. However, the ear should be examined to exclude an acute otitis media. Dental disease is also a common cause of referred otalgia in children. Diets high in sugar content have led to a prevalence of tooth decay. Teething, particularly if unerupted, may cause referred pain. Upper respiratory tract infections are also commonly associated with otalgia due to Eustachian tube dysfunction.

Referred otalgia in adults

Dental pathology is a common cause of referred otalgia. Impacted molars may result in local pain and referred otalgia.

Anatomical and functional abnormalities of the temporomandibular joint (TMJ) are a frequent cause of referred earache. Spasm of the joint muscles may also produce earache, which is aggravated by dental abnormalities, e.g. malocclusion, tilting and loss of teeth. The joint is usually tender to palpation, particularly during jaw opening. Management is directed at relieving any muscle spasm and correcting dental abnormalities.

Cervical spondylosis can cause referred otalgia in the elderly. There is general tenderness around and behind the ear. The range of neck movements, although restricted, may reproduce the earache. Treatment is physiotherapy and anti-inflammatory and analgesic medication.

It is vital not to miss neoplastic causes of referred otalgia. A cancer in the upper air and food passages may be a cause. All sites should be inspected and the neck palpated for masses.

Acute otitis externa

Acute infection of the external ear canal has already been discussed (p. 12). Although otalgia is the predominant symptom, some degree of otorrhoea is common (Fig. 1.29). It is not unusual for certain general skin conditions to cause otitis externa with otorrhoea, e.g. psoriasis, seborrhoeic dermatitis and eczema. It is useful to emphasize that early relapse after treatment with eardrops is usually due to inadequate aural toilet, or colonization of the canal by a secondary fungal growth (Fig. 1.30). Treatment of any underlying eczema in the canal, e.g. with 1% hydrocortisone cream, is important when the inflammation has settled.

Fig. 1.29 Acute otitis externa. The ear canal is occluded due to gross swelling. Manipulation of the pinna or tragus is painful, and chewing commonly produces discomfort due to the temporomandibular joint causing movement of the cartilaginous portion of the external ear canal.

Fig. 1.30 Fungal otitis externa is usually caused by candidial or aspergillus species. This illustration shows the tiny black spores seen in infection with Aspergillus niger.

Chronic otitis externa

Chronic otitis externa is usually bilateral and painless, and tends to relapse. The skin of the canal is permanently thickened and easily traumatized. All canal debris should be removed and the skin kept dry. Antibiotic drops are not advised unless there is acute inflammation. Indeed, they may precipitate an allergic reaction or predispose to fungal infection.

Furunculosis

Furunculosis (p. 12), a severe form of acute otitis externa, produces persistent throbbing pain and a seropurulent otorrhoea if the abscess ruptures. The patient may require an anaesthetic for examination and drainage. Treatment is then continued as for acute otitis externa.

Chronic suppurative otitis media (tubotympanic disease)

Rupture of the tympanic membrane in acute otitis media produces a bloodstained, mucopurulent otorrhoea. The eardrum usually heals quickly, but if the inflammation persists and the eardrum skin fails to heal over the margins of the rupture, a persistent perforation will result. Persistent or recurrent mucoid discharge may then occur, especially if water enters the middle ear or in episodes of upper respiratory tract infections. Perforations as a result of recurrent acute otitis media usually occur in the pars tensa and do not involve the annulus. They are rarely associated with serious disease and are referred to as ‘safe’ perforations (Figs 1.31 and 1.32).

Fig. 1.31 Chronic suppurative otitis media (tubotympanic disease). This is associated with a central perforation of the pars tensa. The otorrhoea is usually profuse and mucoid in the active infection, and exacerbated by any dysfunction of the Eustachian tube, e.g. acute rhinitis.

Fig. 1.32 A central perforation involving the pars tensa associated with chronic suppurative otitis media. This shows an infected perforation with mucoid discharge in the external ear canal.

The initial treatment of a discharging perforation is aural toilet combined with topical steroid eardrops. This will dry up most discharging ears so that an accurate assessment can be made of the drum head and middle ear mucosa. If the perforation persists, the patient has chronic suppurative otitis media (tubotympanic type), which may be inactive or active (if discharging). Use of antibiotic eardrops is no longer recommended routinely as many contain ototoxic aminoglycosides. Some eye drops, such as those containing ofloxacin or ciprofloxacin, are not ototoxic and are effective; however, they are not currently licensed in the UK for aural use.

For those patients who have little trouble, a hearing aid to overcome hearing difficulties may be all that is required. Surgery is recommended for recurring discharge, for patients who are regular swimmers, and to produce a hearing improvement. The material for a graft is usually the patient’s own temporalis fascia, which is easily accessible (Fig. 1.33).

Fig. 1.33 (a) A simple perforation of the eardrum with an intact mobile ossicular chain. (b) An underlay graft to repair the perforation.

Chronic suppurative otitis media (atticoantral disease)

Long-standing Eustachian tube dysfunction may produce retractions and perforations of the tympanic membrane in the attic region, or may involve the annulus (Figs 1.34 and 1.35). These are associated with cholesteatoma (keratinizing epithelium in the middle ear). This is a destructive disease and can be life-threatening owing to the potential complications.

Fig. 1.34 Chronic suppurative otitis media (atticoantral disease). This is associated with a marginal perforation, often in the attic region (pars flaccida). The otorrhoea is usually scanty and foul smelling.

Fig. 1.35 Chronic suppurative otitis media of the atticoantral variety, seen in the attic. Discharge and white keratin debris are seen in the attic perforation.

Aural discharge may be scanty, but is offensive because of underlying osteitis. Bone destruction may occur towards the middle or posterior cranial fossae, often unrecognized until an intracranial complication occurs. The hearing loss with atticoantral disease is usually marked.

Because of the dangerous nature of this disease, surgery is invariably recommended. Excision of disease with preservation of hearing involves surgery on the mastoid and middle ear (mastoidectomy; p. 16). Usually the mastoid is exteriorized by removing the posterior ear canal wall to produce a cavity that can be inspected from the ear canal and cleaned as required. The drum defect may be grafted to minimize postoperative mucous discharge and optimize the hearing.

Discharging mastoid cavities

Many patients have either persistent or recurrent otorrhoea from surgically created mastoid cavities. There are many causes for this and most are amenable to treatment (Table 1.9). Uncontrolled infection of the middle ear or mastoid cavities may over many years predispose to carcinoma. This rare complication is heralded by a change in character of the otorrhoea from mucopurulent to bloody. It is invariably accompanied by the development of progressive otalgia and a facial paralysis.

Table 1.9 Causes and treatment of persistently discharging mastoid cavities

Fracture of the temporal bone

A severe blow to the temporal or parietal region may result in a fracture of the temporal bone (p. 42). A conductive hearing loss is due to a combination of blood in the middle ear, ossicular disruption and tympanic membrane perforation. Sensorineural hearing loss will result if the fracture passes through the cochlea. Cerebrospinal fluid otorrhoea may occur but usually settles spontaneously. The patient should be prescribed systemic antibiotics.

Acute mastoiditis

Mastoiditis is preceded by acute otitis media and is usually seen in young children. Inflammation of the mastoid lining produces severe pain, usually localized over the mastoid process. Perforation of the eardrum from otitis media may relieve the initial discomfort, but a gradual increase in pain with tachycardia and pyrexia suggests extension into the mastoid (Fig. 1.36). Early physical signs include a sagging or oedematous posterior ear canal wall, with oedema over the mastoid and zygomatic areas. Eventually the pinna is pushed down and out by a subperiosteal abscess (Fig. 1.37), and the drum head bulges or discharges pus.

Fig. 1.36 Extracranial complications of middle ear infection.

Fig. 1.37 A child with acute otitis media which has progressed to acute mastoiditis, with development of a subperiosteal abscess. Notice the absence of the postauricular sulcus and how the pinna is pushed down and outward.

Inadequate medical treatment may allow development of mastoiditis from acute otitis media, but some cases progress so rapidly as to present with mastoiditis.

In the early stages, administration of intravenous antibiotics may produce resolution of the inflammation. Prolonged treatment is necessary to ensure that resolution is complete and the hearing returns to normal. If there is any doubt about improvement, or if a subperiosteal abscess has developed, a cortical mastoidectomy is performed (Fig. 1.38).

Fig. 1.38 Surgical approach to the mastoid air system. This can be made through a postauricular incision. In children, the incision is not extended inferiorly due to the risk of damaging the facial nerve, as the mastoid tip which protects it is underdeveloped.

Facial paralysis

If there is a dehiscence in the bony covering of the facial nerve in the middle ear, an acute inflammation may cause a temporary paralysis which recovers as the infection subsides. Exploration of the ear and mastoid is indicated if there is pre-existing chronic ear disease involving the nerve.

Labyrinthitis

Labyrinthitis may occur from acute or chronic ear disease. Signs of labyrinthine inflammation include giddiness and loss of balance with nausea and vomiting. Hearing loss is sensorineural. The patient lies still in bed with the affected ear uppermost (this reduces the sensation of giddiness). High-dose parenteral antibiotics are given to arrest the infection and prevent meningitis. Surgery may be required in cases with pus formation.

Meningitis

Meningitis may occur from infection via the labyrinth, the lateral sinus or through direct extension from the middle ear. Pneumococcal meningitis commonly occurs from the ear. Initially the patient is pyrexial with a headache; later, confusion, irritability and neck stiffness occur. Diagnosis is by lumbar puncture, but a CT scan may be indicated to exclude an intracranial abscess. Intravenous antibiotics should initially control the infection before any surgery is contemplated. Recurrent bacterial meningitis requires an ear, nose and throat (ENT) assessment of the ear and paranasal sinuses for foci of infection, or for evidence of a cerebrospinal fluid leak.

Intracranial abscess

The development of an intracranial abscess (Fig. 1.39) carries a significant mortality. An extradural abscess in the middle or posterior cranial fossa can occur by direct extension of middle ear infection. Erosion of the dural plate produces a dural reaction with granulation and abscess formation.

Fig. 1.39 Intracranial complications of middle ear infection.

Temporal lobe abscess

A temporal lobe abscess may complicate acute or chronic middle ear disease (Fig. 1.40). The patient has a history of hearing loss and/or otorrhoea, and develops signs of cerebritis (headache, rigors, fever and vomiting). There may follow a latent period of up to several weeks, during which time the ear disease may appear to be controlled. The patient may then present with signs of raised intracranial pressure or focal signs of an abscess, e.g. a fit, paralysis or visual field changes. Patients with these signs require a CT or MRI scan. In all cases of cerebritis, high-dose parenteral antibiotics are required. Drainage of an established abscess is usually via a burr hole, and repeated aspiration of the cavity may be necessary.

Fig. 1.40 Temporal lobe abscess. This can result from extension of middle ear disease superiorly through the roof of the middle ear cavity (tegmen tympani).

Cerebellar abscess

A cerebellar abscess is uncommon, but can present with or after treatment for mastoiditis. Homolateral cerebellar signs of nystagmus, past pointing and ataxia, together with headache, demand an urgent CT scan (Fig. 1.41) and surgical drainage.

Fig. 1.41 Cerebellar abscess seen on CT scan. Such an abscess may result from infective haematological spread.

Thrombosis of the lateral venous sinus

Thrombosis of the lateral venous sinus occurs from extension of suppuration within the mastoid. Clot builds up within the vessel until the lumen is occluded. The patient may develop rigors and a high fever, but these signs can be masked by previous antibiotics. The diagnosis is often made at mastoidectomy.

Bell’s palsy (idiopathic facial paralysis)

Bell’s palsy is the most common cause of facial paralysis and is a diagnosis of exclusion. The presumed aetiology is inflammation of the facial nerve which leads to compression within the bony canal, causing a conduction block. Current thinking is that many of these cases may be due to herpes simplex type 1. Discomfort or pain around the mastoid may precede the palsy. Loss of hearing, taste and occasionally hyperacusis can also be present. When the palsy remains incomplete, almost all patients have a satisfactory recovery, usually commencing within 3 weeks of onset. Recovery rates are less good when the palsy is complete: about 85% of patients have an excellent outcome, 10% a partial recovery and 5% a poor outcome. Recent research has demonstrated the value of high-dose oral steroids to improve outcomes. Antivirals are commonly administered but hard evidence of their benefit is lacking.

Trauma

Trauma may cause damage to the facial nerve within the temporal bone or peripherally in the facial soft tissues. Lacerations anterior or inferior to the tragus may divide branches lying in the parotid gland.

Middle ear disease

Trauma

Stapedectomy operations for otosclerosis where the inner ear is opened may result in vertigo. Vertigo can develop at any stage after stapedectomy and usually results from a perilymph leak around the piston. Temporal bone fractures may involve the labyrinth, causing severe vertigo and nystagmus, and can be accompanied by facial nerve paralysis.

Benign paroxysmal positional vertigo

This is an episodic vertigo, usually dramatically described as occurring on turning the head. It can follow an upper respiratory tract infection or head injury. The vertigo lasts for several seconds and fatigues with repetitive stimulation such as repeated positional testing (p. 5). Most cases settle spontaneously or with specific physiotherapy manoeuvres. Vestibular sedatives have no therapeutic advantage.

Ménière’s disease (endolymphatic hydrops)

Ménière’s disease typically affects young to middle-aged adults. The cardinal features are shown in Table 1.14. Attacks tend to occur in clusters. Distortion of hearing is very characteristic. Acute attacks are very distressing and can lead to chronic unsteadiness.

Table 1.14 Cardinal features of Ménière’s disease

In the early stages, medical management usually suffices. Reassurance and a reduction in smoking, caffeine and salt intake are felt to be useful. Betahistine (a vasodilator) and diuretics are often prescribed to reduce the endolymphatic fluid imbalance in the inner ear. Surgical options include decompressing the inner ear (draining the endolymphatic sac), disconnecting the labyrinth (vestibular neurectomy) or labyrinthectomy (destruction of the labyrinth).

Labyrinthitis/acute balance disorder

When an infection is localized to the vestibular labyrinth, the patient experiences rapid onset of vertigo with the presence of nystagmus. Hearing loss is a feature if the cochlea is involved. The patient may be very unwell for the first 24 hours, but improves as central compensation occurs. True vertigo persisting longer than 36 hours suggests central involvement. Rehabilitation after labyrinthitis can be improved by graduated vestibular exercises. Older people take longer to compensate. Failure of both labyrinths produces a bobbing oscillopsia where the normal control of the eyes is lost. The world shakes up and down as the patient walks.

Other otological causes

Otosclerosis, syphilis and ototoxic drugs (aminoglycosides) can all produce imbalance due to involvement of the labyrinth. Acoustic neuromas may result in a sense of imbalance.

Congenital abnormalities

The auricle develops from six separate hillocks on the side of the embryo’s head. Minor congenital abnormalities are not uncommon, and most do not require treatment (Fig. 1.51). Major abnormalities include a complete absence of the pinna (anotia) or severe deformities (Fig. 1.52). Severe malformations of the pinna and ear canal are not always associated with abnormalities of the middle or inner ear, as these two elements have separate embryological origins. Indeed, many children may have a conductive hearing loss but normal inner ear function.

Fig. 1.51 Accessory auricles. These are located along a line from the tragus to the angle of the mouth. They contain cartilage remnants.

Fig. 1.52 Microtia of the pinna showing a small severely deformed appendage.

The results of surgical correction of these auricular defects have been generally unsatisfactory. The recent development of titanium implants, however, allows excellent cosmetic prostheses to be anchored to the mastoid (Fig. 1.53). As well as providing an anchor, the titanium parts can act as the transmitter for a bone conduction hearing aid (p. 11).

Fig. 1.53 (a) Bone-anchored auricular prosthesis and hearing aid in patient with Treacher Collins syndrome. This is a hereditary condition causing hearing loss, usually due to abnormalities of the external ear including atresia of the ear canal and auricular defects. (b) The metal supports for an auricular prosthesis are clearly shown anchored into the skull. Note the excellent cosmetic appearance of the prosthetic auricle.

Bat ears

Bat ears are the most common abnormalities of the auricle and are usually bilateral (Fig. 1.54). Prominent ears may be moulded at birth (within 24 hours), as the cartilage has not formed its ‘memory’ for shape. Surgical correction, however, is best left until about 6–7 years and is mainly designed to recreate an antihelical fold.

Fig. 1.54 Prominent or ‘bat’ ears.

Preauricular sinus

The preauricular sinus is an embryological remnant which appears as a small pit anterior to the helical root. No intervention is required unless the sinus becomes infected (Fig. 1.55). Treatment involves complete excision of the sinus tract to avoid recurrence.

Fig. 1.55 An infected preauricular sinus. The small opening is clearly visible at the root of the helix.

Collaural fistula

A collaural fistula is a rare developmental abnormality in which a tract runs between a pit in the ear canal and the neck skin. It invariably needs excision because of recurrent infection. This may require an extensive dissection of the facial nerve as the tract may pass between nerve branches.

Infections and other conditions

Otitis externa may spread to involve the skin and cartilage of the pinna. Treatment with astringents and systemic antibiotics is needed. Streptococcal infection (erysipelas) is recognized easily by a sharply demarcated ‘serpiginous’ edge which rapidly spreads. The patient is often toxic, but the response to penicillin is rapid.

Dermatitis from nickel jewellery or eardrops is usually localized to the lobule or concha, respectively. Resolution is rapid if the sensitizing agent is removed. Eczematous and psoriatic eruptions of the auricular skin are not uncommon and will require application of topical creams and ointments (Fig. 1.56).

Fig. 1.56 Psoriatic eruption affecting both the pinna and the external ear canal.

Perichondritis is an inflammation of the auricular perichondrium and produces a diffusely swollen, shiny and painful ear. Trauma, otitis externa or surgery may be the cause. Aggressive treatment with broad-spectrum antibiotics, astringents and analgesics is needed to prevent suppuration and cartilage necrosis. This may prevent an ugly, long-term cosmetic defect (cauliflower ear).

Other conditions affecting the auricle include:

Removal of wax

Meatal occlusion, impaction, irritation, hearing loss or otitis externa and clinical inspection of the eardrum are all indications for removing wax. The simplest method is to syringe the ear. Tap water at body temperature is used. The pinna is lifted to straighten the ear canal and the water jet aimed at the roof of the canal, never directly at the eardrum. The canal and drum head must be examined afterwards. Patients who have perforations should not have their ears syringed (Table 1.17). Curetting wax from the canal requires a good light and a cerumen scoop or hoop. In difficult or refractory cases a microscope and sucker may be used in outpatients, or under general anaesthesia. Hard impacted wax may need to be softened with topical ceruminolytic ear drops before removal (p. 28).

Table 1.17 Complications of wax removal

Keratotis obturans

Keratin may desquamate abnormally in the deep meatus to produce a hard ball of debris which is difficult to remove. If left, the ear canal becomes expanded and granulation tissue forms at the margin of the plug. This is a form of cholesteatoma involving the ear canal. Removal is often only possible under a general anaesthetic. Frequent review is necessary to prevent recurrence.

‘Attic’ wax (attic crust)

Chronic suppurative otitis media (atticoantral) with cholesteatoma in the attic can appear on inspection to resemble wax above the malleus handle. This is referred to as ‘attic’ wax (Fig. 1.58). Removal is usually painful and may induce vertigo. The true nature of the problem is revealed once the cholesteatoma is visualized deep to the wax crust.

Fig. 1.58 Otoscopic appearance of wax debris in the posterior attic (attic crust) which was concealing a cholesteatoma.

Auricular haematoma

Blunt trauma to the ear may produce a haematoma. Bleeding occurs deep to the perichondrium, which is stripped from the underlying cartilage so that the ear becomes swollen and the normal architecture of the folds is lost (Fig. 1.59). As the cartilage depends on the perichondrium for survival, necrosis and subsequent scar formation will produce the typical ‘cauliflower ear’.

Fig. 1.59 An auricular haematoma caused by a rugby football injury.

Treatment requires aspiration of the haematoma with a large bore needle under sterile conditions. A firm pressure dressing is applied for 24 hours and the ear re-examined. Reaspiration may be necessary for some days. Unfortunately, haematomas often clot and cannot be aspirated. In such cases the blood is curetted out after raising a skin flap. Pressure is then applied for several days and antibiotics are administered to prevent infection. Aggressive treatment will avoid the late, ugly cosmetic defect.

Lacerations

As the pinna has an excellent blood supply, it is always worth suturing severe lacerations and any avulsed tissue. Exposed cartilage should be trimmed back before closing the skin. Human bites to the pinna tend to become infected. Perichondritis may be prevented by dressing the wound and delaying primary closure for 2–3 days.

The ear lobe may be split by avulsion of an earring in a pierced ear. If sutured directly, these injuries produce an unsightly notched lobe. They should be repaired by a stepped incision with a suture loop to reconstruct the hole.

Keloid scars

Keloid scars are common on the ear lobes, particularly in black-skinned people. They can grow to considerable sizes. The aetiology is an exaggerated healing response producing excess collagen outside the original boundaries of the scar. Treatment is difficult. Simple excision usually produces a recurrence. Compression with a silicone gel clip and steroid injections show some success. Large refractory scars may need excision and local radiotherapy.

Blast injuries

Blast injuries may be produced by either explosions or a simple slap on the ear. There may be multiple sites of damage, depending on the intensity of the pressure wave. The typical injury produces a tympanic membrane rupture. The cochlea may be damaged, resulting in a sensorineural hearing loss and tinnitus, both of which may be permanent. Imbalance occurs if the vestibular apparatus is affected.

Otitic barotrauma

Otitic barotrauma can produce otalgia with some extravasation of blood into the middle ear so that a haemotympanum occurs (Fig. 1.60). In severe cases the eardrum may rupture. The aetiology is an inability to ventilate the middle ear due to abnormal function of the Eustachian tube. The condition is particularly seen when the ambient pressure is rising, e.g. descent in flight or scuba diving. Treatment comprises a repeated Valsalva manoeuvre to open up the Eustachian tube, in addition to topical nasal decongestants. Myringotomy may be needed in some cases. Patients who fly and suffer regularly are instructed to use prophylactic measures to prevent Eustachian tube problems (e.g. topical nasal decongestants and repeated swallows). Occasionally insertion of a ventilation tube overcomes the problem.

Fig. 1.60 Blood in the middle ear (haemotympanum). Causes include otitic barotrauma, secretory otitis media and high jugular bulb.

Head injuries

Head injuries may be associated with temporal bone fractures (p. 42). These cause hearing loss, which may be sensorineural if the fracture line passes through the cochlea. In such cases vertigo and facial paralysis may also be present. However, otological trauma can occur in head injuries without the presence of a fracture. The cochlea can be concussed and produce a hearing loss. Labyrinthine damage may lead to benign paroxysmal positional vertigo or a vague feeling of imbalance. Lesions of the central vestibular apparatus can lead to long-term symptoms if compensation is not complete.

Surgical trauma

Surgical trauma may produce a conductive or sensorineural hearing loss. This is a risk in all ear operations, but particularly in stapedectomy where the inner ear is deliberately entered, or in mastoid surgery where a cholesteatoma may have disrupted the ossicular chain and invaded the cochlea. The facial nerve is also at risk during middle ear procedures.