Conditions of the middle ear (Tab 40.2)

Congenital anomalies

Congenital anomalies of the middle ear may be isolated or may be associated with other ear or general congenital deformities. There is a number of branchial arch syndromes — for example Pierre Robin’s syndrome, craniofacial dysostosis, Down’s syndrome and Treacher Collins’ syndrome. If there is an external ear abnormality, it should raise suspicion of an underlying middle ear deformity. Middle ear deformity can be assessed by high-resolution computerised tomography (CT) scanning and, if the inner ear is normal, reconstructive surgery of the middle ear can be very successful.

Trauma

Trauma to the middle ear can result in a perforated tympanic membrane (Fig. 40.9a). Such perforations usually heal spontaneously (Fig. 40.9b). Trauma can result is ossicular discontinuity and typically it is the incus that is displaced. Various operations termed ‘tympanoplasties’ are available to reconstruct the damaged ossicular chain and repair the tympanic membrane if necessary.

Inflammatory disorders

The most common inflammatory condition of the middle ear is acute suppurative otitis media. It is extremely common in childhood and is characterised by purulent fluid in the middle ear. Mastoiditis may be associated with otitis media because the mastoid air cells connect freely with the middle ear space. The tympanic membrane is hyperemic and bulges owing to pressure from the pus in the middle ear (Fig. 40.10). The child suffers extreme pain until the tympanic membrane bursts. The most common infecting organisms are Streptococcus pneumoniae and Haemophilus influenzae. Appropriate systemic antibiotics should be given for 10 days.

The incidence of acute mastoiditis has diminished with the widespread use of antibiotics for otitis media. Sometimes, however, a child will have had a number of courses of anti­biotics, none of which completely resolves the middle ear infection. In such cases the pain and swelling behind the ear may not be quite so apparent as in Fig. 40.11. When mastoiditis is present, if the tympanic membrane can be seen, there is always a sag in the posterior superior part of the drum. (Conversely, a normal tympanic membrane excludes mastoiditis.) Treatment requires hospital admission and intensive parenteral antibiotics. If this does not resolve the infection quickly a cortical mastoidectomy is required, together with a myringotomy.

Mastoiditis

  Sequelae of acute otitis media

  May be masked by antibiotics

Requires intensive antibiotics and/or drainage

Otitis media with effusion (glue ear) is very common with the majority of children experiencing at least one episode of it during development. Many factors have been implicated, although it is primarily thought to be due to poor eustachian tube function. Oxygen is continually being absorbed by the middle ear mucosa and this results in a negative middle ear pressure unless the eustachian tube opens to replenish the air. This negative middle ear pressure initially results in transudation of fluid into the middle ear space (Fig. 40.12). If the hypoxia continues, a mucoid exudate is produced by the glands within the middle ear mucosa. This sticky exudate is referred to as ‘glue ear’.

The following symptoms may be associated with glue ear:

hearing impairment which often fluctuates;

delayed speech;

behavioral problems;

recurrent ear infections — this occurs because the exudate is an ideal culture medium for microorganisms;

reading and learning difficulties at school.

   If these symptoms are present for a short time only, it is likely that no long-term sequelae will develop. However, if symptoms persist, particularly a long-term bilateral conduc­tive hearing loss, the child will miss out on educational opportunities and may not fulfil his or her academic poten­tial. The otoscopic findings of exudative glue ear are of a dull drum that is immobile on pneumatic otoscopy (Fig. 40.13).

The tympanic membrane is retracted and radial blood vessels may be present (Fig. 40.14). Of children first presenting with bilateral glue ear, 50 per cent of the effusions will resolve spontaneously within 6 weeks of onset. Initially, a ‘wait and watch’ policy is therefore appropriate. If the bilateral glue ear persists with a significant hearing loss then treatment is required.

There is no substantial evidence for medical treatment. Use of the Otovent device (Fig. 40.15) may improve eustachian tube function and is worth trying while waiting for resolution of the effusion. However, surgical intervention is the only effective way of curing glue ear. Both ventilation tube (groin-mets) and adenoidectomy are effective. The controversy is not whether surgery works but when to intervene. insertion of ventilation tubes and/or an adenoidectomy require a general anaesthetic. The ventilation tube is placed in the anterior inferior portion of the tympanic membrane because there is no important clockwork behind this part of the drum. The ventilation tubes stay in position for approximately 6—18 months and are then extruded because of the migratory behaviour of the tympanic membrane. There is no reason why children with ventilation tubes should not be allowed to swim (Fig. 40.16).

Otitis media with effusion (glue ear)

Very common, peaks at 18 months and 5 years

  Majority of children need no treatment

Prolonged hearing loss treated with ventilation tubes and/or adenoidectomy

A middle effusion in adults is relatively rare and when it occurs does not usually last long. The condition is often associated with an upper respiratory tract infection. A per­sistent unilateral effusion in an adult should always be viewed with suspicion. A nasopharangeal carcinoma may cause the effusion by blocking the opening of the eustachian tube in the postnasal space. This is the most common carcinoma in males in southern China.

Chronic suppurative otitis media

Chronic suppurative otitis media (CSOM) is classified into two types: tubotympanic disease, in which there is a perforation of the pars tensa; and atticoantral disease, in which a retraction pocket develops from the pars flaccida.

CSOM of the tubotympanic type. CSOM of the tubo­tympanic type can result from trauma or infection. When perforated the tympanic membrane usually repairs itself, but occasionally the outer layer of the tympanic membrane fuses with inner mucosa and a chronic perforation results (Fig. 40.17). With this type of disease the patient’s main symptoms are of an intermittent or chronic mucoid discharge associated with a mild conductive hearing loss. It is rare for this type of disease to be associated with intracranial complications.

A diagnosis is made on otoscopy and the tuning forks usually suggest a conductive hearing impairment. The first-line treatment is topical antibiotic and steroid drops, and on occasion microsuction. If medical treatment fails, the patient may request an operation to graft the tympanic membrane in order to give a dry ear. This operation is termed a myringoplasty (type I tympanoplasty). The edges of the perforation are freshened and a small piece of temporalis fascia is inserted under the tympanic membrane to graft the drum. The raw epithelial edges then grow across the graft to repair the tympanic membrane.

CSOM of the atticotympanic type. CSOM of the attico­antral type is important because of the complications associated with it. Cholesteatoma is the alternative name and means a cyst or sac of squamous epithelium that is present in the attic part of the middle ear. The exact aetiology of cholesteatoma is not known, although poor eustachian tube function is implicated (e.g. patients with cleft palates have relatively poor eustachian tube function and have a higher incidence of cholesteatoma).

A retraction pocket develops in the pars flaccida and, if the squamous epithelium cannot migrate out of this pocket, a cholesteatoma results. The expanding ball of skin causes a low-grade osteomyelitis which results in the release of fatty acids from the bone. This gives the discharge its characteristic faecal smell. Invariably the discharge is accompanied by hearing loss and mild discomfort. The patient may simply put up with the symptoms until a severe complication occurs.

The hearing loss that is caused by cholesteatoma may be conductive due to erosion of the incus or sensori neural due to direct erosion of the cochlea or migrations of toxins into the inner ear. Vestibular symptoms may occur because of erosion of the semicircular canals or the migration of toxins into the vestibule. Pressure or erosion of the facial nerve is relatively unusual.

The close proximity of the middle ear and mastoid to the middle and posterior cranial fossae means that intracranial

sepsis can result from chronic ear disease. The infection spreads to the dura via emissary veins which connect the middle ear mucosa to the dura or by direct extension of the disease through the bone. Meningitis, extradural, subdural or intracerebral abscess, or a combination of these may occur. The main causes of intracranial sepsis in the UK are chronic ear disease and chronic sinus disease.

Diagnosis should be suspected on otoscopy (Fig. 40.18). Pus, crusts, granulations or a whitish debris in the attic are hallmarks of the disease. Examination under the microscope, audiometry and, sometimes, CT scanning are indicated.

The treatment is surgical and follows the principle of exposing the disease, excising the disease and then exteriorising the affected area. Two commonly applied operations for this disease are an atticotomy and a modified radical mastoidectomy.

An atticotomy or modified radical mastoidectomy is performed by making an incision behind the ear (post auricular), or between the tragus and the pinna (end aural). The attic part of the bony ear can is drilled away and the retraction pocket is followed back into the mastoid until the end of the disease is found. An attempt is made to excise totally the pocket and then the resulting cavity is usually lined with temporalis fascia. A mastoid cavity heals with normal skin that does not migrate, and for this reason patients with a mastoid cavity need to be seen in an out-patients’ clinic on a regular basis. Any skin that collects in the mastoid cavity needs to be removed with the aid of a sucker and a microscope (Fig. 40.19).

Chronic suppurative otitis media (CSOM)

In tubotympanic CSOM there is a perforated tympanic membrane and frequently a mucoid discharge

Atticoantral CSOM:    

  Is skin in an attic retraction? = cholesteatoma Presents with hearing loss and smelly discharge

  Is a common cause of intracranial sepsis

Tuberculous otitis media is an important cause of suppuration in some countries. The diagnosis should always be considered in any ear which fails to respond to standard therapy. A swab for appropriate culture studies, coupled with chest radiography, will usually confirm the diagnosis.

Otosclerosis is a condition in which new abnormal spongy bone is laid down in the dense otic capsule. Of particular importance is the bone that is laid down around the footplate of the stapes which impedes the mobility of the stapes and results in a conductive hearing loss (Fig. 40.20). Toxins released from the new bone formation may also cause a gradual sensorineural hearing loss. Otosclerosis is more common in women, and in 50 per cent of patients there is a family history. The typical presentation is of a conductive hearing loss in a young woman with the condition being exacerbated by the hormonal flux of pregnancy. A similar type of stapes fixation occurs in osteogenesis imperfecta and is known as Van der Hoeve’s syndrome. Otosclerosis is often bilateral. A diagnosis should be suspected in any patient with a conductive hearing loss and a normal tympanic membrane.

The treatment options are simple reassurance, a hearing aid or a stapedotomy operation. In the stapedotomy operation, the stapes crura are removed and a small hole is drilled in the fixed stapes footplate. A vein graft is then inserted over the hole and a piston linking the incus to the vein graft is delicately placed in position (Fig. 40.21). In 90 per cent of cases the operation is highly successful, but rare complica­tions include severe sensorineural hearing loss and balance disturbance.

Otosclerosis

New bone formation in otic capsule

Stapes fixation

Options:

   Reassurance;

   Hearing aid;

   Stapedotomy

Neoplasms

Neoplasms of the middle ear are rare, the most common being a glomus tumour (Fig. 40.22). Glomus tumours arise from nonchromaffin paraganglionic tissue. The carotid body tumour arising in the neck is an example of this type of tumour. In the temporal bone three types of glomus tumour are recognised and classification depends on the location:

glomus tympanicum (arising in the middle ear), glomus jugularae (arising next to the jugular bulb) and glomus vagali (skull base).

Pulsatile tinnitus is a classic symptom of these tumours. Hearing loss occurs and may be either conductive or sensorineural, and paralysis of the VIIth, IXth, Xth, XIth and/or XIIth nerves may occur. The classic sign is a cherry-red mass lying behind the tympanic membrane. An audible bruit may be heard with a stethoscope over the temporal bone. The treatment of choice is preoperative einbolisation followed by surgical excision. Radiotherapy is also effective.

Squamous cell carcinoma may also occur within the middle ear. It usually presents with deep seated pain and a blood­stained discharge. The facial nerve may be paralysed. Squamous carcinomas usually arise in a chronically discharging ear and can certainly arise in a chronically infected mastoid cavity. Radical surgical excision with or without radiotherapy provides the only chance of cure.