Inner Ear Condition (Meniere's Disease)

What is Meniere's Disease?

In 1861, Prosper Meniere identified the inner ear as the source of the triad of symptoms that now bears his name. Although much research has been done to elucidate the aetiology of this condition, it has resulted in little new understanding and generated much controversy. Many theories have been postulated, including viral, autoimmune and allergy. The histopathophysiology of this condition shows a swelling of the endolymphatic compartment within the inner ear and is termed endolymphatic hydrops. The pathogenesis is unknown and could be either overproduction or reduced absorption of endolymph.

Clinical Symptoms

The classic triad of Meniere's Disease is vertiginous (spinning) dizziness, tinnitus and deafness. The majority of patients suffer unilateral disease although some studies report that in up to 35% of patients the second ear becomes involved.
Vertigo--the patient experiences sudden onset of spinning lasting from 20 minutes to 24 hours. This is incapacitating and is associated with nausea and vomiting. The patient prefers to lie down with eyes closed, keeping the head still. Some patients experience a prodrome of ear fullness or tinnitus before the spell starts. Most patients are perfectly well between attacks
Hearing loss--in the early stages, the hearing loss is mainly in the low frequencies and fluctuates (returning to normal between attacks of dizziness). As the disease progresses, all thresholds become involved and the deafness can become severe to profound in the late stages.
Tinnitus--a symptom accompanying the hearing loss which varies in intensity but tends to increase as the hearing deteriorates.
Tumarkin Crisis--a very rare condition where the patient falls spontaneously to the ground without vertigo, hearing loss, tinnitus, nausea and vomiting. Some have described it as a push to the ground. Unless there is injury, the patient is able to resume the previous activity. This crisis is thought to be a sudden, undefined change in the otolithic organs. If patients suffer from this condition, they should not be allowed to drive.
The clinical course of Meniere's disease is unpredictable, with periods of activity separated by periods of quiescence. During the active times there may be frequent attacks which can suddenly settle. The vertiginous spells tend eventually to become less frequent and intense as the condition 'burns' itself out over 10 to 20 years. In the late stages, the hearing loss and tinnitus can be severe.

Investigations

An audiogram will reveal the nature of any hearing loss. In the early stages, a mild low-tone sensorineural deafness may be seen which may fluctuate with thresholds returning to normal when the patient is asymptomatic.
Electronystagmography (ENG) is sometimes performed to confirm the level of function of the diseased ear. In about 50% of patients, a caloric weakness is found confirming a hypofunctioning labyrinth in the suspected ear.

Imaging

All patients with Meniere's disease should have an MRI done to exclude on acoustic nerve tumour.

Management

Acute attacks

The acute attack is best managed by giving the patient bed rest. The only medication that is required at this time is a labyrinthine sedative drug. Many of these patients will vomit and therefore the drug is usually more effective if given intramuscularly or rectally. Stemetil (prochlorperazine) is probably the most useful drug as it has the additional benefit of being an anxiolytic agent.

Prevention of attacks

The long-term management of Meniere's disease is fraught with controversy. Many claims have been made for various regimes but none has been shown to influence the course of the condition in a long-term controlled trial. Vasodilators (betahistine 8 mg tds), oxygen-carrying molecules (Duxaril 1 tab bd), diuretics (hydrochlorthiazide 50 mg OM), sedatives (valium 2 mg tds) are some examples in the literature.
Patients should also be advised to reduce salt and caffeine intake. Stress management should be advocated if possible.

Surgical Treatment

Surgery is indicated only very rarely in Meniere's disease and also tends to be surrounded by controversy. The only indication is to control the attacks of dizziness when they have become incapacitating. All surgical procedures carry some risk to the hearing but they are subdivided into those aimed at perserving hearing and those where the hearing is deliberately sacrificed.

Inner Ear Conditions (Sudden Onset Sensorineural Hearing Loss)

What is Sudden Onset Sensorineural Hearing Loss?

Sudden onset sensorineural hearing loss (SSNHL) is defined as loss of hearing of more than 30 dB over three contiguous frequencies within three days. The pathogenesis is thought to be viral in origin. The incidence is reported to be about 20 per 100000 population, more common with increasing age. The natural history of the condition is for 65 to 70% of patients to recover a significant degree of their hearing. SSNHL is thought to be the result of a viral infection (of cochlea or VII nerve), vascular problems (ischaemia or occlusion) or inner ear membrane rupture. This condition should be considered an emergency and the patient should be referred immediately.

Symptoms and Signs

Typically, patients present with a unilateral hearing loss over 24 to 48 hours. Commonly, there is no preceding or predisposing factor. A proportion will give a history of an upper respiratory tract infection. The degree of hearing loss can range from mild to profound. About 70 to 75% will complain of associated tinnitus and 50% will have concomitant vertigo.
The ear examination is likely to be normal. Tuning fork test will reveal sensorineural hearing loss in the affected ear. The Weber test will show lateralisation to the normal ear. The Rinne test can reveal bone conduction (due to cross-over hearing from the other ear) that is better than air conduction.

Investigations

An audiogram should be performed to confirm the diagnosis and determine the severity and shape of the deafness. Many authors have suggested that the following blood tests be performed in idiopathic SSNHL:
FTA-Abs, ANA, Rheumatoid factor, Autoimmune screen, ESR, Coagulation profile, Full Blood Count (FBC), TSH, Fasting Glucose, Cholesterol and Triglycerides.
However, it is uncommon for any of these tests to reveal the cause of hearing loss.
An MRI to exclude acoustic neuroma can be performed if no recovery of hearing thresholds is seen after six months.

Management

This condition should be treated as a semi-emergency. An audiogram should be performed within the first 48 hours. Many medications have been used but there are no adequate randomised controlled trials to substantiate any treatment except possibly for the use of steroids (Prednisolone 1mg/kg/day for 10 days). Preferably, steroid therapy should be instituted as soon as possible from the onset of hearing loss (patients with mild hearing loss are likely to recover without medication, those with severe hearing loss are unlikely to recover despite treatment). Significant poor prognostic factors include age (less than 15 years, more than 65 years, poorer prognosis) and the presence of vertigo. Good prognostic factors include early commencement of treatment and low-frequency hearing loss.
Surgery is indicated only when a perilymph fistula is suspected.

Middle Ear Conditions (Atticoantral disease)

What is Atticoantral Disease?

This form involves the attic (or epitympanum) of the middle ear and the antrum of the mastoid air cell system and is usually associated with a cholesteatoma. There are many theories of the pathophysiology but the most favoured one is the Theory of Negative Pressure. This purports that chronic negative pressure in the middle ear space results in retraction of the tympanic membrane. The cause of chronic negative pressure is usually some form of Eustachian tube dysfunction. The part of the tympanic membrane that first retracts is the pars flaccida, situated superiorly. Initiall, the retraction pocket is shallow and remains a self-cleaning pocket. As the pocket deepens, squames, debris and wax become trapped and a cholesteatoma forms. This is another term for atticoantral disease. Cholesteatoma is the presence of squamous epithelium in the middle/inner ear with erosive change. The pocket generally progresses posteriorly to the antrum but can also involve the Eustachian tube anteriorly and hypotympanum inferiorly. As it enlarges, it erodes surrounding structures through a combination of pressure and enzymatic erosion. This makes the condition potentially dangerous.

Symptoms and Signs

Like tubotympanic disease, the most common symptons are discharge and deafness. The discharge is foul-smelling as a result of the nature of the infecting organisms and dead skin trapped in the ear. Hearing loss is conductive in nature. Pain is not a distinct feature of this condition.

Investigation

An audiogram is performed to determine the nature of the hearing loss. As all patients are recommended surgical intervention, a CT scan of the temporal bone is ordered for two main reasons. One is to assess the anatomy of the temporal bone prior to surgery and the other is to exclude complications that may exist but are not clinically obvious prior to surgery.

Management

All patients with cholesteatoma are recommended surgery to remove the disease. This is because if the disease is allowed to progress, complications can occur. Surgery is aimed at excising the cholesteatoma and exteriorising the mastoid cavity so that it cannot recur. There are many ways of dealing with the disease that are beyond the scope of this chapter.

Complications

Most of the complications from CSOM result from atticoantral disease. They can be divided broadly into two classes-Extracranial and Intracranial complications.

(A) Extracranial

a. The most common extracranial complication is ossicular chain disruption. The most common site affected is the joint between the incus and stapes bones.

b. Labyrinthine fistula-the lateral semicircular canal makes an impression on the antrum on its medial wall. Like other proccesses, the bone over it can be eroded resulting in exposure of the lateral semicircular canal to the antrum. When this happens, a fistula is created. Patients will experience vertigo on straining and pressure on the ear canal. If allowed to progress, sensorineural hearing loss can result.

c. Cholesteatoma can erode the facial nerve canal resulting in facial palsy. Most commonly, the tympanic portion is affected.

d. Lateral Sinus Thrombosis-The lateral sinus is a venous structure that is situated posteriorly to the mastoid cavity. The bone over the sinus can be eroded and the sinus can be infected resulting in thrombus formation.

(B) Intracranial

The bone separating the middle ear and mastoid cavity from the intracranial cavity is called the tegmen. This thin plate of bone can be eroded and infected from the temporal bone can spread to the intracranial cavity resulting in extradural abscess, subdural abscess, meningitis, encephalitis and cerebral absesses. The most commonly affected areas are the temporal lobes and the cerebellum. With improving standards of medical care and better imaging techniques, these complications have become fairly uncommon.

*ALL THE INFORMATIONS REGARDING THE EAR CONDITIONS ARE PROVIDED BY DR GERARD CHEE HSIEN. copyright reserved.

Middle Ear Conditions (Chronic Suppurative Otitis Media(CSOM))

As the name suggests this condition should have symptoms lasting more than three months, be the result of infection and involve the middle ear cleft. There are two types of CSOM, namely tubotympanic and atticoantral.

What is Tubotympanic Disease?

This type involve the Eustachian tube (tubo-) and the tympanum (middle ear). The classical feature is a central perforation of the tympanic membrane. In general, perforations secondary to ASOM heal spontaneously, but when the acute infection is inadequately treated or if chronic infection sets in, then the perforation may not heal, resulting in a chronic perforation, and hence the name. The bacteria found include Pseudomonas, beta- haemolytic Streptococcus and Haemophilus influenzae.

Symptoms and Signs

The most common symptoms are ear discharge and deafness. Pain is uncommon although itchiness can occur due to secondary external otitis. The discharge is usually odourless and mucoid in nature. Tuning fork tests will point to a conductive hearing loss in the affected ear.

Investigation

Culture and sensitivity of the discharge is taken in cases where treatment is resistant or protracted. An audiogram is always performed prior to any surgical intervention.

Management

Concurrent infection is best treated with combined steroid and antibiotic ear drops (Framycetin, Ciprofloxacin HC, Ofloxacin). Once the infection has settled down for at least one month, surgical closure of the perforation under GA is advised. It is important to be aware of the risks of inner ear damage resulting from the use of aminoglycoside antibiotic ear drops in the presence a perforation and prolonged use is hazardous.

Complications

This form of CSOM is generally not associated with long-term complications. The most common complication is disruption of the ossicular chain which can be repaired during surgical closure of the perforation.

Middle Ear Conditions (Acute Suppurative Otitis Media (ASOM))

What is Acute Suppurative Otitis Media?

ASOM is an infection of the middle ear space. Children are more commonly affected although adults are susceptible. The pathophysiology of ASOM is typically an ascending infections from the nasopharynx up the Eustachian tube to the middle ear. The primary infection can take the form of a viral upper respiratory tract infection (URTI), an acute sinusitis or a lower respiratory tract infection. The purported reasons why children are most susceptible include ineffective Eustachian tube function, chronic adenoidal infection and frequent URTI as a result of schooling. The pathogens include Haemophilus influenzae, Beta-haemolytic Streptococcus and Moxarella catarrhalis.

Symptoms and Signs

In the early stages, there will be some discomfort, sensation of blockage and deafness. As the condition progresses, otalgia becomes the principal complaint, associated with fever and toxicity. There is usually a history of preceding URTI.
On examination, the patient will look ill, with a fever of more than 38 Celsius. The appearance of the eardrum differs during the stages of ASOM. In the first 48 hours, the eardrum is erythematous with some retraction. From two to seven days, there will be accumulation of pus and a bulging tympanic membrane, with pus clearly seen in the middle ear. From then on, as te conditions resolves, the eardrum appears more opaque and less erythematous and bulging.

Investigations

In an acute infection, no investigations are generally warranted. If the infection ruptures the eardrum, a culture and sensitivity of the discharge can be taken.

Management

The management of ASOM is mainly conservative. Pain relief and antipyretics (paracetamol, codeine) are usually required. Antibiotics (Augmentin, Klacid) are generally prescribed although some studies have questioned their efficacy. The symptoms and signs should resolve over three to five days after commencement of treatment. If the symptoms are present after one week, or worsen, a myringotomy should be performed and drainage established.

Complications

Complications from ASOM are uncommon with prompt and effective treatment. The most common complication is perforation of the tympanic membrane resulting in ear discharge and relief of pain. Infection can also spread medially to the inner ear, causing labyrinthitis with deafness and vertigo. It can also spread posteriorly, resulting in an acute mastoiditis with postauricular swelling and pain. Meningitis and facial paralysis are very rare complications.

External Ear Conditions (Malignant Otitis Externa (MOE))

What is Malignant Otitis Externa?

The organism involved in MOE is invariably Pseudomonas aeruginosa. It is a condition that occurs primarily in diabetics who are generally elderly. The Pseudomonas subtype involved produces an exotoxin which in an immunocompromised environment allows the external ear infection to extend beyond the soft tissue confines of the external ear. Hence, the bony external ear becomes infected (osteomyelitis). If left unchecked, the infection spreads into the skull base and its soft tissues. At thia stage, the condition will progress rapidly towards the midline and involve the lower cranial nerves, brainstem, and ultimately result in death.

Clinical Features

The most notable feature is excessive pain in the presence of mild to moderate signs. The pain can interfere with sleep and the ability to function. The patients can look unwell or even toxic. Otorrhoea is usually scant and hearing is at mostly mildly affected. On examination, there is granulation tissue, usually at the bony-cartilaginous junction, scant discharge and an intact eardrum. The lower cranial nerves can be affected. The most common is the facial nerve. Hence, an external ear infection with an ipsilateral facial palsy implies malignant otitis externa.

Investigations

Investigation for MOE are aimed at confirming the diagnosis and determining the extent of disease. Culture and sensitivity and biopsy of granulations are taken. A CT scan of the temporal bone is performed to determined the extend of bony destructon. An MRI scan is crucial in revealing the extent of soft tissue involvement and helpful in differentiating between inflammaton and tumour, e.g. nasopharyngeal cancer. Serial MRIs are done to assess the efficacy of treatment. Occasionally, a bone scan (Gallium) is done. This will reveal hyperintensity of the infected area if osteomyelitis is present.

Management

All patients with suspectedof confirmed MOE are admitted. The aim is to start intensive pharmacological therapy, monitor progression (or resolution) and control predisposing conditions (e.g. diabetes). An anti-pseudomonal antibiotic (Ciprofloxacin, Ceftazidine) is started intravenously for a minimum of eight weeks. Whether combination therapy improves outcome is still a subject of debate. Pain relief and control of diabetes mellitus is also important. The external ear canal is cleared regularly using microsuction. Surgical intervention is limited to clearance of sequestra within the external ear canal and facial nerve decompression when indicated.
*Note: The importance of early diagnosis in patients with MOE cannot be over-emphasised. The early institution of treatment leads to reduced morbidity and mortality. When in doubt, refer patients

*ALL THE INFORMATION REGARDING THE EAR CONDITIONS ARE PROVIDED BY DR GERARD CHEE HSIEN. copyright reserved.

External Ear Conditions (Furunculosis)

What is Furunculosis?

The pathology of furunculosis is an infection of a hair follicle. The causative organism is Staphylococcus aureus.

Clinical Features

The main symptoms is otalgia. Generally there is no otorrhoea or deafness. The patient will complain of pain on tugging the pinna and compression of the tragus. On examination, there is localized swelling with surrounding erythema in the hair-bearing area of the external ear canal.

Management

If the furuncle is not pointing, an antibiotic impregnated wick can be inserted into the canal over the furuncle for about three to five days. If it is pointing , an incision and drainage can be performed in the clinic. A course of antibiotics (Cloxacillin 250 mg qds for one week) can be prescribed. Analgesics will be required for the pain.