Acute Otitis Externa

Red flags

• Complete acute stenosis of the ear canal - you cannot insert a speculum at all

• Cellulitis of the pinna or peri-auricular area

• Ipsilateral cranial nerve palsy

• Ipsilateral severe deep otalgia (eg causing insomnia)

Why is this important? 

Acute otitis externa (AOE) can progress to necrotising otitis externa (NOE), which is an osteomyelitis of the temporal bone and skull base, sometimes with cranial nerve involvement.

When to involve the ENT Registrar

• Soon: When you suspect NOE based on symptoms or neurological deficit

• Routinely: When an outpatient’s AOE has not improved despite two emergency clinic appointments

Who to admit 

• Anyone with symptoms and signs of NOE

• Consider admitting those with pinna cellulitis/perichondritis

• When the ear canal is completely stenosed, the patient should be seen urgently but will rarely need admission

• This is a link to an evidence-based AOE referral score (EARS) that we developed for primary care and emergency department use. 'Significant risk factors' are for severe AOE or the development of a complication.

Assessment and recognition

PRIMARY BACTERIAL AOE usually occurs after a change in the environment of the ear canal (increased humidity, change in pH due to impacted wax or no wax) and/or a break in the skin (eczema, mild trauma from cotton bud use, foreign body). It is sometimes known as 'swimmer's ear'. Common pathogens are Pseudomonas spp or Staphylococcus spp.

There is a short history of increasing otalgia, sometimes severe, with custard-like ear discharge. There may be associated:

• hearing loss

• tinnitus

COMPLICATIONS are more likely if there are significant risk factors:

• diabetes mellitus

• age >65 years

• recurrent AOE

• chemo- or radiotherapy or immune compromise

A serious complication is necrotising otitis externa (NOE). The classical NOE patient is an older diabetic man with a severely painful discharging ear (likened by one patient to an ice pick to the skull). 

SECONDARY AOE usually occurs in the presence of a suppurative otitis media (ie tympanic membrane perforation with watery mucopus coming through) or a foreign body (eg cotton bud tip or toy).

FUNGAL AOE ie OTOMYCOSIS has all the hallmarks of bacterial AOE except the discharge/exudate usually looks more like whitish blobs of rice pudding (Candida albicans) with or without black spots (Aspergillus niger). The cause is usually prolonged use of antibiotic drops. 

OTHER EXTERNAL EAR INFECTIONS: 1) furunculosis, the infection of a hair follicle in the canal; 2) Ramsay-Hunt syndrome, zoster of the VII nerve causing a palsy and vesicles in the canal.

Immediate and overnight management

• Prescribe topical drops. We suggest three drops three times a day to the affected ear(s) for seven to fourteen days, depending on risk stratification.

• A good idea is to prescribe according to local policy and to check with pharmacy what they have in stock. Most topical preparations are equally effective: when prescribing, you should take into account any risks of ototoxicity eg tympanic membrane perforation or bacterial resistance. Frequently used topical treatments include Sofradex drops, Gentisone HC drops and Otomize spray. These all contain both antibiotic and steroid. Ciprofloxacin drops are sometimes used but this is either embargoed or non-formulary in some areas. Canesten drops are useful in fungal AOE; alternatively you could use Locorten Vioform, which has some anti-fungal properties.

• Oral antibiotics do not work for all but the mildest cases of AOE.

• Good analgesia is vital in AOE but often the big reduction in pain only occurs when the infection and inflammation are resolving. This may take place two to three days after starting topical therapy.

See Cochrane Review on Interventions in AOE (Kaushik et al 2010).

• Advise the patient to use water precautions: avoid bathing; when showering, keep the ears dry. One way is to take a ball of cotton wool and cover it with a little Vaseline and gently place it at the external meatus.

• Generally speaking, patients with uncomplicated AOE do not require admission. This usually includes those who need insertion of a Pope wick.

• You can use the EAR Score to stratify a patient’s risk and determine follow-up (see also reference below).

Further management

Patients referred for an emergency ENT appointment will typically have their ears assessed under the microscope. This allows for microsuction of debris to get a better view, to take a swab or to remove some of the infective exudate. There is little evidence either way for microsuction purely to remove exudate and debris. If you are covering ENT and are not comfortable using the microscope in the middle of the night, make an appointment for the following day. 

In patients whose ear canals are acutely stenosed or occluded due to inflammation, a Pope otowick is inserted. This is a tubular piece of dry sponge which is inserted into the external meatus. It expands on contact with fluid and allows the instillation of drops. If you are covering ENT, this does not require the use of a microscope but make sure you have been shown how to do it first. It is painful for the patient but there is no other way to get drops in.

In patients who have a complication of AOE, admit them for IV or oral antibiotics as well as topical drops. Optimise their analgesia. If you suspect NOE, consider a CT scan of the temporal bones.

REFERENCES

Selwyn DM, Lau A. When to refer: Validating the Evidence-based Acute Otitis Externa Referral Score (EARS). Our experience of 287 cases of otitis externa in primary care. Clinical Otolaryngology. 2019 May; 44(3): 475-479

Page last reviewed: 15 December 2019