Complications of 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?
Complications of acute otitis externa (AOE) require urgent identification and treatment as they can potentially be life threatening.
WHEN TO INVOLVE THE ENT REGISTRAR
The ENT registrar should be informed soon if you suspect a complication of AOE, particularly if the patient has any red flags.
Discuss patients immediately if they have central neurological signs such as meningism and reduction in GCS.
WHO TO ADMIT
Admit patients where you have clinical suspicion of necrotising otitis externa (NOE), abscess collection or pinna/facial cellulitis.
Patients with complete acute stenosis of the ear canal alone should be seen urgently as outpatients or in the treatment room but rarely need admission; an otowick should be inserted to keep the inflamed canal open.
ASSESSMENT AND RECOGNITION
Complications of AOE are uncommon but can be serious and therefore should be suspected in patients who do not respond to treatment.
Complications
Necrotising otitis externa (NOE; previously known as malignant otitis externa)
Infection spreads through soft tissue resulting in osteomyelitis of the temporal bone and skull base
Older male patients with diabetes are at high risk (classical presentation); but all immunocompromised patients are at risk
Pseudomonas aeruginosa is the most common causative organism
Characterised by non-resolving AOE despite adequate topical treatment; deep severe pain which is out of proportion to general status (patient patients are apyrexial) and which can cause insomnia; purulent otorrhoea; evidence of granulation and necrotic tissue within the ear canal
Some patients may appear to have non-resolving AOE but, on closer questioning, they turn out never to have been prescribed topical treatment; the vast majority will not have NOE and will get better once they start the correct treatment
In more severe cases, there may be evidence of conductive hearing loss and lower cranial neuropathies (CN VII, IX, X, XI and XII) as the disease becomes more erosive and spreads along the skull base. This may become life threatening if this extends as far as the jugular foramen.
More rarely, NOE may involve the petrous apex leading to CN V and VI nerve palsies (Gradenigo’s syndrome).
Abscess formation
AOE can lead to localised abscess formation; this is usually as a result of Staphylococcus aureus
This presents with localised fluctuant swelling, which may form in or around the affected ear
Occlusion of the ear canal may lead to a conductive hearing deficit; If the abscess ruptures, there may be evidence of purulent discharge
Peri-auricular or pinna cellulitis
This presents with erythema, swelling and warmth of the pinna or around the ear, which may extend to surrounding tissues overlying the parotid gland, mastoid and sternomastoid. Pain is present, particularly on manipulation of the pinna, but is usually moderate in comparison to NOE
There may be systemic symptoms including fever, generalised illness and regional lymphadenopathy
Chronic stenosis of the ear canal or false fundus
In patients with recurrent AOE, fibrosis within the canal can lead to chronic stenosis or complete obstruction of the ear canal (formation of a false fundus covering the tympanic membrane). This is distinct from acute stenosis due to inflammation, which is reversible.
IMMEDIATE AND OVERNIGHT MANAGEMENT
This depends on the complication. In general, the following would be appropriate in most cases with an acute complication.
Investigations
Microbiology swabs of any discharge prior to initiating management
IV access and FBC, U&E, serum glucose, CRP, ESR
Blood cultures if pyrexial
Don't forget the Sepsis Six bundle
CT Temporal bone (fine slice) if NOE is suspected
Treatment
Treatment should always be based on topical antibiotics, good analgesia and water precautions
NOE
Antibiotic treatment usually consists of a combination of IV ceftazidine or tazocin with oral ciprofloxacin, however you should seek local microbiology guidance
Prolonged courses of IV antibiotics (six weeks) are frequently needed
Abscess or cellulitis
Can often be treated initially with IV or oral antibiotics; antibiotic choice will vary according to local guidance though penicillins are often recommended
Diabetic patients should have meticulous blood glucose monitoring and control, which may necessitate use of sliding scale insulin.
FURTHER MANAGEMENT
NOE
Progress can be monitored with bi-weekly CRP/ESR
Progress can also be ascertained with Isotope scans every 4 to 6 weeks
MRI of ears and skull base if progression/severe disease suspected
Discussion at skull base MDT is useful
Baseline audiogram
Biopsy of granulation tissue will help to exclude possible squamous cell carcinoma (this can wait until working hours if you have not done it before)
Surgical debridement of granulation tissue and bony sequestra may be required
Hyperbaric oxygen therapy is often reserved for refractory or recurrent cases or for patients with extensive skull base and intracranial involvement
Abscess or cellulitis
Incision and drainage will be required (aspiration if small) - discuss with the ENT registrar
Ear canal stenosis
If acute and due to inflammation, the use of an otowick may be required to help delivery of topical therapy
Where recurrent infection causes permanent fibrotic stenosis and even more infections, surgery can be performed to improve patency (but see below)
Sometimes, recurrent infection leads to formation of a false fundus and patients tend to find that they suffer little or no further AOE; they may choose to live with the hearing deficit
PROGNOSIS of noe
NOE is potentially curable if recognised and treated early and aggressively: mortality rate can still be up to 15% in these cases. If, however, diagnosis and treatment is delayed, mortality can be up to 75%. Facial nerve palsy is a poor prognostic factor and its presence indicates a need for a longer course of antibiotics. Facial nerve function may never fully recover.
Page last reviewed: 15 December 2019