Furunculosis of the External Auditory Canal

A localised staphylococcal abscess of a hair follicle in the cartilaginous outer third of the canal, the only part of the canal that bears hair and pilosebaceous units. It is a circumscribed collection, unlike the diffuse inflammation of acute otitis externa, and this distinction dictates that drainage rather than drops is often the definitive treatment.

Staphylococcus aureus is the causative organism in almost all cases, with methicillin resistant strains in patients with healthcare exposure, prior colonisation or recurrent disease.
Trauma from cotton buds, fingernails, scratching and hearing aid moulds initiates follicular inoculation.
Recurrent or multiple furuncles suggest diabetes mellitus, nasal staphylococcal carriage, immunodeficiency, iron deficiency, or chronic corticosteroid use.

Because the cartilaginous canal skin has a subcutaneous layer, swelling is localised and pointing occurs. Infection may track through the fissures of Santorini into the parotid region or spread posteriorly, producing postauricular swelling that mimics mastoiditis.

Severe localised pain out of proportion to the size of the lesion, aggravated by jaw movement, chewing, and any pressure on the tragus or traction on the pinna.
Pain increases over 2 to 4 days, then abruptly settles if the furuncle discharges.
Hearing is usually normal. Loss occurs only when the swelling completely occludes the canal.
Scant bloodstained purulent discharge after rupture. Copious discharge points to a different diagnosis.
Fever and systemic upset are uncommon and suggest spreading cellulitis.

Signs

A tender, erythematous, dome shaped swelling confined to the outer canal, sometimes with a visible punctum or pointing yellow head.
The medial canal and tympanic membrane are normal when they can be seen.
Tender preauricular, postauricular or upper cervical lymphadenopathy.
Swelling over the mastoid region when the furuncle arises from the posterior canal wall.

Distinguishing furunculosis from acute mastoiditis

In furunculosis, hearing is normal, there is no history of preceding middle ear disease or discharge, the tympanic membrane is normal, and the postauricular sulcus is preserved.
In mastoiditis, conductive hearing loss is present, there is a preceding otitis media, the sulcus is obliterated, the pinna is pushed forward and downward, and the tympanic membrane is abnormal.

Clinical, based on the localised swelling in the hair bearing canal with exquisite tenderness.

Pus swab for culture and sensitivity when discharging or after incision, particularly to identify methicillin resistant Staphylococcus aureus.
Capillary glucose and HbA1c in all patients, and especially with recurrent lesions.
For recurrent furunculosis: full blood count, ferritin, HIV testing, and nasal swab for staphylococcal carriage. Consider immunoglobulin studies where furunculosis occurs alongside other recurrent pyogenic infections.
Imaging is not required unless mastoiditis, parotid abscess or spreading deep neck infection is suspected, in which case contrast enhanced computed tomography is appropriate.

Differential diagnosis

Diffuse acute otitis externa: circumferential oedema, no discrete swelling, greater discharge.
Acute mastoiditis: as distinguished above.
Perichondritis: the whole pinna is involved with lobule sparing.
Herpes zoster oticus: vesicular eruption, severe neuralgic pain, possible facial palsy.
Parotid abscess: swelling anterior and inferior to the tragus with pus at the parotid duct orifice and trismus.
Malignancy in the older patient with a non resolving canal lesion.

Analgesia, which is the most immediate need

Paracetamol 1 g orally every 6 hours, maximum 4 g in 24 hours, reduced to 3 g in adults under 50 kg or with hepatic risk.
Ibuprofen 400 mg orally every 8 hours with food, maximum 2.4 g in 24 hours, avoided in renal impairment and peptic ulcer disease.
Codeine phosphate 30 to 60 mg every 6 hours or oxycodone 5 mg every 4 to 6 hours for 48 to 72 hours in severe cases.
Local heat applied externally is helpful and encourages pointing.

Topical measures

Ichthammol 10 percent in glycerine on a ribbon gauze wick, changed daily for 3 to 5 days. It is hygroscopic, reduces oedema and relieves pain, and remains a valuable low cost measure.
Aluminium acetate 8 to 13 percent on a wick is an alternative astringent.
Topical antibiotic drops are of limited value because the lesion is a closed collection, but ciprofloxacin 0.3 percent with dexamethasone 0.1 percent, 4 drops twice daily, is reasonable once drainage has occurred.
Mupirocin 2 percent ointment applied to the canal meatus twice daily for 5 days after drainage.

Systemic antibiotics

Indicated for surrounding cellulitis, fever, multiple furuncles, immunocompromise, diabetes, or failure of local measures.

Flucloxacillin 500 mg orally four times daily for 5 to 7 days, taken 30 to 60 minutes before food. Paediatric dose 12.5 to 25 mg/kg four times daily.
Clindamycin 300 to 450 mg orally four times daily in penicillin allergy, with counselling about Clostridioides difficile risk.
Clarithromycin 500 mg orally twice daily as an alternative, noting QT prolongation and CYP3A4 interactions with statins and warfarin.
Methicillin resistant Staphylococcus aureus: doxycycline 100 mg orally twice daily, or trimethoprim with sulfamethoxazole 960 mg orally twice daily, for 7 days. Avoid doxycycline in children under 8 years and in pregnancy.
Severe cellulitis or systemic sepsis: flucloxacillin 2 g intravenously every 6 hours, or vancomycin with target trough 15 to 20 mg/L when resistant organisms are suspected.

Incision and drainage

Indicated once the furuncle is fluctuant or pointing, and is the definitive treatment for pain.
Under microscopic vision with topical or infiltrative local anaesthesia, or general anaesthesia in children.
A single stab incision with a number 11 blade over the point of maximal fluctuance, kept superficial and parallel to the canal axis to avoid injuring cartilage and perichondrium.
Express pus, send for culture, then insert a small wick to keep the cavity open for 24 to 48 hours.
Do not incise a non fluctuant lesion, which causes chondritis without relieving pain.

Recurrent disease

Decolonisation: mupirocin 2 percent nasal ointment applied to both anterior nares three times daily for 5 days, plus chlorhexidine 4 percent body wash daily for 5 days, plus hot washing of bed linen and towels. Repeat after 4 weeks if recurrence continues, and consider treating household contacts.
Optimise glycaemic control and correct iron deficiency.
Stop all cotton bud use permanently and review hearing aid mould hygiene.

Complications

Spreading canal cellulitis and perichondritis of the pinna, requiring systemic antipseudomonal and antistaphylococcal cover and drainage of any subperichondrial collection.
Parotid space infection through the fissures of Santorini.
Canal stenosis after repeated episodes with scarring.
Rarely, septicaemia in the immunocompromised.

Review at 48 hours if not drained, and at 5 to 7 days after drainage to confirm resolution and to exclude an underlying diffuse otitis externa.

Clinical toolsCalculators

BMI GCS EDD Parkland Formula

Corrected Sodium Corrected Calcium Anion Gap Creatinine Clearance Insulin Calculations qSOFA Wells PE Wells DVT CHA₂DS₂-VASc HAS-BLED CURB-65 Centor/McIsaac

Benign Paroxysmal Positional Vertigo

Also known as: BPPV

Brief episodes of vertigo provoked by changes in head position relative to gravity, caused by displaced otoconia within the semicircular canals. It is the commonest cause of vertigo, accounting for around 20 to 30 percent of all presentations to dizziness clinics, and it is curable in a single consultation, which makes failure to diagnose it a significant clinical failure.

Mechanism

Calcium carbonate otoconia detach from the utricular macula and enter a semicircular canal.

Canalolithiasis: free floating particles within the canal lumen. Head movement causes them to fall under gravity, dragging endolymph and deflecting the cupula. Latency of 1 to 5 seconds reflects the time for particles to begin moving; the nystagmus crescendos then decays over 10 to 60 seconds as they settle; fatigability occurs on repetition.
Cupulolithiasis: particles adherent to the cupula, making it gravity sensitive. Nystagmus begins immediately without latency, persists as long as the position is maintained, and does not fatigue.

Canal involvement

Posterior canal in 80 to 90 percent, because it is the most dependent canal in the upright and supine positions.
Horizontal or lateral canal in 5 to 15 percent, subdivided into geotropic canalolithiasis and apogeotropic cupulolithiasis.
Anterior or superior canal in 1 to 3 percent, which is rare because its position makes spontaneous clearance likely, and which requires exclusion of a central cause because downbeat nystagmus is its hallmark.

Causes

Idiopathic in 50 to 70 percent, particularly in older women.
Head trauma, including minor trauma, which produces multicanal and bilateral disease more often.
Vestibular neuritis and labyrinthitis, from utricular damage.
Ménière disease.
Prolonged supine positioning, including after surgery and dental procedures.
Osteoporosis and vitamin D deficiency, which are associated with recurrence, and reduced serum vitamin D is a modifiable recurrence risk factor.
Migraine.

Brief rotational vertigo lasting seconds, characteristically under 60 seconds, provoked by rolling over in bed, lying down, sitting up, looking up to a high shelf, or bending forward.
Attacks come in clusters over days to weeks, often worst on waking.
Nausea, and occasionally vomiting, disproportionate to the brief vertigo.
Persistent low grade unsteadiness and light headedness between attacks, which patients often report as the dominant symptom and which can obscure the positional pattern.
No hearing loss, tinnitus or aural fullness. Their presence points to another diagnosis.
No loss of consciousness, no focal neurological symptoms.

Features that indicate a central cause and require imaging

Downbeat or purely vertical nystagmus that does not fit the expected canal pattern.
Nystagmus without latency, without fatigue, and not matching any canal plane.
Vertigo without nystagmus on positioning.
Associated diplopia, dysarthria, dysphagia, limb ataxia or sensory symptoms.
Severe headache, particularly occipital, of sudden onset.
Failure to respond to correctly performed repositioning after several attempts.

The diagnosis is made at the bedside by provoking and observing the nystagmus. Use Frenzel glasses or video goggles where available, since visual fixation suppresses the nystagmus and causes false negatives.

Dix Hallpike manoeuvre for the posterior and anterior canals

Seated with the head turned 45 degrees to the test side, the patient is laid rapidly supine with the head extended 20 to 30 degrees below the horizontal, and held for at least 30 seconds.
Posterior canal canalolithiasis: upbeating torsional nystagmus with the top pole of the eye beating toward the dependent ear, after a latency of 1 to 5 seconds, lasting under 60 seconds, with reversal on sitting up and fatigue on repetition.
Anterior canal: downbeating nystagmus with a torsional component toward the affected ear. Because downbeat nystagmus is also a central sign, anterior canal disease should not be diagnosed without careful exclusion of central pathology.

Supine roll test for the horizontal canal

Performed when the Dix Hallpike is negative but the history is convincing.

Supine with the head flexed 30 degrees, the head is turned rapidly 90 degrees to one side, held, returned to centre, then turned to the other side.
Geotropic nystagmus beating toward the ground on both sides indicates canalolithiasis, with the affected side being the one producing the stronger nystagmus.
Apogeotropic nystagmus beating away from the ground indicates cupulolithiasis, with the affected side being the one producing the weaker nystagmus.

Additional assessment

Full neurological and cerebellar examination.
Head impulse test, spontaneous nystagmus assessment and test of skew.
Otoscopy and audiometry where any auditory symptom is present.
Magnetic resonance imaging is not required for typical benign paroxysmal positional vertigo and should not be ordered routinely. It is indicated for atypical nystagmus, central signs, or failure of repositioning.
Consider vitamin D and bone density assessment in recurrent disease.

Particle repositioning is the treatment and is effective in the great majority at the first or second attempt.

Posterior canal: Epley manoeuvre

From the Dix Hallpike position with the affected ear down, hold for 30 seconds or until the nystagmus stops.
Rotate the head 90 degrees to the opposite side, hold 30 seconds.
Roll the patient onto the shoulder with the head turned a further 90 degrees so the face is directed toward the floor, hold 30 seconds.
Sit the patient up with the chin tucked.
Success rate is 80 to 90 percent after one manoeuvre and above 95 percent after repeated treatments.
Repeat the manoeuvre in the same session if nystagmus persists.

Posterior canal alternative: Semont manoeuvre

Used where neck or back limitation makes the Epley difficult. The patient is moved rapidly from lying on the affected side to lying on the opposite side, with the head position maintained relative to the body.

Horizontal canal

Geotropic canalolithiasis: barbecue or Lempert roll, rotating the patient 360 degrees in 90 degree increments away from the affected side, holding each position 30 seconds; or the Gufoni manoeuvre, lying rapidly on the unaffected side then turning the head 45 degrees toward the floor.
Apogeotropic cupulolithiasis: Gufoni manoeuvre toward the affected side to convert cupulolithiasis to canalolithiasis, followed by treatment of the resulting geotropic form; or head shaking to dislodge particles from the cupula.
Horizontal canal disease is more resistant and often requires several sessions.

Anterior canal

Deep head hanging manoeuvre or a reverse Epley, after central pathology has been excluded.

Post manoeuvre instructions

Post procedural restrictions such as sleeping upright and avoiding head movement for 48 hours do not improve outcomes and are not required.
Warn about residual unsteadiness for a few days, which is common and does not indicate failure.
Advise caution with driving immediately after treatment.

Home exercises

Brandt Daroff exercises, performed five repetitions three times daily, are less effective than a properly performed repositioning manoeuvre and are reserved for patients with residual symptoms, for those who cannot attend for treatment, and for frequently recurrent disease where the patient can self treat.

Medication

Vestibular sedatives do not treat benign paroxysmal positional vertigo, do not shorten its course, and impair the compensation that resolves residual symptoms. They also mask the nystagmus needed for diagnosis.
A single dose of an antiemetic before a manoeuvre is reasonable for a patient who vomits severely, but routine prescription of prochlorperazine for this condition is inappropriate and is a common error.
Betahistine has no role.

Refractory and recurrent disease

Recurrence occurs in around 15 to 50 percent within 5 years. Teach self administered repositioning to frequent recurrers.
Correct vitamin D deficiency, with supplementation reducing recurrence in deficient patients.
Reconsider the diagnosis after three or four failed correctly performed manoeuvres, and image for central pathology.
Surgical posterior canal occlusion is a last resort for truly intractable, disabling, unilateral posterior canal disease, carrying a risk of sensorineural hearing loss of a few percent. Singular neurectomy is now rarely performed.

Special considerations

Elderly patients: benign paroxysmal positional vertigo is a substantial and treatable cause of falls and hip fracture. Actively screen for it in any older patient presenting with falls or dizziness, since many do not report the positional trigger.
Cervical spine disease, atlantoaxial instability, carotid stenosis, retinal detachment and recent neck surgery require modification of the manoeuvre or use of the Semont alternative.
Bilateral and multicanal disease is common after head trauma and requires treating one canal at a time, beginning with the most symptomatic.

Furunculosis of the External Auditory Canal

Overview

Clinical Features

Diagnosis

Management

Overview

Clinical Features

Diagnosis

Management