10-Complications of middle-ear infection

10-Complications of middle-ear infection

Complications develop when infection spreads beyond the middle ear (Fig. 10.1). They may be extracranial – mastoiditis, deafness and facial palsy – or intracranial.

Acute mastoiditis

Acute mastoiditis (Fig. 10.2) is the extension of acute otitis media into the mastoid air cells with suppuration and bone necros

Symptoms 

• Pain – persistent and throbbing 
• (Ear discharge (otorrhoea
•  Increasing deafness 

Signs 

• Pyrexia 
•  Swelling and redness in the postauricular region; the pinna is pushed down and forward 
•  Marked tenderness over the mastoid
• The tympanic membrane is either perforated and the ear discharging, or it is red and bulging 

Treatment 

When the diagnosis of acute mastoiditis has been made, do not delay 

•  Admit the patient to hospital 
•  Commence IV antibiotics immediately. If the organism is not known start with a cephalosporin 

and metronidazole

•  Surgery: If there is a subperiosteal abscess or if the response to antibiotics is not rapid and complete, the pus needs to be drained under anaesthesia

Figure 10.1 Complications of chronic otitis media: 1, acute mastoiditis; 2, meningitis; 3, extradural abscess; 4, brain abscess (temporal lobe and cerebellum); 5, subdural abscess; 6, labyrinthitis; 7, lateral sinus thrombosis; 8, facial nerve paralysis and 9, petrositis

Figure 10.2 (a) Acute mastoiditis; (b) MRI scan showing mastoid abscess 

Facial paralysis

Facial paralysis can result from both acute and chronic otitis media

•  Acute otitis media – especially in children and especially if the facial nerve canal in the middle ear is dehiscent. It is uncommon and prognosis for complete recov- ery is excellent

•  Chronic otitis media – cholesteatoma may erode the bone around the facial nerve, and infection and granulations can cause facial paralysis 

Treatment of facial palsy due to otitis media 

•  If due to acute otitis media, expect a full recovery with antibiotics
•  If due to chronic suppurative otitis media (CSOM), mastoidectomy is required with clearance of disease from around the facial nerve 
• Facial palsy in the presence of chronic ear disease is not Bell’s palsy and active treatment is needed if the palsy is not to become permanent. Do not give steroids 

Labyrinthitis 

Infection can spread from the middle ear to the cochlea but the inner ear is very well protected in its bony covering and this is a rare event. Infection may reach the labyrinth by erosion of a fistula by cholesteatoma. This can cause severe dizziness and sensorineural deafness. 

Treatment is with antibiotics but you may need to prescribe antihistamines and anti- emetics for the dizziness and vomiting. 

Intracranial complications of otitis media 

These arise when infection spreads from the ear into and beyond the meninges (Fig. 10.3). A number of clinical scenarios may ensue, i.e. meningitis, extradural ab- scess, brain abscess, subdural abscess, venous sinus thrombosis. 

• Meningitis 

Clinical features 

•  The patient is unwell. 
•  Pyrexia – may only be slight. 
•  Neck rigidity. 
• Positive Kernig’s sign. 

•  Photophobia.

Figure 10.3 Computerized Tomography (CT) scan with contrast showing temporal lobe abscess resulting from chronic middle ear disease (courtesy of Dr T. Hodgson). 

Diagnostic lumbar puncture to examine and culture cerebrospinal fluid (CSF) is es- sential unless there is raised intracranial pressure. 

• Brain abscess 

Otogenic brain abscess may occur in the cerebellum or in the temporal lobe of the cerebrum. The two routes by which infection reaches the brain are direct spread via bone and meninges or via blood vessels, i.e. thrombophlebitis. 

A brain abscess may develop with great speed or more gradually over a period of months.

 The clinical effects are produced by: 

•  systemic effects of infection, i.e. malaise, pyrexia; 
• raised intracranial pressure, i.e. headache, drowsiness, confusion, impaired con- sciousness, papilloedema; 
•  focal signs, depending on where the abscess is, e.g. hemiparesis. 

Diagnosis of intracranial sepsis 

•  Any patient with chronic ear disease who develops headache, neurological signs or any of the features of meningitis – e.g. neck stiffness or photophobia – should be suspected of having intracranial extension. 
•  Any patient who has otogenic meningitis, labyrinthitis or lateral sinus thrombosis may have a brain abscess as well. 
•  Lumbar puncture may be dangerous owing to pressure coning but is the best way to confirm meningitis. Seek expert advice. 
•  Seek neurosurgical advice early if you suspect intracranial suppuration. 
•  Confirmation and localization of the abscess will require further investigation. 

Computerized tomography (CT) scanning will demonstrate intracranial abscess- es reliably. Magnetic resonance (MR) imaging shows soft-tissue lesions with more detail than CT but gives no bone detail. If in doubt what to do, discuss the problem with a radiologist. 

Treatment 

It is the brain abscess that will kill the patient, and this must take surgical priority. Get the advice of a senior neurosurgeon. Small abscesses can be treated with high- dose antibiotics but often the abscess will need to be drained through a burr hole, or excised via a craniotomy. Then, if the patient’s condition permits, mastoidectomy should be performed under the same anaesthetic. After pus has been obtained 

for culture, aggressive therapy with antibiotics is essential, to be amended as necessary when the sensitivity is known. 

Prognosis 

The prognosis of brain abscess has improved with the use of antibiotics and modern diagnostic methods but still carries a high mortality; the outlook is better for cerebral abscesses than cerebellar, in which the mortality rate and the frequency of residual complications may be especially high. Left untreated, death from brain abscess occurs from pressure coning, rupture into a ventricle or spreading encephalitis. Patients who recover may be left with hemiparesis or epilepsy.