Infection in the middle ear commonly involves the mastoid by direct extension,
but other surrounding structures may be involved. This can occur by direct
spread through an area eroded by disease, or through a congenital dehiscence or
a fracture line. The other mode of spread is by thrombophlebitis of emissary
veins.
ROUTES OF INFECTION. From the middle ear and mastoid antrum infection may spread
in the following directions:
1. Medially to the labyrinth, through the oval window, round window or by
erosion of the horizontal semicircular canal. Occasionally there may be erosion
of the promontory or the other semicircular canals. Meningitis commonly occurs
in this way.
2. Superiorly towards the middle cranial fossa resulting in an extradural
abscess or in an abscess of the temporal lobe; meningitis occasionally results
from spread of infection by this route.
3. Posteriorly towards the posterior cranial fossa producing (a) an extradural
abscess between the sigmoid sinus and its bony wall (perisinus abscess) or in
abscess medial to the sinus, (b) septic thrombosis of the sigmoid sinus,
(c)meningitis beginning in the posterior cranial fossa, (d) cerebellar abscess.
4. Inferiorly through the floor of the tympanum producing a septic thrombosis of
the bulb of the internal jugular vein. In rare cases this may result in an
abscess developing below the petrous bone and formation of a parapharyngeal
abscess.
Complications are more likely to arise from chronic otitis media than from acute
otitis media and are conveniently divided into two groups - extracranial and
intracranial. They are not mutually exclusive, however, as one complication may
precede or lead to another, e.g. labyrinthitis may lead to meningitis or
mastoiditis may lead to an extradural abscess.
Complications of otitis media
Extracranial:
Mastoiditis
acute
masked
chronic
Petrositis
Retropharyngeal abscess
Labyrinthitis
circumscribed
diffuse
serous
purulent
Intracranial:
Extradural abscess
Lateral (Sigmoid) sinus thrombosis
Otitic hydrocephalus
Meningitis
Brain abscess
temporal lobe
cerebellum
Subdural abscess
Cortical thrombophlebitis
EXTRACRANIAL COMPLICATIONS
Acute mastoiditis
Mastoiditis is a complication of otitis media in which infection spreads from
the tympanic antrum to involve the bony walls of the cells of the mastoid
process. The infection may be acute or chronic.
AETIOLOGY. Acute mastoiditis arises from an acute otitis media by extension of
infection from the mastoid antrum to the air cells, and occurs therefore in a
cellular temporal bone. In many cases of acute otitis media infection, although
present in the cellular system, produces no bone destruction, but in severe
acute infections there is a greater inflammatory reaction resulting in pus
formation, increased tension, resorption of bone with loss of trabeculation and
the formation of an empyema. Eventually the inflammatory process may erupt
through the lateral surface to produce a subperiosteal abscess. An untreated
abscess may spread in several directions: (1) through the periosteum and skin
covering the mastoid process, (2) into the external meatus to simulate a
discharging furuncle, (3) through the medial aspect of the mastoid tip into the
digastric fossa (Bezold's mastoiditis), (4) through the posterior root of the
zygoma beneath the temporal fascia (zygomatic mastoiditis) causing slight oedema
of the upper eyelid as an early sign, (5) through the canal for the mastoid
emissary vein or through the temporo-occipital suture to form an abscess
posterior to the mastoid process, (6) beyond the confines of the middle-ear
cleft giving rise to intracranial complications.
SYMPTOMS. The symptomatology of the majority of cases of acute mastoiditis seen
in hospital practice has been modified or obscured by previous unsuitable or
inadequate antibiotic therapy. In acute otitis media pain behind the ear and
tenderness over the area of the mastoid antrum are commonly present but are
relieved by successful antibiotic treatment. Increasing pain, or the return of
pain, and increasing mastoid tenderness are therefore significant. Tenderness
occurs not only over the mastoid antrum but may be elicited on pressure over the
mastoid tip and posterior border. In an untreated case of mastoiditis discharge
from the ear will usually have increased with extension of the disease, but in a
"masked" case discharge may be absent and the perforation may have healed. Fever
is not marked in adults but may be high in children, in whom a rising pulse rate
is a potential danger signal. Deafness is present in most cases but varies in
severity. Local signs vary with the stage and extent of the infection.
In the case of periostitis gentle palpation over the mastoid area may reveal
thickening of the periosteum on the affected side. Later there is oedema of the
soft tissues with displacement of the auricle downwards and outwards which is
often seen more easily from behind the patient. If a subperiosteal abscess forms
there is a fluctuant swelling behind the ear. Narrowing of the external meatus
due to sagging of the posterosuperior meatal wall is a significant finding on
otoscopy, which may reveal a perforated drumhead with pulsating discharge or an
intact one which has a thickened or full appearance. Patients generally look ill
and feel off colour and disinterested.
DIAGNOSIS. In some cases difficulty may arise in distinguishing between
mastoiditis and furunculosis of the posterior meatal wall. Considerable help in
arriving at a diagnosis of mastoiditis may be obtained from radiography of the
mastoids by comparing films of the affected and unaffected sides in different
views of the temporal bone. The radiograph shows the type of mastoid process and
the extent of cellular development. In early cases of mastoid infection, slight
blurring of the cellular outlines is present on the affected side and the
outline of the bony plate of the lateral sinus becomes more prominent.
Increasing opacity with pus formation is followed by loss of cellular outlines
or trabeculation, by destruction of bone proceeding eventually to formation of
an abscess cavity. The radiological appearances should at all stages be
correlated with the clinical manifestations and follow-up radiography is often
necessary.
Blood examination generally shows a polymorphonuclear leucocytosis and the ESR
is increased, except possibly in those patients who have had antibiotic
treatment.
TREATMENT. The incidence of acute mastoiditis has been greatly reduced since the
advent of antibiotic treatment. The majority of cases of acute suppurative
otitis media now resolve by early and adequate treatment with parenteral
penicillin combined, if necessary, with paracentesis. The presence of pus in the
middle ear may be associated with increased tension requiring relief by surgical
drainage.
When the clinical features of mastoiditis develop the patient should be confined
to bed and antibiotic administration commenced. Until pus from the ear is
available for bacteriological examination, penicillin should be given by
intramuscular injection starting with 1 million units (benzylpenicillin)
followed by 500000 units 6-hourly. Lack of improvement in the patient's
condition in 48 hours is an indication for a change of antibiotic or a cortical
mastoidectomy.
The indications for the cortical mastoid operation, also known as Schwartze's
operation, are: (1) continued pain and mastoid tenderness for more than 2 or 3
days despite antibiotic therapy in full dosage and adequate drainage by
paracentesis; (2) increasing constitutional signs, e.g. fever and rising pulse
rate; (3) copious pulsating discharge, rapidly refilling the meatus after
mopping out; (4) sagging of the meatal wall, increasing oedema over the mastoid
process or zygoma; (5) symptoms or signs of labyrinthine or intracranial
complication; (6) onset of facial paralysis; (7) persistent suppurative otitis
media for more than 2 weeks despite efficient treatment; (8) progressive
deafness.
Masked mastoiditis
This serious and treacherous condition, associated with an unresolved or latent
otitis media, is the result of inadequate treatment with antibiotics. Failure to
recognize the state of the infection and to apply vigorous treatment may result
in the development of an intracranial complication such as meningitis or lateral
sinus thrombosis. At the present time it occurs mostly after the administration
of oral penicillin given for too short a period of time and, in some cases, in
inadequate dosage.
DIAGNOSIS. Many cases are referred to hospital because of the persistence of
pain, deafness, fever and discharge or because of the appearance of an intact
unresolved reddish drumhead. Others are seen on account of recurrence of these
symptoms after an apparent recovery. The persistence of deafness is an important
symptom. There may be mastoid tenderness and headache with a slight rise in
temperature. The drumhead is usually congested and full or thickened in
appearance. Mastoid radiographs show opacity or haziness with, in some cases,
loss of cellular outlines on the affected side.
TREATMENT. Admission to hospital for observation and adequate treatment is
necessary. Resumption of full antibiotic therapy is justifiable in the absence
of acute signs of mastoiditis, a watch being kept on the patient's general
condition, temperature chart, tympanic membrane, mastoid process and hearing. In
the absence of early signs of improvement, and whenever some doubt exists, a
cortical mastoidectomy is indicated, effective drainage of the middle ear
reducing the possibility of some permanent conductive deafness.
The Cortical Mastoid Operation (Schwartze's Operation)
The aim of this operation is to remove all infected mastoid cells. A postaural
incision is made, the mastoid bone is exposed and Shipo's triangle identified.
The cortex is removed using a drill, although where an abscess is present the
cortex will be soft and necrotic. Each group of cells is systematically explored
and cleared so as to leave an appearance. Particular attention is paid to
removing infection in the tip cells and the cells in the sinodural angle. If
necessary the zygomatic cells are removed. If the plates of bone overlying the
dura mater and the lateral sinus appear healthy they are not opened to expose
these structures, but unhealthy bone in these situations must be removed and the
dura and sinus wall examined for extension of disease. A swab of pus will be
taken routinely for culture and sensitivity, and any granulation tissue should
be sent for histological examination. The wound is sutured and a rubber drain is
left in the lower part of the incision. The drain is removed after 24 to 48
hours and the stitches are removed in one week.
Lack of healing or continued meatal discharge suggests that some infected cells
may have been missed or that spicules of infected bone have been left in the
cavity, and in either case the wound may have to be reopened.
Labyrintitis
This is a not uncommon complication of otitis media and, if suspected, must be
treated vigorously and promptly. Failure to do so may lead to total
sensorineural deafness or meningitis. The least severe form is circumscribed
labyrinthitis, also known as paralabyrinthitis, and this is easily the most
common type. Serous labyrinthitis is less common, but more serious. The least
common but most dangerous variety is purulent labyrinthitis which inevitably
leads to a total and permanent loss of vestibular and auditory function.
PATHOLOGY. Circumscribed labyrinthitis is almost invariably due to a fistula,
i.e. cholesteatomatous erosion of the bony capsule of the labyrinth, usually the
horizontal semicircular canal but occasionally the promontory or other canals.
Diffuse labyrinthitis may be an extension of the circumscribed type but it more
frequently follows invasion through the oval or round windows, especially the
former. It involves the peri- and endolymphatic spaces. Diffuse labyrinthitis
may be serous or purulent. In serous labyrinthitis there is a general
non-purulent inflammation of the labyrinth with occasionally a fibrinous or
serous exudate. In purulent labyrinthitis there is infiltration of the spaces by
polymorphs, pus cells and destruction of the vestibular and cochlear structures.
Occasionally the bony capsule becomes involved.
Labyrinthitis may follow an acute otitis media, tuberculous otitis media or
chronic otitis media. Other causes of labyrinthitis include trauma, bloodborne
infection, bacterial or viral, and meningitis.
CLINICAL FEATURES Circumscribed labyrinthitis. There may be an initial bout of
vertigo and deafness in the formative stage of the fistula. Once the fistula is
established the main complaint may be of intermittent vertigo brought on by
sudden movements, cold water or air in the ear or, in more advanced cases, by
moving the auricle. There is usually evidence of chronic otitis media on
otoscopy and the diagnosis is confirmed by demonstrating a fistula sign, but a
negative fistula sign does not rule out a fistula. There may be a slight
sensorineural hearing loss in addition to the conductive hearing loss due to the
otitis media.
Serous labyrinthitis. This may follow circumscribed labyrinthitis or any of the
other causes mentioned. There is hearing loss, occasionally pain and tinnitus,
but the main feature is vertigo, associated with nausea and vomiting. There may
be a sensation of objects moving from the diseased to the healthy side, i.e.
nystagmus, towards the diseased side. The patient invariably is bed-ridden, at
least initially, and lies on the unaffected ear and looks towards the diseased
side because this reduces the vertigo. As a rule there is no pyrexia. Caloric
reactions, if tested after the acute phase, are diminished on the affected side.
Purulent labyrinthitis. The symptoms are similar to those of serous
labyrinthitis but the vertigo and vomiting may be more frequent and severe.
Nystagmus, although initially directed towards the diseased ear, soon changes
direction towards the good ear. Total deafness develops. Caloric testing should
not be done during the acute phase because it can exacerbate roe vertigo, but if
done later a canal paresis is commonly found on the affected side. There is no
pyrexia unless there is an intracranial complication.
TREATMENT Circumscribed labyrinthitis. Suspicion of labyrinthine erosion by
cholesteatoma or granulations is an indication for surgery. Tomography may show
labyrinthine erosion. The mastoid is cleared of disease by a modified radical
mastoidectomy. The fistula may be exteriorized if caused by cholesteatoma. In
some cases the cholesteatoma can be removed and the fistula is covered by
temporalis fascia.
Serous labyrinthitis and purulent labyrinthitis. Bed-rest is essential in the
initial stages. Sedation with labyrinthine sedatives is required, dimenhydrinate
(Dramamine), promethazine hydrochloride (Pipolphen) or prochlorperazine
(Novamine) being useful. Parenteral antibiotics in adequate dosage are required.
A combination of penicillin and a sulphonamide can be used empirically until
swab results are known. Most patients settle on this regime. If the
precipitating cause were an acute exacerbation of chronic otitis media this can
be dealt with subsequently. Occasionally a myringotomy will be required in acute
otitis media, and occasionally it is necessary to deal surgically with a
mastoiditis. In a few cases persistence of symptoms with evidence of
intracranial irritation may call for exploration and a labyrinthectomy.
Labyrinthectomy. This is now rarely done but may be required in suppurative
labyrinthitis. It is also indicated in an ear where the cochlear function has
been severely damaged by chronic otitis media and there is persistent vertigo.
Occasionally it is indicated in Meniere's disease. A radical mastoidectomy is
performed. The lateral semicircular canal is exposed and opened and the
membranous labyrinth removed. The oval and round windows are joined and the
contents of the vestibule removed by suction. Some authorities recommend opening
all three canals.
INTRACRANIAL COMPLICATIONS
There has been a marked reduction in incidence of these complications over the
past four decades, the reasons for this being the same as for extracranial
complications. When they do occur, however, their morbidity and mortality are
still high. Even today a person who has a brain abscess has a 40% chance of
dying from it. It is vital, in any suspected case of intracranial extension of
disease, to liaise closely with the neurosurgeons. The only exception to this
rule being a small extradural abscess where the diagnosis is made during the
course of exploratory mastoid surgery.
Extradural abscess
An extradural abscess consists of a collection of pus between the bone and the
dura mater. Unless it is opened and drained it is frequently followed by other
intracranial complications. It is more common in the posterior than in the
middle cranial fossa, in some cases forming between the lateral sinus and the
bone of the posterior cranial fossa (perisinus abscess). Extradural abscess
occurs more commonly in acute than in chronic middle-ear suppuration. In chronic
purulent otitis media it is met with chiefly in cases of cholesteatoma and in
acute exacerbations of chronic suppuration. The extent of the abscess varies
greatly; it may be quite small or, in chronic cases, it may attain a
considerable size.
CLINICAL FEATURES. The symptoms are rarely characteristic and the majority of
extradural abscesses are only discovered at the time of operation. The condition
is associated with deep-seated boring pain, tenderness on tapping over the
temporal region or posterior fossa, and rise of temperature. If the abscess is
large, there may be evidence of compression of the brain. There are rarely any
localizing symptoms although occasionally paresis of the VIth nerve may be
encountered.
DIAGNOSIS. This is not easy as a rule. The relief of pain by the spontaneous
evacuation of a large quantity of pus, or the aspiration of much pus by mopping
or aspiration through the external meatus, may suggest the diagnosis. The
continuation of pain, pyrexia and a raised pulse rate after operation for a
mastoid complication should suggest the probability of the presence of a
deeper-seated collection of pus.
TREATMENT. This consists in opening the abscess and evacuating its contents by
free removal of the bony wall. When the abscess is opened the pus flows out in a
pulsating manner. The affected dura mater may be covered with red "healthy"
granulations, or it may be greyish-green and slough-like. Removal of the
underlying bony wall should be continued until the whole abscess cavity has been
freely exposed. The cortical or the radical operation - according to
circumstances - is performed at the same time. The patient should be carefully
watched in order to detect the first signs of further intracranial
complications, e.g. sinus thrombosis, brain abscess or meningitis.
Lateral (sigmoid) sinus thrombosis
This condition used to account for about 30% of all cases of intracranial
complications in the pre-antibiotic era, but now it occurs much less frequently
and today makes up less than 10% of the total. About half of these are
associated with other intracranial complications, usually cerebellar abscess or
meningitis. It is still a dangerous condition which must be recognized as early
as possible and treated vigorously.
PATHOLOGY. The initial lesion is inflammation of the wall of the sinus secondary
to local infection. This can be due to local venous thrombophlebitis but it is
usually a result of an extradural perisinus abscess, which has sometimes been
present for a considerable time. It occurs in both acute and chronic mastoid
infections although more frequently in the latter. The local inflammation in the
wall of the sinus results in thrombus formation which can spread to involve the
whole lumen. In untreated or rapidly developing cases the thrombus may extend in
either direction to involve the superior petrosal sinus (rare), cavernous sinus
(rare), jugular bulb (common) or the internal jugular vein (rare). The thrombus
tends to stop where two vessels meet. If the thrombus becomes infected an
abscess can develop and this may result in pieces of infected clot breaking away
and being carried to other parts of the body.
A pyaemia therefore occurs and abscesses are set up in the lungs and other
organs. If the infection breaches the medial wall of the sinus, meningitis,
subdural abscess or brain abscess can develop.
CLINICAL FEATURES. Sinus thrombosis may run its course without symptoms,
particularly where antibiotics have been used, and be found later at a
definitive operation for the underlying chronic otitis media. The classical
presentation, now rarely seen, consists of the occurrence of chilly sensations
or rigors in which the temperature rises suddenly to 39,5 or 40oC and falls
again as rapidly, the fall being accompanied by profuse sweating. There may be
only one rigor daily, usually in the afternoon or evening, or several. There is
a concomitant rise in the pulse rate. A high evening temperature for several
days after a mastoid operation calls for exploration of the sinus. In the
intervals between the rigors the patient is free from symptoms, although in
advanced cases there is persistent pyrexia. Headache and vomiting occasionally
occur, the tongue is dry, there may be herpes on the lips, an enlarged spleen
and a congested optic disc. Lumbar puncture, which should only be done if a
brain abscess can be excluded, may demonstrate raised cerebrospinal fluid
pressure, particularly when complete occlusion is present. In such cases the
Tobey-Ayer test is positive. This consists of compressing the jugular vein of
the normal side which causes a rise of cerebrospinal fluid pressure in the
manometer connected to the lumbar puncture needle, while compression of the vein
on the affected side produces little or no rise in pressure. Occasionally oedema
is present in the neighbourhood of the mastoid emissary vein (Griesinger's
sign).
If the thrombosis extends into the neck torticollis may develop, and there may
be tenderness over the line of the jugular vein. Occasionally a cavernous sinus
thrombosis can occur. As a result of escape of portions of the clot into the
general circulation pneumonia or lung abscess may arise. If the particles are
small, metastatic abscesses may appear in other parts of the body, especially in
the subcutaneous tissues or in the bones and joints.
DIAGNOSIS. The conditions with which sinus thrombosis is most likely to be
confused are malaria, typhoid fever, bronchopneumonia and erysipelas. The
diagnosis of sinus thrombosis is suggested by the occurrence of rigors in the
course of middle-ear suppuration; it is more difficult if the condition is
complicated by the presence of meningitis or brain abscess, both of which must
be treated first. Examination of the peripheral blood will show a
polymorphonuclear leucocytosis. In severe infections a falling haemoglobin can
occur. Blood cultures are rarely of value.
TREATMENT. Early energetic antibiotic and anticoagulant therapy often makes
operative treatment unnecessary. The same antibiotic regime as for labyrinthitis
is recommended. When active surgical intervention is required this consists of
removing the primary focus of disease by performing a cortical mastoidectomy in
cases due to acute middle-ear suppuration, and a radical operation in cases of
chronic suppuration. If sinus thrombosis is present there is usually excessive
bleeding from the bone at the mastoid operation. In every case which shows
symptoms suggestive of extradural perisinus abscess or sinus thrombosis the
sigmoid sinus should be exposed until the healthy wall is seen. A healthy sinus
wall is blue in colour and it is easily compressed. If a perisinus abscess is
found and there are healthy granulations on the sinus wall, and if only one
rigor has occurred, it is advisable to leave the wound open and pack the cavity
with tampon. The sinus should be opened if there are persistent rigors or if the
wall of the sinus is greyish-yellow, brownish-green or slough-like at the first
or subsequent operations. Before opening, the sinus plate is removed to expose
the healthy sinus wall above and below the diseased area. Gauze packing is
inserted between the sinus and bone superiorly and inferiorly to reduce any
bleeding and the sinus is slit open. All necrotic thrombus and tissue are
removed until either healthy clot is identified or free bleeding occurs. The
sinus and cavity are packed with tampon and the wound left open to be closed at
a second stage some 7 days later.
Septic thrombosis can follow injury to the sinus during mastoid operations.
Injury to the wall should be treated by application of a piece of temporalis
fascia or muscle to arrest the bleeding. Should rigors occur postoperatively the
case is treated as a sinus thrombosis.
PROGNOSIS. The prognosis of sinus thrombosis is more favourable since the
introduction of antibiotics. It is more favourable than that of brain abscess if
an operation is performed before systemic infection has occurred, and if there
is no other intracranial complication. With antibiotics and timely surgery a
cure is to be expected.
Meningitis
This complication accounts for about one-third of all intracranial
complications, only brain abscess being more common. Even with the armamentarium
of antibiotics available today it can still be fatal and must be suspected in
all cases of otitis media where there are symptoms and signs suggestive of
intracranial spread of disease. Like the other complications of otitis media it
is decreasing in incidence.
PATHOLOGY. Meningitis is an infection of the pia mater which invests the brain,
the arachnoid mater which is closely adherent to the under surface of the dura
mater, and the cerebrospinal fluid which lies between these two layers. It can
occur during an acute infection but is more commonly associated with chronic
otitis media. There are several ways in which infection can reach the meninges:
(1) direct extension through the dura mater due to thrombophlebitis of
communicating veins, erosion by disease or surgery, or congenital or traumatic
dehiscences; (2) extension of disease from an extradural abscess or lateral
sinus thrombophlebitis; (3) extension of a suppurative labyrinthitis via the
cochlear aqueduct or the subarachnoid sleeve of the VIIIth nerve.
As in other infections there is often an initial inflammatory response with
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