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Full text of "Diseases Of The Nose Throat And Ear"

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Labyrinthine and intracranial complications have become rare, not only
because of the widespread use of antibiotics but also because both acute
and chronic otitis media are in most cases adequately treated. Nevertheless
these are dangerous complications which, if not recognized or if neglected,
can lead to a fatal outcome. The importance of the early recognition and
treatment of labyrinthine and intracranial complications of middle ear
suppuration can hardly be stressed enough.

ROUTES OF INFECTION. From the middle ear and tympanic antrum infection
may spread in the following directions:

1.  Medially to the labyrinth either through the oval or round windows
or by erosion of the lateral semicircular canal. In rare cases the promontory
may be eroded, especially in tuberculous disease.

2.  Upwards towards the middle cranial fossa resulting in extradural
abscess or in abscess of the temporal lobe; purulent meningitis is a very rare
complication from spread of infection by this route.

3.  Backwards towards the posterior cranial fossa producing (a) an extra-
dural abscess between the sigmoid sinus and its bony wall or an abscess
medial to the sinus, i.e. between the posterior surface of the petrous bone
and the cerebellar dura mater; (b) septic thrombosis of the sigmoid sinus;
(c) purulent meningitis beginning in the posterior cranial fossa; (d) cere-
bellar abscess.

4.  Downwards through the floor of the tympanum producing septic
thrombosis of the bulb of the internal jugular vein. In rare cases downward
spread of infection may lead to abscess formation below the petrous bone
resulting in retropharyngeal abscess.

PATHOLOGY. From the point of view of pathology labyrinthitis may be
circumscribed or diffuse. The circumscribed form may affect the bony cap-
sule alone or it may invade the perilymph space, and it is almost invariably
due to cholesteatoma which has eroded the bony prominence of the hori-
zontal (lateral) semicircular canal in the aditus. Diffuse labyrinthitis may be
an extension of the circumscribed type, but it more frequently follows inva-
sion through the oval and round windows, especially the former. It may
involve the peri- and endolymphatic spaces, and there may also be infection
of the bony capsule.

Labyrinthitis may follow an acute otitis media, tuberculous otitis media
or chronic otitis media with cholesteatoma; it may be caused by a fracture
of the base of the skull; or it may be due to direct injury with a pointed
object such as a knitting needle or to unfortunate attempts at removal of a
foreign body from the external meatus. While most cases of labyrinthitis
follow otitis media some may be associated with meningitis.