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

LABYRINTHITIS

351

Serous labyrinthitis may result from oedema during an acute otitis media
or following radical mastoid surgery. Infection reaches the labyrinth from
the middle ear via the oval or round windows or through a fistula of a semi-
circular canal or of the promontory. The usual cause of such fistula is
erosion of the bony wall by cholesteatoma to expose the endosteal lining
to infection (Fig. 178). If air pressure in the external meatus is artificially

Fig. 178. Chronic middle ear suppuration and
cholesteatoma. Note erosion of bony pro-
minence of lateral canal. 1, Erosion of bone
over prominence of lateral canal (so-called
'fistula'); 2, Endolymph space of canal; 3,
Perilyniph space, largely filled up by new
connective tissue; 4, Granulation tissue on
inner wall of tympanum below; 5, Facial
nerve; 6, Cholesteatoma lining aditus and
antrum.

Fig. 179. From a case of acute purulent otitis
media followed by purulent labyrinthitis and
meningitis without rupture of the tympanic
membrane. 1, Swollen, engorged and infiltrated
mucosa of tympanum; 2, Pus in tympanic
cavity; 3, Footplate of stapes; 4, Anterior cms
of stapes—note that pus is entering the vestibule
between the stapes and the margins of the oval
window; 5, Pus in internal meatus; 6, Saccule;
7, Pus in vestibule; 8, Haemorrhage and pus;
9, Utricle.

increased, this is communicated through the tympanic perforation and the
fistula to the labyrinthine fluid and so to the crista of the lateral (horizontal)
canal. Giddiness and nystagmus are thus produced (fistula sign). Hearing
loss is not greatly aggravated in serous labyrinthitis and recovery is
usual.

Purulent labyrinthitis implies a continuation of the inflammatory process
so that the serofibrinous exudate in the labyrinth becomes purulent (fig.
179). There is severe giddiness, vomiting and loss of balance with the sensa-
tion of external objects rotating. Deafness is complete, but there is not
much tinnitus. If untreated, or if treatment is delayed, the membranous
labyrinth may be destroyed within a few days. The condition passes into
a latent phase during which granulations, connective tissue and finally new
bone form within the labyrinth (Fig. 180). This produces a spontaneous cure
as far as vertigo is concerned but hearing never returns. Labyrinthitis may
lead to meningitis as a result of spread either along the cochlear aqueduct