Page 105 - Edited - Webster HEAD AND NECK - part 2-Merge PDF

ΗΝ 299

(b) Limitation of Movements of the Tympanic Membrane and Ossicles for Other Reasons: Otitis
Media and "Glue Ear"
(i) Accumulation of fluid in the middle ear - which may be uninfected liquid or pus. "Glue ear" and
otitis media are examples. ("Glue ear" is commoner in the children of parents who smoke....). Pus can be
drained by incising the ear drum, and inserting a "grommet" if necessary to prevent the hole healing over. A
badly managed otitis media will destroy the ear ossicles and result in permanent conduction deafness in that
ear. There is also the risk that the infection will erode through the thin bone of the tegmen tympani and spread
to the middle cranial fossa, resulting in meningitis and/or brain abscess.

(ii) Ankylosis of the synovial joints between the ossicles. Only small amounts of pathologically
desposited "new" bone need accummulate to impede the action at such small joints. This is otosclerosis.
Ankylosis (effectively the joining together of two bones at a normally mobile articulation) is especially
common where the stapes footplace abuts the oval window. The ENT surgeon chips it free.....
Sensory Innervation

The mucous membrane of the middle ear, including inner surface of the ear drum, is supplied by the
glossopharyngeal (IXth cranial) nerve via its tympanic branch. This arrangement affords opportunity for
referral of pain between the palatine tonsil and its bed on the one hand, and the middle ear on the other ear
ache" is common in those who have palatine tonsillitis - especially infants and children.

Geniculate Herpes.

The facial nerve also innervates the skin of the external meatus, and especially the lateral (external) surface of
the tympanic membrane. The cell bodies of these axons are in the geniculate ganglion, and in geniculate
herpes (shingles) an eruption of vescicles appears in the external auditory meatus as well as in the mouth (oral
tongue and the palate - taste fibres) – HN 252. There is dysfunction of these sensory axons for the durat on of
the illness: tingling: and food and drink tastes "mouldy". The infection causes oedema of the geniculate
ganglion and because it is located as an intrinsic part of the facial nerve within the bony facial canal (HN 240;
249; 296) the entire nerve is compressed. This produces not only a Bell's palsy (skeletomotor - muscles of
facial expression) – HN 248 - but also failure of the parasympathetic secretomotor outflow (submandibular,
sublingual salivery glands on side of herpes, and palative and oral flow glands on same side) and the lacrimal
gland of the eye on the side of the Bell's palsy (HN 246, 252, 253). Failure of lacrimation is serious, especially
in an eye which has a poor or absent blink reflex (HN 185; 253). Finally, the skeletomotor axons to the
middle ear stapedius muscle are also paralyzed: high pitched, loud noises become painful in the affected ear.
This is "hyperacusis". This entire association of signs and symptoms is known as the Ramsay-Hunt syndrome.

K.E.W.

\NewCMedPhysSc\25 HN 301 Deafness.