Describe labyrinthitis and labyrinthine fistula.

Labyrinthine Fistula

• A labyrinthine fistula is an abnormal communication between the middle ear and the labyrinth, created by erosion of the bony capsule.
• The lateral (horizontal) semicircular canal is by far the commonest site, because its prominence lies in the medial wall of the attic where cholesteatoma sits.
• Cause — cholesteatoma in the great majority; also chronic osteitis, trauma, previous surgery, tumour and syphilis

Labyrinthitis

• Suppurative labyrinthitis is a medical and surgical emergency, not because the ear can be saved — it cannot — but because the labyrinth is the gateway to the meninges through the internal acoustic meatus and the cochlear aqueduct. Labyrinthitis is therefore a warning of impending meningitis
• Management of suppurative labyrinthitis — admit; high-dose intravenous antibiotics crossing the blood-brain barrier; vestibular sedatives briefly and fluids for vomiting; urgent mastoid surgery to eradicate the source; and labyrinthectomy only where infection persists or to drain the labyrinth in the presence of meningitis
• Do not continue vestibular sedatives beyond a few days.
• Encourage early mobilisation and vestibular exercises.
• Test hearing early and consider cochlear implantation urgently where the loss is profound, before ossification
• The lateral semicircular canal is the commonest site, its prominence lying exactly where attic cholesteatoma sits
• Ask about vertigo on nose-blowing or straining; pressure-provoked vertigo is the symptom that suggests a fistula
• A negative fistula test may mean a dead labyrinth, which is not reassurance but the worst possible result
• Hennebert sign is a false positive, occurring in congenital syphilis and Meniere disease without any fistula
• Get a CT before operating on a suspected fistula, since the surgical plan depends on its size and site
• The matrix over a fistula may be left and exteriorised, particularly in an only hearing ear or where the fistula is large
• Remove the matrix last if at all, gently and under irrigation, and seal the fistula immediately with fascia or bone pate
• Nystagmus toward the diseased ear is irritative and suggests serous labyrinthitis that may still be reversible
• Nystagmus away from the diseased ear is paralytic and means the labyrinth has been destroyed
• Labyrinthitis is a warning of meningitis, the labyrinth being the gateway through the internal meatus and cochlear aqueduct
• Stop vestibular sedatives after a few days; they delay the central compensation that is the patient only route to recovery
• Reassure that vertigo settles even with a dead labyrinth.
• Encourage early mobilisation and exercises, which accelerate compensation and shorten the disability
• Ossification begins within weeks after suppurative labyrinthitis, which is why implantation cannot wait for convalescence
• Serous labyrinthitis is toxin diffusion through the round window without organisms entering the labyrinth itself