Q. WHAT ARE THE CAUSES OF LABYRINTHINE FISTULA? WHAT ARE THE TYPES OF NYSTAGMUS PRESENT IN DIFFERENT STAGES OF LABYRINTHINE FISTULA? HOW DO YOU TREAT IT?
Labyrynthine fistula is a leak through an abnormal third window.
Following active mucosal disease
Following COM squamosal ( Cholesteatoma)
-4-13 % of cases
-Most common complication
-LSCC is the most common site
Localized infection in CWD Mastoidectomy cases
DIFFERENT STAGES AND NYSTAGMUS IN VARIOUS STAGES:
PRE-LIMINARY STAGE →Bony erosion with blue line of labyrinth.
STAGE → Endosteal membrane exposed but intact.
STAGE II → Membranous SC in contact with cholesteatoma matrix and perilymphatic space open. This is the irritative phase which shows nystagmus with slow phase in contralateral side and fast phase in ipsilateral side.
STAGE III → Direct involvement of membranous labyrinth. This is a paralytic phase in which the slow phase is in ipsilateral side and fast phase in contralateral side.
Many fistula shows spontaneous bony closure after removal of the offending cholesteatoma or infection.
If severe: Most surgeons recommends CWD Mastoidectomy and closure.
-The cholesteatoma matrix should be left undisturbed over the SCC until all other disease is removed and all
aspect of procedure such as meatoplasty is completed.-Then the matrix should be carefully lifted and the fistula is identified. The matrix should be peeled off the mebranous labyrinth very meticulously following which the fistula must be sealed immediately with fascia and bone dust.