Interpretation
Labyrinthine fistula (LF) is a known complication of cholesteatomas,
most common in the lateral SCC, but also affects superior SCC in 6% and
posterior SCC in 2% of LFs (6). Clinical suspicion of LFs is limited by
non-specific symptoms – mostly sensorineural or mixed hearing loss,
accompanied by vertigo, otorrhea and otalgia also present in
chronic otitis media. Classic
clinical signs such as fistula sign may only have a sensitivity of
21.7% to 60% (7), false negative rate of up to 54% (8). Also, there
is lack of uniformity in performing the test.
While some centres have used the Dornhoffer and Milewski classification
to stage fistulas based on bony defects and size of fistulas to
determine surgical method, the fistula size, size and grade have been
reported to not correlate with surgical outcomes (9). Surgeon 1’s
technique of matrix removal was applied to all LFs, irrespective of size
of fistula. Sealing of fistulas included bone wax and temporalis fascia,
consistent with literature also reporting the use of bone wax,
temporalis fascia, bone dust, tissucol, fibrin glue, Spongiostan and
autogenous tissues (6, 9).
Postoperative hearing deterioration rate has been reported in 2.8-26.9%
(9), possibly attributed to the removal of cholesteatomas and
granulation tissue previously acting as conduits in conducting sound
into ear. Postoperative deterioration in sensorineural hearing loss
occurs in 23% to 50% that underwent complete matrix removal and 1 to
44% for matrix left in-situ (9). Unlike the review by Lim et al (9),
our patients with matrix preservation had poorer hearing outcome,
perhaps due to longer follow-up
time. Matrix removal, however, had hearing preservation in 78% although
2 ears had initial worsening within 120 days postoperatively. This is in
contrary to greater deterioration of long-term hearing outcomes found by
Katsura et al (10), despite initial improvements within the first year,
postulated to the involvement of third window during the initial
recovery stage. Postoperative persistent hearing loss could be a result
of inflammatory effects of the remnant cholesteatoma matrix.