4.1 Complications
A lot of studies [7-10]had found that nearly one
fifth of the overall study population suffered complications, the
majority of these side effects were technique-related, very transient
and self-resolving. They included transient dizziness/vertigo
postinjection, ear fullness and slight otalgia during injection which
can be all caused by the immediate injection technique. But in our study
we have found some steroid-related side effects, including tympanic
membrane atrophy thinning and external auditory canal mycosis.
4.2 Tympanic
membrane atrophy thinning
In our study, tympanic membrane atrophy thinning were observed in 5
ears. The tympanic membrane is composed of three layers: the upper
cortex, the fibrous layer and the mucosal layer. Keratinocytes,
fibroblasts and the extracellular matrix (ECM) are the main components
of the tympanic membrane. The damage of keratinocytes, fibroblasts and
ECM will affect the morphology and function of the tympanic membrane. In
1978, Wilson et al.[11]reported that steroid can
modify fibroblasts in vitro and inhibit the activity of these cells to
varying degrees. Schoepe et al.[12]found that the
proliferation and ECM protein synthesis of keratinocytes and fibroblasts
were suppressed by steroid. Thereby, the stratum corneum got thinner,
followed by an increased transepidermal water loss. Then, the epithelial
layer lost its tensile strength and elasticity caused by the water loss
and the degraded ECM. So the steroid can make the epithelial layer
atrophy and steroid-induced tympanic membrane atrophy is characterized
by a profound increase in
transparency of skin, a cigarettepaper-like consistency accompanied by
an increased fragility, tearing, bruising, thin, shiny, and
telangiectatic which is consistent with what we had found in the 5 cases
of tympanic membrane atrophy thinning in this study. The membrane
presented increased transparency, more shiny, and visually felt thin. It
was worth noting that the five patients in our study had no tympanic
membrane perforation during the entire observation period, so tympanic
membrane atrophy near the injection port was not the result of healing
after tympanic membrane perforation.