Modern surgical treatment of otosclerosis - Helda - Helsinki.fi

Discussion
postoperative night in hospital. They did not need medications during the night following
surgery and were discharged on the first postoperative day in good health. The vestibular
symptoms experienced were unrelated to abnormal nystagmus findings, which might be
due to the subjective sensations mostly occurring immediately after the operation, and our
recordings being performed later, on average four hours postoperatively, when all but one
patient was free of symptoms.
Audiological results were comparable with those in the literature with postoperative AB-
GAPs of 6 dB (III) and 8 dB (IV). No significant SNHL occurred in either study. Similar
to a study by Aantaa and Virolainen (1978), no association existed between hearing results
and vestibular symptoms.
The eye movements in Studies III and IV were thoroughly evaluated at multiple timepoints,
but no association with type of nystagmus or vestibular symptoms was found. This
suggests that vestibular symptoms have a diverse origin. Appearance of vestibular
symptoms with rotatory and also with floating and tilting sensations immediately after
surgery are in concordance with this suggestion. In measurements immediately after
surgery, we saw signs of disturbance of the semicircular canals. However, mechanical or
other stimulation of the otolith organ might be another cause of dizziness, as suggested by
the symptoms of floating and tilting in some of our patients, although we observed no
signs of obvious eye deviation or counter-rolling on the videotapes. Postoperatively,
increased resting activities of utricular afferents without semicircular canal irritation have
been suggested. This was explored by evaluating the results of subjective visual horizontal
and VOG measurements after stapedotomy (Tribukait and Bergenius 1998). Those authors
found no correlation between vestibular symptoms and objective measurements. This
could be due to late measurements, a few days after surgery, similarly to our results. In a
study by Wang et al. (2005), saccular irritation caused by the prosthesis was suggested as
a reason for vestibular symptoms. In that study, an anatomically modified tip of the
prosthesis to avoid contact with the saccule was found effective in preventing
postoperative vestibular symptoms. This is, however, not in concordance with other
studies concerning changes in saccular function after stapes surgery. VEMPs arising from
the saccule are not decreased after the surgery, indicating that the function of the saccule
has been maintained (Singbartl et al. 2006, Stapleton et al. 2008). In our study, VOG was
found to be an effective method for evaluating vestibular organ irritation. In the future, to
unveil the pathological process leading to postoperative vertigo, the gap between opening
the oval window and objective measurements should be as short as possible and
measurements for otolith organs should be included.
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