Results of 100 vestibular schwannoma operations.

Between 1991 and 2000, 154 cerebello-pontine angle (CPA) tumors were seen at the University ENT-department of the Sint-Augustinus Hospital, Antwerp. Amongst these, 127 were vestibular schwannomas detected by MR-imaging. Noteworthy is that in 5% of these, the ABR latencies were within normal limits. One hundred patients underwent tumor removal either by the translabyrinthine (66) or by the retrosigmoid (34) approach and all had a follow-up of at least two years. For large tumors (> 2 cm extension in the CPA) or in the case of poor hearing the translabyrinthine approach was used. For patients with tumor extension in the CPA ofless than 2 cm and with serviceable residual hearing on the affected side, (at least < 50 dB PTA, > 50% SSD) the retrosigmoid approach with endoscopic control was used. Most patients (96%) had a House-Brackmann grade 1 or 2 facial function before surgery. Although this group dropped to 76% 6 months after surgery it increased again to reach 84% within 2 years. Thus, 88% percent of patients with normal preoperative facial function achieved a Grade I or II after two years. The facial outcome is very much dependent on the size of the tumor. A good result (House-Brackmann Grade 1 or 2) is the rule (92%) for small tumors (< 10 mm extension in the CPA), still attainable (82%) for medium tumors (11-25 mm), but less apparent (56%) for large tumors (> 26 mm). It was possible to preserve hearing in 38% of the retrosigmoid interventions. Although unbalance and headache are rather frequent early postoperative symptoms (respectively 52% and 31%), these complaints decrease with time and are infrequent after two years (unbalance = 7%, headache = 4%). Our results were compared with three large multicentric studies. They are in line with data from the literature and compare favorably with the better results. Although good grading systems exist for facial nerve and hearing outcomes, the authors regret that a general consensus on tumor size measurement is still not yet available. It would facilitate data comparison between different centers and the choice between the therapeutical modalities.

Middle ear status in ears showing high admittance tympanograms. Clinical value of the use of the two-component 678 Hz oto-admittance tympanogram.

The present paper reports on the results of a retrospective study using 678 Hz susceptance-conductance tympanometry performed on abnormally high admittant middle ears. High admittance was proven to be caused by (partial) disruption or lysis of the ossicular chain. Retrospective analysis shows that 678 Hz tympanometry seems to be more accurate in the differential diagnosis of ossicular chain disruptions compared to CT-imaging of the ossicular chain (88% versus 81% correct identification respectively). Classic tympanometry using a probe frequency of 226 Hz was abnormal in only 43% of the cases.