Table 2.
Differences in clinical and operative parameters according to the outcome of facial nerve function after vestibular schwannoma surgery
| Good outcome (HB 1–2) n = 59 (67%) |
Moderate outcome (HB 3–4) n = 14 (16%) |
Poor outcome (HB 5–6) n = 15 (17%) |
Difference between groups | |
|---|---|---|---|---|
| Age (mean ± SD) | 51 ± 13 years | 55 ± 16 years | 55 ± 15 years | |
| Gender (male/female) | 20/39 | 7/7 | 6/9 | |
| Size1 | p < 0.05 | |||
| Intrameatal | 2 (4.1%) | 1 (7.1%) | 1 (7.7%) | |
| Small | 6 (12.2%) | 1 (7.1%) | – | |
| Medium | 31 (63.3%) | 4 (28.6%) | 5 (38.5%) | |
| Large | 10 (20.4%) | 8 (57.1%) | 7 (53.8%) | |
|
Largest diameter2 (mean ± SD, range) |
24 ± 12 mm 0–53 mm |
33 ± 10 mm 0–51 mm |
32 ± 15 mm 0–50 mm |
p < 0.05 |
|
Volume2 (mean ± SD, range) |
9000 ± 11,000 mm3 26–49,000 mm3 |
16,000 ± 11,000 mm3 3200–34,000 mm3 |
17,000 ± 21,000 mm3 2700–47,000 mm3 |
p < 0.05 |
|
Koos grade (mean ± SD, range) |
3.4 ± 0.9 1–4 |
3.6 ± 0.6 2–4 |
3.8 ± 0.4 3–4 |
|
| Clinical presentation | ||||
| Hydrocephalus | 7 (11.9%) | 4 (28.6%) | 5 (33.3%) | |
| Headache | 9 (15.3%) | 4 (28.6%) | 5 (33.3%) | |
| Vertigo | 35 (59.3%) | 6 (42.9%) | 6 (40.0%) | |
| Imbalance/ataxia | 12 (20.3%) | 5 (35.7%) | 9 (60.0%) | p < 0.01 |
| Hearing | 51 (86.4%) | 11 (78.6%) | 14 (93.3%) | |
| Tinnitus | 19 (32.2%) | 3 (21.4%) | 6 (40.0%) | |
| Facial | 1 (1.7%) | 2 (14.3%) | 3 (20.0%) | p < 0.05 |
| Trigeminal | 15 (25.4%) | 3 (21.4%) | 2 (13.3%) | |
| Brainstem/cerebellar | 5 (8.5%) | 1 (7.1%) | 5 (33.3%) | p < 0.05 |
| Hearing class3 (mean, range) | ||||
| Preoperative | 2.4 (1–5) | 2.6 (1–3) | 3.3 (2–5) | |
| Postoperative | 4.1 (1–5) | 4.2 (1–5) | 5.0 (5) | |
| Change | 1.8 | 1.6 | 2.3 | |
| Extent of resection | ||||
| Gross total | 17 (29.3%) | 4 (28.6%) | 5 (33.3%) | |
| Near total | 35 (60.3%) | 10 (71.4%) | 7 (46.7%) | |
| Subtotal | 6 (10.3%) | – | 2 (13.3%) | |
| Partial | – | – | 1 (6.7%) | |
| Drilling4 | 28 (48.3%) | 7 (50.0%) | 7 (46.7%) | |
| Threshold increase5 | 2 (2.3%) | 2 (16.7%) | 4 (66.7%) | p < 0.001 |
| Loss of response5 | – | 2 (15.4%) | 3 (37.5%) | p < 0.01 |
| Complication6 | 4 (6.8%) | 2 (14.3%) | 4 (26.7%) | |
| Regrowth7 | 12 (20.3%) | 3 (23.1%) | 6 (40.0%) | |
Differences between groups were tested using the Kruskall-Wallis test and the chi square test. Significant differences have been indicated. Valid percentages of available data are reported for each parameter
1Size is determined according to largest extrameatal diameter (small ≤ 15 mm, 15 mm < medium ≤30 mm, large >30 mm)
2Diameter and volume are calculated for the extrameatal part of the tumor
3Koos grading of vestibular schwannoma: 1, intrameatal; 2, extending to the cerebellopontine angle; 3, in contact with the brainstem; 4, compressing the brainstem
4Hearing is determined according to the WHO classification
5Drilling of internal acoustic meatus
6Intraoperative increase in stimulation threshold or loss of response in facial nerve monitoring
7Postoperative complication requiring re-operation
8Regrowth during subsequent follow-up leading to intervention