206 / 264
patients developed hydrocephalus. Of these, two (5%)
patients were treated with placement of a ventriculoperi-
toneal shunt. Two patients had delayed onset facial pare-
sis greater than 4 months following SRS, with HB scores
of II and III, respectively. Of the 17 patients who had serv-
iceable hearing (class A and B) prior to treatment, 15 lost
useful hearing, and only one retained class A hearing after
SRS at a median follow-up of 40 months after treatment.
Characteristics of Recurrent Vestibular
Schwannoma
Primary treatment failure was defined as tumor
growth after initial treatment with or without new
symptoms (37, 97%), or development of refractory symp-
toms related to mass effect necessitating intervention (1,
3%). Thirty-six of 38 (95%) subjects had two or more
post-SRS imaging studies available for review, and the
median number of MRI studies per case was four (range
1–9). Two patients had only one MRI scan following pri-
mary SRS. In both cases, the degree of tumor growth led
to a decision to treat with salvage surgery rather than
continue observation. One of these subjects had a tumor
that doubled in greatest linear dimension (0.6–1.2 cm)
over 2 years. The second subject had 0.8 cm of tumor
growth over a 2.8-year interval. Only one patient had
salvage surgery for a nongrowing tumor. This patient
TABLE I.
Description of Primary Radiation Therapy.
Radiation Modality
Parameters
Median (Range)
Complications
Gamma Knife Radiosurgery*
(n
5
35)
Marginal dose 12 Gy (12–14 Gy)
Maximal dose 26 Gy (24–40 Gy)
Number of isocenters 8 (4–60)
Volume treated 3.4 cm
3
(0.34–17 cm
3
)
2 late onset facial weakness
17 loss of useful hearing (class D)
3 hydrocephalus
Fractionated stereotactic
radiosurgery (n
5
2)
CyberKnife 18 Gy, 3 fractions (n
5
1)
20 Gy, 4 fractions (n
5
1)
0
*Elekta Instruments AB, Stockholm, Sweden.
Gy
5
gray.
TABLE II.
Comparison of Preoperative Baseline Patient Features: Cohort Composed of Previously Irradiated VS
and Control Subjects Composed of Previously Untreated VS.
Feature
Study Cohort
(n
5
37)
Matched Controls
(n
5
37)
P
Value
Female gender (n, %)
19 (51%)
21 (57%)
0.8
Age (yrs) Median (range)
61 (31–84)
60 (31–72)
0.7
HB Score (n, %)
I (35, 95%)
II (1, 3%)
III(1, 3%)
I (37, 100%)
0.3
Hearing class (n, %)
A (1, 3%)
B (0, 0%)
C (1, 3%)
D (33, 89%)
A 7 (19%)
B 8 (22%)
C 2 (5%)
D 19 (51%)
0.001*
Tumor size (cm) Median (range)
2.0 (0.56–4.12)
1.9 (0.5–4.5)
0.4
Tumor laterality, right-sided (n, %)
24 (65%)
27 (73%)
0.6
Intracanalicular (n, %)
0
1 (3%)
1.0
Cystic (n, %)
7 (19%)
9 (24%)
0.8
Brainstem edema (n, %)
2 (5%)
2 (5%)
1.0
Brainstem compression (n, %)
14 (38%)
18 (49%)
0.5
Hydrocephalus (n, %)
1 (3%)
2 (5%)
1.0
Trigeminal dysfunction (n, %)
6 (16%)
9 (24%)
0.6
Intermittent facial spasm (n, %)
3 (8%)
0
0.2
Imbalance (n, %)
10 (27%)
13 (35%)
0.6
Headache (n, %)
1 (3%)
0
1.0
RT, radiation therapy; HB Score
5
House-Brackmann Score.
Wise et al.: Surgical Salvage for Recurrent VS
185