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nerve outcome (HB I-II) between study and control sub-
jects (Table V).
DISCUSSION
We present a large multicenter case-control study
comparing outcomes between postradiated sporadic VS
and nonradiated control subjects. Among 37 sporadic
VSs that failed primary SRS, our data demonstrate that
approximately 77% of patients with normal preoperative
facial nerve function retained good (HB I or II) function
after salvage surgery, and GTR can be achieved in at
least half of the cases. Overall, the rate of long-term
facial nerve paresis was similar to a size-matched con-
trol population of primary VS; however, the rate of less-
than-complete resection was significantly higher in the
postradiation group.
In 2005, Friedman et al. similarly reviewed a series
of 38 patients (28 sporadic, 10 NF2) who received sal-
vage microsurgery following failed primary radiation
therapy compared to a historical nonradiated control
group matched according to age and tumor size.
7
Similar
to the current study, they found that the rate of gross
total resection was lower in the irradiated group (78.9%
vs. 97.4%); however, in contrast they found that facial
nerve outcomes were poorer than age- and size-matched
nonradiated controls (37% vs. 70% HB I or II). The latter
discrepancy may be partly explained by several differen-
ces between study populations. In our study, the major-
ity of patients (95%) underwent Gamma Knife (Elekta
Instruments AB) radiosurgery after the year 2000 using
current low-dose treatment parameters. In contrast, the
study from the House Ear Clinic spanned the years
between 1985 and 2004 and included heterogeneous
radiation delivery: gamma knife, linear accelerator
(LINAC), and proton beam. Their median length of
follow-up was 15 months compared to 26 months.
Finally, 10 of the 38 patients had NF2. Patients with
NF2-associated VS are known to have poorer postopera-
tive facial nerve outcomes compared to patients with
sporadic VS.
15
In 2011, Friedman et al. reported an
updated institutional experience, including 17 NF2
patients and 56 sporadic VSs, advocating for partial or
near-total resection when required in order to preserve
facial nerve integrity.
6
In this updated series, 79.5%
received GTR and 20.5% received partial resection. Over-
all, 65% of patients had postoperative HB grade I or II
function; 57% following gross total resection compared to
92% following partial resection. Anatomical continuity of
the facial nerve was lost in 10 (13.7%) cases. A control
group was not included in this latter analysis.
In 2012, Gerganov et al. also found a much higher
rate of poor facial nerve function (43% HB gr 3–6) after
salvage surgery in patients who had prior radiation com-
pared to nonradiated controls (30% HB gr 3–6). Gross
total resection was performed in all but one control
case.
9
In 2013, Husseini et al. compared surgical out-
comes of 15 patients who had prior radiation therapy
(13 sporadic, 2 NF2) to a control group consisting of 15
nonradiated VSs matched according to age, tumor size,
and surgical approach.
8
Overall, 13 (87%) previously
irradiated VSs were managed with gross total resection.
The facial nerve was anatomically preserved in 14 of 15
cases, but only four of 13 (31%) patients who had HB
grade I or II function preoperatively maintained HB I or
II function following salvage surgery. None of the
patients in any of these series experienced recurrence
following salvage surgery, regardless of extent of
TABLE V.
Multivariate Logistic Regression Analysis Investigating
Independent Associations With Good Postoperative
Facial Nerve Outcome (HB I-II).
Variable
Odds Ratio (95% CI)
P
Value
Study vs. control subjects
0.61 (0.18–2.04)
0.424
Presurgical tumor size
0.69 (0.33–1.45)
0.332
Age
0.94 (0.87–1.01)
0.079
Extent of resection
GTR vs. STR
0.18 (0.02–1.37)
0.097
Extent of resection
NTR vs. STR
0.67 (0.07–6.67)
0.730
Length of follow-up after
salvage
0.92 (0.74–1.14)
0.436
CI
5
confidence interval; GTR
5
gross total resection; HB
5
House-
Brackmann; NTR
5
near total resection; STR
5
subtotal resection.
Fig. 2. Comparison of facial nerve out-
comes between study and control subjects
by extent of resection
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