HSC Section 8_April 2017

TABLE I. Description of Primary Radiation Therapy.

Parameters Median (Range)

Radiation Modality

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 ) CyberKnife 18 Gy, 3 fractions (n 5 1) 20 Gy, 4 fractions (n 5 1)

2 late onset facial weakness 17 loss of useful hearing (class D) 3 hydrocephalus

Fractionated stereotactic radiosurgery (n 5 2)

0

*Elekta Instruments AB, Stockholm, Sweden. Gy 5 gray.

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.

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

Characteristics of Recurrent Vestibular Schwannoma

Primary treatment failure was defined as tumor growth after initial treatment with or without new

TABLE II. Comparison of Preoperative Baseline Patient Features: Cohort Composed of Previously Irradiated VS and Control Subjects Composed of Previously Untreated VS.

Study Cohort (n 5 37)

Matched Controls (n 5 37)

Feature

P Value

Female gender (n, %)

19 (51%)

21 (57%)

0.8

Age (yrs) Median (range)

61 (31–84)

60 (31–72)

0.7

I (37, 100%)

0.3

HB Score (n, %)

I (35, 95%) II (1, 3%) III(1, 3%) A (1, 3%) B (0, 0%) C (1, 3%) D (33, 89%)

0.001*

A 7 (19%) B 8 (22%) C 2 (5%) D 19 (51%) 1.9 (0.5–4.5)

Hearing class (n, %)

Tumor size (cm) Median (range)

2.0 (0.56–4.12)

0.4

Tumor laterality, right-sided (n, %)

24 (65%)

27 (73%)

0.6

Intracanalicular (n, %)

0

1 (3%)

1.0 0.8

Cystic (n, %)

7 (19%)

9 (24%)

Brainstem edema (n, %)

2 (5%)

2 (5%)

1.0

Brainstem compression (n, %)

14 (38%)

18 (49%)

0.5 1.0

Hydrocephalus (n, %)

1 (3%)

2 (5%)

Trigeminal dysfunction (n, %)

6 (16%)

9 (24%)

0.6

Intermittent facial spasm (n, %)

3 (8%)

0

0.2 0.6

Imbalance (n, %)

10 (27%)

13 (35%)

Headache (n, %)

1 (3%)

0

1.0

RT, radiation therapy; HB Score 5 House-Brackmann Score.

Wise et al.: Surgical Salvage for Recurrent VS

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