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J Neurol Surg B Skull Base 2021; 82(05): 491-499
DOI: 10.1055/s-0040-1714110
Original Article

Clinical and Imaging Response to Trigeminal Schwannoma Radiosurgery: A Retrospective Analysis of a 28-Year Experience

Ajay Niranjan
1   Department of Neurological Surgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States
,
Sudesh S. Raju
2   Department of Neurological Surgery, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
,
Hideyuki Kano
1   Department of Neurological Surgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States
,
John C. Flickinger
3   Department of Radiation Oncology, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States
,
Lawrence Dade Lunsford
1   Department of Neurological Surgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States
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Abstract

Objective The purpose of this study was to evaluate long-term clinical outcomes and tumor control after stereotactic radiosurgery (SRS) for trigeminal schwannoma (TS).

Methods During a 28-year period (1989–2017), 50 patients underwent SRS for TS. The median patient age was 51 years (range: 15–87 years). A total of 17 patients had a previous tumor resection: 10 had a single procedure, 5 had two procedures, and 2 had three procedures. The median and mean times between tumor resection and SRS were 12 and 24 months (range: 1–90 months), respectively. Four patients had neurofibromatosis II (NF2). Based on location, tumors were classified as root type (7), ganglion type (22), or dumbbell type (21). The median radiosurgery target volume was 3.4 cm3 (range: 0.10–18 cm3), median target dose was 14 Gy (range: 12–20 Gy), and the median number of isocenters was 6 (range: 1–15). The median and mean times to last follow-up was 36.9 and 55.2 months (range: 4–205 months), respectively. Eighteen patients (36%) had longer than 5-year follow-up, and seven patients (14%) had longer than 10-year follow-up.

Results The tumor control rate was 92% and the clinical improvement or stabilization rate was 94%. After SRS, the rates of progression free survival (PFS) at 1, 5, and 10 years were 98, 84, and 84%, respectively. Factors associated with improved PFS were female sex (p = 0.014) and smaller tumor volume (p = 0.022). In this series, we did not find that tumor type (root, ganglion, and dumbbell) had a statistically significant correlation to PFS. Forty-seven patients had neurological signs or symptoms at presentation. At last follow-up, neurological signs or symptoms improved in 22/47 (47%), remained unchanged in 24/50 (48%), and worsened due to tumor progression in 3/50 (6%). One patient (2%) developed temporary symptomatic adverse radiation effect (ARE) and three additional patients (6%) had transient imaging evidence of peritumoral reactive edema but no new symptoms.

Conclusion As a single outpatient procedure, SRS was associated with long-term freedom from additional management in 84% of patients. Nearly half the treated patients experienced improvement in neurological symptoms or signs.

Keywords

stereotactic radiosurgery - gamma knife - trigeminal schwannoma


Publication History

Received: 24 March 2020

Accepted: 17 May 2020

Article published online:
14 August 2020

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