Ju Hyung Moon, Won Seok Chang, Hyun Ho Jung, Kyu Sung Lee, Yong Gou Park and Jong Hee Chang
The aim of this study was to evaluate the tumor control rate and functional outcomes after Gamma Knife surgery (GKS) among patients with a facial nerve schwannoma.
The authors reviewed the radiological data and clinical records for 14 patients who had consecutively undergone GKS for a facial nerve schwannoma. Before GKS, 12 patients had facial palsy, 7 patients had hearing disturbance, and 5 patients had undergone partial or subtotal tumor resection. The mean and median tumor volumes were 3707 mm3 and 3000 mm3, respectively (range 117–10,100 mm3). The mean tumor margin dose was 13.2 Gy (range 12–15 Gy), and the mean maximum tumor dose was 26.4 Gy (range 24–30 Gy). The mean follow-up period was 80.7 months (range 2–170 months).
Control of tumor growth was achieved in all 12 (100%) patients who were followed up for longer than 2 years. After GKS, facial nerve function improved in 2 patients, remained unchanged in 9 patients, and worsened in 3 patients. All patients who had had serviceable hearing at the preliminary examination maintained their hearing at a useful level after GKS. Other than mild tinnitus reported by 3 patients, no other major complications developed.
GKS for facial nerve schwannomas resulted in excellent tumor control rates and functional outcomes. GKS might be a good primary treatment option for patients with a small- to medium-sized facial nerve schwannoma when facial nerve function and hearing are relatively preserved.
Hun Ho Park, Min Chul Oh, Eui Hyun Kim, Chan Yun Kim, Sun Ho Kim, Kyu-Sung Lee and Jong Hee Chang
The authors investigated the value of retinal nerve fiber layer (RNFL) thickness in predicting visual outcome after surgery for parachiasmal meningioma.
Forty-nine eyes of 25 patients who underwent craniotomy and resection of a parachiasmal meningioma were analyzed retrospectively. Visual parameters including visual field (VF) (recorded as the mean deviation [MD]), visual acuity (VA), and RNFL thickness (via optical coherence tomography) were measured before and 1 week, 6 months, and 1 year after surgery. Postoperative visual outcome was compared among the patients with a thin or normal RNFL. A separate analysis of data pertaining to 22 eyes of 13 patients with severe VF defects (MD ≤ −10 dB) was performed to compare visual outcome for those with a thin or normal RNFL.
Of the 23 eyes that showed VF improvement, 22 (95.7%) had normal RNFL thickness. The positive predictive value of normal RNFL thickness for VF improvement was 78.6%. The VF of patients with normal RNFL thickness improved in 6 months and continued improving 1 year after surgery (MD −5.9 dB before surgery, −5.5 dB 1 week after surgery, −2.8 dB 6 months after surgery [p < 0.01], and −1.1 dB 1 year after surgery [p < 0.01]). In contrast, those with a thin preoperative RNFL showed deterioration at first and then slower, worse visual recovery after surgery (MD −18.1 dB before surgery, −22.4 dB 1 week after surgery, −21.2 dB 6 months after surgery, and −19.1 dB 1 year after surgery). VA also showed significant progress 6 months after surgery in patients with normal RNFL thickness (0.6 before surgery, 0.7 one week after surgery, 0.9 six months after surgery [p = 0.025], and 0.9 one year after surgery [p = 0.050]) compared to those with a thin RNFL (0.3 before surgery, 0.2 one week after surgery, 0.3 six months after surgery, and 0.4 one year after surgery). Preoperative differences in VF MD and VA were noted between the 2 groups (p < 0.01). Even patients with severe VF defects and normal RNFL thickness improved by 11.1 dB by 1 year after surgery compared with patients with a thin RNFL (−0.01 dB) (p < 0.01). Patients with normal RNFL thickness also did better in VA improvement (from 0.7 to 1.1) than those with a thin RNFL (from 0.2 to 0.3), but these results were not statistically significant.
RNFL thickness measured by optical coherence tomography has significant value as a prognostic factor of postoperative visual recovery for parachiasmal meningioma. Patients with normal RNFL thickness before surgery are more likely to have visual improvement after surgery than patients with a thin RNFL.