Peripheral nerveRadiosurgery for bilateral neurinomas associated with neurofibromatosis type 2
Section snippets
Current indications for radiosurgery
Of primary cerebellopontine angle tumors less than 30 mm in mean diameter, those that are growing constantly or progressively in a short period are indicated for radiosurgery. Usually larger tumors which may compress the brain stem in patients with no serviceable hearing are selected for the treatment. When serviceable hearing is preserved without any progression of neurological signs, simple observation is usually recommended. However, if hearing is lost bilaterally, both tumors are treated
Neurological outcome
There was no mortality during the mean follow-up period of 33.6 months (range, from 18 to 84 months). Neurological signs were stable in many cases, but some worsened because of progression of contralateral tumors. Ipsilateral hearing in the treated ear deteriorated further in eight cases, remained stable in three, and improved in one after some fluctuation. The other eight were already deaf at the time of radiosurgery and showed no change subsequently.
Contralateral hearing did not improve in
NF2 18-year-old male
Because of hearing deterioration, a right acoustic tumor was treated with the gamma knife with a marginal dose of 12.5 Gy. Although the treated tumor showed minor shrinkage at 30 months, the contralateral tumor apparently enlarged, causing facial palsy, and was treated with a second course of radiosurgery (12 Gy at the margin). Both hearing preservation and tumor control were achieved in this case (Figure 3 A,B).
NF2 49-year-old male
Radiosurgery to the right acoustic tumor (13.8 Gy at the margin) resulted in a
Tumor control
The majority of unilateral acoustic tumors have reportedly been controlled or reduced in size after radiosurgery 9, 11, 12, 15, 16. Noren et al [11] presented the results of 36 acoustic neurinoma patients who had radiosurgery with the gamma knife between 1975 and 1980, in which 92% tumor growth control was achieved in a mean follow-up of more than 12 years. These favorable results prompted us to use the same procedure for NF2 tumors.
Besides tumor control, there are a couple of important points
Conclusion
Radiosurgery can control the majority of acoustic tumors associated with NF2 for a long time, whereas 40% of contralateral (untreated) tumors continue to grow. Although hearing preservation is often difficult, preservation of facial nerve function is excellent compared with operative intervention. Therefore, radiosurgery should be incorporated in the treatment of bilateral acoustic tumors. Combined treatment with operation and radiosurgery is preferable in cases of large tumors.
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2022, Neurologic ClinicsNeurofibromatosis type 2 (NF2): Diagnosis and management
2013, Handbook of Clinical NeurologyCitation Excerpt :It successfully controls tumor growth in 66–100% of cases over a 5-year period (Linskey et al., 1992; Subach et al., 1999; Kida et al., 2000; Mathieu et al., 2007; Vachhani and Friedman, 2007; Meijer et al., 2008; Rowe et al., 2008; Phi et al., 2009). It also carries a 33–57% chance of preserving serviceable hearing over a 5-year period (Linskey et al., 1992; Subach et al., 1999; Kida et al., 2000; Mathieu et al., 2007; Meijer et al., 2008; Rowe et al., 2008; Phi et al., 2009). There is a 0–10% risk of significant permanent facial weakness although 10–17% of patients develop at least a transient weakness (Linskey et al., 1992; Kida et al., 2000; Mathieu et al., 2007; Meijer et al., 2008; Rowe et al., 2008).
Brain Tumors Associated with Neurofibromatosis
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