PMC8571193_01
(a-d) Pre-SRS images of the left jugular foramen schwannoma: (a) pre-SRS axial enhanced T1-weighted MRI used in radiosurgery; (b) pre-SRS coronal enhanced T1-weighted MRI used in radiosurgery; (c) MR venography showing the obstructed left jugular bulb; (d) positron emission tomography with fluorodeoxyglucose. These images revealed a well-enhanced, dumbbell-shaped, solid mass extending to the intracranial- and extracranial space, causing expansion of the jugular foramen and invading the hypoglossal canal. (e-i) Chronological changes on axial enhanced T1-weighted MRI at the level of the internal auditory canal where brainstem compression was evident, and computed tomography at the time of the intratumoral hemorrhage; (e) pre-SRS; (f) tumor expansion was observed 5 days after SRS; (g) further expansion 5 months after SRS; (h) computed tomography indicating intratumoral hemorrhage 7 months after SRS; (i) evident tumor shrinkage at the last follow-up 4 years after SRS. SRS: stereotactic radiosurgery, MR: Magnetic resonance, MRI: Magnetic resonance image.
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The mass mildly compressed brainstem and had no evident sign of hemorrhage [Figure 1a and  1b]. MR venography demonstrated that the left jugular bulb was obliterated because of tumor compression [Figure 1c]. The tumor showed no signs of calcification or hypervascularity, and positron emission tomography with fluorodeoxyglucose did not exhibit increased uptake consistent with malignancy [Figure 1d] or any evidence of other tumors throughout the body. T1-weighted MRI at the level of the internal auditory canal indicated minimal brainstem compression before treatment [Figure 1e]. MRI on post-SRS day 5 showed tumor expansion without peritumoral edema [Figure 1f]. Although his symptoms improved, follow-up MRI at 5 months from SRS showed further tumor expansion with central necrosis and peritumoral edema, albeit asymptomatic [Figure 1g]. Imaging studies revealed intratumoral hemorrhage with exacerbation of peritumoral edema [Figure 1h]. He finally recovered almost completely within 2 months after the hemorrhage, and follow-up images at 4 years from SRS demonstrated significant tumor shrinkage [Figure 1i].