Juglar foramen schwannomas are benign tumors located in jugular foramen, hey can arise from cranial nerves IX,X or XI, with IX being the most common. Jugular foramen schwannomas (JFS), can present with various symptoms depending on the size and the anatomic location of the tumor. They are a rare type of tumors accounting for 2-4 % of all intracranial schwannomas. The patients can present with hearing loss, hoarseness of voice, ataxia, difficulty in swallowingand headache.
There are four types of tumor which are classified radiologically by their growthpattern: Type A (intracranial type), Type B (intraosseous type), Type C (extracranial type),and Type D (intra- and extracranial type). Resection has been considered as the primarytreatment option for JFS. However, complete resection is often difficult because of theanatomical location of the tumor and its relationship to adjacent critical cranial nerves, brain,and vascular structures. Stereotactic radiation therapy has been considered as an equally goodand safer alternative to surgery, especially for small volume tumors. It has a high tumorcontrol rate, a high rate of cranial nerve preservation, and low morbidity. The median margindose prescribed in various institutions is 12.5 Gy (range 10–18 Gy).
We had a 59 year old diabetic and hypertensive male who presented with hoarseness of voice and difficulty in speaking. There was no difficulty in swallowing. He was physically examined and investigated for the same. CECT of the neck and brain was done which was normal. Then he was advised MRI of the brain, which revealed a well-defined lobulated extra axial lesion measuring 13.7 x 9.8 x 10.0 mm, seen within the left jugular foramen, expanding it and projecting into the left cerebello- medullary cistern (Figure1). It appeared iso to hypointense on T1 and hyperintense on T2/Flair. It was causing compression on the IX, X and XI cranial nerves. Features were suggestive of jugular foramen schwannoma. Our patient belonged to type A category radiologically.
The patient was given the option of surgical resection Vs stereotactic radiosurgery. All the pros and cons of both the therapies were explained in detail. Patient chose stereotactic radiosurgery (SRS) in view of non-invasive technique. After proper consent, patient was taken for planning of radiation. He was immobilized using stereotactic head thermoplastic cast with rigid mouth and head fixation. Then CECT scans were acquired at 1mm slice thickness and imported in Monaco TM treatment planning system (TPS) for planning. The CECT images were fused with MRI images for delineation of the tumor and other critical structures delineation. Proper optimization followed by Monte Carlo dose calculation algorithms were used for SRS plan generation. Finally, he underwent SRS treatment on 6MV Linear Accelerator using micro multileaf collimator to the localized and marked portal. The tumor volume was 1.01cc. The prescribed dose to tumor was 15 Gy in single fraction. The 80% isodose line coverage to tumor was ensured to 98.7% volume (Figure 2). The mean dose to tumor/Planned target volume (PTV) was 14.58 Gy. In addition, dose received by nearby critical organs such as cochlea, brain stem, left optic nerve, right optic nerve and optic chiasm were found well within the tolerance level. As of now, patient is improving, and his repeat MRI scan is to be done.
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