| SKULL BASE REGION | Meckel’s cave and prepontine cistern |
| HISTOPATHOLOGY | N/A |
| PRIOR SURGICAL RESECTION | No |
| PERTINENT LABORATORY FINDINGS | N/A |
Case description
The patient is a 50-year-old female patient with a known history of a tuberculum sellae meningioma status post microsurgical resection. She also has had a dumbbell-shaped lesion—most likely a trigeminal schwannoma (TS)—for 7 years. The TS exhibited a volumetric increase in size during follow-up ( Figure 5.20.1 ). The patient remained asymptomatic from this lesion. A Gamma Knife radiosurgery (GKR) treatment was recommended, and the patient agreed to proceed with this treatment option ( Figure 5.20.2 ).
| Radiosurgery Machine | Gamma Knife – Icon |
| Radiosurgery Dose (Gy) | 12, at the 50% isodose line |
| Biologically Effective Dose (Gy) | 69.9 Gy |
| Number of Fractions | 1 |
T1-gadolinium injected MRI in the axial plane showing a dumbbell-shaped lesion, with components within both Meckel’s cave and the prepontine cistern, the latter of which is in contact with the brainstem.
From left to right and up to down: multimodal radiosurgery stereotactic neuroimaging including T1 noninjected, T1-gadolinium injected, T2 CISS/Fiesta noninjected, and T2 CISS/Fiesta injected MRI. The dosimetry is colored in yellow and corresponds to the 12-Gy marginal dose prescription. CISS, Constructive interference in steady state.
| Critical Structure | Dose Tolerance |
|---|---|
| Brainstem | Marginal dose is 12 Gy, although there is contact between TS and brainstem; the risk of adverse radiation events (ARE) at the brainstem level remains virtually zero due to such a low marginal dose prescription |
| Side Effects/Complications | Frequency |
|---|---|
| Pseudoprogression | 2.2%–37.5% |
| Trigeminal nerve dysfunction | Up to 30%, usually transient |
| Increased pain | 10% |
| Expansion/enlarged cyst | 11% |
Related posts:
Esthesioneuroblastoma – delayed postoperative radiosurgery for recurrence at long-term
Null cell – delayed postoperative radiosurgery for growing perioptic residual
Chordoma – immediate postoperative/post-proton therapy radiosurgery for residual disease
Trigeminal neuralgia due to microvascular conflict – upfront radiosurgery
Capillary hemangioma – postoperative radiosurgery for residual tumor
Superior sagittal sinus meningioma – delayed postoperative, multisession radiosurgery for growing residual
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
