Planum sphenoidale/orbital roof meningioma – delayed postoperative radiosurgery for recurrence

Skull Base Region	Planum Sphenoidale/Orbital Roof
Histopathology	Meningioma, WHO 1
Prior Surgical Resection	Yes
Pertinent Laboratory Findings	N/A

Case description

The patient is a 72-year-old male who developed nocturnal generalized seizures. Imaging demonstrated a tumor arising from the roof of the right orbit with significant surrounding edema ( Figure 2.9.1 ). He underwent a craniotomy and resection of the tumor and subsequently did well. He was tapered off his antiepileptic medications without seizures or neurological sequelae. On surveillance imaging, he was found to have a recurrence adjacent to the prior tumor along the planum sphenoidale at 2 years after surgery ( Figure 2.9.2 ). He underwent radiosurgery with 6 isocenters to cover a tumor volume of 272 cc (margin dose 16 Gy; maximum dose 32 Gy) ( Figure 2.9.3 ).

Radiosurgery Machine	Gamma Knife – Perfexion
Radiosurgery Dose (Gy)	16, at 50% isodose line
Number of Fractions	1

Critical Structure	Dose Tolerance
Optic nerve/chiasm	10 Gy maximum point dose <0.2 cc > 8 Gy, goal <6 Gy
Pituitary gland	Stalk-to-gland radiation dose <0.8

Side Effects/Complications	Frequency
Visual dysfunction	<1% with a limited dose
Olfactory dysfunction	34% change in smell with >5.1 Gy
Symptomatic edema	5%–43%

Success Rate/Control Rate	Frequency
Progression-free survival	97% at 5 years, 94.4% at 10 years
Local control	71%–100% at 10 years

Patient outcome

Postoperatively, the patient is doing well. The tumor remained stable in size for 6 years after stereotactic radiosurgery (SRS) ( Figures 2.9.4 and 2.9.5 ), and the patient is asymptomatic, without changes in vision. He continues to have satisfactory olfaction, without signs of radiotoxicity to surrounding structures.