PMC4628183_01
Case 1, first operation. A: Computed tomography (CT) scan shows bone erosion caused by expansile mass in the left petrous apex. B: T2-weighted magnetic resonance imaging (MRI) reveals a hyperintense mass in the left petrous apex. C: After removing the inferior posterolateral wall of the sphenoid sinus and cutting the cyst wall, a brownish fluid, typical of CG, flowed out. D: After debridement of the granuloma, the dura of the posterior fossa (asterisk) was identified through the fenestration (solid line). CG: cholesterol granuloma, IC: internal carotid artery, SS: sphenoid sinus.
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F1
Computed tomography (CT) of the petrous bone and skull base performed on admission showed an expansile mass in the left petrous apex with bone remodeling of the clivus and skull base (Fig. 1A). Magnetic resonance imaging (MRI) revealed a large left petrous apex mass abutting the sphenoid sinus (Fig. 1B). The inferior posterolateral wall of the sphenoid sinus, i.e., the clivus, was removed, revealing a large, dark, fluid-filled cyst in the petrous apex (Fig. 1C). The cyst was opened, drained, and widely marsupialized, and the dura of the posterior fossa was identified through the fenestration, measuring 15 mm in diameter (Fig. 1D).
Case 1, second operation. A: Preoperative T2-weighted magnetic resonance imaging (MRI) reveals obstruction by a scar (asterisk) at the fenestration site and reaccumulation of fluid in the cyst. The nasoseptal flap was partially overlaid (B), and a modified silicone T-tube (arrow) was placed in the drainage port (C). D, E: The schema and the T-tube. F: Two years after surgery, patent cyst fenestration was confirmed by fiberscopic examination after T-tube removal.
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F2
MRI revealed a scar occluded at the fenestration site and reaccumulation of fluid in the cyst (Fig. 2A). T-tube (RD-T drain, CREATE MEDIC Co., Yokohama, Kanagawa) was cut to 4 cm in length and placed into the cyst cavity with the flap (Fig. 2B-E). The postoperative course after the second operation was uneventful. Two years later, the T-tube was removed, and fiberscopic examination showed that the orifice of the cyst was preserved and covered with mucosa (Fig. 2F).
PMC4628183_02
Case 2. A: T1-weighted magnetic resonance imaging (MRI) reveals a hyperintense mass in the left petrous apex. B: A stoma created to allow drainage of the CG in the petrous apex. The septal flap was partially overlaid (C) and a modified silicone T-tube (arrow) was placed in the drainage port (D). E: Patent cyst fenestration was confirmed after T-tube removal by fiberscopic examination 1 year after surgery. F: T1-weighted MRI reveals no recurrence of the lesion in the left petrous apex. CG: cholesterol granuloma, SS: sphenoid sinus.
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F3
T1- and T2-weighted images in the left petrous apex, expanding into the posterior fossa (Fig. 3A). There was evidence of bony erosion on CT scan. A 1.5-cm stoma was created to allow the drainage of the CG in the petrous apex (Fig. 3B). After complete debridement of the cyst, a vascularized nasoseptal flap was elevated and overlaid around the drainage route (Fig. 3C). T-tube (RD-T drain, CREATE MEDIC Co.) was cut to 3 cm in length and placed with the flap to secure the drainage route (Fig. 3D). The patient recovered uneventfully and was discharged 7 days after the procedure. Fiberscopic examination demonstrated complete opening of the cyst, and the orifice was covered with the nasoseptal flap (Fig. 3E). At the 1-year follow-up, MRI showed no recurrence (Fig. 3F) and the patient reported significant improvement of her headache.