Unusual Cerebral Aneurysm after Stereotactic Radiosurgery to Treat Trigeminal Neuralgia.

Stereotactic radiosurgery is a treatment option for trigeminal neuralgia. This procedure is minimally invasive, but tumor development and facial numbness have been reported. Here, we report an unusual presentation after stereotactic radiosurgery to treat trigeminal neuralgia. A 60-year-old man demonstrated typical signs for type 1 trigeminal nerve neuralgia and was treated with medication for 5 years. Owing to an intolerance to that medication, he received stereotactic radiosurgery with 66 Gy. During a 9-year follow-up exam, dizziness with a spinning sensation was reported and a right superior cerebellar thrombosed aneurysm was diagnosed. He received transarterial embolization with coiling of aneurysm and subsequently reported no complications on follow-up exams. Although stereotactic radiosurgery is a promising treatment for trigeminal neuralgia, aneurysm development may be considered a possible complication. Long-term follow-up care of these patients should be considered. To understand the relationship between radiosurgery and the potential development of a cerebral aneurysm, further research is needed.

Quantitative comparison of endoscopically assisted endonasal, sublabial and transorbital transmaxillary approaches to the anterolateral skull base.

OBJECTIVES: The aim of this anatomical study is to make quantitative comparison among three endoscopic approaches, encompassing contralateral endonasal transseptal transmaxillary transpterygoid approach (contralateral EEA), endoscopic sublabial transmaxillary transalisphenoid (Caldwell-Luc) approach and endoscopic transorbital transmaxillary approach through inferior orbital fissure (ETOA), to the anterolateral skull base for assisting preoperative planning. DESIGN & PARTICIPANTS: Anatomical dissections were performed in four adult cadaveric heads bilaterally using three endoscopic transmaxillary approaches described above. SETTING: Skull Base Laboratory at the National Defense Medical Center. MAIN OUTCOME MEASURES: The area of exposure, angles of attack and depth of surgical corridor of each approach were measured and obtained for statistical comparison. RESULTS: The ETOA had significantly larger exposure over middle cranial fossa (731.40 ± 80.08 mm2 ) than contralateral EEA (266.60 ± 46.74 mm2 ) and Caldwell-Luc approach (468.40 ± 59.67 mm2 ). In comparison with contralateral EEA and Caldwell-Luc approach, the ETOA offered significantly greater angles of attack and shorter depth of surgical corridor (P < .05 for all comparisons). CONCLUSIONS: The ETOA is the superior choice for target lesion occupying multiple compartments with its epicentre located in the middle cranial fossa or superior portion of infratemporal fossa.

Endoscopic transorbital approach to anterolateral skull base through inferior orbital fissure: a cadaveric study.

BACKGROUND: Endoscopic transorbital approach (eTOA) has been announced as an alternative minimally invasive surgery to skull base. Owing to the inferior orbital fissure (IOF) connecting the orbit with surrounding pterygopalatine fossa (PPF), infratemporal fossa (ITF), and temporal fossa, the idea of eTOA to anterolateral skull base through IOF is postulated. The aim of this study is to access its practical feasibility. METHODS: Anatomical dissections were performed in five human cadaveric heads (10 sides) using 0-degree and 30-degree endoscopes. A stepwise description of eTOA to anterolateral skull base through IOF was documented. The anterosuperior corner of the maxillary sinus in the horizontal plane of the upper edge of zygomatic arch was defined as reference point (RP). The distances between the RP to the foramen rotundum (FR), foramen ovale (FO), and Gasserian ganglion (GG) were measured. The exposed area of anterolateral skull base in the coronal plane of the posterior wall of the maxillary sinus was quantified. RESULTS: The surgical procedure consisted of six steps: (1) lateral canthotomy with cantholysis and preseptal lower eyelid approach with periorbita dissection; (2) drilling of the ocular surface of greater sphenoid wing and lateral orbital rim osteotomy; (3) entry into the maxillary sinus and exposure of PPF and ITF; (4) mobilization of infraorbital nerve with drilling of the infratemporal surface of the greater sphenoid wing and pterygoid process; (5) exposure of middle cranial fossa, Meckel's cave, and lateral wall of cavernous sinus; and (6) reconstruction of orbital floor and lateral orbital rim. The distances measured were as follows: RP-FR = 45.0 ± 1.9 mm, RP-FO = 55.7 ± 0.5 mm, and RP-GG = 61.0 ± 1.6 mm. In comparison with the horizontal portion of greater sphenoid wing, the superior and inferior axes of the exposed area were 22.3 ± 2.1 mm and 20.5 ± 1.8 mm, respectively. With reference to the FR, the medial and lateral axes of the exposed area were 11.6 ± 1.1 mm and 15.8 ± 1.6 mm, respectively. CONCLUSIONS: The eTOA through IOF can be used as a minimally invasive surgery to access whole anterolateral skull base. It provides a possible resolution to target lesion involving multiple compartments of anterolateral skull base.