Endoscopic removal of a suprasellar arachnoid cyst: an anatomical study with special reference to skull base.

BACKGROUND: Suprasellar arachnoid cysts are rare entities in adults, representing 10% of all cysts. Endoscopic treatment is now preferred for this pathology, allowing a new anatomical approach to skull base structures.

OBJECTIVES: The aim of this study is to present the relevant anatomy of the skull base viewed during an endoscopic procedure for a suprasellar arachnoid cyst.

METHOD: A 77-year-old man with 6 months history of walking disorder was referred for neurosurgical evaluation. Physical examination did not show any oculomotor or endocrine disorder. Sagittal T1-weighted MRI demonstrated a large suprasellar arachnoid cyst. The patient underwent a ventriculocystocisternostomy without complications. Postoperative neurologic examination showed an initial improvement of walking disorders. Cerebral CT scan showed a slight reduction in cyst dimensions.

RESULTS: During the endoscopic procedure, the anatomical view of the skull base was demonstrative. From the interior of the cyst we were able to identify the following structures: the clivus, pituitary stalk, pituitary gland, basilar artery, posterior cerebral arteries, posterior communicating arteries, oculomotor nerves and the superior wall of cavernous sinus. We identified a slit valve mechanism in the arachnoid next to the basilar artery.

CONCLUSION: Ventriculocystocisternostomy is a useful procedure in treating arachnoid cyst. Moreover, during this procedure, the endoscope allows for better and safer visualization of skull base structures.