Anatomical variations and neurosurgical significance of Liliequist's membrane

Liliequist's membrane is an arachnoid membrane that forms a barrier within the basilar cisternal complex. This structure is an important landmark in approaches to the sellar and parasellar regions. The importance of this membrane was largely recognized after the advance of neuroendoscopic techniques. Many studies were, thereafter, published reporting different anatomic findings. A detailed search for studies reporting anatomic and surgical findings of Liliequist's membrane was performed using "PubMed," and included all the available literature. Manual search for manuscripts was also conducted on references of papers reporting reviews. Liliequist's membrane has received more attention recently. The studies have reported widely variable results, which were systematically organized in this paper to address the controversy. Regardless of its clinical and surgical significance, the anatomy of Liliequist's membrane is still a matter of debate.