The middle clinoid process, a variation of parasellar region of sphonoid

Introduction Middle clinoid process (MCP) is a very important structure in surgeries performed on the parasellar and sellar regions. MCP is a bony eminence located on the body of the sphenoid, posteriorly to the anterior clinoid process and anteriorly to the posterior clinoid process. It becomes clinically important when it reaches the height of at least 1.5 mm. It can form many variations, the most common is the caroticoclinoid foramen. Aim To evaluate detailed knowledge, profound understanding of MCP and its role during parasellar region operations. Case study During studies at Department of Anatomy, a dry skull specimen projecting bilaterally clinically important MCP was found. This skull belonged to a 60 years old Caucasian male. Results and discussion It becomes clinically important when it reaches the height of at least 1.5 mm. The mean height measures 2.59 mm. MCP occurs in about 40% of the population. It can project either unilaterally or bilaterally. No significant differences between age or sex were observed. Conclusions Recognition of MCP or its variations on preoperative imaging is crucial for planning endonasal approach in treatment of paraclinoidal ICA aneurysm, pituitary adenomas or clinoidectomies.