Absence and Duplicate Foramen Spinosum in the Same Patient: An Extremely Rare Variation.

The foramen spinosum, one of the important openings at the base of the cranium, is the opening through which the middle meningeal artery enters the cranium. The variations of the foramen spinosum should be well known to be an important landmark in middle fossa surgeries and to understand better the clinical conditions related to the middle meningeal artery passing through it. A total of 35 bones (32 cranial base and 3 separate sphenoid bones) of individuals of unknown age, sex, and ethnicity in the Laboratory of the Department of Anatomy, Gaziantep University, Faculty of Medicine were examined bilaterally in this study. One of the 35 bones was found to have a duplicated foramen spinosum on the left side and an absence foramen spinosum on the right side. Foramen spinosum variations should be considered in middle fossa approaches and procedures involving the middle meningeal artery.