Analysis of variations in morphological characteristics of orbito-meningeal foramen: An anatomical study with clinical implications

Introduction: The aim of present study was to undertake detailed analysis of variations in morphology of orbito-meningeal foramen (OMF), a clinically relevant entity due to possible association with major arterial branches. Materials & methods: The study was conducted on 70 bony orbits of 35 dry adult human skulls. Precise identification of OMF's were ensured and other known bony canals in the orbit were excluded. All observations and measurements were undertaken by two observers independently to reduce chances of error. Results: Overall incidence of OMF was 71.24% (left side 76% and right side 68%) and were present as single entity in orbit in most cases (80.56%) with multiplicity noted. The OMF's in present study were classified according to three parameters: size of lumen (large/medium/small), termination of canal in cranial fossa (M-Type/A -Type/ND Type) and bony component of orbit where it was located (frontal/sphenoid/fronto-sphenoid suture). Variations were noted regarding the morphology of OMF across all the three parameters in comparison to published literature. Most of the large OMF (80%) were of M-Type (opened in the middle cranial fossa). M-Type of OMF were single entities in 78.26% cases and were distributed proportionately across all three bony components of orbit. Conclusion: Based on analysis of findings it is suggested that presence of solitary OMF with large (>0.3 mm) lumen in any of the three bony components of orbit is mostly M-Type and has a high possibility of a major arterial branch passing through it. Findings could be useful towards pre-operative workup before orbital surgeries. Knowledge regarding the variations in morphological details of OMF may reduce the risk of inadvertent vascular injury in orbital region