Radio-anatomic variability in sphenoid sinus pneumatization with its relationship to adjacent anatomical structures and their impact upon reduction of complications following endonasal transsphenoidal surgeries

Sphenoid sinus is deeply located in the neurocranium of skull and is the most inaccessible paranasal air sinus. A disease of the sphenoid sinus is difficult to diagnose so that it requires a high index of suspicion and multi-detector radiological imaging techniques and surgical biopsy. Moreover, compared with other paranasal air sinuses, the sphenoid sinus is considered the most variable sinus in terms of its patterns of pneumatization, number and inter-sphenoidal sinus septal deviation and its relationship with the surrounding anatomical structures. Thus, the study of sphenoid sinus pneumatization has increased added importance due to newer developments in trans-sphenoidal sinus surgeries and its utility in assessing the complications involving the cranial cavity. Though extensive pneumatization of sphenoid sinus facilitates free routes of endoscopic trans-sphenoidal surgeries, it poses an increased risk of nerve lesions, intracranial hemorrhage, CSF leakage, sinusitis and destructive bone erosions. In this review, we tried to present the variability of patterns of sphenoid sinus pneumatization with related neurovascular structures, a discrepancy of intra-sphenoid sinus septa and the presence of unusual central Onodi cells among racial variants across different geographical or ethno-geographical diversity. A literature search of PubMed, Google Scholar, and Embase databases was performed.Much progress has been made on the radio-anatomical assessments of the sphenoid sinus, but none of these studies reported the sphenoid sinus pneumatization and its relationship with cavernous sinus, abducens nerve and ophthalmic artery. So, further study is needed to show frequent association of these structures with sphenoid sinus pneumatization