Rare Case of Bilateral Coexistence of Caroticoclinoid Foramen, Inter-Clinoid Bar and Posterior Clinoid Foramen in a Dry Human Skull..

ABSTRACT

The superior surface of the body of the sphenoid is centrally occupied by sella turcica. The sella turcica has median depression called as hypophysial fossa; its anterior border is formed by tuburculum sella and posterior by dorsum sellae. It is surrounded by two anterior and posterior clinoid processes at its corners. Some parts of the sphenoid bone are connected by the ligaments that occasionally ossify.1 These ligaments have important relations with the surround vascular and neuronal structures. Hence such altered anatomy leads to difficulties or serious complications during surgical approach of this region in various conditions like aneurysm of internal carotid artery (ICA), caroticoclinoid fistula, pituitary adenoma and tuberculum sellae meningiomas etc.Knowledge of such variations would help radiologists and neurosurgeons in accurate diagnosis and treatment of the patients.Caroticoclinoid foramen (CCF) is an inconstant or abnormal anatomical feature formed due to ossification of a ligament between anterior and middle clinoid processes. It was first described by Henle (1855) as quoted by Mallik S and Sawant VG.2It was postulated that although ossification of the ligaments is normally age dependent physiological condition but CCF is an exception as its existence is seen even in the fetal and infant skull because of developmental anomaly.3The development of the sphenoid bone is complex has 18 or 19 ossification centers which may lead to early ossification of carotico-clinoid ligament.4CCF allows the passage of clinoid segment of the internal carotid artery.5 It may lead to compression, tightening or stretching and cause changes in the artery which reflects in compression of the cavernous sinus6. CCF may also cause endocrinal problems affecting hypothalamus or hypophysis cerebri and neurological problems by affecting oculomotor nerve, optic nerve or pituitary gland, which manifest in different ways as headache, behavioural changes, hormonal disturbances, visual problems, epileptic seizers, craniofacial disorders and tooth anomalies.7 Interclinoid osseous bar (ICB) results from ossification of the interclinoid ligament present between anterior and posterior clinoid processes.8 The osseous bridges represent a developmental anomaly of the embryonic chondrocranium.4 The ICB can be partial or complete; unilateral or bilateral.2 ICB may influence structures like trochlear nerve, oculomotor nerve, pituitary gland or remains as a normal variant. ICB is demonstrated radiologically in idiots, criminals, epileptics and cases of mental disorders.2,8Posterior clinoid foramen (PCF) is very rare and scarcely mentioned in the literature. Jolly Agarwal and Virendra Kumar recorded it in one specimen unilaterally (2.5%). PCF, when present exists on the sphenoid bone posterior to CCF. It is created between middle and posterior clinoid processes when the interclinoid bar is complete (i.e. between anterior and posterior clinoid processes).9