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Incidence, Anatomy and Clinical Significance of Carotico-clinoid Foramen and Interclinoid Osseous Bridge in Human Skulls in Gujarat Region |
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Binita J Purohit, Praveen R Singh 1. Assistant Professor, Department of Anatomy, Pramukhswami Medical College, Karamsad, Anand, Gujarat, India. 2. Professor and Head, Department of Anatomy Pramukhswami Medical College, Karamsad, Anand, Gujarat, India. |
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Correspondence Address : Dr. Binita J Purohit, Assistant Professor, Department of Anatomy, Pramukhswami Medical College, Karamsad, Anand-388325, Gujarat, India. E-mail: purohitbinita@gmail.com |
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| ABSTRACT |  | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
: Introduction: Carotico-clinoid foramen is an ossified carotico-clinoid ligament or a dural fold between anterior and middle clinoid processes situated in the middle cranial cavity. It is related to cavernous sinus, pituitary gland and sphenoidal air sinus. Interclinoid osseous bridge is the ossification of ligament or dural fold between anterior, middle and posterior clinoid processes. Aim: To observe incidence, anatomy and clinical significance of carotico-clinoid foramen and interclinoid osseous bridge in the Gujarat region. Materials and Methods: The present study was conducted in the Department of Anatomy, total 200 dry adult human skulls were examined to observe incidence, size, shape and various types of carotico-clinoid foramen (complete, contact, incomplete). The incidence of interclinoid osseous bridge was observed bilaterally and divided into four types. Result: The incidence of carotico-clinoid foramen was 10.5% (21 skulls out of 200). The foramen was bilaterally present in six (3%) and unilateral in 15 (7.5%). The incidence of complete and incomplete foramen was 11 (5.5%) and 10 (5%), respectively. The mean of maximum dimensions of carotico-clinoid foramen was 5.432±1.043 mm on right side and 5.623±0.651 mm on left side. The Type II interclinoid osseous bridge was found in four (2%) skulls. Type I bridge suggests carotico-clinoid foramen itself, while Type III and Type IV bridges were not found in the current study. Conclusion: The study of carotico-clinoid foramen has clinical importance as its presence can cause compression of internal carotid artery which may result into insufficient blood supply to brain. Further, the presence of this foramen and interclinoid osseous bridge can complicate neurosurgery in this region. Therefore, the detailed anatomical knowledge is very important for clinicians to increase success rate in the regional surgery. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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| Keywords : Internal carotid artery, Lesser wing of sphenoid, Middle cranial cavity | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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DOI and Others :
DOI: 10.7860/IJARS/2018/35641:2391
Financial OR OTHER COMPETING INTERESTS: None. Date of Publishing: Apr 15, 2018 |
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| INTRODUCTION |
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Lesser wing of sphenoid is an important bony structure which has been most often used landmark in neurosurgery. The projecting medial ends are called anterior clinoid processes which are connected to middle clinoid processes by the carotico-clinoid ligament or by a dural fold extending between these two processes. Occasionally, ossification of the ligament or dural fold results in formation of carotico-clinoid foramen (1). Thus, carotico-clinoid foramen is one of the inconstant foramen situated in the base of the cranial cavity. There are the other ligaments which connect certain parts of sphenoid bone which occasionally ossify. The pterygospinous ligament (between the spine of sphenoid and the upper part of the lateral pterygoid plate) and interclinoid ligament (between Keywords: Internal carotid artery, Lesser wing of sphenoid, Middle cranial cavity the anterior, middle and posterior clinoid processes) are the examples which sometimes get ossified (2). Internal carotid artery is the artery of ‘anterior circulation’ supplying majority of forebrain. The artery is divided into 3 parts-petrous part, cavernous part and intracranial part. After traversing through cavernous sinus it curves up medial to anterior clinoid process. Finally, the artery emerges through dural roof of cavernous sinus (1). The clinoidal segment of artery is situated in the collar of dural lining of cavernous sinus where it is completely encased by connective tissue. Here, the artery is situated between proximal and distal dural rings. The proximal (lower) ring is formed by medial extension of dura mater from lower surface of anterior clinoid process and distal (upper) ring is formed by medial extension of dura mater from upper surface of anterior clinoid process (2). Anterior clinoid process is usually removed in order to approach cavernous sinus and related structures in neurosurgery. The presence of carotico-clinoid foramen and interclinoid osseous bridge create obstacles while approaching anterior clinoid process in the regional neurosurgery and increases the risks, especially if aneurysm of internal carotid artery is present. Further, the high incidence of these structures has been reported in the subjects with hormonal disturbance, idiots, criminals and epileptics (3). Therefore, detailed anatomical knowledge of the carotico-clinoid foramen and interclinoid osseous bridge are requisite to obtain successful results while operating this region for various clinical conditions. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Material and Methods |
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This observational study was conducted in the Department of Anatomy at Pramukhswami Medical College and other medical colleges of Gujarat region from May 2013 to August 2016, after obtaining permission from the institutional Human Research Ethics Committee. The study included 200 intact dry adult human skulls. The skulls having crack or fracture lines in the region of orbit were excluded from the study. The anterior, middle and posterior clinoid processes were examined to note the presence of carotico-clinoid foramen and interclinoid osseous bridge. Three types of connection between anterior and middle clinoid processes were observed and divided according to classification of Keyes (4): i) Complete type-If complete foramen is present without having break. ii) Contact type-If suture is there between anterior and middle clinoid processes. iii) Incomplete type-If spicules of bone extended between anterior and middle clinoid process without any contact. Measurement of the foramen was taken along the maximum diameter, which is the transverse diameter. The complete type of foramina was measured along transverse diameter. The incomplete foramina were measured by passing ruler between the tips anterior and middle clinoid process. The incidence of interclinoid osseous bridge was observed too bilaterally and divided into four types according to classification proposed by Archana R et al., (5). Type I: Bridge present between anterior and middle clinoid process (carotico-clinoid foramen); Type II: Bridge between anterior, middle and posterior clinoid process; Type III: Bridge between anterior and posterior clinoid process; Type IV: Bridge between middle and posterior clinoid process. Statistical Analysis Mean and standard deviation of diameter (maximum dimension) were calculated for the carotico-clinoid foramen using SPSS version 14.0. The incidence of carotico-clinoid foramen and interclinoid osseous bridge were calculated too. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Results |
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Out of 200 skulls, the carotico-clinoid foramen was present in 21 (10.5%) skulls. The foramen was present in 12 (6%) skulls on right side, 16 (8%) skulls on left side. It was present unilaterally in 15 (7.5%) and the bilateral presence was noted in 6 (3%) skulls. The incidence of complete, contact and incomplete caroticoclinoid foramen is shown in the (Table/Fig 1). It is noteworthy that the ‘contact’ type of foramen was not found in the current study. Bilateral presence of the complete foremen (Table/Fig 2) and unilateral presence (Table/Fig 3). Bilateral incomplete caroticoclinoid foramen (Table/Fig 4). The mean maximum dimensions of this foramen were 5.432±1.043 mm on right side and 5.623±0.651 mm on left side. Interclinoid osseous bridge was found in four (2%) skulls (unilateral in three skulls and bilateral in one skull). Here, Type II bridge was found connecting anterior, middle and posterior clinoid processes in all these four skulls. Type I bridge suggests presence of carotico-clinoid foramen, which has separate narration in the present study. Type III and Type IV bridges were not found in the skulls observed in the current study. Bilateral presence of interclinoid osseous bridge with bilateral complete carotico-clinoid foramen (Table/Fig 5) and unilateral (left sided) interclinoid osseous bridge with bilateral complete foramen are shown in (Table/Fig 6). | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Discussion |
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Ossification in human body is a normal age dependent physiological process. Hochstetter F et al., and Kier EL stated that an osseous carotico-clinoid foramen and interclinoid osseous bridge are developmental anomalies and showed the existence of the same structures in fetal and infant skulls (6),(7). Thus, ossification of interclinoid ligament is not age dependent and results because of complex embryology of sphenoid bone which has 14 centres of ossification. Ossification of ligamentous structures can be possible reason for compression of neighbouring structures. Sometimes, they produce complications while performing regional surgery (2). The word ‘clinoid’ is derived from the Greek word ‘cline’ which means a bed and the meaning of ‘oid’ is inclined. The anterior and posterior clinoid processes form four corners of sella turcica. Here sella turcica can be resembled as ‘bed’ (8). “Clinoid space’’ is a small triangular area on the superior surface of cavernous sinus with thin underlying dura mater which becomes evident after removal of anterior clinoid process. The dimensions of the space vary according to size of anterior clinoid process. The space is located lateral to emergence of internal carotid artery from the cavernous sinus. The important fact is that an interclinoid osseous bridge can be possible reason for formation of complete bony ring around clinoid segment which affect the course of internal carotid artery (3). The incidence of carotico-clinoid foramen and interclinoid osseous bridge has been studied by various researchers in different populations (3),(4),(5),(9),(10),(11),(12),(14),(14),(15),(16),(17),(18),(19),(20),(21),(22),(23),(24) (Table/Fig 7). Out of 50 fresh autopsy bodies studied by Ozdogmus O et al., they found complete ossification of carotico-clinoid ligament in 27 sides and the incomplete one was observed in 55 sides of skull of autopsy case (2). Bilateral complete ossification of interclinoid ligament was found in three male autopsy cases. The presence of carotico-clinoid foramen can produce compression, stretching or tightening of internal carotid artery which give rise to headache and other neuronal symptoms due to insufficient blood supply to brain (2),(5),(20). The removal of anterior clinoid process is an important step of neurosurgery while approaching cavernous sinus for the management of proximal Internal carotid artery aneurysms. On the inferomedial aspect of anterior clinoid process, clinoid segment of internal carotid artery is situated. On the lateral wall of cavernous sinus, the oculomotor, trochlear, abducent and ophthalmic division of trigeminal nerve travel within a dural fold just below and lateral to anterior clinoid process. Among these four clinoid segment of internal carotid artery and Oculomotor nerve can be damaged during removal of anterior clinoid process (2),(5),(17),(20). Sometimes, anterior clinoid process can be pneumatised or the bone marrow may be having varying density. Therefore, the anterior clinoid process should be carefully drilled without injuring internal carotid artery and optic nerve. It is prerequisite that anterior clinoid process should be evaluated with computed tomography prior to regional surgery (3),(5),(17),(20). | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Acknowledgement |
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I am very grateful to the Professor and Head of Department of Pramukhswami Medical College, Karamsad; Government Medical College, Surat; Government Medical College, Vadodara; BJ Medical College, Ahmedabad; Sumandeep Medical College, Vadodara; Government Dental College, Ahmedabad and DDIT Dental College, Nadiad for allowing me to avail the facilities of the respective departments. I am also thankful to the staff members of respective departments for helping me in my project. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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