eISSN 1308-4038 International Journal of Anatomical Variations (2010) 3: 149–150 Case Report

The caroticoclinoid foramen formation in the human skull and its clinical correlations

Published online September 24th, 2010 © http://www.ijav.org Alexandre Rodrigues FREIRE [1] ABSTRACT [1] Ana Cláudia Rossi Numerous structures of the skull are well defined in literature. But there are some inconstant structures, which Felippe Bevilacqua PRADO [1] when present may be located in the sphenoid bone by the junction of the anterior and middle clinoid processes. Paulo Henrique Ferreira CARIA [1] The aim of this study was to evaluate the characteristics of caroticoclinoid foramen in Brazilian human skull. [2] This case report shows a female dry human skull with 2 caroticoclinoid foramina. The largest diameter of this Paulo Roberto BOTACIN structure was found 5.5 mm on the right side and 5.4 mm on the left. Although being an uncommon foramen, the knowledge is important because it is located in the sphenoid bone, an important region for neurosurgery. © IJAV. 2010; 3: 149–150.

Department of Morphology, State University of Campinas - UNICAMP, Piracicaba [1], Department of Basic Sciences, Paulista State University - UNESP, Araçatuba [2], SP, BRAZIL.

Mr. Alexandre Rodrigues Freire Postgraduate Student Department of Morphology State University of Campinas UNICAMP, Piracicaba, SP, BRAZIL. +55 19 21065200 [email protected]

Received February 8th, 2010; accepted August 4th, 2010 Key words [caroticoclinoid foramen] [human skull] [neurosurgery]

Introduction fossa, and related medial to the anterior clinoid process The caroticoclinoid foramen is an inconstant structure and lateral to the tuberculum of sella turcica. It was also which is located in the anterior cranial fossa, composed located posterior to the optic canal and anterior to the by the ossification of a fibrous ligament [1] that begins pituitary fossa, as was observed in this case (Figure 1). on the anterior clinoid process and binds to the middle The morphometry of each foramen was performed using clinoid process [2]. Caroticoclinoid foramen, allows the a manual caliper. The larger transverse diameter was passage of one of six segments of the internal carotid measured, from the edge formed by the ossified ligament artery, the clinoidal segment [3]. until the edge formed by the anterior clinoid process. To The fibrous ossification of ligaments is considered a avoid errors in measurement, it was performed three normal physiological process that occurs with aging, times by the same examiner being regarded as the however this process is an exception when one considers repeated values. The diameter of the foramen was 5.5 the formation of the caroticoclinoid foramen [4]. Study mm on the right side and 5.4 mm on the left. by Hochstetter [5] revealed the presence of this foramen Discussion in fetuses and children skulls. Caroticoclinoid foramen is formed after the ossification The aim of this study was to evaluate the characteristics of the fibrous ligament that connects the anterior and of caroticoclinoid foramen in a Brazilian dry human middle clinoid processes. When there is no ossification skull and the clinical influences that this structure of the fibrous ligament in the dry skull only a space may generate, covering an area where neurosurgical between the anterior and middle clinoid processes is operations are common. observed (Figure 2). Case Report In this case, the foramen observed had a diameter of 5.5 This work reports about caroticoclinoid foramen, on both mm on the right side and 5.4 mm on the left, similar to sides, encountered in a dry adult human skull, female, results reported by Ozdogmus et al. [4], who performed belonging to the anatomy laboratory of the Department measurements of the caroticoclinoid foramen in 50 of Basic Sciences, Faculty of Dentistry of Araçatuba, human autopsies (average of 5.14 mm on the right side Paulista State University. The anterior clinoid process and 5.25 mm on the left); there was no statistically was intact and there was complete ossification of the significant difference when comparing gender and age. fibrous ligament between anterior and middle clinoid Erturk et al. [6] measured the diameter of the distal processes. This foramen was located in the middle cranial area of internal carotid artery in its clinoid segment and 150 Freire et al.

In clinical practice, when occurs a paraclinoid aneurysm, the anterior clinoid process is removed as a treatment OC [8]. In this treatment there is more difficulty when the CCF caroticoclinoid foramen is present, causing higher TS possibility of serious bleeding in this region [10]. Due to the great caliber of internal carotid artery in this region, the possibility of headache due to compression by the foramen is high [4]. This feature is crucial for the choice of surgical removal of the anterior clinoid process. ACP PF OL After the removal of the anterior clinoid process, a space MCP is observed: the clinoid space, which has triangular shape and small size [7]. Sekhar and Akin [11] affirmed that this space varies according the dimensions of anterior clinoid process and the internal carotid artery [11]. Furthermore, their work showed the position of the caroticoclinoid foramen in an area close to the one occupied by the Figure 1. Internal view of skull with the caroticoclinoid foramen and cavernous sinus. The formation of the caroticoclinoid adjacent structures. (CCF: caroticoclinoid foramen; ACP: anterior foramen may change the dimensions of this area [11], clinoid process; OL: ossified ligament; MCP: middle clinoid process; considered by some authors as intracavernous [8]. Other OC: optic canal; TS: tuberculum sellae; PF: pituitary fossa) authors consider it as an area outside the cavernous sinus [2,3]. The formation of the caroticoclinoid foramen may cause changes in the internal carotid artery, especially in clinoid TS segment, when comparing the transverse diameter of these structures. Thus, it is concluded that the presence of this foramen has important clinical implications, and its knowledge is required for better planning of surgical ACP treatments that involve this region. MCP References

[1] Standring S. Overview of the Development of the Head and Neck Head: Skull and Mandible. In: Standring S, ed. Gray’s Anatomy: the Anatomical Basis of Clinical Practice. 39th Ed., New York, Elsevier. 2005; 462–467. [2] Sicher H, Du Brul EL. Oral Anatomy. 6th Ed., Saint Louis, The C.V. Mosby Company. 1975; 12. [3] Williams PL, Warwick R, Dyson M, Bannister L. Gray’s Anatomy. 37th Ed., Edinburgh, Churchill Livingstone. 1989; 373–377. Figure 2. Internal view of skull with absence of the ossified ligament [4] Ozdogmus O, Saka E, Tulay C, Gurdal E, Uzun I, Cavdar S. The anatomy of the carotico-clinoid foramen between anterior and middle clinoid processes. (TS: tuberculum and its relation with the internal carotid artery. Surg Radiol Anat. 2003; 25: 241–246. sellae; ACP: anterior clinoid process; MCP: middle clinoid process) [5] Hochstetter F. Über die Taenia interclinoidea, die Commissura alicochlearis und die Cartilago supracochlearis des menschlichen Primordialkraniums. Gegenbaurs Morph Jahrb. 1940; 84: 220–243. (German) found an average diameter of 5.24 mm on the right side [6] Erturk M, Kayalioglu G, Govsa F. Anatomy of the clinoidal region with special emphasis on the and 5.25 mm on the left, diameters were larger than the caroticoclinoid foramen and interclinoid osseous bridge in a recent Turkish population. Neurosurg Rev. caroticoclinoid foramen. 2004; 27: 22–26. The formation of this foramen may cause compression [7] Inoue T, Rhoton AL Jr, Theele D, Barry ME. Surgical approaches to the cavernous sinus: a microsurgical and narrowing of the internal carotid artery, located study. Neurosurgery. 1990; 26: 903–932. medially to the anterior clinoid process [4]. Changes in [8] Seoane E, Rhoton AL Jr, de Oliveira E. Microsurgical anatomy of the dural collar (carotid collar) and internal carotid artery may cause compression of the rings around the clinoid segment of the internal carotid artery. Neurosurgery. 1998; 42: 869–886. cavernous sinus because of its medial position [7,8]. The [9] Das S, Suri R, Kapur V. Ossification of caroticoclinoid ligament and its clinical importance in skull-based study by Das et al. [9] shows that the presence of the surgery. Sao Paulo Med J. 2007; 125: 351–353. caroticoclinoid foramen causes morphological changes [10] Narolewski R. Significance of anatomic variants of bony surroundings of the internal carotid artery and in the internal carotid artery in almost all cases. These their significance for lateral surgical approaches to the cavernous sinus. Ann Acad Med Stetin. 2003; variations occur due to the presence of foramen, which 49: 205–229. (Polish) cause difficulty in performing a neurosurgical technique [11] Sekhar LN, Burgess J, Akin O. Anatomical study of the cavernous sinus emphasizing operative in the region [7]. approaches and related vascular and neural reconstruction. Neurosurgery. 1987; 21: 806–816.