Surgical Anatomy and Morphometric Analysis of the Occipital Condyles and Foramen Magnum

Abstract

Summary: Surgical anatomy that provides the basis for dealing with lesions arising in the lower clivus and ventral foramen magnum was reviewed in 8 adult cadaver heads and 76 dry skulls. The extreme lateral transcondylar approach was performed in cadavers; the morphometric analysis was studied in both the cadavers and the skulls. The landmarks, distances and structures were selected in order to guide the surgical operations in this area. In the paper, surgical approaches to this region are reviewed, and the results are discussed from the standpoint of surgical importance.There are many kinds of pathological processes that involve the craniovertebral junction. These lesions include intradural tumors such as meningiomas, neurinomas or vascular lesions such as aneurysms and arteriovenous malformations of the vertebral artery and vertebrobasilar junction, extradural tumors such as chordomas, basilar invagination and other congenital anomalies, nontraumatic (rheumatoid) and traumatic entities with C1-C2 subluxation. Anterior cranial base approaches are appropriate for surgical management of extradural lesions which are localized strictly to the midline. Basilar invagination and congenital anomalies, rheumatoid compression of the craniocervical region, and some traumatic lesions can be treated successfully using the transoral") and transmaxillary1 3) procedures or the mandibular swing-transcervical approach1). For intradural lesions, the transoral, transmaxillary and transmandibular approaches can still be utilized"• 14'16), but are suboptimal because of the lack of proximal and distal vascular control, limited lateral exposure and the possibility of contamination of the cerebrospinal fluid with oral flora resulting in lifethreatening meningeal infection. Suboccipital approach, with or without upper cervical vertebral laminectomy, is the traditional approach used for intradural lesions of the posterior fossa and craniovertebral junction, but in case the lesion is placed ventrally, this approach provide very poor exposure and required retraction of the brainstem.The extreme lateral transcondylar and transjugular approach (ELTCA) offers a very lateral view of the structures located at the lower diva! area and craniovertebral junction. This lateral cranial base approach permits a controlled resection or reconstruction of the lesions in this area through direct view of the vertebral artery, lower cranial nerves, and the interface between the lesion and the brainstem. It is also possible to achieve an occiput-to-C1-3 fusion during the same operation, if necessary. Furthermore, because there is a wellvascularized muscle covering of this area, reconstruction of the operative field is perfect and infectious or vascular complications in the postoperative period oftenly can be managed with good results2,3,5,8,20,2 1). Surgical anatomy of the occipital condyles (0C) is critical for ELTCA, and this study aims to study surgical anatomical and morphometric details of the relevant region.

Morphological Analysis of Occipital Condyles and Foramen Magnum as a Guide for Lateral Surgical Approaches

“…Comparison of our findings with earlier studies is shown in Table 4. The measurements in these studies are similar in value, except for the posterior intercondylar distance measured by Bozbuga et al [41] which is lower, possibly due to different reference points taken for the measurement.…”

Morphological Analysis on the Occipital Condyles and Review of the Literature

“…Several classifications have been created to define different morphological types of occipital condyle, but without determining the prevalence of each of these types (Bozbug˘a et al;Olivier, 1975;Guidotti, 1984). Guidotti analyzed 741 skulls belonging to the Institute of Anatomy of the University of Siena and propose a classification of occipital condyles based on (1) division of their surface into planes; (2) partition without interruption of the joint surface; (3) partition with an evident angle but without separation of the two surfaces; and (4) Table II shows the variance and discordance regarding the morphological types of occipital condyles, along with their prevalence.…”

“…There are several anatomical studies in the literature reporting the importance of morphometric variations of the occipital condyles (Kumar & Nagar, 2014, Kavitha et al, Natsis et al, Bayat et al, Das et al, Naderi et al, Ozer et al, Kizilkanat et al, Muthukumar et al, Avci et al, 2011, Bozbug˘a et al, 1999, Kalthur et al, 2014, El-Gaidi et al, 2014, Gapert et al, 2009) and radiological studies have also been conducted (Avci et al, Le et al, 2011, Hong et al, 2011, Noble & Smoker, 1996. Knowledge of the topography of different neurovascular structures located around the region of the occipital condyles is highly important with regard to conducting neurosurgical procedures (transcondylar approach) and obtaining good results.…”

Morphometry of the Occipital Condyle and Basilar Process of Nigerian Skulls

“…[5][6][7][8] The occipital condyle (OC) and basilar process (BP) are structures located at the skull base which forms part of the floor of the cranial cavity which by location, differentiates the brain from facial structures and suprahyoid neck (Rautet al, 2012). [9] Name & Address of Corresponding Author Aigbogun (Jr) [8,13,14] with higher values reported for the Asians (Bozbugaet al, 1999; Yu et al, 2015; Salujaet al, 2016), [14][15][16] and lower values for the Caucasians and Australians (Wen et al 1997;Bazyatet al, 2014), [17,18] while for Africans the values fall between values of Asians and Caucasians (Salihet al, 2014; Agnihotriet al, 2014). [19,20] Only a few studies have reported morphometric values for the basilar process (clivus), with dimensions ranging from 24mm to 27mm (Oliviera, 1975; Wescott and Moore-Jansen, 2001), [21,22] and higher values for whites when compared to blacks (Wescott and Moore-Jansen, 2001).…”

“…[19,20] Only a few studies have reported morphometric values for the basilar process (clivus), with dimensions ranging from 24mm to 27mm (Oliviera, 1975; Wescott and Moore-Jansen, 2001), [21,22] and higher values for whites when compared to blacks (Wescott and Moore-Jansen, 2001). [22] Le et al, 2011; [13] Bozbugaet al, 1999; [14,15] Yu et al, 2015 Lang and Hornung, 1993; [23] have suggested that the inconsistencies in the morphometric values of the OC in different population could be attributed to differences in data acquisition, methodology and genetic endowment. Good knowledge of the morphometry of the occipital condyles are very important in surgical interventions, for example, the need to carryout OC recession during various surgical approaches to pathological conditions at the posterior part of the cranial base (Agnihotriet al, 2014; Kalthuret al, 2014; Parvindokhtet al, 2015).…”