Int J Anat Res 2015, 3(2):1039-42. ISSN 2321-4287 1039

Case Report

OSSIFICATION OF CAROTICOCLINOID AND PETROSPHENOIDALLIGAMENTS OF SKULLKavitha Kamath.B *1, Vinayak Kamath 2.

ABSTRACT

Address for Correspondence: Dr. Kavitha Kamath.B, Assistant Professor, Department of Anatomy,Shimoga Institute of Medical Sciences, Sagar Road, Shimoga, Karnataka. 577201, India.E-Mail: drkavithakamath@rediffmail.com

*1 Assistant Professor, Dept of Anatomy, Shimoga Institute of Medical Sciences, Shimoga, Karnataka,India.2 Lecturer, Dept of Public health dentistry, A.B Shetty Institute of Dental Sciences, Derlakatte,Mangalore, Karnataka, India.

Ossification of various ligaments in the body may result in clinical symptoms due to compression ofneighbouring structures and complications in regional surgeries. This case reports of a dry skull that presentedwith two rare bony anomalies - caroticoclinoid and petrosphenoid bridges. Simultaneous occurrence of boththese anomalies is a unique morphological event with neurovascular implications. Considering the fact thatmajority of textbooks in anatomy do not provide a detailed description of these entities, the present report isvery much relevant for neurosurgeons and radiologists in day to day practice.KEY WORDS: Caroticoclinoid ligament, petrosphenoidal ligament, clinoid processes, abducent nerve, internalcarotid artery.

INTRODUCTION

International Journal of Anatomy and Research,Int J Anat Res 2015, Vol 3(2):1039-42. ISSN 2321- 4287

DOI: http://dx.doi.org/10.16965/ijar.2015.152

Access this Article online

Quick Response code Web site:

Received: 30 Mar 2015 Accepted: 27 Apr 2015Peer Review: 30 Mar 2015 Published (O):31 May 2015Revised: None Published (P):30 June 2015

International Journal of Anatomy and ResearchISSN 2321-4287

www.ijmhr.org/ijar.htm

DOI: 10.16965/ijar.2015.152

A myriad of intricate structures are found in thepetroclival region, which are especiallyimportant in procedures involving the skull base.Knowledge of anatomy of this area is essentialfor successful surgical treatment of lesions inthis region. Surgical approaches to the clivus,petroclival region and cavernous sinus requirean excellent knowledge of the anatomy of thisregion [1].Ossification of ligaments around the sellaturcica may give rise to bony bridges thatconnect the clinoid processes with othersurrounding structures. These sellar bridges candevelop unilaterally or bilaterally and vary infrequency [2]. As a result of abnormal develop-

ment in anterior, middle and posterior clinoidprocesses, these bony structures could fuse,forming osseous bridges. Bridge formation couldeither occur between the anterior and middle(caroticoclinoid bridge forming caroticoclinoidforamen of Henle), the anterior and posterior orbetween middle and posterior clinoid processes.In addition, a bony bridge could also developbetween the posterior clinoid process andsuperior margin of petrous part of temporal bone,the sphenopetrous bridge [3]. The caroticoclinoid foramen is an inconstantstructure of the middle cranial fossa, formed byossification of the fibrous interclinoid ligamentor dural fold between the anterior and middleclinoid process. It allows the passage of the

Int J Anat Res 2015, 3(2):1039-42. ISSN 2321-4287 1040

Kavitha Kamath.B, Vinayak Kamath. OSSIFICATION OF CAROTICOCLINOID AND PETROSPHENOIDAL LIGAMENTS OF SKULL: A CASEREPORT.

CASE REPORT

clinoid segment of internal carotid artery as itturns upwards to supply the brain [4]. Thepresence of ossified caroticoclinoid ligament islikely to cause compression, tightening orstretching of internal carotid artery [5].The petrosphenoidal ligament (Gruber’sligament) is located between the petrous apexand posterior clinoid process and forms the roofof Dorello’s canal through which the abducentnerve passes [1]. Dorello’s canal was describedby Gruber in 1859 as an osteofibrous canal(foramen petro-sphenoideum) located at theapex of petrous bone containing the abducentnerve, inferior petrosal sinus and dorsalmeniningeal branch of meningohypophysealtrunk [1,6,7]. Clinicians might considerossification of petrosphenoidal ligament inunexplained cases of abducent nerve palsy [6].Records of the variations stated above are veryfew in medical literature and their simultaneousoccurrence in same skull is exceptional andrequires reporting. Descriptions of such entitiesare important because of their applicability insurgical interventions involving regionsurrounding the sella turcica.

During routine osteology classes for first yearmedical students of 2013-14 batch, bilateralcomplete caroticoclinoid bridges were seenextending from anterior to middle clinoidprocess resulting in the formation of bilateralcaroticoclinoid foramina which were circular inshape with smooth outline. They were located

Fig. 1: Showing bilateral completecaroticoclinoid bridges and right sidedcomplete petrosphenoidal bridge.

(CCB- Caroticoclinoid bridge, CCF-Caroticoclinoid foramen, ACP-Anteriorclinoid process, MCP- Middle clinoidprocess, PCP- Posterior clinoid process,PSB- Petrosphenoidal bridge, PTB-Petrous part of temporal bone. OC- Opticcanal)

anterolateral to sella turcica, medial tosuperior orbital fissure and behind the opticcanal on both sides. In addition, a completelyossified petrosphenoidal ligament was seenextending from apex of petrous temporal boneto the posterior surface of posterior clinoidprocess on right side of skull forming anelliptical bony foramen beneath this bridge.

DISCUSSION

Incidence of caroticoclinoid foramen in variousstudies ranged between 6.27-36% [4,8-10].Unilateral and incomplete caroticoclinoidforamen are more common than bilateral andcomplete foramen [4,10,11]. The incidenceshows racial trends; showing high occurrencein Turks, Americans, Portuguese, Nepalese andlow in Brazilians, Japanese, Koreans and Indians[4,9-13].The caroticoclinoid bridge could cause pressureon the internal carotid artery that lies in thecavernous sinus, changing the morphology in theterminal end of the groove of internal carotidartery [3]. Due to greater calibre of internalcarotid artery in this region compared to thediameter of caroticoclinoid foramen, thepossibility of headache due to compression bythe foramen is high. Caroticoclinoid foramen isan important structure due to its relations withcavernous sinus and its contents, sphenoid sinusand pituitary gland [5]. On one hand a wideforamen may provide safety cover for the artery;on the other hand it may confuse radiologistswhile doing carotid arteriograms and pneumat-

Int J Anat Res 2015, 3(2):1039-42. ISSN 2321-4287 1041

-ization or marrow assessments of anteriorclinoid process. It poses accessibility andbleeding problems during neurosurgical invasiveprocedures of the region [11].The internal carotid artery enters thesubarachnoid space through a thick ring ofduramater called the distal dural ring. Theinternal carotid artery is also surrounded withanother ring of dura, the proximal dural ringwhich is exposed after the anterior clinoidprocess is removed. The area in between thesetwo rings is called the clinoidal space. Theclinoidal segment of the internal carotid arterylocated in this space is exposed by removingthe anterior clinoid process. During surgicalapproaches to the sellar region for tumors oraneurysms, the anterior clinoid process isremoved carrying risk of damage to the internalcarotid artery during these approaches [10].Approach to the cavernous sinus commonlyinvolves removal of anterior clinoid process toexpose the structures in the superior part ofcavernous sinus. Presence of caroticoclinoidbridge makes removal of anterior clinoid processmore difficult and increases the risk ofcomplications, especially if aneurysm is present.Oculomotor nerve may also be damaged duringthe removal of anterior clinoid process. Soserious weighing of risks and benefits ofoperative approaches must be done before theoperation because of the magnitude ofoperating procedure and risks of neural andvascular injury [3].In presence of caroticoclinoid foramen it isimpossible to retract or mobilize the cavernoussegment of carotid artery even after releasingthe proximal and distal carotid rings.Preoperative recognition of caroticoclinoidforamen is important because undue retractionof cavernous segment of internal carotid arterymay tear or rupture it and cause fatal cerebralinfarction [12].Incidence of petrosphenoidal bridges in variousstudies was found to be 5-17.7% [1,3,7,14]. Anossified petrosphenoidal ligament may play arole in abducent nerve palsy and can be detectedby multidetector computed tomogaphy [14]. Theabducent nerve may be compressed withinDorello’s canal by an accompanying artery

usually the dorsal meningeal branch ofmeningohypophyseal trunk. If Gruber’s ligamentis ossified then vascular compression may bemore likely [6].The petrosphenoidal ligament is an importantstructure in the petroclival area, not only fromanatomical point of view but also for surgicaland endovascular practice. This ligament islocated at the petrovenous confluence ofsuperolateral part of the basilar plexus, theposterior portion of cavernous sinus, superiorpart of inferior petrosal sinus and anterior partof sphenoparietal sinus. This interdural regionis commonly used for treatment of carotidcavernous sinus fistulas. The main function ofpetrosphenoidal ligament is reported to befixation of sheath of abducent nerve inpetroclival venous confluence. The nerve is alsoprotected by this ligament during petrous bonedrilling during anterior petrosal approach [1].Ossification of fibrous ligaments is considereda normal physiological process that occurs withage [10]. There is statistically significantassociation between calcification of petroclinoidand interclinoid ligaments because of possibilitythat these ligaments are parts of same duralfolds. Hence age may be a significant factor inrisk of ossification of cranial ligaments [15].However this process is an exception in theformation of caroticoclinoid foramen since it ispresent in foetuses and children [16,17 ]. Sellarbridges are laid down in cartilage during earlystage of sphenoid development and ossify inearly childhood [18].Although Dorello’s canal in modern human is anosteofibrous structure and elliptical in shape,in primates it is round osseous opening closedsuperiorly by the fused petrosal spine andaccessory clinoid process. These differencesbetween the primate and human configurationsare the source of abducent nerve vulnerability.Changes in the anatomy of the cranial baseduring the course of human evolution, stemmingpossibly from the increase in endocranialcapacity have brought about distancing ofdorsum sella and petrous apex, therebyelongating the horizontal axis of Dorello’s canaland causing the discontinuity of its osseousperimeter. Hence the petrosphenoidal ligament

Kavitha Kamath.B, Vinayak Kamath. OSSIFICATION OF CAROTICOCLINOID AND PETROSPHENOIDAL LIGAMENTS OF SKULL: A CASEREPORT.

Int J Anat Res 2015, 3(2):1039-42. ISSN 2321-4287 1042

of Gruber replaced the bony bridge and Dorello’scanal became an osseofibrous structure,rendering its contents susceptible tocompression against the cranial base. A bonypetrosphenoidal bridge is far moreadvantageous than a fibrous one as deformationinflicted on a ligament by intracranial masseswould be greater. Apes are less prone toabducent neuropathies resulting fromcompression of the nerve than humans as thenerve is protected by an osseous canal [19].

CONCLUSION

Considering the fact that anatomy textbooks donot provide detailed description of theseentities, the present study is of relevance toneurosurgeons and radiologists in day to dayclinical practice for understanding the etiologyof clinical symptoms, reducing errors indiagnostic procedures and increasing successof surgical procedures. It is concluded thatpresence of these anomalies have importantclinical implications and their knowledge isrequired for better planning of surgicaltreatments involving this region.List of abbreviations:

Conflicts of Interests: None

REFERENCES

CCB- Caroticoclinoid bridgeCCF- Caroticoclinoid foramenACP-Anterior clinoid processMCP- Middle clinoid processPCP- Posterior clinoid processPSB- Petrosphenoidal bridgePTB- Petrous part of temporal boneOC- Optic canal

[5]. Ozdogmus O, Saka E, Tulay C, Gurdal E, Uzun I,Cavdar S. The anatomy of the carotico-clinoidforamen and its relation with the internal carotidartery. Surg Radiol Anat 2003;25:241-46.

[6]. Tubbs RS, Sharma A, Loukas M, Cohen-Gadol AA.Ossification of the petrosphenoidal ligament:unusual variation with the potential for abducensnerve entrapment in Dorello’s canal at the skullbase. Surg Radiol Anat 2014;36:303-5.

[7]. Umansky F, Elidan J, Valarezo A. Dorello’s canal: Amicroanatomical study. J Neurosurg 1991;75:294-98.

[8]. Azeredo RA, Liberti EA, Watanabe IS. Anatomicalvariations of the clinoid process of the humansphenoid bone. Arq Cent Estud Curso Odontol1988;25-26:9-11.

[9]. Aggarwal B, Gupta M, Kumar H. Ossified ligamentsof the skull. J Anat Soc India 2012;61:37-40.

[10]. Erturk M, Kayalioglu G, Govsa F. Anatomy of theclinoidal region with special emphasis on thecaroticoclinoid foramen and interclinoid osseousbridge in a recent Turkish population. NeurosurgRev 2004;27:22-26.

[11]. Hasan T. Bilateral caroticoclinoid and absentmental foramen: rare variations of cranial baseand lower jaw. Italian Journal of Anatomy andEmbryology 2013;118:288-97.

[12]. Lee Hy, Chung IH, Choi BY, Lee KS. Anterior clinoidprocess and optic strut in Koreans. Yonsei MedicalJournal 1997;38:151-54.

[13]. Keyers JEL. Observations on four thousand opticforamina in human skulls of known origin. ArchOpthalmol 1935;13:538-68.

[14]. Osgur A, Esen K. Ossification of the petrosphenoidalligament: multidetector computed tomographyfindings of an unusual variation with a potentialrole in abducens nerve palsy. Jpn J Radiol [Internet]2015 Mar: about 5p. doi:10.1007/s11604-015-0410-9. (accessed on 22 March 2015)

[15]. Cederberg RA, Bensen BW, Nunn M, English JD.Calcification of the interclinoid and petroclinoidligaments of sells turcica: a radiographic study ofthe prevalence. Orthod Craniofacial Res2003;6:227-32.

[16]. Hochstetter F. Uber die Taenia interclinoidea, dieCommisura alicochlearis und die Carti lagosupracochlearis des menschlichenPrimordialkraniums. Gegenbaurs Morph Jahrb1940;84:220-243.

[17]. Kier EL.Embryology of the normal optic canal andits anomlies. An anatomic and roentgenographicstudy. Invest Radiol 1966;1:346-62.

[18]. Lang J. Structure and postnatal organization ofheretofore uninvestigated and infrequentossifications of the sella turcica region. Acta Anat1977;99:121-39.

[19]. Marom A. A new look at the old canal. Skull base2011;21:53-57.

[1]. Icke C, Ozer E, Arda N. Microanatomicalcharacteristics of the petrosphenoidal ligament ofGruber. Turkish Neurosugery 2010;20:323-27.

[2]. Ozdogmus O, Saka E, Tulay C, Gurdal E, Uzun I,Cavdar S. Ossification of interclinoid ligament andits clinical significance. Neuroanatomy 2003;2:25-27.

[3]. Peker T, Anil A, Gulekon N, Turgut B, Pelin C, KarakoseM. The incidence and types of sella andsphenopetrous bridges. Neurosurg Rev2006;29:219-23.

[4]. Freire AR, Rossi AC, Prado FB, Groppo FC, Caria PHF,Botacin PR. Caroticoclinoid Foramen in HumanSkulls: Incidence, Morphometry and its ClinicalImplications. Int J Morphol 2011;29:427-31.

Kavitha Kamath.B, Vinayak Kamath. OSSIFICATION OF CAROTICOCLINOID AND PETROSPHENOIDAL LIGAMENTS OF SKULL: A CASEREPORT.

How

to c

ite th

is a

rtic

le: K

avith

a Ka

mat

h.B,

Vin

ayak

Kam

ath.

OSS

IFIC

ATIO

N O

F CA

ROTI

COCL

INO

ID A

ND

PETR

OSP

HEN

OID

AL L

IGAM

ENTS

OF

SKU

LL: A

CAS

E RE

PORT

. Int

J An

at R

es20

15;3

(2):1

039-

1042

. DO

I: 10

.169

65/ij

ar.2

015.

152