Skip to main content

Magnetic resonance angiographic study of variations in course of paraclival and parasellar internal carotid artery in relation to expanded endonasal endoscopic approaches



To study the variations in the course of the paraclival and parasellar carotid arteries in normal subjects using magnetic resonance angiography as is relevant from an endoscopic endonasal perspective.


Two hundred MR angiographies of normal subjects were analyzed in a prospective study. The intercarotid distances were measured at fixed points along the paraclival and parasellar segments of the internal carotid artery. The intercarotid spaces thus obtained were categorized into trapezoid, square and hourglass shapes. The angle between the posterior ascending vertical and horizontal bend of the parasellar ICA was also measured and analyzed.


The trapezoid shape of intercarotid space is the most common (52.5%), followed by the square (35%) and the hourglass (12.5%) shaped spaces. Angle of < 80° between the posterior ascending vertical and horizontal bend of the parasellar ICA was found in 39% of subjects, angle between 80° and 100° was found in 9% subjects, angle > 100° was found in 43% while asymmetric angles on the two sides was found in 9% of subjects.


A thorough understanding of the course of the ICA is important in planning the approach and preventing injury to the ICA.

This is a preview of subscription content, access via your institution.

Fig. 1
Fig. 2
Fig. 3

Availability of data and material



  1. 1.

    Fischer E (1938) Die Lageabweichungen der vorderen Hirnarterie im Gef~issbild. Zentralbl Neurochir 3:300–312

    Google Scholar 

  2. 2.

    Gibo H, Lenkey C, Rhoton AL Jr (1981) Microsurgical anatomy of the supraclinoid portion of the internal carotid artery. J Neurosurg 55(4):560–574

    CAS  Article  Google Scholar 

  3. 3.

    Bouthillier A, van Loveren HR, Keller JT (1996) Segments of the internal carotid artery: a new classification. Neurosurgery 38(3):425–432

    CAS  PubMed  Google Scholar 

  4. 4.

    Labib MA, Prevedello DM, Carrau R, Kerr EE, Naudy C, Abou Al-Shaar H, Corsten M, Kassam A (2014) A road map to the internal carotid artery in expanded endoscopic endonasal approaches to the ventral cranial base. Neurosurgery 10(3):448–471

    PubMed  Google Scholar 

  5. 5.

    Cebula H, Kurbanov A, Zimmer LA, Poczos P, Leach JL, De Battista JC, Froelich S, Theodosopoulos PV, Keller JT (2014) Endoscopic, endonasal variability in the anatomy of the internal carotid artery. World Neurosurg 82(6):e759–e764

    Article  Google Scholar 

  6. 6.

    Dolci RLL, Ditzel Filho LFS, Goulart CR, Upadhyay S, Buohliqah L, Lazarini PR, Prevedello DM, Carrau RL (2018) Anatomical nuances of the internal carotid artery in relation to the quadrangular space. J Neurosurg 128(1):174–181

    Article  Google Scholar 

  7. 7.

    Fisch U (1978) Infratemporal fossa approach to tumours of the temporal bone and base of the skull. J Laryngol Otol 92(11):949–967

    CAS  Article  Google Scholar 

  8. 8.

    Fisch U (1983) The infratemporal fossa approach for nasopharyngeal tumors. Laryngoscope 93(1):36–44

    CAS  Article  Google Scholar 

  9. 9.

    Zoli M, Milanese L, Bonfatti R, Faustini-Fustini M, Marucci G, Tallini G, Zenesini C, Sturiale C, Frank G, Pasquini E, Mazzatenta D (2018) Clival chordomas: considerations after 16 years of endoscopic endonasal surgery. J Neurosurg 128(2):329–338

    Article  Google Scholar 

  10. 10.

    Beer-Furlan A, Abi-Hachem R, Jamshidi AO, Carrau RL, Prevedello DM (2016) Endoscopic trans-sphenoidal surgery for petroclival and clival meningiomas. J Neurosurg Sci 60(4):495–502

    PubMed  Google Scholar 

  11. 11.

    Zanation AM, Snyderman CH, Carrau RL, Gardner PA, Prevedello DM, Kassam AB (2009) Endoscopic endonasal surgery for petrous apex lesions. Laryngoscope 119(1):19–25

    Article  Google Scholar 

  12. 12.

    Mason E, Van Rompaey J, Carrau R, Panizza B, Solares CA (2014) Anatomical and computed tomographic analysis of the transcochlear and endoscopic transclival approaches to the petroclival region. Laryngoscope 124(3):628–636

    Article  Google Scholar 

  13. 13.

    Koutourousiou M, Fernandez-Miranda JC, Vaz-Guimaraes Filho F, de Almeida JR, Wang EW, Snyderman CH, Gardner PA (2017) Outcomes of endonasal and lateral approaches to petroclival meningiomas. World Neurosurg 99:500–517

    Article  Google Scholar 

  14. 14.

    Kassam AB, Prevedello DM, Carrau RL, Snyderman CH, Gardner P, Osawa S, Seker A, Rhoton AL Jr (2009) The front door to meckel’s cave: an anteromedial corridor via expanded endoscopic endonasal approach- technical considerations and clinical series. Neurosurgery 64(3):71–82

    Google Scholar 

  15. 15.

    Falcon RT, Rivera-Serrano CM, Miranda JF, Prevedello DM, Snyderman CH, Kassam AB, Carrau RL (2011) Endoscopic endonasal dissection of the infratemporal fossa: anatomic relationships and importance of eustachian tube in the endoscopic skull base surgery. Laryngoscope 121(1):31–41

    Article  Google Scholar 

  16. 16.

    Kassam AB, Vescan AD, Carrau RL, Prevedello DM, Gardner P, Mintz AH, Snyderman CH, Rhoton AL (2008) Expanded endonasal approach: vidian canal as a landmark to the petrous internal carotid artery. J Neurosurg 108(1):177–183

    Article  Google Scholar 

  17. 17.

    Oakley GM, Ebenezer J, Hamizan A, Sacks PL, Rom D, Sacks R, Winder M, Davidson A, Teo C, Solares CA, Harvey RJ (2018) Finding the petroclival carotid artery: the Vidian-Eustachian junction as a reliable landmark. J Neurol Surg B Skull Base 79(4):361–366

    Article  Google Scholar 

  18. 18.

    Fernandez-Miranda JC, Zwagerman NT, Abhinav K, Lieber S, Wang EW, Snyderman CH, Gardner PA (2018) Cavernous sinus compartments from the endoscopic endonasal approach: anatomical considerations and surgical relevance to adenoma surgery. J Neurosurg 129(2):430–441

    Article  Google Scholar 

  19. 19.

    Valentine R, Wormald PJ (2011) Carotid artery injury after endonasal surgery. Otolaryngol Clin North Am 44(05):1059–1079

    Article  Google Scholar 

  20. 20.

    Chin OY, Ghosh R, Fang CH, Baredes S, Liu JK, Eloy JA (2016) Internal carotid artery injury in endoscopic endonasal surgery: a systematic review. Laryngoscope 126(3):582–590

    Article  Google Scholar 

  21. 21.

    AlQahtani A, Castelnuovo P, Nicolai P, Prevedello DM, Locatelli D, Carrau RL (2016) Injury of the internal carotid artery during endoscopic skull base surgery: prevention and management protocol. Otolaryngol Clin North Am 49(01):237–252

    Article  Google Scholar 

  22. 22.

    Mehta GU, Raza SM (2018) Endoscopic endonasal transpterygoid approach to petrous pathologies: technique, limitations and alternative approaches. J Neurosurg Sci 62(3):339–346

    Article  Google Scholar 

  23. 23.

    Serra C, Maldaner N, Muscas G, Staartjes V, Pangalu A, Holzmann D, Soyka M, Schmid C, Regli L (2017) The changing sella: internal carotid artery shift during transsphenoidal pituitary surgery. Pituitary 20(6):654–660

    Article  Google Scholar 

  24. 24.

    Sasagawa Y, Tachibana O, Doai M, Akai T, Tonami H, Iizuka H (2013) Internal carotid arterial shift after transsphenoidal surgery in pituitary adenomas with cavernous sinus invasion. Pituitary 16(4):465–470

    Article  Google Scholar 

  25. 25.

    Hoffmann A, Warmuth-Metz M, Lohle K, Reichel J, Daubenbüchel AM, Sterkenburg AS, Müller HL (2016) Fusiform dilatation of the internal carotid artery in childhood-onset craniopharyngioma: multicenter study on incidence and long-term outcome. Pituitary 19(4):422–428

    Article  Google Scholar 

  26. 26.

    Koutourousiou M, Vaz Guimaraes Filho F, Fernandez-Miranda JC, Wang EW, Stefko ST, Snyderman CH, Gardner PA (2017) Endoscopic endonasal surgery for tumors of the cavernous sinus: a series of 234 patients. World Neurosurg 103:713–732

    Article  Google Scholar 

  27. 27.

    Woodworth GF, Patel KS, Shin B, Burkhardt JK, Tsiouris AJ, McCoul ED, Anand VK, Schwartz TH (2014) Surgical outcomes using a medial-to-lateral endonasal endoscopic approach to pituitary adenomas invading the cavernous sinus. J Neurosurg 120(5):1086–1094

    Article  Google Scholar 

  28. 28.

    Gore JC (2020) Artificial intelligence in medical imaging. Magn Reson Imaging 68:A1–A4

    Article  Google Scholar 

  29. 29.

    Shaari H, Kevrić J, Jukić S, Bešić L, Jokić D, Ahmed N, Rajs V (2021) Deep learning-based studies on pediatric brain tumors imaging: narrative review of techniques and challenges. Brain Sci 11(6):716

    Article  Google Scholar 

  30. 30.

    Quon JL, Chen LC, Kim L, Grant GA, Edwards MSB, Cheshier SH, Yeom KW (2020) Deep learning for automated delineation of pediatric cerebral arteries on pre-operative brain magnetic resonance imaging. Front Surg. 7:517375

    Article  Google Scholar 

Download references


No funding was received for conducting this study.

Author information



Corresponding author

Correspondence to Narayan Jayashankar.

Ethics declarations

Conflicts of interest

The authors have no relevant financial or non-financial interests to disclose.

Ethics approval

Approval was obtained from the ethics committee of Nanavati Superspeciality Hospital. The procedures used in this study adhere to the tenets of the Declaration of Helsinki.

Consent to participate

Informed consent was obtained from all individual participants included in the study.

Consent for publication

Patients signed informed consent regarding publishing their data and photographs.

Additional information

Publisher's Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Jayashankar, N., Patangrao, H. Magnetic resonance angiographic study of variations in course of paraclival and parasellar internal carotid artery in relation to expanded endonasal endoscopic approaches. Eur Arch Otorhinolaryngol (2021).

Download citation


  • Internal carotid artery
  • Paraclival ICA
  • Parasellar ICA