Skip to main content
SpringerLink
Log in

Root exit zone of the trochlear nerve on the dorsal brainstem: an MRI study

  • Original Article
  • Published:
Surgical and Radiologic Anatomy Aims and scope Submit manuscript

Abstract

Purpose

To date, no study has explored the root exit zone of the trochlear nerve (TroN) on the dorsal brainstem; therefore, we aimed to characterize the location using magnetic resonance imaging (MRI).

Methods

A total of 85 patients underwent thin-slice axial T2-weighted MRI.

Results

TroN was identified in 91% of 85 patients, 60 (71%) on the right side, and 67 (79%) on the left. The distances between the apex of the inferior colliculus and the original site of TroN on the dorsal brainstem were variable, with mean values of 2.4 ± 1.8 mm (range 0–8 mm) on the right and 2.2 ± 1.7 mm (range 0–5 mm) on the left. Most of the root exit zones were distributed within 0–5 mm below the apex of the inferior colliculus. In addition, the distances between the midline and the root exit zones of the TroN were variable, with mean values of 4.4 ± 1.4 mm (range 1.9–7.5 mm) on the right and 4.6 ± 1.6 mm (range 1.1–7.8 mm) on the left. Most of the root exit zones were located within 1–7 mm range lateral to the midline.

Conclusions

The root exit zone of the TroN may be mostly located in a small square area measuring 8 mm × 8 mm, lying at and below the apex of the inferior colliculus. The TroN may arise from any site in the square area, and significant attention is necessary when performing surgical maneuvers in and around it.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7

Similar content being viewed by others

References

  1. Agarwal N, Ahmed AK, Wiggins RH 3rd, McCulley TJ, Kontzialis M, Macedo LL, Choudhri AF, Ditta LC, Ishii M, Gallia GL, Aygun N, Blitz AM (2021) Segmental imaging of the trochlear nerve: anatomic and pathologic considerations. J Neuroophthalmol 41:e7–e15

    Article  Google Scholar 

  2. Ammirati M, Musumeci A, Bernardo A, Bricolo A (2002) The microsurgical anatomy of the cisternal segment of the trochlear nerve, as seen through different neurosurgical operative windows. Acta Neurochir (Wien) 144:1323–1327

    Article  CAS  Google Scholar 

  3. Bisaria KK, Premsagar IC, Lakhtakia PK, Saxena RC, Bisaria SD (1990) The superficial origin of the trochlear nerve with special reference to its vascular relations. J Anat 170:199–201

    CAS  PubMed  PubMed Central  Google Scholar 

  4. Bunch PM, Kelly HR, Zander DA, Curtin HD (2017) Trochlear groove and trochlear cistern: useful anatomic landmarks for identifying the tentorial segment of cranial nerve IV on MRI. AJNR Am J Neuroradiol 38:1026–1030

    Article  CAS  Google Scholar 

  5. Diora JR, Plager DA (2019) Sudden-onset trochlear nerve palsy: clinical characteristics and treatment implications. J AAPOS 23:e1-321.e5

    Article  Google Scholar 

  6. Gupta T, Gupta SK, Sahni D (2014) Anatomy of the tentorial segment of the trochlear nerve in reference to its preservation during surgery for skull base lesions. Surg Radiol Anat 36:967–971

    Article  Google Scholar 

  7. Hardy DG, Peace DA, Rhoton AL Jr (1980) Microsurgical anatomy of the superior cerebellar artery. Neurosurgery 6:10–28

    Article  CAS  Google Scholar 

  8. Iaconetta G, de Notaris M, Benet A, Rincon J, Cavallo LM, Prats-Galino A, Samii M, Cappabianca P (2013) The trochlear nerve: microanatomic and endoscopic study. Neurosurg Rev 36:227–238

    Article  Google Scholar 

  9. Joo W, Rhoton AL Jr (2015) Microsurgical anatomy of the trochlear nerve. Clin Anat 28:857–864

    Article  Google Scholar 

  10. Kanoto M, Toyoguchi Y, Hosoya T, Oda A, Sugai Y (2013) Visualization of the trochlear nerve in the cistern with use of high-resolution turbo spin-echo multisection motion-sensitized driven equilibrium. AJNR Am J Neuroradiol 34:1434–1437

    Article  CAS  Google Scholar 

  11. Lekskul A, Wuthisiri W, Tangtammaruk P (2021) The etiologies of isolated fourth cranial nerve palsy: a 10-year review of 158 cases. Int Ophthalmol 41:3437–3442

    Article  CAS  Google Scholar 

  12. Marinković S, Gibo H, Zelić O, Nikodijević I (1996) The neurovascular relationships and the blood supply of the trochlear nerve: surgical anatomy of its cisternal segment. Neurosurgery 38:161–169

    Article  Google Scholar 

  13. Mclaughlin N, Ma QF, Emerson J, Malkasian DR, Martin NA (2013) The extended subtemporal transtentorial approach: the impact of trochlear nerve dissection and tentorial incision. J Clin Neurosci 20:1139–1143

    Article  Google Scholar 

  14. Park HS, Chung MS, Shin DS, Jung YW, Park JS (2015) Whole courses of the oculomotor, trochlear, and abducens nerves, identified in sectioned images and surface models. Anat Rec (Hoboken) 298:436–443

    Article  Google Scholar 

  15. Pescatori L, Niutta M, Tropeano MP, Santoro G, Santoro A (2017) Fourth cranial nerve: surgical anatomy in the subtemporal transtentorial approach and in the pretemporal combined inter-intradural approach through the fronto-temporo-orbito-zygomatic craniotomy. A cadaveric study. Neurosurg Rev 40:143–153

    Article  CAS  Google Scholar 

  16. Rusu MC, Vrapciu AD, Pătraşcu JM (2015) Variable relations of the trochlear nerve with the pontomesencephalic segment of the superior cerebellar artery. Surg Radiol Anat 37:555–559

    Article  Google Scholar 

  17. Szyszka-Mróz J (2000) Development of the trochlear nerve in the human embryos. Folia Morphol (Warsz) 58:307–313

    Google Scholar 

  18. Tsutsumi S, Ono H, Ishii H (2021) Trochlear cistern of the cavernous sinus: an anatomical study using magnetic resonance imaging. Surg Radiol Anat 43:1279–1284

    Article  Google Scholar 

  19. Tubbs RS, Oakes WJ (1998) Relationships of the cisternal segment of the trochlear nerve. J Neurosurg 89:1015–1019

    Article  CAS  Google Scholar 

  20. Villain M, Segnarbieux F, Bonnel F, Aubry I, Arnaud B (1993) The trochlear nerve: anatomy by microdissection. Surg Radiol Anat 15:169–173

    Article  CAS  Google Scholar 

Download references

Funding

No funding was received for this study.

Author information

Authors and Affiliations

  1. Department of Neurological Surgery, Juntendo University Urayasu Hospital, 2-1-1 Tomioka, Urayasu, Chiba, 279-0021, Japan

    Satoshi Tsutsumi & Hisato Ishii

  2. Division of Radiological Technology, Medical Satellite Yaesu Clinic, Tokyo, Japan

    Hideo Ono

Authors
  1. Satoshi Tsutsumi
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Hideo Ono
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Hisato Ishii
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

All the authors equally contributed to the study.

Corresponding author

Correspondence to Satoshi Tsutsumi.

Ethics declarations

Conflict of interest

The authors declare that they have no conflicts of interest.

Ethical approval

All procedures performed in the study were in accordance with the ethical standards of the institutional and/or national research committee and the 1964 Declaration of Helsinki and its later amendments or comparable ethical standards.

Informed consent

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

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

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Tsutsumi, S., Ono, H. & Ishii, H. Root exit zone of the trochlear nerve on the dorsal brainstem: an MRI study. Surg Radiol Anat 44, 399–405 (2022). https://doi.org/10.1007/s00276-021-02874-8

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s00276-021-02874-8

Keywords

Search

Navigation