Skip to main content
SpringerLink
Log in

An anatomical study of the foramen of Monro: implications in management of pineal tumors presenting with hydrocephalus

  • Original Article - Neurosurgical Anatomy
  • Published:
Acta Neurochirurgica Aims and scope Submit manuscript

Abstract

Background

For pineal tumors presenting with hydrocephalus, simultaneous endoscopic third ventriculostomy (ETV) and tumor biopsy is commonly used as the initial step in management. To analyze the restriction which the foramen of Monro poses to this procedure, one must start with a detailed description of the microsurgical anatomy of the foramen in living subjects. However, the orientation and shape of the foramen of Monro make this description difficult with conventional imaging techniques.

Method

Virtual reality technology was applied on MRIs on living subject without hydrocephalus, as well as patients with hydrocephalus, to generate precise anatomical models with sub-millimeter accuracy. The morphometry of the foramen of Monro was studied in each group. In addition, displacement of the margins of the foramen was studied in detail for simultaneous ETV and pineal tumor biopsy through a single burr hole.

Results

In 30 normal subjects, the foramen of Monro had oval-shaped openings averaging 5.23 mm2. The foramen was larger in people above age 55 (p = 0.007) and on the left side compared to the right (p = 0.002). For patients with clinical presentation of hydrocephalus, the average opening was 32.6 mm2. Simulated single burr hole simultaneous ETV and pineal tumor biopsy was performed in 10 specimens. Average displacement of the posterior and anterior margins of the foramen was 5.71 mm and 5.76 mm, respectively. However, maximum displacement reached 9.3 mm posteriorly and 10 mm anteriorly.

Conclusions

The foramen of Monro is an oval-shaped cylinder that changes in size and orientation in the hydrocephalic patient. If universally applied to all patients regardless of foramen and tumor size, ETV/biopsy can displace structures around the Foramen of Monro up to 1 cm, which can potentially lead to neurological damage. Careful pre-operative assessment is critical to determine if a single burr hole approach is safe.

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.

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5

Similar content being viewed by others

Abbreviations

ETV:

Endoscopic third ventriculostomy

FoM:

Foramen of Monro

VR:

Virtual reality

NPH:

Normal pressure hydrocephalus

References

  1. Abbassy M, Aref K, Farhoud A, Hekal A (2018) Outcome of single-trajectory rigid endoscopic third ventriculostomy and biopsy in the management algorithm of pineal region tumors: a case series and review of the literature. Child Nerv Syst 34:1335–1344

    Article  Google Scholar 

  2. Ahmed AI, Zaben MJ, Mathad NV, Sparrow OCE (2015) Endoscopic biopsy and third ventriculostomy for the management of pineal region tumors. World Neurosurg 83(4):543–547

    Article  PubMed  Google Scholar 

  3. Chen F, Nakaji P (2012) Optimal entry point for endoscpic third ventriculostomy: evaluation of 53 patients with volumetric imaging guidance. J Neurosurg 116:1153–1157

    Article  PubMed  Google Scholar 

  4. Knaus H, Matthias S, Koch A, Thomale U-W (2011) Single burr hole endoscopic biopsy with third ventriculostomy – measurements and computer-assisted planning. Child Nerv Syst 27:1233–1241

    Article  Google Scholar 

  5. Last RL, Tompsett DH (1953) Casts of the cerebral ventricles. Br J Surg 40(164):525–543

    Article  CAS  PubMed  Google Scholar 

  6. Morgenstern PF, Osbun N, Schwartz TH, Greenfield JP, Tsiouris AJ, Souweidane MM (2011) Pineal region tumors: an optimal approach for simultaneous endoscopic third ventriculostomy and biopsy. Neurosurg Focus 30(4):E3

    Article  PubMed  Google Scholar 

  7. Morgenstern PF, Souweidane MM (2013) Pineal region tumors: simultaneous endoscopic third ventriculostomy and tumor biopsy. World Neurosurg 79(2S):S18 E9–S18 13

    Google Scholar 

  8. O’brien DF, Hauhurst C, Pizer B, Mallucci CL (2006) Outcomes in patients undergoing single-trajectory endoscopic third ventriculostomy and endoscopic biopsy for midline tumors presenting with obstructive hydrocephalus. J Neurosurg (Suppl Pediatr) 105(2):219–226

    Article  Google Scholar 

  9. Robinson S, Cohen AR (1996) The role of neuroendoscopy in the treatment of pineal region tumors. Surg Neurol 48:360–367

    Article  Google Scholar 

  10. Trimarchi F, Bramanti P, Marino S, Milardi D, Di Mauro D, Ielitro G, Valenti B, Vaccarino G, Milazzo C, Cutroneo G (2013) MRI 3D lateral cerebral ventricles in living humans: morphological and morphometrical age, gender-related preliminary study. Anat Sci Int 88:61–69

    Article  PubMed  Google Scholar 

  11. Tubbs RS, Oakes P, Maran IS, Salib C, Loukas M (2014) The foramen of Monro: a review of its anatomy, history, pathology and surgery. Child Nerv Syst 30:1645–1649

    Article  Google Scholar 

  12. Yamada S, Ishikawa M, Yamamoto K (2015) Optimal diagnostic indices for idiopathic normal pressure hydrocephalus based on 3D quantitative volumetric analysis for the cerebral ventricle and subarachnoid space. AJNR Am J Neuroradiol 36(12):2262–2269

    Article  CAS  PubMed  Google Scholar 

  13. Yamamoto I, Rhoton AL, Peace DA (1981) Microsurgical anatomy of the 3rd ventricle, part I: microsurgical anatomy. Neurosurg 8(3):334–355

    Article  CAS  Google Scholar 

  14. Zhu XL, Gao R, Wong GKC, Wong HT, Ng RYT, Yu Y, Wong RKM, Poon WS (2013) Single burr hole rigid endoscopic third ventriculostomy and endoscopic tumor biopsy: what is the safe displacement range for the foramen of Monro? Asian J Surg 36:74–82

    Article  PubMed  Google Scholar 

Download references

Author information

Authors and Affiliations

  1. Department of Neurosurgery, The George Washington University, 2150 Pennsylvania Avenue, NW Suite 7-420, Washington, DC, 20037, USA

    Walter C. Jean & Elizabeth Hogan

  2. Department of Neurosurgery, Georgetown University, Washington, DC, USA

    Alexander X. Tai & Daniel R. Felbaum

  3. Surgical Theater LLC, Cleveland, OH, USA

    Aalap Herur-Raman

  4. Department of Neurosurgery, Allegheny General Hospital, Pittsburgh, PA, USA

    Jody Leonardo

  5. Department of Neurosurgery, University of Virginia, Charlottesville, VA, USA

    Hasan R. Syed

Authors
  1. Walter C. Jean
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Alexander X. Tai
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Elizabeth Hogan
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Aalap Herur-Raman
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Daniel R. Felbaum
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. Jody Leonardo
    View author publications

    You can also search for this author in PubMed Google Scholar

  7. Hasan R. Syed
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Walter C. Jean.

Ethics declarations

Conflict of interest

Author AH-R is employed by Surgical Theater LLC as on-site senior clinical engineer for its VR system at George Washington University. All other authors certify that they have no affiliations with or involvement in any organization or entity with any financial interest (such as honoraria; educational grants; participation in speakers’ bureaus; membership, employment, consultancies, stock ownership, or other equity interest; and expert testimony or patent-licensing arrangements), or non-financial interest (such as personal or professional relationships, affiliations, knowledge or beliefs) in the subject matter or materials discussed in this manuscript.

Ethical approval

There were no procedures performed in studies involving human participants. As a retrospective study, patient data were identified for examination and thereafter, only the gender and age were kept. For this type of study, formal consent is not required.

Additional information

Comments

This is a very interesting and well-presented study on the emerging use of virtual reality to study surgical neuroanatomy, here specifically the foramen of Monro. This manuscript would be of interest to readers and illustrates a meaningful potential application of novel technology to surgical planning. The study is well-organized, with the methodology and limitations adequately described. If possible, a higher quality image for Figure 5 would improve the manuscript. Overall, the authors are congratulated for their work.

Publisher’s note

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

This article is part of the Topical Collection on Neurosurgical Anatomy

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Jean, W.C., Tai, A.X., Hogan, E. et al. An anatomical study of the foramen of Monro: implications in management of pineal tumors presenting with hydrocephalus. Acta Neurochir 161, 975–983 (2019). https://doi.org/10.1007/s00701-019-03887-4

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s00701-019-03887-4

Keywords

Search

Navigation