Absence of the torcular, review of venous sinus anatomy, and the simplified dural sinus classification

Fidel Valero-Moreno, Michael W. Pullen, Guiselle Navarro-Martínez, Henry Ruiz-Garcia, Ricardo A. Domingo, Jaime L. Martínez, Paola Suarez-Meade, Aaron Damon, Alfredo Quiñones-Hinojosa, Sukhwinder Js Sandhu, Rabih G. Tawk, W. Christopher Fox

Research output: Contribution to journalArticlepeer-review


Background: Classically, the torcular Herophili is described as the symmetric junction between the superior sagittal sinus (SSS), transverse sinuses (TSs), and straight sinus (SS). However, finding this pattern in practice is not standard. Anatomical variations are common, and different drainage patterns should be expected. Existing literature proposes highly detailed descriptions and classifications of this region. Still, a simplified and practical categorization is not available. Methods: We present an anatomical finding of the torcular Herophili discovered on a cadaveric dissection. Then, we conducted a retrospective study examining the 100 most recent cranial magnetic resonance venographies (MRVs) from the Mayo Clinic, labeling them with a new proposed dural sinus classification system. Images were initially classified by two authors and further validated by a board-certified neurosurgeon and a board-certified neuroradiologist from our institution. To measure consistency in image identification, two additional international neurosurgeons were asked to classify a subset of the same MRV images, and their answers were compared. Results: Of the MRV cohort, 33 patients were male and 67 were female. Their ages ranged from 18 to 86 years, with a mean of 47.35 years and a median of 49 years. Upon examination, 53 patients presented as confluent (53%), 9 as SSS divergent (9%), 25 as SS divergent (25%), 11 as circular (11%), and 2 as trifurcated (2%). The inter-rater reliability ranked very good; agreement between the two neurosurgeons was 83% (κ = 0.830, p < 0.0005). Conclusion: The confluence of the venous sinuses is a highly variable anatomical area that is rarely evaluated with neuroimaging before surgery. The classic textbook configuration is not the rule. Using a simplified classification system may increase awareness and hopefully patient safety by preparing the physician for anatomical variations that they will encounter in a surgical or clinical scenario.

Original languageEnglish (US)
Pages (from-to)1781-1790
Number of pages10
JournalActa Neurochirurgica
Issue number7
StatePublished - Jul 2023


  • Confluence of sinuses
  • Dural sinus classification
  • Straight sinus
  • Superior sagittal sinus
  • Torcular Herophili
  • Transverse sinus

ASJC Scopus subject areas

  • Surgery
  • Clinical Neurology


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