Venous anastomotic circle, multiple varices and oculomotor palsy--a rare coincidence

Mapping the circle of Trolard: A holistic view of its role in neurosurgical practice, anatomical perspectives and clinical applications

Introduction

An anatomical structure that resembles the circle of Willis, the circle of Trolard is generated in the basal cistern and travels around the midbrain in a roundabout manner, passing adjacent to the lateral side of the cerebral peduncle.

Research question

The primary objective of this article is to provide neurosurgeons with a comprehensive understanding of Trolard's circle, emphasizing its anatomical features and clinical significance.

Material and methods

A comprehensive evaluation of the available literature pertaining to the venous circle of Trolard was conducted by conducting searches in the PubMed, Web of Science, and Scopus databases. In the present overview, the terminologies "venous circle of Trolard," "basal venous circle," and "basal vein of Rosenthal" were employed.

Results

Upon doing a comprehensive examination of the existing literature and primary sources pertaining to the venous circle of Trolard, it was discovered that an only six studies had been conducted on this particular subject matter. We made observations regarding the anatomical characteristics of the subject and engaged in a discussion regarding their prospective applications and importance within the context of neurosurgical procedures.

Discussion and conclusion

The scarcity of research on these structures is attributed to the challenges associated in studying them in vivo. Through directing focus towards these structures, our aim is to stimulate further investigation into their potential involvement in a range of neurological and neurosurgical disorders.

The Venous Circle of Trolard: An Anatomical Study with Application to Approaches to the Basal Brain

BACKGROUND

The arterial circle of Willis is a well-known and interconnecting set of blood vessels at the base of the brain. However, its lesser-known venous counterpart, the circle of Trolard, has had almost no attention in the extant medical literature.

METHODS

Twenty-four adult human brains underwent dissection of the circle of Trolard. When identified, its component vessels and relationships with adjacent structures were confirmed and documented with photography and measured using microcalipers.

RESULTS

A complete circle of Trolard was identified on 42% of specimens. Most (64%) incomplete circles were incomplete anteriorly with no anterior communicating vein. The anterior communicating veins joined the anterior cerebral veins superior to the optic chiasm and continued posteriorly. The anterior communicating veins had a mean diameter of 0.45 mm. The length of these veins ranged from 0.8 mm to 1.45 mm. Thirty-six percent of circles were incomplete posteriorly with lack of a posterior communicating vein. The posterior communicating veins were always larger and longer than the anterior cerebral veins. The posterior communicating veins had a mean diameter of 0.8 mm. The length of these veins ranged from 2.8 to 3.9 cm. In general, the circles of Trolard were more or less symmetrical. However, in 2 specimens, asymmetry existed.

CONCLUSIONS

A better understanding of the venous circle of Trolard might decrease iatrogenic injury during approaches to the base of the brain and improve diagnoses based on imaging of the skull base. To our knowledge, this is the first anatomical study dedicated to the circle of Trolard.