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Table of Contents    
CASE REPORT
Year : 2020  |  Volume : 68  |  Issue : 6  |  Page : 1450-1452

Persistent Falcine Sinus-The Variant Venous Structure With Anterior Interhemispheric Type And The Classic Posterior Location: Report of Two Cases


Imaging Science and Intervention Radiology (IS/IR), Sree Chitra Institute of Medical Sciences and Technology, Trivandrum, Kerala, India

Date of Web Publication19-Dec-2020

Correspondence Address:
Dr. Dev P Sharma
Department of Imaging Science and Intervention Radiology, Sree Chitra Institute of Medical Sciences and Technology, Trivandrum - 695 011, Kerala
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0028-3886.304081

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  Abstract 


A 14-year-old girl presented with suspected dermoid cyst of scalp underwent Neuroimaging to look for intracranial communication. Her neurological examination was essentially normal. On Magnetic Resonance Imaging(MRI), an anterior persistent falcine sinus(PFS) was noted draining into the middle portion of the superior sagittal sinus. There was developmental venous anomaly (DVA) involving the right frontal lobe. To our knowledge, it is a rare instance of the combination of an anterior persistent falcine sinus and associated DVA.


Keywords: Developmental venous anomaly, magnetic resonance imaging, persistent falcine sinus, superior sagittal sinus
Key Messages: Persistent falcine sinus drains normal brain parenchyma and is associated with other potential malformations of the neuroparenchyma. When adjacent vascular malformations exist, falcine sinus should not be mistaken as massive draining vessel. The anterior interhemispheric variant is rare entity and can be mistaken as extra-axial mass lesion, like meningioma.


How to cite this article:
Sharma DP, Thomas B, Prasad AB, Kesavadas C. Persistent Falcine Sinus-The Variant Venous Structure With Anterior Interhemispheric Type And The Classic Posterior Location: Report of Two Cases. Neurol India 2020;68:1450-2

How to cite this URL:
Sharma DP, Thomas B, Prasad AB, Kesavadas C. Persistent Falcine Sinus-The Variant Venous Structure With Anterior Interhemispheric Type And The Classic Posterior Location: Report of Two Cases. Neurol India [serial online] 2020 [cited 2021 Jan 16];68:1450-2. Available from: https://www.neurologyindia.com/text.asp?2020/68/6/1450/304081




Falcine sinus is a vascular channel between the two layers of falx cerebri that is present during the fetal period and usually closes before birth. The continued presence or recanalization of the falcine sinus after birth is considered to be a variation or anomaly. Lack of awareness about its uncommon anterior interhemispheric variant may lead to a wrong diagnosis of meningioma and/or dilated venous channel leading to potential catastrophic clinical scenario.

During early embryonic development, the primitive falx cerebri contains the sagittal plexus, a mesh of anastomotic venous loops. As the dorsal dominant venous channel of the sagittal plexus eventually develops into the anterior aspect of superior sagittal sinus (SSS), the ventral aspect of the sagittal plexus becomes the inferior sagittal sinus and the straight sinus, and the smaller channels between them disappear. With the development of the occipital lobe, the SSS and straight sinus start extending towards the occipital pole, recruiting more caudal venous loops of the sagittal plexus and forming a complete SSS and straight sinus. Falcine sinus is formed by one of the caudal anastomotic loops of the sagittal plexus, and disappears after complete development of the SSS and straight sinus. The development of the falcine sinus is closely associated with that of the posterior aspect of the SSS and the straight sinus.[1]

Some studies suggested that persistent or recanalized falcine sinus might result from an enlargement of certain venous channels caused by an obstruction of the venous sinuses. These may be located between posterior part of the SSS and the vein of Galen or the anterior part of straight sinus.[2] Instead of developing from one specific venous channel of the sagittal plexus, the falcine sinus may form by a random opening of certain venous channels or the combination of a number of small channels.

These falcine sinuses might be the traces of incomplete degradation of sagittal venous plexus during the convergence of the SSS and straight sinus towards the occipital pole.[3] As per author's knowledge only four cases of anterior falcine sinus has been reported with present case being 5th in the world.[4]


  Case History Top


Case 1

A 14-year-old female presented with small subcutaneous swelling over the back of right ear for which imaging was done to rule out intracranial extension of dermoid. Incidentally, detected lesion in the brain. No h/o headache, vomiting, seizure, speech difficulty, loss of consciousness, gait disturbance [Figure 1], [Figure 2], [Figure 3].
Figure 1: Case 1 Post contrast enhancing mass which is hyperdense on Non contrast CT (NCCT) scan

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Figure 2: Case 1: Sagittal Venogram and post contrast Sagittal MRI Brain showing anterior persistent falcine sinus (PFS)

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Figure 3: Case 1: MRI Perfusion showing high perfusion and classic location on Sagittal T2WI/FLAIR images

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Case 2

(Companion case) showing posterior, more common location of the persistent falcine sinus, in a 5 years/female who had midline parietal swelling likely dermoid for which imaging was done to confirm the intracranial extension. No seizure, no weakness. Normal developmental milestones [Figure 4].
Figure 4: Case 2: Classic posterior location, MR Venogram and T2WI sagittal Brain, associated dermoid

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  Discussion Top


Falcine sinus is a normal venous channel in falx cerebri which connects the vein of Galen and the posterior part of superior sagittal sinus (SSS) during the antenatal period, and normally closes before or shortly after birth. The falcine sinus develops from mesenchyme in the mesencephalic flexure, the same area that gives rise to the straight sinus. When the straight sinus is absent or rudimentary, the falcine sinus can be recanalized to enable venous drainage in response to the atretic straight sinus. Streeter defined the sagittal plexus as a mesh of anastomotic loops from which the superior sagittal sinus and the straight sinus develop. Persistent falcine sinus, has been reported in most previous studies as a rare intracranial venous anomaly frequently associated with cerebral abnormalities. Anomalies of straight sinus and SSS are commonly combined with falcine sinus as a result of their embryonic correlations during the fetal period. There is associated aplasia, or absence of the venous sinus, and their incidence is low. Most cases are asymptomatic.[5]

Most cases of persistent falcine sinus combined with cerebral abnormalities were presented in case reports.[6] The reported abnormalities were multiple such as dysplasia of the tentorium cerebelli, malposition of the SSS, dilation of the vein of Galen, and mid-brain arteriovenous malformation, total absence of the corpus callosum, Apert's syndrome and Chiari's II malformation.[7],[8]

We report a rare case of an anterior PFS combined with a DVA [Table 1]. This entity is very rarely described in literature, but the knowledge of which is of paramount importance for the practicing neuroradiologists. One interesting note here is also made that the case reports with anterior PFS is commoner in females than males. It is seen in pediatric as well as in the adult population.
Table 1: Demographics and anatomic characteristics of anterior persistent falcine sinus[4]

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Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Manoj KS, Krishnamoorthy T, Thomas B, Kapilamoorthy TR. An incidental persistent falcine sinus with dominant straight sinus and hypoplastic distal superior sagittal sinus. Pediatr Radiol 2006;36:65-7.  Back to cited text no. 1
    
2.
Sunilkumar D, Nagarajan K, Kiran M, Manjubashini D, Sabarish S. Persistent falcine sinus with temporo-occipital schizencephaly: Case report with a review of literature in relation to the undeveloped vein of Galen and/or straight sinus. Childs Nerv Syst 2020;36:417-21.  Back to cited text no. 2
    
3.
Manjila S, Bazil T, Thomas M, Mani S, Kay M, Udayasankar U. A review of extraaxial developmental venous anomalies of the brain involving dural venous flow or sinuses: Persistent embryonic sinuses, sinus pericranii, venous varices or aneurysmal malformations, and enlarged emissary veins. Neurosurg Focus 2018;45:E9.  Back to cited text no. 3
    
4.
Koo HW, Kang HK, Lee CH, Han SR, Choi CY, Sohn MJ, et al. Rare combination of a persistent anterior falcine sinus with developmental venous anomaly: A case report and literature review. Interdiscip Neurosurg 2018;12:4-7.  Back to cited text no. 4
    
5.
Kim MS, Lee GJ. Two cases with persistent falcine sinus as congenital variation. J Korean Neurosurg Soc 2010;48:82.  Back to cited text no. 5
    
6.
Ryu CW. Persistent falcine sinus: Is it really rare? Am J Neuroradiol 2010;31:367-9.  Back to cited text no. 6
    
7.
Lin L, Lin JH, Guan J, Zhang XL, Chu JP, Yang ZY. Falcine sinus: Incidence and imaging characteristics of three-dimensional contrast-enhanced thin-section magnetic resonance imaging. Korean J Radiol 9:463-9.  Back to cited text no. 7
    
8.
Kim MS, Lee GJ. Two cases with persistent falcine sinus as congenital variation. J Korean Neurosurg Soc 2010;48:82.  Back to cited text no. 8
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4]
 
 
    Tables

  [Table 1]



 

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