Atormac
Neurology India
menu-bar5 Open access journal indexed with Index Medicus
  Users online: 4332  
 Home | Login 
About Editorial board Articlesmenu-bullet NSI Publicationsmenu-bullet Search Instructions Online Submission Subscribe Videos Etcetera Contact
  Navigate Here 
 Search
 
  
 Resource Links
    Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
    Article in PDF (542 KB)
    Citation Manager
    Access Statistics
    Reader Comments
    Email Alert *
    Add to My List *
* Registration required (free)  

 
  In this Article
   References
   Article Figures

 Article Access Statistics
    Viewed1231    
    Printed31    
    Emailed0    
    PDF Downloaded57    
    Comments [Add]    

Recommend this journal

 


 
Table of Contents    
NEUROIMAGE
Year : 2014  |  Volume : 62  |  Issue : 5  |  Page : 580-581

Angiographic "Tau (τ)" sign in persistent trigeminal artery


1 Department of Neurosurgery, National Neurosciences Centre, Kolkata, West Bengal, India
2 Department of Radiodiagnosis, Peerless Hospital and Bhudeb Kanti Roy Research Centre, Kolkata, West Bengal, India

Date of Web Publication12-Nov-2014

Correspondence Address:
Krishnan Prasad
Flat 3B, 9 Southend Park, Kolkata - 700 029, West Bengal
India
Login to access the Email id

Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0028-3886.144519

Rights and Permissions



How to cite this article:
Prasad K, Thamatapu E, Saha M, Das S. Angiographic "Tau (τ)" sign in persistent trigeminal artery. Neurol India 2014;62:580-1

How to cite this URL:
Prasad K, Thamatapu E, Saha M, Das S. Angiographic "Tau (τ)" sign in persistent trigeminal artery. Neurol India [serial online] 2014 [cited 2019 Sep 18];62:580-1. Available from: http://www.neurologyindia.com/text.asp?2014/62/5/580/144519


Brain magnetic resonance imaging (MRI) of a 44-year-old lady done as part of the evaluation of non-specific headache, revealed a left side vascular anomaly. Neurologic examination was normal. MR-angiogram with Time Of Flight (TOF) sequence showed a persistent trigeminal artery on the left side extending backwards by the side of the sella from the internal carotid artery to the basilar artery [Figure 1]. Coronal T2 and reconstructedimages showed that the artery was joining the basilar trunk below the origin of the superior cerebellar artery [Figure 2]. The vertebrobasilar complex below the union was hypoplastic. Sagittal reconstructions showed that both posterior communicating arteries were absent and "tau" sign was present at the site of origin of the vessel from the internal carotid artery [Figure 3].
Figure 1: MR angiogram [Time of Flight sequence] showing a persistent trigeminal artery on the left side extending backwards by the side of the sella from the internal carotid artery to the basilar artery

Click here to view
Figure 2: Coronal T2 and reconstructed MR angiogram showing that the artery was joining the basilar trunk below the origin of the superior cerebellar artery. The vertebrobasilar complex below the union is hypoplastic. Both superior and posterior cerebellar arteries are seen originating from the distal basilar artery

Click here to view
Figure 3: Sagittal reconstructions showing that both posterior communicating arteries are absent and "Tau" sign is present at the site of origin of the vessel from the internal carotid artery

Click here to view


Persistent trigeminal artery is an embryological remnant of the anastamosis that existed in fetal life between the developing carotid arteries and the longitudinal neural arteries that go on to make the vertebrobasilar system. [1],[2] Its incidence is reported to be 0.1% to 1% [1] and it isthe commonest (accounting for 85%) [1],[2] of all the fetal carotid basilar anastamosis that may persist- the others being the persistent otic, hypoglossal and proatlantal arteries. [1] Its termination may be in one of 3 ways - anastamosing with the basilar artery below the superior cerebellar artery and supplying both posterior cerebral and superior cerebellar arteries (Saltzman Type 1), anastamosing with the basilar artery below the superior cerebellar artery but supplying only both superior cerebellar arteries and one or both posterior cerebral arteries being supplied by the posterior communicating arteries (Saltzman Type 2) or it may end in one of the cerebellar arteries (Saltzman Type 3). [1],[2],[3],[4] Our case was one of Saltzman Type 1.

The "Tau (τ)" sign is a classic angiographic sign of a persistent trigeminal artery. [5] It is so called because of the visual similarity on sagittal images to the Greek letter "Tau" - the vertical and anterior horizontal limbs of which are formed by the internal carotid arteries and the posterior limb by the persistent trigeminal artery. The only other vessel that may arise in this vicinity from the ICA and course backwards to meet the basilar complex is the otic artery but its origin is lower and also the vertical limb of the ICA can be seen above its the point of origin thereby precluding any cause of confusion.

The existence of the persistent trigeminal artery is often underdiagnosed and underreported . Usually diagnosed incidentally, [1],[2] it may rarely cause cranial neuropathies (like trigeminal neuralgia) [3] and this anomaly must be kept in mind during any surgeries involving this area to prevent iatrogenic injury. [3],[4]

 
  References Top

1.
Luh GY, Dean BL, Tomsick TA, Wallace RC. The persistent fetal carotid-vertebrobasilar anastomoses. AJR Am J Roentgenol 1999;172:1427-32.  Back to cited text no. 1
    
2.
Azab W, Delashaw J, Mohammed M. Persistent primitive trigeminal artery: A review. Turk Neurosurg 2012;22:399-406.  Back to cited text no. 2
    
3.
Alcalá-Cerra G, Tubbs RS, Niño-Hernández LM. Anatomical features and clinical relevance of a persistent trigeminal artery. Surg Neurol Int 2012;3:111.  Back to cited text no. 3
    
4.
Pereira LP, Nepomuceno LA, Coimbra PP, Oliveira Neto SR, Natal MR. Persistent trigeminal artery: Angio-tomography and angio-magnetic resonance finding. Arq Neuropsiquiatr 2009;67:882-5.  Back to cited text no. 4
    
5.
Chavhan GB, Shroff MM. Twenty classic signs in neuroradiology: A pictorial essay. Indian J Radiol Imaging 2009;19:135-45.  Back to cited text no. 5
[PUBMED]  Medknow Journal  


    Figures

  [Figure 1], [Figure 2], [Figure 3]



 

Top
Print this article  Email this article
   
Online since 20th March '04
Published by Wolters Kluwer - Medknow