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|LETTER TO EDITOR
|Year : 2014 | Volume
| Issue : 5 | Page : 560-561
A rare association of intracranial vertebral artery fenestration with nonaneurysmal perimesencephalic subarachnoid hemorrhage
Sunil Kumar1, Trilochan Srivastava1, Shankar Tejwani2
1 Department of Neurology, Sawai Man Singh Medical College,Jaipur, Rajasthan, India
2 Department of Radiology, Sawai Man Singh Medical College,Jaipur, Rajasthan, India
|Date of Submission||27-Sep-2014|
|Date of Decision||28-Sep-2014|
|Date of Acceptance||28-Sep-2014|
|Date of Web Publication||12-Nov-2014|
Department of Neurology, Sawai Man Singh Medical College,Jaipur, Rajasthan
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Kumar S, Srivastava T, Tejwani S. A rare association of intracranial vertebral artery fenestration with nonaneurysmal perimesencephalic subarachnoid hemorrhage. Neurol India 2014;62:560-1
|How to cite this URL:|
Kumar S, Srivastava T, Tejwani S. A rare association of intracranial vertebral artery fenestration with nonaneurysmal perimesencephalic subarachnoid hemorrhage. Neurol India [serial online] 2014 [cited 2020 Feb 19];62:560-1. Available from: http://www.neurologyindia.com/text.asp?2014/62/5/560/144493
Perimesencephalic subarachnoid hemorrhage (SAH) accounts for about 10% of all SAHs, and digital subtraction angiography (DSA) is mostly found to be normal in such patients.  The vertebral artery fenestration is a rare developmental anomaly. It represents a distinct vascular segment with a single origin, which is divided into two separate lumens that converge during their course thus, restoring the primary vessel. Each of the lumen has its own tunica muscularis and endothelial layers.  The term 'duplication' is sometimes confused with 'fenestration' but it has two separate origins without distal convergence of artery.  The prevalence of the vertebral artery fenestration is about 0.23% to 1.95%.  An association has been described between vertebral artery (VA) fenestration and intracranial aneurysm formation.
A 50-year-old woman presented with sudden-onset severe headache and recurrent vomiting. Neurological examination was unremarkable. Cranial computed tomography (CT) scan revealed perimesencephalic cistern SAH [Figure 1]. DSA did not demonstrate any intracranial aneurysm. However, incidental finding of left VA fenestration originating distal to posterior inferior cerebellar artery (PICA) [Figure 2]. The fenestration segment connected the fourth portion of left VA (LV4) to the proximal basilar artery. The patient was managed conservatively and she is currently asymptomatic at six months follow up.
|Figure 1: Non-contrast CT brain showing subarachnoid hemorrhage in perimesencephalic cisterns|
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|Figure 2: Digital Subtraction Angiography (DSA): The left vertebral angiogram demonstrated a fenestration in intracranial portion of vertebral artery (LV4 segment). There was no evidence of intracranial aneurysm|
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Vertebral artery fenestration occurs predominantly on left side with asymmetry of lumen diameters similar to our patient.  About two-third of VA fenestrations are extracranial, while one-third are intracranial. Improper regression of embryonic arteries seems to be the most probable explanation for VA fenestration.  However, some literature suggest that intracranial VA fenestration is more likely due to the persistence of fetal anastomotic vessels.
Vertebral artery fenestrations are associated with increased risk of aneurysm formation at its location. According to Drapkin, symptomatic intracranial aneurysms were found in about 20% of patients with VA fenestration.  Such aneurysm when found is usual site for SAH. The high preponderance of aneurysm formation in the fenestration segment may be related to abnormal tunica media and hemodynamic stress to the vessel wall at the proximal site. There are many case reports supporting the increased risk of SAH in VA fenestration due to aneurysm formation. Our patient is unique as it is the first report where perimesencephalic nonaneurysmal SAH is associated with VA fenestration. This important DSA finding should not be overlooked because it may predispose the patient to pathological conditions like SAH.
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[Figure 1], [Figure 2]