Clinical Neurology and Neurosurgery 119 (2014) 133–136
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Letters to the Editor Variations of the vertebrobasilar circulation and its impact on the neurosurgical interventions Keywords: Anatomy Basilar artery CT MR PICA Variation Vertebral artery
features and variations of intracranial arteries and its ﬁne calibrated branches can be demonstrated adequately and precisely without administration of the contrast material and ionizing radiation exposure in patients without contraindication for MR examination [2,3]. Akgun et al.  reported that there is no statistical difference between CT angiography and MR angiography to determine normal anatomical features and variations of the vertebrobasilar circulation and its branches.
Conﬂict of interest Dear Sir, We read the recent article titled “Importance of the perforating arteries in the proximal part of the PICA for surgical approaches to the brain stem and fourth ventricle – an anatomical study” by Kayaci et al.  with great interest. The authors evaluated the perforating arteries in the proximal part of the posterior inferior cerebellar artery (PICA) for surgical approaches to the brain stem and fourth ventricle in 26 adult cadavers. We would like to make a contribution regarding the impact on the neurosurgical interventions and radiologic evaluation of vertebrobasilar variations. Kayaci et al.  suggested that in the absent PICA cases, surgical approach from agenesic side of the PICA should be preferred to avoid the ischaemic complications due to iatrogenic damage of perforating arteries. A recent and comprehensive study based on the normal anatomical features and variations of the vertebrobasilar circulation and its branches in computed tomography (CT) and 3T magnetic resonance (MR) angiography performed by Akgun et al.  showed that only 34.8% (47/135) of the cases had wellknown normal vertebrobasilar system anatomy. In the rest of the cases (65.2%), there was at least one anatomic variation. The most common variations were isolated agenesis of right PICA (17.8%) and isolated agenesis of left PICA (11.1%). Akgun et al.  also reported that there was no PICA bilaterally in 4 cases (3%). In all of bilaterally absent PICA cases there were bilaterally well-developed anterior inferior cerebellar arteries (AICAs). Moreover majority of the cases without right PICA or without left PICA, there were moderately or well-developed contralateral PICAs and/or ipsilateral AICAs . Although Kayaci et al.  suggested that in the absent PICA cases agenesic side may be safe, we think that unexpected terminal branches originating from well-developed contralateral PICA or ipsilateral AICA and its perforating arteries may be encountered in surgical approach at the agenesic PICA side. As also reported by Kayaci et al. , the preoperative identiﬁcation of normal anatomy and variations of the vertebrobasilar circulation and its branches are important in planning surgical strategy and in preventing complications when approaching the brain stem and fourth ventricle pathologies. CT angiography permits an accurate and detailed analysis of normal vascular anatomy and variations of the intracranial arteries. However, after the introduction of high magnetic ﬁeld MR systems, normal anatomical
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The authors declare that they have no conﬂict of interest.
References  Kayaci S, Caglar YS, Bas O, Ozveren MF. Importance of the perforating arteries in the proximal part of the PICA for surgical approaches to the brain stem and fourth ventricle – an anatomical study. Clin Neurol Neurosurg 2013;115:2153–8.  Akgun V, Battal B, Bozkurt Y, Oz O, Hamcan S, Sari S, et al. Normal anatomical features and variations of the vertebrobasilar circulation and its branches: an analysis with 64-detector row CT and 3T MR angiographies. Sci World J 2013;2013:620162, http://dx.doi.org/10.1155/2013/620162.2013.  Battal B, Akgun V, Sari S. Variations of the vertebrobasilar circulation and its impact on the clinical and radiologic evaluation. Surg Radiol Anat 2013, http://dx.doi.org/10.1007/s00276-013-1164-7.
Salih Hamcan Agri Military Hospital, Department of Radiology, Agri, Turkey Yalcin Bozkurt Veysel Akgun Bilal Battal ∗ Gulhane Military Medical School, Department of Radiology, Ankara, Turkey ∗ Corresponding author at: Gulhane Military Medical School, Department of Radiology 06018, Etlik, Ankara, Turkey. Tel.: +90 533 4330667; fax: +90 312 304 4700. E-mail address: bilbat [email protected]
3 October 2013 Available online 4 February 2014 http://dx.doi.org/10.1016/j.clineuro.2013.10.027
In reply Dear Sir, We would like to thank Dr Battal and his colleagues for their attention and contribution to our article.