Asian Pac. J. Health Sci., 2015; 2(1): 161-166 e-ISSN: 2349-0659, p-ISSN: 2350-0964 ____________________________________________________________________________________________________________________________________________ Variations in the branches of basilar artery in adult human cadavers Harish A. Wankhede 1*, Dipti A. Nimje 2, Prakash B. Hosmani 3 1Assistant Professor of Anatomy, Government Medical College, Miraj, India 2Assistant Professor of Anatomy, Dr. Bhausaheb Hire Memorial Government Medical College, Dhule, India 3Associate Professor of Anatomy, Vaishampayan Memorial Government Medical College, Solapur, India ABSTRACT Various variations of branches of the basilar artery are mentioned in the literature but the exact cause is not known. Anomalies of the vertebro-basilar vessels arise as early embryonic developmental deterioration. Many studies are available on the anterior circulation of the brain but studies on the posterior circulation are very few. Hence the present study is concentrated on morphological variations in branches of the basilar artery. The anterior inferior cerebellar arteries appear normal except one hypoplastic seen on left side. Many labyrinthine or internal auditory arteries arise from the anterior inferior cerebellar artery (60% on right and 65% on left). Numbers of the pontine branches on right side ranges from 3-7 and on left side numbers of branches are 4-7. Most of the superior cerebellar arteries arise from the basilar artery (85% on right and 80% on left). Variation in the superior cerebellar artery is unilateral duplication. Bilateral duplication of the superior cerebellar artery and the superior cerebellar artery arising from the posterior cerebral artery was also seen. The posterior cerebral artery most commonly appear as adult type (75% bilaterally), fetal type was seen more common on left side and transitional types was seen more common on right side. Neurosurgical importance of this study lies during the exposure of the region for different purposes. Knowledge of variations will increase the success of the surgical and radiological procedures. Key words: anterior inferior cerebellar artery, basilar artery, internal auditory artery, labyrinthine artery, posterior cerebral artery, pontine artery, superior cerebellar artery Introduction The basilar artery is a large median vessel formed by The superior cerebellar artery arises near the distal the union of the vertebral arteries. It gives the portion of the basilar artery, immediately before the following branches on either side 1) Pontine branches; formation of the posterior cerebral arteries. It passes 2) Anterior inferior cerebellar artery; 3) Internal laterally below the oculomotor nerve, which separates auditory (Labyrinthine) artery; 4) Superior cerebellar it from the posterior cerebral artery, and curves round artery; 5) Posterior cerebral artery . The pontine the cerebral peduncle below the trochlear nerve to gain branches are numerous small branches which arise the superior cerebellar surface. The posterior cerebral from the front and sides of the basilar artery along its artery is a terminal branch of the basilar artery. course and supply the pons. The internal auditory Surgical nomenclature divides the vessel into three (labyrinthine) artery the long slender branch has a parts or segments: P1 – from the basilar bifurcation to variable origin. It usually arises from the anterior the junction with the posterior communicating artery; inferior cerebellar artery. The anterior inferior P2 – from the junction with the posterior cerebellar artery is given off from the lower part of the communicating artery to the portion in the basilar artery and runs posterolaterally, usually ventral perimesencephalic cistern; and P3 – the portion that to the abducent, facial and vestibulocochlear nerves. runs in the calcarine fissure. An annular network of _______________________________ leptomeningeal arteries arise from the vertebral and *Correspondence basilar arteries and embrace the cerebellum and brain Dr. Harish A. Wankhede stem. The meningeal arteries so formed have been Assistant Professor of Anatomy, classified into three groups, namely paramedian, short Government Medical College, Miraj, India circumferential and long circumferential arteries. They Email: [email protected] can be distributed both supratentorially and infratentorially, and all give off fine side branches and end as penetrating arteries. Infratentorial meningeal ____________________________________________________________________________________________________________________________________________ Wankhede et al ASIAN PACIFIC JOURNAL OF HEALTH SCIENCES, 2015; 2(1): 161-166 www.apjhs.com 161 Asian Pac. J. Health Sci., 2015; 2(1): 161-166 e-ISSN: 2349-0659, p-ISSN: 2350-0964 ____________________________________________________________________________________________________________________________________________ arteries are very variable. The paramedian arteries, after possible anatomical variations can prevent inadvertent arising from the basilar or vertebral arteries, penetrate the trauma & bleeding to a very great extent.[5] brain stem directly. The short circumferential arteries end Many studies are available on vessels of the anterior at the lateral surface of the brain before penetration and circulation of the brain i.e. on vessels of the circle of the long circumferential arteries later form the range of Willis but studies on the posterior circulation are very cerebellar arteries. These vessels, arranged as a series of few. Such studies so far had been done mostly in the loops over the brain, arise from the brain stem vessels on American and European races and are mostly based on the base of the brain.[1] Various variations of branches of imaging techniques. Studies in the Indian population have the basilar artery are mentioned in the literature. Many been few. Hence the present study is concentrated on the variations in position of arteries of the vertebro-basilar morphological variations of the branches of the basilar system and the loop formation are quoted in the literature, artery of human adult cadaver brain, to show the but the exact cause is not known. Ageing and frequency and type of anomalies in branches of the basilar haemodynamic factors have been postulated as a probable artery. reasons.[2] Anomalies of the vertebrobasilar vessels arise as early embryonic developmental deteriorations. The Material and methods majority of them are seen in position, origin and shape of the vertebral and or basilar arteries.[3]The microsurgical In present study the basilar artery is studied by dissection anatomy of the posterior circulation is very complex and method[6] in 40 human adult brain specimens from variable. Surgical approaches to this area are considered embalmed human cadavers collected from various risky due to the presence of the various important blood medical colleges of Maharashtra. Male, female vessels and neural structures. Many authors have differentiation was not made while collecting the data documented various anomalies as well as differences of since numbers of female cadavers was less. Branches of the anatomy in this area in the Indian population as the basilar artery were studied. Variations in the branches compared to the Western literature.[4] Prior knowledge of of basilar artery were noted and photographed. Results Table 1: Incidence of variation in the anterior inferior cerebellar artery Anterior inferior cerebellar artery Right Left Normal Specimens 40 39 Percentage 100% 97.5% Hypoplastic Specimens 0 1 Percentage 0% 2.5% Chi-square test value for left side=36.1, DF=1, P<0.01 (highly significant) Figure 1: Arrow showing hypoplastic left anterior inferior cerebellar artery ____________________________________________________________________________________________________________________________________________ Wankhede et al ASIAN PACIFIC JOURNAL OF HEALTH SCIENCES, 2015; 2(1): 161-166 www.apjhs.com 162 Asian Pac. J. Health Sci., 2015; 2(1): 161-166 e-ISSN: 2349-0659, p-ISSN: 2350-0964 ____________________________________________________________________________________________________________________________________________ Table 2: Variation in the Internal auditory (Labyrinthine) artery Origin of the Internal auditory (Labyrinthine) Normal From AICA Other artery from BA variation Total Right Specimens 16 24 0 Percentage 40% 60% 0% Left Specimens 14 26 0 Percentage 35% 65% 0% Chi-square test value for right side=1.6, DF=1, P>0.05 (not significant), Chi-square test value for left side=3.6, DF=1, P>0.05 (not significant). Table 3: Number of pontine branches Number of pontine branches Right Left Mean ± S.D. 4.5±0.75 4.7±0.83 Maximum 7 7 Minimum 3 4 Table 4: Variation in the Superior cerebellar artery Variation in SCA Right Left Specimen Percentage Specimen Percentage Normal arising from BA 34 85% 32 80% Unilateral duplication 3 7.5% 5 12.5% arising from BA Unilateral duplication with 0 0% 2 5% one SCA arising from PCA Unilateral duplication with 1 2.5% 0 0% both arising from PCA Single SCA arising from 0 0% 1 2.5% PCA Bilateral duplication 1 (2.5%) Chi-square test value on right side=80.69, DF=3, P<0.01 (highly significant), Chi-square test value on left side=87.65, DF=4, P<0.01 (highly significant) Figure 2: Arrow showing duplication of Figure 3: Arrow showing the bilateral duplication the left superior cerebellar artery. of the superior cerebellar artery. ____________________________________________________________________________________________________________________________________________