A STUDY OF TEMPORAL BRANCHES OF MIDDLE CEREBRAL ARTERY

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1 J. Anat. Sciences, 23(2) : Dec. 2015, Original Article A STUDY OF TEMPORAL BRANCHES OF MIDDLE CEREBRAL ARTERY Medha Das*, Shirin Jahan*, Pranjal Pankaj** * Department of Anatomy, Rama Medical College, Mandhana ** Department of Medicine, Rama Medical College, Mandhana. ABSTRACT Introduction : The microsurgical anatomy of middle cerebral artery is of particular interest to the cerebrovascular surgeons as it supplies the most of the superolateral surface of cerebral hemispheres and is the most commonly involved artery in stroke.. There are cases in which a temporal branch might represent the preferred recipient vessel when considering a patient for microsurgical cerebral revascularization. However, descriptions of the middle cerebral temporal branches which we found in the literature did not correlate with our preliminary observations of these arterial branches.objective : This study was done to define further the arterial anatomy of the temporal lobe, hoping to find immediate application of our findings in the field of microsurgical cerebral revascularization. Materials and Methods : Total 20 middle cerebral arteries were studied obtained from 10 brains.meticulous dissection was done and middle cerebral artery was exposed and cleaned in lateral sulcus on the inferior surface of brain. Its temporal branches were studied in detail.digital photographs were taken. Result : In 16 out of 20 Middle cerebral arteries studied, a temporal branch was the first branch taking origin from M1 segment of Middle cerebral artery. In rest 4 specimens orbitofrontal artery was the first branch,temporal being the second. Keywords : middle cerebral artery, M1 segment,temporal branches,stroke, cerebral revascularization. INRTODUCTION : The middle cerebral artery (MCA) is one of the three major paired arteries that supplies blood to the cerebrum. The MCA arises from the internal carotid artery as the larger terminal branch.at first it runs in the lateral fissure,then posterosuperiorly on the insula,and divides into branches distributed to the insula and the adjacent lateral cerebral surface. It also supplies blood to the anterior temporal lobes and the insular cortices[1]. The left and right MCAs arise from bifurcations of the internal carotid arteries and thus are connected to the anterior cerebral arteries and the posterior communicating arteries, which connect to the posterior cerebral arteries. The MCAs are not considered a part of the Circle of Willis. The middle cerebral artery can be classified into 4 parts[2] M1: The sphenoidal segment, so named due to its origin and loose lateral tracking of the sphenoid bone. Although known as the horizontal segment, the segment may descend, remain flat, or extend posteriorly in different individuals. The M1 segment perforates the brain with numerous anterolateral central (lateral lenticulostriate) arteries, which irrigate the basal ganglia. M2: Extending anteriorly on the insula, this segment in known as the insular segment. It is also known as the Sylvian segment when the opercular segments are included. The MCA branches may bifurcate or sometimes trifurcate into trunks in this segment which then extend Address for Correspondence : Dr Medha Das Assistant Professor Department of Anatomy Rama Medical College Hospital & Research Institute Mandhana, Kanpur drmedhadas@rediffmail. 15

2 A Study of Temporal Branches of Middle Cerebral Artery into branches that terminate towards the cortex. M3: The opercular segment extends laterally, exteriorly from the insula towards the cortex. This segment is sometimes grouped as part of M2. M4: These finer terminal or cortical segments irrigate the cortex. They begin at the external end of the Sylvian fissure and extend distally away on the cortex of the brain. The branches (ramus) of the MCA can be described by the areas they irrigate.the temporal lobe branches are named as:[3-4] Temporopolar: The artery extends from the sphenoidal segment of the MCA via the operculum inferior surface and supplies the polar and anterior lateral portions of the temporal lobe. The vessel can be identified in 52% of normal angiograms Anterior temporal: This artery extends in a similar fashion as the temporopolar and vascularises the same regions. Middle temporal: This artery extends from the Sylvian fissure opposite to the inferior frontal gyrus and suppies the superior and middle portion of the middle temporal lobe. It can be identified in 79% of angiograms. Posterior temporal: This artery extends out and away from the operculum and turns in a step-wise manner first inferiorly then posteriorly into the superior temporal sulcus then to the middle temporal sulcus. This vessel supplies the posterior portion of the temporal lobe and is the origin of several perforating arteries that irrigate the insula. It is readily identifiable most angiogram Materials and methods The present work was carried out in Department of Anatomy, RIMS, Ranchi and continued in Rama medical college,kanpur. Middle cerebral artery was observed in the brain obtained from cadaver used for routine educational dissection.total 20 MCAs were studied obtained from 10 brains. After removal of brain from the skull,blood vessels on the base of brain were cleaned from piamater on the external surface of which it lies.through meticulous dissection middle cerebral artery was cleaned and variation in origin of temporal branches was observed. Digital photographs were taken. OBSERVATION AND RESULTS In all the cadavers middle cerebral artery originated from internal carotid artery (ICA) as the larger terminal branch opposite optic chiasma. In 16 out of the 20 middle cerebral arterial specimens, the first major branch of the middle cerebral artery was a branch or trunk supplying the temporal lobe.in rest four specimen orbitofrontal artery(obf) was the first branch originating from M1 segment of MCA ;temporal being the second.[table No. 1] In 10 out of 16 specimens the first trunk from M1 segment immediately divided into temporopolar and anterior temporal artery (Fig.1).The middle and posterior temporal artery were taking origin from inferior division in these cases. In 4 out of 16 specimen the first branch was temporopolar artery(tpa) arising separately from M1 segment of MCA(Fig.2). In these cases, second branch from M1segment was orbitofrontal artery. Other temporal branches ; anterior temporal(ata) and middle temporal(mta) were taking origin from inferior division of MCA which continued as posterior temporal artery(pta). In 2 out of 16 specimens the branch from M1 segment was a large arterial trunk supplying entire temporal lobe by forming temporopolar,anterior temporal,middle temporal and posterior temporal arteries and then continuing as angular artery(fig.3).[table No.2 ]. In these specimens only the origin of MTA and PTA was from M1segment of MCA ;in rest 18 specimens their origin was from inferior division of M2 segment.[table No. 3 ] In remaining 4 specimen where the first branch from M1 segment of MCA was orbitofrontal artery,the second branch was a trunk which divided into temporopolar and anterior temporal artery (Fig. 4).Middle temporal and posterior temporal arteries were taking origin from inferior division. These temporal branches or trunk arose from the middle cerebral artery proximal or opposite to the lenticulostriate arteries in 12 of the 20 cases (Fig.5), 16

3 Medha Das, Shirin Jahan, Pranjal Pankaj and distal to the lenticulostriate arteries in eight cases. After arising from the middle cerebral artery, the temporal branches coursed over the superior surface of the temporal pole and temporal lobe. Individual branches then emerged from the Sylvian fissure and ran posteroinferiorly over the superior temporal gyrus to supply the anterior, middle, and posterior parts of the temporal lobe. The temporopolar artery arose as a branch of M1 segment in all the specimen and travelled in the pia-arachnoid anteroinferiorly over the anterior and medial aspects of the temporal pole.during the arterial dissections, the arterial branches emerging from the Sylvian fissure were arbitrarily grouped into anterior, middle, or posterior temporal branches. TABLE No. 1 showing first branch from M1 segment of MCA First branch of M1segment of MCA Number of specimen Temporal trunk 16 TABLE No.2 showing branching pattern of first temporal trunk from M1 segment of MCA Total No. of specimen with temporal trunk as first branch from M1 segment Combined trunk for temporopolar and anterior temporal artery Temporopolar artery arising separately from M1 segment Single trunk from M1 segment giving origin to all temporal branches TABLE No. 3 showing origin of MTA and PTA from MCA Origin of MTA and PTA Total 20 specimen From M1 segment of MCA from M2 segment of MCA (interior division ) 2 18 Orbitofrontal artery 4 Fig. 01 showing origin of TPA and ATA by a common trunk from M1 segment of MCA.ICA =internal carotid artery,mca=middle cerebral artery,tpa=temporopolar arety,ata =anterior temporal artery 17

4 A Study of Temporal Branches of Middle Cerebral Artery Fig.02 Showing origin of TPA separately as the first branch of M1 segment of MCA.ICA =internal carotid artery,mca =middle cerebral artery,tpa = temporopolar artey,obf = orbitofrontal artery Fig. 03 showing a large trunk from MCA supplying the temporal lobe by forming TPA, ATA,MTA,PTA and then continuing as angular artery. MCA=middle cerebral artery,tpa= temporopolar artery,ata = anterior temporal artery,mta =middle temporal artery,pta =posterior temporal artery 18

5 Medha Das, Shirin Jahan, Pranjal Pankaj Fig.04 showing origin of TPA and ATA by a common trunk from M1 segment ; in these specimen the first branch from M1 segment was OBF artery.obf= orbitofrontal artery,tpa =temporopolar artery,ata= anterior tempolar artery Fig : 05 showing origin of temporal branch opposite lenticulostriate branches. 19

6 A Study of Temporal Branches of Middle Cerebral Artery DISCUSSION The microsurgical anatomy of MCA has interested many researchers for years specially with the advent of microneurosurgical techniques in cerebrovascular surgery. Ring and Waddington [5-7] have described the terminal configuration of the middle cerebral artery, as well as the branching pattern of the artery within the Sylvian fissure. Foix and Levy[8] described an anterior temporal branch coursing from the middle cerebral artery near its origin, and Vander Eecken [9] mentions an anterior temporal artery as well as an inconstant temporopolar artery. The origins of the temporopolar artery and the anterior temporal artery have been illustrated by Stephens and Stilwell [10] in their meticulous photographic study of the cerebral vasculature, and the angiographical anatomy of the temporopolar branches has been illustrated by Dahlstrom et al [11]. In 1967 Donaghy and Yasargil, working independently at that time, each constructed in a patient a superficial temporal artery-cortical artery vascular bypass in an effort to relieve symptoms of cerebrovascular insufficiency [12-13]. This procedure has now been done by many neurosurgeons throughout the world, but evaluation of the procedure as a means of mitigating the effects of cerebrovascular disease remains in the embryonic stage. Yasargil has recommended that an arterial branch lying on the temporal lobe be used as a convenient recipient for such microsurgical anastomoses.however, in cases of middle cerebral artery stenosis or occlusion, such an artery may not be a suitable recipient. If such patient is subjected to such surgery, and if an artery lying on the anterior temporal lobe had been used as the recipient vessel, the angiogram demonstrates that any new collateral blood delivered from the superficial temporal artery via the anastomosis either would have been carried into the middle cerebral artery proximal to the occlusion, or would have been carried distally into the terminal branches of the temporal arteries. None would have been delivered to the ischemic area of the cerebral hemisphere distal to the middle cerebral artery occlusion. Delong (1973) had studied temporal branches of MCAs in 23 specimen. He reported that Nineteen out of 23 middle cerebral arterial specimens had as the first major branch of the middle cerebral artery a sizable anterior temporal artery; a trunk forming the anterior and middle temporal branches; a trunk forming the anterior, middle, and posterior temporal arteries; or a trunk forming temporal and angular arterial branches [14]. In 14 specimens the first major branch of the middle cerebral artery was an anterior temporal-middle temporal-posterior temporal trunk, a temporalangular trunk, or an anterior temporal-middle temporal trunk. In three specimens, the first major branch was the anterior temporal artery which was followed immediately by a middle temporal-posterior temporal- angular trunk. In two specimens the first major branch was the anterior temporal artery, with the middle and posterior temporal branches arising more distally from the middle cerebral complex. In the remaining four specimens, the orbitofrontal and operculofrontal complexes arose proximal to the origins of the temporal branches. 1n 1984, Umansky studied microsurgical anatomy of proximal segment of middle cerebral artery in 70 specimens. The authors studied the outer diameter (OD), length, site of origin, and pattern of branching of the main trunk, secondary trunks, and the initial insular portion of the cortical branches of the MCA.. The mean OD of the cortical branches measured near their origin in the main and secondary trunks indicated that the angular artery was the largest vessel, with a mean OD of 1.5 mm on both sides of the brain. The temporopolar artery was the smallest, with a mean OD of 0.8 mm in the right hemisphere and 0.9 mm in the left hemisphere [15]. In 2005,Pai and Varma did dissection based study on the microsurgical anatomy of the MCA.In all 10 MCAs they studied the temporopolar(tpa) and the anterior temporal (ATA) arose as a common trunk. In few cases, the middle temporal artery (MTA), and the posterior temporal artery (PTA) arise as a common trunk from the M1 segment [16]. Ogengo (2011) studied branching pattern of middle cerebral artery in African population. In this study early cortical branch was reported in 47% of the cases.in 63.9% of these 47% cases,the early cortical branch was a temporal trunk [17]. 20

7 Medha Das, Shirin Jahan, Pranjal Pankaj CONCLUSION There are cases in which a temporal lobe arterial branch might represent the preferred recipient vessel when considering a patient for microsurgical cerebral revascularization. In patients harbouring surgically inaccessible internal carotid stenoses or occlusions, microsurgical anastomosis of the superficial temporal artery to an anterior temporal arterial branch might result in the delivery of a new blood supply proximal to the lenticulostriate arteries close to the origin of the middle cerebral artery. Such an anastomosis in these cases would be ideal for potentially perfusing the ischemic middle cerebral arterial tree. REFERENCES 1. Standring S. Grey s Anatomy.Arterial supply of brain,40th edition,elsevier Ltd,spain.2008 p Krayenbühl, Hugo; Yasargil, M G; Huber, Peter; Bosse, George, CerebralAngiography; Thieme Medical publishers Inc.1982, pp , 3. Kiernan JA. Blood Supply of the Central Nervous System. In: Kiernan JA, editor. Barr's the human nervous system: an anatomical viewpoint. Philadelphia: Lippincott-Raven, 1998: pp Osborn, Anne G; Jacobs, Jacobs, John M, Diagnostic cerebral angiography, Lippincott Williams and Wilkins,1999.pp Ring BA: Middle cerebral artery: Anatomical and radiographic study. Acta Radiol 57: 1962, pp Ring BA, Waddington M: Ascending frontal branch of middle cerebral artery. Acta Radiol [Diagn] (Stockholm) 6.,1967,pp Ring BA:, The neglected cause of stroke: intracranial occlusion of the small arteries. Radiology May;88(5): pp Foix C, Levy M: Les ramollissements sylviens. Rev Neurol 2, 1927:pp Eecken HN Vander: Anastomoses Between Leptomeningeal Arteries. Springfield, Illinois,Ateries,Charles C Thomas, 1959.p Stephens RB, Stilwell DL: Arteries and Veins of the Human Brain. Springfield, Illinois, Charles C Thomas,1969,p 27, 35, Dahlstrom L, Fagerberg G, Lanner L, et al: Anatomical and angiographic studies of arteries supplying anterior part of temporal lobe: A preliminary report Acta Radiol [Diagn] (Stockholm) 9: 1969,pp Yasargil MG: Microsurgery Applied to Neurosurgery. New York, Academic Press,1969, p Yasargil MG, Krayenbuhl HA, Jacobson JH: Microneurosurgical arterial reconstruction. Surgery 67:1970,pp Delong Bradford W. ;Anatomy of the Middle Crebral Artery :The Temporal Branches,Stroke :1973,vol 4,pp Umansky F, Juarez SM, Dujovny M,Ausman JI,Diaz FG,Gomes F.Microsurgical anatomy of the proximal segments of the middle cerebral artery. J Neurosurg. 1984; 61 (3):pp Pai SB, Varma RG, Kulkarni RN. ;Microsurgical Anatomy of Middle cerebral Artery :Neurol India; 2005,53:pp Ogengo JA, Njongo W, Hemed E, Obimbo MM, Gimongo J. Branching pattern of Middle cerebral artery in an African population. Clin Anat. 2011;Sep;24(6): pp