Middle cerebral artery

Middle cerebral artery

The middle cerebral artery (MCA) is the largest and most complex of the three major cerebral arteries 1).

Most of the authors who have carried out anatomical studies of the middle cerebral artery agree on this being one of the least variable arteries. Nevertheless, they describe early bifurcationtrifurcationquadrifurcationduplication, single non-bifurcating trunk, hypoplasiafenestrations, etc. Considered to be having one of the most extensive irrigation territories in the brain. The artery arises below the anterior perforated substance, lateral to the optic chiasm. It runs along the sylvian fissure up to the limen insulae, where it bends at an angle which can be upto 90° and it is at that point where the bifurcation usually occurs.

The MCA arises from the internal carotid artery and continues into the lateral sulcus where it then branches and projects to many parts of the lateral cerebral cortex. It also supplies blood to the anterior temporal lobes and the insula. The artery supplies a portion of the frontal lobe and the lateral surface of the temporal and parietal lobes, including the primary motor and sensory areas of the face, throat, hand and arm, and in the dominant hemisphere, the areas for speech.

The left and right MCAs rise from trifurcations of the internal carotid arteries and thus are connected to the anterior cerebral artery and the posterior communicating artery, which connect to the posterior cerebral artery. The MCAs are not considered a part of the Circle of Willis.

The angular artery is a significant terminal branch of the anterior or middle trunk of the middle cerebral artery (MCA).

Variations

Duplicated middle cerebral artery.

Accessory Middle cerebral artery 2).

Teal et al. 3) further classified two types of accessory MCAs based on the origin of variant vessels, which can be proximal (type 1) or distal (type 2) segments of the ACA 4).

Classification

MCA was studied by Gunnal et al., in detail and classified it in four different types as bifurcated, trifurcated, quadrifurcated MCA and MCA with no trunks or single main trunk as per the termination 5).

Kahilogullari et al. proposed a way of classification made in relation to the terminology of the intermediate trunk, which is still a subject of debate. The intermediate trunk was present in 61% of cadavers and originated from a superior trunk in 55% and from an inferior trunk in 45%. Cortical branches supplying the motor cortex (precentral, central, and postcentral arteries) significantly originated from the intermediate trunk, and the diameter of the intermediate trunk significantly increased when it originated from the superior trunk. In measurements of the angles between the superior and intermediate trunks, it was found that the intermediate trunk had significant dominance in supplying the motor cortex as the angle increased. The intermediate trunk was classified into 3 types based on the angle values and the distance to the bifurcation point as Group A (pseudotrifurcation type), Group B (proximal type), and Group C (distal type). Group A trunks were seemingly closer to the trifurcation structure that has been reported on in the literature and was seen in 15%. Group B trunks were the most common type (55%), and Group C trunks were characterized as the farthest from the bifurcation point. Group C trunks also had the smallest diameter and fewest cortical branches. Similarities were found between the angles in cadaver specimens and on 3D CT cerebral angiography images. Beyond the separation point of the MCA, trunk structures always included the superior trunk and inferior trunk, and sometimes the intermediate trunk.

Interrelations of these vascular structures and their influences on the cortical branches originating from them are clinically important. The information presented in this study will ensure reliable diagnostic approaches and safer surgical interventions, particularly with MCA selective angiography 6).

Areas

The MCA territory was divided into 12 areas: orbitofrontal, prefrontal, precentral, central, anterior parietal, posterior parietal, angular, temporo-occipital, posterior temporal, middle temporal, anterior temporal, and temporopolar. The smallest cortical arteries arose at the anterior end and the largest one at the posterior end of the Sylvian fissure. The largest cortical arteries supplied the temporo-occipital and angular areas 7).

Perforators

Three distinct patterns of perforators arising from the proximal middle cerebral artery were found 8).


Marinković et al., divided it into medial, middle, and lateral groups. Those in the medial group usually arose directly from the MCA main trunk close to the carotid bifurcation. There were usually three vessels in the middle group, which originated not only from the MCA trunk, but also from the MCA collateral (cortical) branches. Common stems, when present, gave rise to individual perforating vessels and occasionally to thin olfactory and insular rami. Perforating arteries in the lateral group varied from one to nine in number. In addition to an origin from the MCA trunk, they also arose from cortical branches supplying the frontal and temporal lobes. The fact that lateral perforating vessels often originated from division sites and from terminal branches of the MCA is of clinical significance, because aneurysms are more commonly located at the MCA bifurcation. Anastomoses were not found among the perforating arteries. In two specimens, a fusion between a perforating artery and the MCA trunk was noted. Since the perforating vessels are obviously end arteries, injury to them must be avoided during operations for MCA aneurysms 9).

Segments

Branches

Pathology

References

1)

Rhoton AL., Jr The supratentorial arteries. Neurosurgery. 2002;51(Suppl 4):53–120.
2)

Uchino A, Kato A, Takase Y, Kudo S. Middle cerebral artery variations detected by magnetic resonance angiography. Eur Radiol. 2000;10(4):560-3. PubMed PMID: 10795531.
3)

Teal JS, Rumbaugh CL, Bergeron RT, Segall HD. Anomalies of the middle cerebral artery: accessory artery, duplication, and early bifurcation. Am J Roentgenol Radium Ther Nucl Med. 1973 Jul;118(3):567-75. PubMed PMID: 4723180.
4) , 7)

Gibo H, Carver CC, Rhoton AL Jr, Lenkey C, Mitchell RJ. Microsurgical anatomy of the middle cerebral artery. J Neurosurg. 1981 Feb;54(2):151-69. PubMed PMID: 7452329.
5)

Gunnal SA, Farooqui MS, Wabale RN. Study of Middle Cerebral Artery in Human Cadaveric Brain. Ann Indian Acad Neurol. 2019 Apr-Jun;22(2):187-194. doi: 10.4103/0972-2327.144289. PubMed PMID: 31007431; PubMed Central PMCID: PMC6472224.
6)

Kahilogullari G, Ugur HC, Comert A, Tekdemir I, Kanpolat Y. The branching pattern of the middle cerebral artery: is the intermediate trunk real or not? An anatomical study correlating with simple angiography. J Neurosurg. 2012 May;116(5):1024-34. doi: 10.3171/2012.1.JNS111013. Epub 2012 Feb 24. PubMed PMID: 22360571.
8)

Grand W. Microsurgical anatomy of the proximal middle cerebral artery and the internal carotid artery bifurcation. Neurosurgery. 1980 Sep;7(3):215-8. PubMed PMID: 7207737.
9)

Marinković SV, Kovacević MS, Marinković JM. Perforating branches of the middle cerebral artery. Microsurgical anatomy of their extracerebral segments. J Neurosurg. 1985 Aug;63(2):266-71. PubMed PMID: 4020447.

3D Neurotrainer

3D Neurotrainer

The joint work of neurosurgeons of the University General Hospital of Alicante and a toy company of Onil has resulted in a pioneering advance in the treatment of tumors at the base of the brain. This is a 3D printed surgical simulation model, presented in the framework of the XIV National Congress of the Spanish Society of Skull Base Pathology that took place in the hospital. Those responsible said that, after being improved and implemented, it will also be announced next November at a medical meeting in Orlando.

According to Pablo González, neurosurgeon of the Hospital and member of the Neurosciences Group of the Institute of Sanitary and Biomedical Research of Alicante (Isabial), the main advance of this model is that it allows to simulate a surgery in real conditions, not only seeing the anatomy of the area but the distortion caused by that injury at the base of the brain. They started from a few models developed three years ago together with the Bioengineering department of the Miguel Hernández University (UMH) of Elche, to which the German toy company Sempere de Onil has now been incorporated, which has made the technology available to medicine impression they use to make dolls. The novelty lies, above all, in the choice of the materials used, which perfectly reproduce the real organs and even the textures of the tumor to be treated.

One of the advantages of this system is that it allows planning the surgical activity, carrying it out in the most realistic conditions possible. In addition, a system of detection of nerves and more important neural structures has been incorporated, which guides the surgeon. “When we are 10 millimeters from the nerves, it emits intermittent beeps, similar to the assistant to park the car, and when the distance is two, the frequency of the sound is continued,” said Dr. González López, who also highlighted the help he gives to the surgeon in terms of anatomical orientation.

Dr. Javier Abarca, a neurosurgeon at the Skull Base Unit, said that so far these types of surgeries were performed by dissecting them in bodies, using virtual surgical planning models or synthetic prototypes. Now it has managed to combine all that and it has also improved, allowing to perform the surgery in the most realistic way possible. «In the models made with plastic, when we broke the part that simulated the bone with an engine it was burned. However, with the material used now, the material splinters forming chips with the same consistency. It looks like a real surgery, ”he said.

Now, the goal is to improve the model, reproducing even other anatomical regions. Although both the generation of the files used for three-dimensional reproduction and printing – which lasts between 90 and 100 hours – are complicated processes, the idea is to be able to “customize” each model to simulate real scenarios.

Dr. Irene Monjas, otolaryngologist at the Hospital de Alicante, stressed the progress of replacing anatomical specimens with this simulator, less and less available and at a much higher cost. “In addition, this makes it possible to reproduce exactly the pathologies to be treated, plan operations and even become a learning tool for residents,” he said.

In the General Hospital of Alicante about forty or fifty interventions are performed a year at the base of the brain, between vestibular schwannomas, meningiomas of the posterior fossa and epidermoid tumors. Although fortunately most tumors in this area are benign (95%), if they are not operated it can end up affecting the nerves and neural structures and even plugging a circuit of fluid circulation in the brain, causing hydrocephalus, which is potentially serious In addition, these tumors experience very slow growth, which helps to generate the model and plan the surgery with time until it is optimal. “The objective is to be able to operate these pathologies and above all without affecting the nervous structures,” said Dr. Gonzalez after the operating simulation performed before the leading figures in neurosurgery worldwide.

THE SECRETS OF ‘3D NEUROTRAINER’

Materials. For the first time, it has been possible to manufacture operable tumors, with materials that simulate the tissues with great precision, created individually for patients to be treated in the future.

Alarm system. Toy engineers have even included an acoustic and visual alarm system to save important nerve structures and make the approach safer.

Substitution. This training model will serve as a complement to the usual study of anatomy in corpses, since it provides benefits, such as availability, biosecurity and the ability to develop individual models, simulating with great precision the pathology of each patient.

Ponticulus posticus

Ponticulus posticus

The ponticulus posticus is a bony bridge in the atlas between the lateral mass and the posterior arch. It results due to ossification of the posterior atlantooccipital ligament of atlas and encloses the vertebral artery and the first cervical nerve root.

It is a normal anatomical variant of atlas vertebrae (C1) and resides in the posterior arch of atlas in relation to the vertebral artery. It is an incidental finding visualised from lateral cephalograms taken for routine orthodontic treatment purposes. Ponticulus posticus in Latin means ‘little posterior bridge’. Other synonyms for ponticulus are arcuate foramen, kimerle anomaly, retroarticular foramen and retocondylar foramen.

An overall incidence of ponticulus posticus has been reported to be 16.7%. Literature reveals a higher incidence in females compared with males and this anomaly was age-independent.

Diagnosis

Failure to detect ponticulus posticus can have grave complications during cervical spine surgical intervention, especially those requiring screw placement in lateral mass region of Atlas vertebra 1).


Consecutive computed tomography scans (n=210) were reviewed for PP and high-riding vertebral artery (HRVA) (defined as an internal height of <2 mm and an isthmus height of <5 mm). In scans with PP+HRVA, we measured the ipsilateral pedicle width, pars length, and laminar thickness and compared them with controls (those without PP or HRVA).

PP was present in 14.76% and HRVA in 20% of scans. Of the 420 sides in 210 scans, PP+HRVA was present on 13 sides (seven right and six left). In scans with PP+HRVA, the length of the C2 par was shorter compared with controls (13.69 mm in PP+HRVA vs. 20.65 mm in controls, p<0.001). The mean C2 pedicle width was 2.53 mm in scans with PP+HRVA vs. 5.83 mm in controls (p<0.001). The mean laminar thickness was 4.92 and 5.48 mm in scans with PP+HRVA and controls, respectively (p=0.209).

The prevalence of PP+HRVA was approximately 3% in the present study. Our data suggest that, in such situations, C2 pedicle width and pars length create important safety limitations for a proposed screw, whereas the translaminar thickness appears safe for a proposed screw 2).


In CT scans some anomalies, such as abnormal facet complex and arch anomalies, have to be differentiated from fractures in a trauma patient. Other anomalies, like PP, have to be looked for during preoperative planning to avoid complications during surgery. Therefore, knowledge of these anomalies is important as different anomalies have different clinical courses and management 3).

Case series

Thirty-three consecutive patients with unstable odontoid fractures underwent Goel technique and Harms technique (C1–2 arthrodesis). Surgery was performed with the aid of lateral fluoroscopy control in 16 cases (control group) that was supplemented by Doppler ultrasonography in 17 cases (Doppler group). Two patients in each group had a C1 ponticulus posticus. In the Doppler group, Doppler probing was performed during lateral subperiosteal muscle dissection, stepwise drilling, and tapping. Blood flow velocity in the V3 segment of the VA was recorded before and after posterior arthrodesis. All patients had a 12-month outpatient follow-up, and the outcome was assessed using the Smiley-Webster Pain Scale. Neither VAI nor postoperative neurological impairments were observed in the Doppler group. In the control group, VAIs occurred in the 2 patients with C1 ponticulus posticus. In the Doppler group, 1 patient needed intra- and postoperative blood transfusions, and no difference in terms of Doppler signal or VA blood flow velocity was detected before and after C1-C2 posterior arthrodesis. In the control group, 3 patients needed intra- and postoperative blood transfusions.Useful in supporting fluoroscopy-assisted procedures, intraoperative Doppler may play a significant role even during surgeries in which neuronavigation is used, reducing the chance of a mismatch between the view on the neuronavigation screen and the actual course of the VA in the operative field and supplying the additional data of blood flow velocity 4).

References

1)

Elliott RE, Tanweer O. The prevalence of the ponticulus posticus (arcuate foramen) and its importance in the Goel-Harms procedure: meta-analysis and review of the literature. World Neurosurg. 2014 Jul-Aug;82(1-2):e335-43. doi: 10.1016/j.wneu.2013.09.014. Epub 2013 Sep 18. Review. PubMed PMID: 24055572.
2)

Kothari MK, Dalvie SS, Gupta S, Tikoo A, Singh DK. The C2 Pedicle Width, Pars Length, and Laminar Thickness in Concurrent Ipsilateral Ponticulus Posticus and High-Riding Vertebral Artery: A Radiological Computed Tomography Scan-Based Study. Asian Spine J. 2019 Apr;13(2):290-295. doi: 10.31616/asj.2018.0057. Epub 2018 Dec 7. PubMed PMID: 30521747; PubMed Central PMCID: PMC6454277.
3)

N V A, Avinash M, K S S, Shetty AP, Kanna RM, Rajasekaran S. Congenital Osseous Anomalies of the Cervical Spine: Occurrence, Morphological Characteristics, Embryological Basis and Clinical Significance: A Computed Tomography Based Study. Asian Spine J. 2019 Mar 14:535-543. doi: 10.31616/asj.2018.0260. [Epub ahead of print] PubMed PMID: 30866614; PubMed Central PMCID: PMC6680038.
4)

Lofrese G, Cultrera F, Visani J, Nicassio N, Essayed W, Donati R, Cavallo MA, De Bonis P. Intraoperative Doppler ultrasound as a means of preventing vertebral artery injury during Goel and Harms C1-C2 posterior arthrodesis: technical note. J Neurosurg Spine. 2019 Aug 16:1-7. doi: 10.3171/2019.5.SPINE1959. [Epub ahead of print] PubMed PMID: 31419805.

COVID-19 is an emerging, rapidly evolving situation.

Get the latest public health information

WhatsApp WhatsApp us
%d bloggers like this: