Classification of variants of arteries and variants of the arterial circle of the human brain


Pathological tortuosity (kinking) of the carotid arteries is one of the least studied and mysterious diseases. The role of pathological tortuosity in the development of symptoms of cerebrovascular insufficiency is still being studied, but it has been established that every third person who died from a stroke had pathological bends of the carotid or vertebral arteries. In 16-26% of the adult population, various variants of elongation and tortuosity of the carotid or vertebral arteries in the neck are detected. Pathological tortuosity is the uneven course of an artery with the formation of bends, loops and twists, which affects the nature of blood flow through the artery and can contribute to the development of acute cerebrovascular accidents.

Treatment methods at the Innovative Vascular Center

The vascular surgeons of our clinic have significant experience in unique operations on the carotid arteries with pathological tortuosity. The main problem for surgical treatment is determining clear indications for surgical treatment. Our clinic has developed a clear diagnostic protocol that allows us to determine the clinical significance of a particular tortuosity and the degree of its effect on cerebral blood flow. The experience of successful operations in our clinic for pathological tortuosity exceeds 200 cases.

Causes and prevalence of pathological tortuosity

Pathological tortuosity always develops due to the elongation of the internal carotid artery, which is forced to fold into bends or even loops. Excessive length of the internal carotid artery is often formed during embryonic development, that is, the tortuosity of the artery is most often congenital. With age, further twisting of the redundant carotid artery into a loop may occur. According to some researchers, pathological tortuosity may be the cause of neurological and intellectual problems in children of preschool and primary school age.

Lengthening of the internal carotid artery can also develop as a result of advanced hypertension, when constantly elevated blood pressure causes changes in the artery wall and its bends. Such tortuosity rarely affects cerebral hemodynamics and is more often a phenomenon detected incidentally by ultrasound of the great arteries.

Pathological tortuosity of the carotid arteries was detected in 16% of patients who died from ischemic stroke; more than 23% of children who suffered an ischemic stroke had pathological tortuosity. When examining patients undergoing treatment for cerebrovascular accidents, pathological tortuosity was detected by ultrasound angioscanning in 12%. Various disorders of the internal carotid arteries, according to pathological studies, were identified in 40% of people.

Read also

Neuropathy

In the human body, the work of internal organs and systems is regulated by the brain, namely by nerve impulses emanating from it.
These impulses travel along nerve fibers. Damage to them may damage this... Read more

Intracranial hypertension on MRI

Intracranial hypertension is an increase in intracranial pressure. Normal intracranial pressure is 15 mm Hg. When blood pressure doubles, a stroke occurs. At a pressure of 50 mm Hg, the patient can...

More details

Arnold-Chiari malformation

Due to the availability of the study and the high resolution of MRI, we quite often come across the conclusion - Arnold-Chiari anomaly. What is meant by this concept? Arnold-Chiari malformation...

More details

Atherosclerosis

Atherosclerosis is a vascular disease that is caused by a decrease in the elasticity of the vascular wall, the deposition of cholesterol on the inner surface and, as a result, the appearance of atherosclerotic plaques. Atherosclerosis…

More details

Epicondylitis

Do you know this disgusting feeling when you are passionately doing something, and suddenly, quite by accident, your elbow bumps into something hard and in that very place, after the impact of which the whole arm weakens...

More details

Clinical and anatomical options

Lengthening the artery. The most common is elongation of the internal carotid or vertebral artery, which leads to the formation of smooth bends along the course of the vessel. An elongated artery is rarely a cause of concern and is usually discovered during random examination. Lengthening the artery is important for ENT doctors, since the artery wall may be abnormally close to the palatine tonsils and may be accidentally damaged during tonsillectomy. With age, the elasticity of the arterial wall changes and smooth bends of the artery can become kinks, with the development of a picture of cerebral circulation disorders. When arteries are lengthened without kinks, ultrasound examination of blood flow does not detect any disturbances.

Kinking is a bend in an artery at an acute angle. Kinking can be congenital, when cerebral circulation disorders are detected from early childhood and develop over time from an elongated carotid artery. The formation of kinks is promoted by arterial hypertension and the progression of atherosclerosis in the internal carotid artery. Clinically, kinking of the internal carotid artery is manifested by transient disturbances of cerebral circulation. With kinking of the vertebral artery, vertebrobasilar insufficiency develops. Identification of kinking with brain symptoms raises the question of surgical correction of tortuosity.

Coiling is the formation of a loop of an artery. Despite the smooth movement of the loop, changes in blood flow in it are very significant. The nature of the bends during coiling may change depending on body position and blood pressure. A chaotic nature of the blood flow is observed, which leads to a decrease in blood pressure after the loop and, accordingly, to a decrease in blood flow through the cerebral arteries. If a person has a well-developed circle of Willis on the lower surface of the brain, then he will never know about the existence of a loop or inflection. The appearance of symptoms of cerebral circulatory failure indicates disturbances in blood flow compensation and dictates the need for detailed examination and treatment.

Medical Internet conferences

O.A. Fomkin - Saratov State Medical University named after. IN AND. Razumovsky Ministry of Health of Russia, assistant at the Department of Human Anatomy, Candidate of Medical Sciences; V.N. Nikolenko - State Budgetary Educational Institution of Higher Professional Education First Moscow State Medical University named after. THEM. Sechenov Ministry of Health of Russia, Vice-Rector for Scientific and Innovation Activities, Professor of the Department of Human Anatomy, Director of the Research Institute of Molecular Medicine, Professor, Doctor of Medical Sciences; Yu.A. Gladilin – State Budgetary Educational Institution of Higher Professional Education Saratov State University named after. IN AND. Razumovsky Ministry of Health of Russia, Associate Professor of the Department of Human Anatomy, Doctor of Medical Sciences.

Introduction. Variability as a general biological phenomenon does not lose its relevance and deserves the attention of many scientists [1, 2]. Variability shows the plasticity of living systems and is associated with the implementation of the adaptive strategy of a natural population. The study of variability makes it possible to judge the interaction of the genotype with environmental factors during ontogenesis [3].

In response to the demands of clinical medicine, at present, detailed information is required not so much on the typical structure or average anatomical norm of an organ, but on the entire spectrum of its individual, typical and combined variability [2]. This also applies to the arterial vessels of the brain.

The subject of this study is the posterior communicating artery (PCA). As a branch of the cerebral part of the internal carotid artery, it participates in the formation of the arterial (Circle of Willis) circle of the brain. It has been proven that blood through this artery can flow in both directions [4]. In this regard, the PCA plays an important role in the implementation of compensatory collateral blood flow between the systems of the internal carotid and vertebral arteries.

The structure of the posterior communicating arteries varies greatly. Compared to other cerebral arteries, they have a small diameter and almost a pinpoint lumen [5-7].

Purpose of the study: to determine the variants of the posterior communicating artery (PCA) of adults depending on the individual and combined variability of its morphometric parameters.

Materials and methods . The study material was PCA obtained from autopsies of 115 corpses of people aged 21 to 84 years who died for reasons not related to acute or chronic cerebrovascular pathology. A total of 230 artery samples were examined. To study the morphology of the artery, transverse millimeter sections were made using a razor. Then the sections were placed in a Petri dish with saline solution and the outer diameter and wall thickness of the artery were measured under a microscope with an accuracy of 0.01 mm. The diameter of the artery lumen is presented in the study as the difference between the outer diameter and twice the thickness of the artery wall.

The obtained data were processed by the variation-statistical method using the Statistica-6 application package and Microsoft Exsel Windows-XP. To check the presence of a normal distribution, the Kolmogorov-Smirnov test was used. The distribution of parameters in the studied sample did not differ from normal. In this regard, for all parameters, the minimum and maximum values, the arithmetic mean (M), the error of the arithmetic mean (m), the standard deviation (s), and the coefficient of variation (Cv) were determined. To assess the reliability of differences between series, a parametric test (Student's test) was used. In this case, the differences were considered significant at a 95% probability threshold (p < 0.05). When studying individual variability, like most researchers dealing with the range of anatomical norms, we took the variation interval M ± σ as the average value of a trait. Since statistically significant gender differences in the length, wall thickness and lumen diameter of the PCA were found [6], variations in these parameters were calculated separately for men and women.

Results. The average values ​​of the morphometric parameters of the PCA (230 samples), excluding gender, age and cerebral hemisphere, were: 1) length 12.26±0.19 mm (A=5.30-20.10 mm; s=2.89 mm; Сv=23.6%); 2) outer diameter – 1.33±0.02 mm (A=0.80-2.10 mm; s=0.26 mm; Cv=19.2%); 3) wall thickness – 0.23±0.01 mm (A=0.12-0.40 mm; s=0.06 mm; Cv=26.2%); 4) lumen diameter – 0.88±0.02 mm (A=0.46-1.46 mm; s=0.25 mm; Cv=28.0%).

Significant variability in the morphometric parameters of the PCA made it possible to identify groups of variants of their values ​​(Table 1).

According to the length of the PCA, they were divided into: short - length less than 9.89 mm in men and less than 8.80 mm in women; medium in length - with a length from 9.90 to 15.72 mm for men and from 8.81 to 11.51 for women; long – with a length of more than 15.73 mm in men and more than 11.52 mm in women. The average age of subjects with short PCAs was 1.2 times greater than that of people with long arteries – 51.3±2.9 years and 43.0±2.6 years, respectively (p=0.039). The quantitative ratio of men and women in the group of subjects with short arteries is 39.5 and 60.5%; in the group of subjects with long arteries – 71.9 and 28.1%.

Based on the size of the outer diameter, SSAs are: thin - diameter less than 1.06 mm; medium diameter (medium wide) - the diameter ranges from 1.07 to 1.59 mm and wide - with a diameter of more than 1.60 mm. Subjects with wide PCA were on average 1.2 times older than people with thin arteries - 55.0±3.0 years and 45.5±2.1 years, respectively (p=0.011). The quantitative ratio of men and women in the group of subjects with thin arteries is 59.0 and 41.0%; in the group of subjects with wide arteries, the representation of men and women is equal – 50% each.

Based on the wall thickness, the PCA was divided into: thin-walled - wall thickness less than 0.17 mm in men and less than 0.14 mm in women; medium in thickness - with a wall thickness from 0.18 to 0.30 mm for men and from 0.15 to 0.25 mm for women; thick-walled - with a wall thickness of more than 0.31 mm in men and more than 0.26 mm in women. The average age of subjects with thick-walled PCAs was 1.7 times greater than that of people with thin-walled arteries - 69.2±2.3 years and 40.7±2.5 years, respectively (p=1·10-6). The quantitative ratio of men and women in the group of subjects with thin-walled arteries was 25.7 and 74.3%; in the group of those studied with thick-walled arteries – 78.9 and 21.1%.

Depending on the size of the lumen diameter, we have identified PSA: with a narrow lumen - the lumen diameter is less than 0.58 mm in men and less than 0.68 mm in women; with an average lumen - the diameter of the lumen varies from 0.59 to 1.07 mm in men and from 0.69 to 1.19 mm in women; with a wide lumen - the lumen diameter exceeds 1.08 mm in men and 1.20 mm in women. The age of subjects with a narrow and wide lumen of the PCA did not differ significantly - 51.2 ± 2.5 years and 45.6 ± 3.1 years, respectively (p = 0.163). The quantitative ratio of men and women in the group of subjects with a narrow lumen of the PCA was 75.6 and 24.4%; in the group of those studied with a wide lumen of the PCA – 43.6% and 56.4%.

It was noted that approximately 71.9% of all thin ACAs had a narrow lumen, and 28.2% had an average lumen. At the same time, thin PCAs had thin wall thickness in 23.1% of cases, thick wall thickness in 5.2% of cases, and medium wall thickness in 71.8% of cases (Table 2).

Medium-wide arteries in 87.1% of cases were characterized by an average lumen diameter; in 7.7% of cases, such PCAs had a narrow, and in 5.2%, a wide lumen diameter. Medium-wide arteries, as a rule, had an average wall thickness (67.1% of observations); thin- and thick-walled PCA were also found in this group – in 12.9 and 20% of cases, respectively.

Wide PCAs had a wide lumen diameter in 86.1% of cases and an average lumen diameter in 13.9% of cases. Moreover, in 13.9% of cases they were thin- or thick-walled, and in the remaining 72.2% they were characterized by an average wall thickness.

The combined variability of the morphometric parameters of the PCA made it possible to identify 18 of its types. The most common are medium-wide ACAs with an average wall thickness and an average lumen (43.0%). Rare types (frequency of occurrence less than 1%) include thin PCA (with an average wall thickness and lumen diameter, with a thin wall and a narrow lumen, a thick wall and a narrow lumen, a thick wall and an average lumen); ASA with a medium outer diameter, a thick wall and a wide lumen; wide PCA with a thick wall and medium lumen (Fig. 1). Thin-walled SSAs based on our material never had a wide lumen diameter.

Rice. 1.Frequency of occurrence of types of PSA,% ( OD – outer diameter , TS – wall thickness, DP – lumen diameter ): 1 – average for ND, TS and DP; 2 – thin with medium TS and narrow DP; 3 – wide with medium TC and wide DP; 4 – average in ND, with a thick wall and average DP; 5 – average according to ND with a thin wall and average DP; 6 – thin with a thin wall and medium DP; 7 – average according to ND with a thick wall and narrow DP; 8 – average according to ND, with a thin wall and wide DP; 9 – average for ND, vehicles with narrow DP; 10 – wide with a thin wall and wide DP; 11 – wide with average wall thickness and average DP; 12 – wide with a thick wall and wide opening; 13 – thin with medium TC and medium clearance; 14 – average in ND, with a thick wall and wide DP; 15 – thin with a thin wall and narrow DP; 16 – thin with a thick wall and narrow DP; 17 – thin with a thick wall and medium DP; 18 – wide with a thick wall and medium DP.

Discussion. The vast majority of works concerning PCA are devoted to variants of its development: aplasia, hypoplasia, the presence of a vascular network at the site of the artery, etc. [5, 8, 9]. We presented information on the individual typological variability of the morphometric parameters of the PCA for the first time.

As a result of the study, it was revealed that the morphological parameters of the PCA (length, outer and inner diameter, wall thickness) are characterized by significant individual variability. The coefficient of variation of the studied parameters varies from 19.2% (outer diameter) to 28.0% (lumen diameter). For each of the parameters, we have identified 3 groups of arteries: I – with a value of the attribute less than average (<М-σ); II – with the average value of the trait (M±σ); III – with a trait value greater than average (>M+σ). No clear pattern was found in the predominance of men or women in the extreme groups of variability (groups I and II). Thus, among subjects with short, thin-walled arteries and arteries with a wide lumen, women predominate, and among subjects with long, thin, thick-walled arteries and arteries with a narrow lumen, men predominate. In the group of those studied with wide ACAs, the percentage representation of men and women is the same.

The average age of subjects whose PMA, based on the size of their outer diameter, wall thickness and lumen diameter, belongs to group III, is statistically significantly 1.2-1.7 times greater than that of people with PMA belonging to group I variability. The average age of men and women with short PCA (group I), on the contrary, is 1.2 times greater than that of people with long PCA (group III). The age of subjects with narrow or wide lumen PCA did not differ significantly.

Conclusion. Thus, the analysis of individual variability in the length, outer and inner diameters and wall thickness of the PCA made it possible to identify 3 groups of artery variants for each of the parameters: with an average value of the attribute, with a value of the attribute less and more than the average. The combined variability of the morphometric parameters of the PCA made it possible to identify 18 of its types.

The data obtained will complement and organize the existing information on the dimensional characteristics of the PCA, which is important for a better understanding of the area of ​​neuromorphology under study, and can also be useful in modeling blood flow in the arterial circle of the brain.

Course of the disease

If tortuosity of the carotid artery becomes symptomatic, then it is quite painful for the patient. Minor signs and symptoms of the disease gradually intensify and lead to decreased ability to work. The presence of pathological tortuosity can lead to symptomatic hypertension, which in turn contributes to the progression of tortuosity and the formation of kinks. In places where the carotid artery is bent, adhesions can form, which further disrupts the nature of blood flow, making it turbulent. Ultimately, these processes can lead to transient ischemic attacks or stroke.

Rating
( 1 rating, average 5 out of 5 )
Did you like the article? Share with friends:
For any suggestions regarding the site: [email protected]
Для любых предложений по сайту: [email protected]