Description of the cerebral vasculature in a southern African cadaver cohort

Cilliers, Karen (2016-03)

Thesis (MSc)--Stellenbosch University, 2016.

Thesis

ENGLISH ABSTRACT: Few studies give a complete description on the origin, absence, duplication and triplication of the cerebral cortical branches. The anterior cerebral artery (ACA) varies considerably and this complicates the description of the normal anatomy. The most commonly discussed branching types of the middle cerebral artery (MCA) include bifurcation and trifurcation. Branching of the posterior cerebral artery (PCA) has not been adequately described; only the division level of the parieto-occipital (PoA) and calcarine arteries has been discussed. Anomalies of the cerebral arteries have been reported. To the author’s best knowledge, no previous studies have investigated the anatomy of the cerebral arteries in a Western Cape population. Therefore, the aim of this study is to describe the anatomy and anomalies of the cerebral vasculature in a Southern African cadaver cohort. Twenty hemispheres were used for the pilot study and 126 hemispheres for the present study. These 126 hemispheres consisted of 88 males and 38 females, between the ages of 22 and 84. Specimens were distributed over three population groups, namely, coloured (n=76), black (n=38), white (n=10) and unknown (n=2). The arteries were injected with coloured silicone. The external diameter and length of all the cortical branches of the cerebral arteries were measured using a digital micrometre. The diameter and lengths indicated statistically significant differences on the right and left side, between males and females, different population groups and different age groups. The most commonly absent artery was the callosomarginal artery, and the most commonly duplicated artery was the paracentral lobule artery. The origin of the cortical branches was similar to the descriptions in the literature; however, the common trunks and unusual origins were also noted. The branching pattern of the MCA was classified according to the 11 different subtypes described in the literature. Medial bifurcation was most commonly observed. The branching pattern of the PCA was assessed, and in most cases there was additional branching before the division of the calcarine artery and PoA. Anomalies observed in the present study included bihemispheric ACA (19.8%), median ACA (11.6%) and fenestration of the PCA (1.6%). The only anomaly observed in the pilot study was fenestration of the PCA (5.0%). A shorter trunk may play a role in aneurysm formation, and changes in vessel diameter could indicate early signs of several pathological conditions. Aneurysms can be observed at the branching of cerebral vessels, highlighting the importance of a thorough knowledge of the vascular anatomy. The MCA branching subtypes were described, since only bifurcation and trifurcation are usually noted. Furthermore, the branching pattern of the PCA has not been adequately described in previous reports; therefore the possible branching types were defined. Anomalies of the cerebral arteries are usually only mentioned; therefore the bihemispheric and median ACA were fully described (origin, length, diameter and area supplied). Given the important implications that the anatomical variation of the cerebral arteries

AFRIKAANSE OPSOMMING: Min studies bied 'n volledige beskrywing van die oorsprong, afwesigheid, duplisering en triplisering van die serebrale kortikale arteries. Die verloop van die anterior serebrale arterie (ASA) varieer aansienlik wat beskrywing van die normale anatomie bemoeilik. Die mees algemeenste vertakkingstipes van die middel serebrale arterie (MSA) sluit bifurkasie en trifurkasie in. Vertakking van die posterior serebrale arterie (PSA) word nie voldoende beskryf nie; slegs die vlak van die oorsprong van die parieto-oksipitaal (PoA) en kalkariene arteries word bespreek. Variasies in die anatomie van die serebrale arteries kan waargeneem word. Sover die kennis van die outeur strek, is geen studies oor die anatomie van die serebrale arteries voorheen op 'n Wes-Kaapse populasiegroep voltooi nie. Die doel van hierdie studie is om die kortikale arteries in 'n Suid-Afrikaanse kadawer populasie te beskryf. Twintig hemisfere is vir die loodsstudie en 126 hemisfere vir die huidige studie gebruik. Die 126 hemisfere het bestaan uit 88 mans en 38 vrouens, tussen die ouderdom van 22 en 84 jaar. Die studiepopulasie het bestaan uit drie populasie groepe; kleurling (n=76), swart (n=38), wit (n=10) en onbekende (n=2) groepe. Die arteries is met gekleurde silikoon ingespuit. Die eksterne deursnit en lengte van al die kortikale arteries is met 'n digitale mikrometer gemeet. Die deursnit en lengtes het statisties beduidende verskille tussen links en regs, mans en vrouens, verskillende populasiegroepe en verskillende ouderdomsgroepe getoon. Die kallosomarginale arterie was oor die algemeen die meeste afwesig, en die parasentrale lobule arterie was die mees algemeenste arterie wat verdubbeld is. Alhoewel gemeenskaplike stamme en ongewone oorspronge ook opgemerk is, is die oorspronge van die kortikale arteries soortgelyk aan beskrywings wat in die literatuur voorkom. Die vertakkingspatroon van die MSA is volgens die 11 verskillende subtipes wat in die literatuur beskryf is, geklassifiseer. Mediale bifurkasie is die meeste waargeneem. Die vertakkingspatroon van die PSA is geëvalueer, en in die meeste gevalle was daar 'n bykomende vertakking voor verdeling van die PoA en kalkariene arterie. Abnormale variasies wat in die huidige studie waargeneem is sluit ‘n bihemisferiese ASA (19.8%),’n mediaane ASA (11.6%) en fenestrasie in die PSA (1.6%) in. Die enigste abnormale variasie wat in die loodsstudie waargeneem is, was fenestrasie in die PSA (5.0%). ‘n Korter arteriële stam kan 'n rol speel in die vorming van aneurismes, en veranderinge in die deursnit kan vroeë tekens van verskeie patologiese toestande aandui. Aneurismes word dikwels by die vertakking van serebrale arteries waargeneem, wat die belang van 'n deeglike kennis van die vaskulêre anatomie beklemtoon. Die vertakking subtipes van die MSA is deeglik beskryf, aangesien slegs bifurkasie en trifurkasie gewoonlik in die literatuur bespreek word. Die vertakkingspatroon van die PSA is nie voldoende in vorige studies beskryf nie; dus is al die moontlike vertakkingstipes gedefinieer. Abnormale variasie van die serebrale arteries word gewoonlik net genoem; dus is die bihemisferiese en mediaane ASA volledig beskryf (oorsprong, lengte, deursnit en area van voorsiening). Gegewe die implikasies van anatomiese variasies van die serebrale arteries

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