Download Distribution of the Occipital Branches of the Posterior Cerebral Artery

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Distribution of the Occipital Branches of the
Posterior Cerebral Artery
Correlation With Occipital Lobe Infarcts
Slobodan V. Marinkovic", MD, Milan M. Milisavljevic", MD,
Vera Lolid-Draganid, MD, and Miroslav S. Kovac'evic', MD
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The occipital branches of the posterior cerebral artery were examined in 31 human brains. The
authors determined the origin, course, and region of supply of each occipital branch: the parietooccipital, calcarine, posterior temporal, and common temporal arteries, as well as the lingual gyrus
artery. These vessels were found in all the brains examined except the lingual gyrus artery, which was
present in only 8.3%. The occipital branches were noted to supply variable cortical regions. In
addition, they sometimes took part in irrigation of deep forebrain structures. It was concluded that
occlusion of a certain occipital artery may cause varying clinical signs and symptoms in different
patients. The neurologic deficits that may occur following the isolated occlusion of individual occipital
branches of the posterior cerebral artery are discussed. (Stroke 1987;18:728-732)
T
he occipital lobe is involved in many aspects of
visual function. '~3 The knowledge of its arterial supply is essential in understanding the syndromes occurring in occlusive cerebrovascular disease. Although several authors6"10 have described the
cortical (leptomeningeal) branches of the posterior cerebral artery (PCA), there is a lack of detailed information concerning the regions of supply of the individual
branches. The aim of this study was 1) to determine the
variability of theregionssupplied by individual occipital branches, and 2) to compare the anatomic data to
the neurologic deficits produced by occlusion of individual occipital arteries.
Subjects and Methods
Thirty-one human brains taken from patients aged
22-63 years were used for the anatomic study. Both
right and left PCAs were perfused with a saline solution, then injected with 10% India ink and gelatin or
with a radiopaque substance (Micropaque), and fixed
in 10% formaldehyde solution for 3 weeks or more.
We microdissected all the branches of the PCA and
examined the origin, course, and distribution of their
terminal vessels. We drew each specimen and counted
the frequency of therelevantvariations. One brain was
used for making a plastic cast of the PCA, according to
a previously described injection method."
Results
The main cortical branches of the PCA are the parieto-occipital artery, the calcarine artery, and the anterior, middle, and posterior temporal arteries (Figure
From the Institute of Anatomy (S. V.M., M.M.M., V.L.-D.) and
the Department of Neurology (M.S.K.), University Medical
School, Belgrade, Yugoslavia.
Address for reprints: Dr. Slobodan V. Marinkovid, MD, Institute
of Anatomy, University Medical School, Subotideva 4/n, 11000
Belgrade, Yugoslavia.
Received September 12, 1986; accepted February 2, 1987.
1). The temporal vessels often arise from a common
trunk called the common temporal artery. A few of the
mentioned cortical branches supply the occipital lobe:
the parieto-occipital and calcarine arteries, the posterior or common temporal artery, and, when present, the
lingual gyrus artery.
Parieto-Occipital Artery
The parieto-occipital artery originated from the
PCA in either the ambient (in 15% of the brains examined) or quadrigeminal cistern (18.3%), or in the calcarine sulcus (66.7%). The artery was almost always
singular (98.3%). It entered the rostral portion of the
calcarine sulcus and then continued along the parietooccipital sulcus. In 1 of the mentioned sulci, the artery
divided into 2 (Figure 1), 3, or 4 terminal stems, the
branches of which were distributed to the medial and
sometimes the lateral surface of the occipital and parietal lobes. In addition to the floor and banks of the
parieto-occipital sulcus, these branches also supplied
10-40% of the precuneus and 10-20% of the cuneus
(Figure Id), 50-90% of the precuneus and 10-20% of
the cuneus (Figure 2b), 10-30% of the precuneus and
20-50% of the cuneus (Figure 2c), 40-90% of the
precuneus and 50-80% of the cuneus (Figure Id),
40-90% of the precuneus and 80-90% of the cuneus
(Figure 2e), 10-20% of the precuneus and 50-80% of
the cuneus (Figure If), or 10-20% of the precuneus
and 80-90% of the cuneus (Figure 2g).
The parieto-occipital artery gave rise to the following collateral vessels: the calcarine branch (in 20% of
the brains examined), the anterior (3.3%) or middle
(1.7%) or posterior (3.3%) temporal arteries, the hippocampal branches (3.3%), the thalamogeniculate
branches (15%), the medial (5%) or lateral (23.3%)
posterior choroidal arteries, and the branch to the
splenium of the corpus callosum (48.3%).
In 23.3% of the cases, the parieto-occipital artery
supplied the lateral occipital gyri and the superior pari-
Marinkovii et al
Occipital Branches of the PCA
729
etal lobule. When the artery was large, it also nourished the retrosplenial area and the most caudal part of
the cingulate gyrus (Figure 2, b, d, and e) as well as the
most caudal part of the parahippocampal gyrus occasionally.
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FIGURE 1. Main cortical branches of the posterior cerebral
artery. 1, Anterior temporal arteries; 2, middle temporal artery; 3, posterior temporal artery; 4, parieto-temporal artery
dividing into 2 terminal stems (4' and 4"); 5, right posterior
cerebral artery; 6, basilar artery. Plastic cast, dorsal view.
Calcarine Artery
This artery had the same origin as the parieto-occipital artery (Figure 1), namely, they both arose from the
same site of the distal segment of the PCA or from the
same terminal stem (called the medial occipital artery)
of the PCA. The calcarine artery was singular in 80%
of the cases and double in 20%. In the latter group, 1 of
the 2 vessels always originated from the parieto-occipital artery.
The single calcarine artery, which arose in the ambient or quadrigeminal cistern or in the proximal part of
the calcarine sulcus, entered the latter and ran along it.
In half of the cases the artery divided into 2, and more
rarely into 3, terminal stems. One of the 2 terminal
stems usually coursed along the floor of the calcarine
sulcus, while the other was more superficially located.
When 2 calcarine arteries were present, the smaller
one, which arose from the parieto-occipital artery,
supplied the rostral or superficial part of the calcarine
sulcus.
In addition to the floor and the dorsal and ventral
bank of the calcarine sulcus, the calcarine artery also
supplied 80-90% of the cuneus (Figure 3a), 80-90%
of the cuneus and most of the lingual gyrus (Figure
3b), 50-80% of the cuneus (Figure 3c), 50-80% of the
cuneus and most of the lingual gyrus (Figure 3d),
20-50% of the cuneus (Figure 3e), 20-50% of the
cuneus and most of the lingual gyrus (Figure 3/),
10-20% of the cuneus (Figure 3g), or 10-20% of the
cuneus and most of the lingual gyrus (Figure 3h).
FIGURE 2. Variation in the areas supplied by branching of the terminal stems of
the parieto-occipital artery in 31 human
brains. Frequencies in percent.
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Vol 18, No 4, July-August 1987
FIGURE 3. Variation in areas supplied by
calcarine artery in 31 human brains.
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The proximal part of the calcarine artery gave off
one or more of the following collateral branches: the
middle (in 1.7% of the brains examined) or posterior
(5%) temporal arteries, the hippocampal vessels
(8.3%), and branches to the medial geniculate body
(1.7%), the medial (1.7%) or lateral (1.7%) posterior
choroidal arteries, and the splenial branch (1.7%).
In 13.3% of the cases, the calcarine artery supplied
not only the medial surface, but also a part of the lateral
surface of the occipital lobe.
Lingual Gyrus Artery
This artery was present in 8.3% of the brains examined. It arose from the terminal stem of the PCA, close
to the most rostral part of the calcarine sulcus. The
artery coursed along the lingual gyrus, which it supplied entirely (Figure 4a). In 1 case, the lingual gyrus
artery gave off a branch to the caudal part of the calcarine sulcus.
Posterior Temporal Artery
The posterior temporal artery was present in 60% of
the cases (Figure 1). It was singular and very rarely
duplicated (only 2.8% of the brains examined). The
artery arose in the ambient cistern, either from the
PCA (86.1%) or from the parieto-occipital (5.5%) or
calcarine (8.3%) arteries. It coursed caudally and laterally, along the ventral surface of the hemisphere. The
artery supplied the ventral surface of the occipital and
the ventrocaudal portion of the temporal lobes. More
precisely, it nourished the caudal part of the parahippocampal gyrus, the lingual gyrus (Figure 4c), the caudal
half or two-thirds of the occipito-temporal (fusiform)
gyrus (Figure 4, b and c), and the caudal third or half of
the inferior temporal gyrus. In 41.6% of the cases, it
irrigated a part of the lateral occipital gyrus, including
the occipital pole, as well. In 3.4% of the brains, the
artery gave off a branch to the caudal part of the calca-
rine sulcus. Finally, the proximal portion of the artery
gave rise to the hippocampal branches (in 61.1 % of the
brains examined) and to the lateral posterior choroidal
artery (2.8%).
Common Temporal Artery
This common stem of the temporal arteries is also
called the lateral occipital artery or the temporo-occipital artery. It arose as the second terminal stem of the
PCA in 40% of the cases. The origin was in the ambient cistern, usually at the level of the lateral geniculate
body. The artery coursed across the parahippocampal
FIGURE 4. Variation in the areas supplied by (a) the lingual
artery (no variation), (b, c) the posterior temporal artery, and
fd, e) the common temporal artery in 31 human brains.
Marinkovid et al
Occipital Branches of the PCA
gyrus and then distributed its branches to the ventral
surface of the temporal and occipital lobes. The common temporal trunk almost entirely supplied the parahippocampal, occipito-temporal, and inferior temporal
gyri (Figure Ad). In addition, it also supplied the lingual gyrus in 28.4% of the hemispheres (Figure Ae).
The proximal part of the common temporal artery gave
rise to the hippocampal branches (in 55.4% of the
brains examined) and to the lateral posterior choroidal
artery (12.5%).
Discussion
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Our anatomic results clearly showed that the individual cortical branches of the PCA have variable regions of supply. Thus, the parieto-occipital artery irrigated almost the entire precuneus and cuneus in certain
specimens (Figure 2, d and e), but in others it supplied
only a narrow strip along the parieto-occipital sulcus
(Figure la). The extent of a region supplied by a cortical artery depends mainly on the size and territory of
the ramifications of that artery as well as on the size of
the neighboring cortical branches of the posterior,
anterior, or middle cerebral arteries. Some cortical
regions may have various sources of blood supply. For
example, the lingual gyrus can be irrigated by the
calcarine, posterior temporal, common temporal, or
lingual gyrus arteries (Figures 3 and 4). Certain cortical regions are sometimes supplied by several arteries.
Thus, the calcarine cortex receives its main blood supply from the calcarine artery. In addition, the parietooccipital artery gave off a branch to the rostral or
superficial calcarine cortex in 20% of the cases, and in
some other specimens (Figure 2, e and g) it supplied
the rostrodorsal striate cortex. Finally, the temporal
arteries sometimes gave off branches to the caudal
portion of the calcarine cortex.
The last anatomic fact of possible clinical significance is the finding that some of the occipital arteries
also gave off branches to the thalamus, geniculate
bodies, internal capsule, and splenium of the corpus
callosum. This means that occlusion of such an artery
may be followed not only by infarction of certain cortical regions, but also of the deep forebrain structures.
In general, our results are in accordance with the
data from the literature.6-10 However, there are some
differences concerning the anatomic features and regions of supply of certain arteries.
According to Zeal and Rhoton,9 the parieto-occipital
artery occasionally supplies the caudal part of the paracentral lobule. However, in all the specimens we have
examined, this part of the paracentral lobule was nourished by the paracentral and/or the superior parietal
branch of the anterior cerebral artery.
We found the lingual gyrus artery in 8.3% of the
cases studied. This vessel was actually observed by
Smith and Richardson,6 but it was incorrectly identified as the posterior temporal artery, or even as the
second calcarine artery. The lingual gyrus artery, however, has all the features of a separate branch of the
PCA.
731
The vessels that may supply the ventral surface of
the occipital and temporal lobes are the common temporal artery; the posterior, middle, and anterior temporal arteries; and the hippocampal vessels. The common
temporal artery was seen more frequently in our study
than in other reports.89 The posterior temporal artery is
one of the largest temporal vessels. It occasionally
originated from the parieto-occipital or calcarine arteries instead of from the main stem of the PCA. The
middle temporal artery is the least constant vessel,9
supplying the rostral portions of the parahippocampal,
occipito-temporal, and inferior temporal gyri. The
anterior temporal artery may arise as a single trunk or
as multiple branches8 and nourishes the rostroventral
part of the temporal lobe. According to Zeal and Rhoton,9 there are 1 or 2 hippocampal arteries; however,
we found as many as 5 arteries in the same specimen
(personal observation). They originated from the main
stem of the PCA and/or from the initial portions of the
temporal arteries. The hippocampal vessels supplied
the uncus and hippocampal formation.
Occlusion of a given occipital or a temporal artery
leads to brain tissue ischemia in its region of supply.
The size and extent of the ischemic zone depends on 1)
the size of the region supplied by the affected artery, 2)
the cause of the occlusion, 3) the efficiency of the
arterial anastomoses, and 4) the characteristics of the
general and local brain vasculature and blood flow.12-'4
This is the reason for discrepancies between the expected and the real size and shape of the ischemic zone
in some patients.
As a result, various neurologic signs and symptoms
may follow the occlusion of these branches of the
PCA. Isolated occlusion of the parieto-occipital artery,
which often takes part in supplying the most rostral or
rostrodorsal part of the striate cortex, may cause an
incongruous homonymous hemianopia or inferior
quadrantanopia sparing central fixation.2 Because of
the damage to the parietal (precuneal) cortex, visual
disorientation and metamorphopsia could also develop. 15 In almost half of the patients, the parieto-occipital artery gives off the splenial branch, which nourishes the callosal fibers connecting the right visual
areas to the left angular gyrus. Hence, occlusion of the
left parieto-occipital artery in some patients can produce impaired color naming or pure alexia.16
Isolated occlusion of the calcarine artery may produce a complete homonymous hemianopia. 23 However, when the most caudal part of the striate cortex is
supplied by the temporal branches of the PCA or the
temporo-occipital or angular gyrus arteries," a homonymous hemianopia sparing central fixation will develop. Because of the additional participation of the parieto-occipital artery in irrigation of the rostral or
superficial striate cortex, an incongruous homonymous hemianopia is also possible.2 Occlusion of a
small branch of the mentioned arteries may produce a
small central or peripheral scotoma. 26
Unilateral occlusion of the posterior temporal or the
common temporal arteries (which supply, among other
regions, the fusiform and often the lingual gyri) may
732
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cause pure alexia or hemiachromatopsia and color
anomia.416 In cases with bilateral infarctions in the
temporo-occipital regions, the patients may have
achromatopsia, visual object agnosia, and prosopagnosia.3'416 Finally, ischemia of the hippocampus (bilaterally or on the left side only) may cause the impairment of memory.1
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KEY WORDS • posterior cerebral artery • occipital lobe
occlusive cerebrovascular disease • visual symptom
computed tomography
Distribution of the occipital branches of the posterior cerebral artery. Correlation with
occipital lobe infarcts.
S V Marinkovic, M M Milisavljevic, V Lolic-Draganic and M S Kovacevic
Stroke. 1987;18:728-732
doi: 10.1161/01.STR.18.4.728
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