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co - planar stereotaxic atlas of the human brain - j. talairach, p. tournoux (thieme)

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Contents

1 Direct and Indirect Radiologic Localization

Relative Variability of the Cerebral Con- volutions Direct Localization Indirect Localization Indirect Localization in the Interpretation of Cortical Images 2 Reference System: Basal Brain Line CA-CP Millimetric and Volumetric Readings

3 Cerebral Structures in Three-Dimensional Space: sce ei ee SiN eER Be RE ES wR Tracts ae we ee oe ee ey ee ee Cortical Areas Frontal Lobe Parietal Lobe Occipital Lobe Temporal Lobe Cingulate Gyrus Corticothalamic Connections Cerebral Functions and Reference System

4 Practical Examples for the Use of the Atlas in Neuroradiologic Examinations First Example: CTScan -

Second Example: MR without Reference System Third Example: MR with Reference System 5 Three-Dimensional Atlas of a human Brain Reference System Demonstration of ColorCode - 19 19 22 2ó Sagittal Sections Millimetric Reading (level of sections) 38 Volumetric Reading 39 Proportional Grid System 40 Sagittal Seclions 41

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1 Direct and Indirect Radiologic Localization

Relative Variability of the Cerebral Convolutions

The brain is a compact mass in which a certain number

of structures may be immediately remarkably well dis-

played today by an appropriate neuroradiologic exami-

nation Other neuroanatomic structures cannot be ap- preciated directly, but only indirectly by knowledge of

their spatial relationship to other visible structures This is still the case of certain nuclei, of the great tracts of white matter (in particular motor, sensory, visual, auditory), of the large association bundles, of the archi- tectonic cortical areas — until the day when new tech- niques will enable us to isolate the various systems as they function Thus, stereotaxis has used from the time

of its origin for the central gray nuclei and subsequent-

ly for the entirety of the telencephalon, two different procedures for the localization of cerebral structures: direct and indirect (51, 53, 55, 57)

A combination of these two approaches may be used

today to enrich the interpretation of the sections fur- nished by the new neuroradiologic methods: computer tomography (CT), magnetic resonance (MR), positron

emission tomography scans, etc Direct Localization

Direct localization was initially limited to structures made visible by radiologic examinations employing

contrast materials (vascular system, cerebrospinal fluid,

pathway spaces) and the rare structures made opaque

by calcification

The CT and the MR scanners have transformed the

scope of this localization in a spectacular manner by

making visible — if not always identifiable - almost all

components of the brain and its pathologic processes Progress has been such that neurosurgeons and neuro-

radiologists have come to develop a simple procedure

for direct surgical localization of lesions by coupling a

stereotaxic apparatus to the CT or MR scanner to per-

form, for example, biopsies of tumors The stereotaxic apparatus serves at the same time as a frame of refer- ence and as a guide for surgical intervention

Despite its practical interest, this oversimplification is

not entirely satisfactory In the ensemble of compact

structures that constitute the brain, knowledge of the space occupied by the pathologic process itself repre-

sents only one aspect of the problem Knowledge of

the anatomic structure that is involved in the lesion, and

of adjacent structures that are or will be disturbed by

the lesion or by the therapy, in other words, knowing

how to localize the pathologic process correctly in its anatomo-

physiologic environment constitutes another important

aspect This knowledge should facilitate the choice of a path of approach to the lesion in therapy, thereby mini-

mizing the risks, and should allow a more differentiat-

ed review of the therapeutic perspectives with their functional implications

Despite appearances and progress, medical imaging does not as yet result in a response that is entirely sa- tisfactory to this last aspect of direct localization The radiologic image, beautiful though it may be, cannot

furnish all the information contained within the brain section, if it does not correspond to a well-defined

anatomic plane of section related to a known anatomic

level (Fig 1)

Figure 1 Direct localization Sulci and convolutions are clearly

defined However, for any one of them, accurate identification is impossible without a system of reference for anatomic orienta- tion (basal lines) For example: the situation of the central sul-

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2 1 Direct and Indirect Radiologic Localization

Indirect Localization

Elements of the brain that cannot be directly visualized

or identified must be defined in relation to other ana- tomic cerebral structures The latter, which are localiz- able, serve as a basis for a system of reference (basal

brain lines) with which they have a statistically proved relationship

It has always been the dream of neuroradiologists to develop a system of reference based on cranial land- marks, easy to visualize and always dependable, but everyone agrees that the relationships between these landmarks and cerebral structures are not fully reliable With the development of MR imaging, Cabanis et al

(11) have recently proposed a new plane of reference:

the neuro-ocular plane However, it is significant that most of these lines have not been the target of studies

to determine the quality of their relationship with the ensemble of cerebral structures

We have demonstrated on several occasions since 1952 (50-53) that a line passing through the anterior and posterior commissures has a definite relationship to

the gray central nuclei and a sufficiently precise rela-

tionship to the telencephalon This line, with slight

modifications, has been adopted by the majority of

neuroanatomists and stereotactic neurosurgeons, in

particular, Schaltenbrand and Bailey (39), Van Buren and Borke (10), and others The CA-CP line defines the horizontal plane The vertical line VCA passing

through the anterior commissure defines a verticofron- tal plane These two lines, as well as the midline, con-

stitute the axes of reference of our system of indirect local-

ization

The three-dimensional proportional system, as we will show later, allows for a practical exploitation of this modality

of localization (indirect localization system) and per-

mits the collection of “normalized” data

Recently, Olivier et al (33) have proposed using the

corpus callosum as a system of reference because it is

easily visualized in MR imaging and indirectly by an- giography The corpus callosum has, in fact, as we had shown in the past for localization within the parietal

lobe (54), relationships that are without doubt satisfac- tory with the telencephalon, but its relationship is more

tentative with the central gray nuclei In any event, a statistical anatomic study should be carried out

Indirect Localization

in the Interpretation of Cortical Images

An examination of the cerebral gyri of two hemis-

pheres of the same brain and of hemispheres of differ- ent brains (Figs 2, 3) demonstrates the enormous varia- bility in these structures At first, it would seem that

they escape all possibility of indirect localization To

think so, however, would be forgetting that there are

major lines of cortical enfolding that give the cortex its

general morphology regardless of the brain under con-

sideration (2, 8, 13, 15, 16, 21, 22, 24, 25)

If one studies the relationship between the basal lines

and the principal sulci (central, lateral, superior tem- poral, calcarine, parieto-occipital, cingulate), it appears to be relatively constant (43, 44, 46, 52, 55)

If certain variations in the shape of these sulci exist,

they are not fundamental and remain within a known

general orientation For example, the central sulcus

(fissure of Rolando) is found consistently between the

verticals VCA-VCP (see Fig 7), taking its origin caudal-

ly, 0.5 cm in front of or behind VCA, to end in the mid-

line approximately 1 cm posterior to VCP, after a more

or less sinuous course, which may also differ between the two hemispheres

Apart from the major convolutions and fissures, it is

evident that the cerebral structures classically de-

scribed on the convexity of the hemisphere are often difficult to recognize Due to numerous secondary

folds, which alter the shape of the convolutions, a greater or lesser contribution from the imagination

seems necessary to define their course and limits

Nonetheless, all these cerebral convolutions have an

orientation typical for their lobar region (frontal, pari-

etal, occipital, temporal), in such a manner that the role of imagination in defining them can be restricted

Thus, the general layout of the cortex remains relative-

ly constant This constancy can be exploited

The image of the cortex that is currently being offered

to us by MR is much better than that with CT scans and should greatly reduce the uncertainties of indirect lo-

calization Nevertheless, the gyri observed in an MR

image will not, for the most part, be individually ident-

ifiable without the use of a reference system that can

localize individual convolutions statistically to a given

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Figure 2 Examples demonstrating the variation of localization VCP lines Note also the different sizes of these two brains of

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4 1 Direct and Indirect Radiologic Localisation

Figure 3 Anterosuperior view of brain Example of the diversity of form of the gyri and sulci of two hemi- spheres of one brain Note also the secondary folds of the fissure of Rolando of the left hemisphere and

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2 Reference System: Basal Brain Line CA-CP

Millimetric and Volumetric Readings

Three reference lines form the basis for our three-

dimensional proportional grid system: CA-CP, VCA, midline

1 CA-CP line

This line passes through the superior edge of the anterior commissure and the inferior edge of the

posterior commissure It follows a path essentially

parallel to the hypothalamic sulcus, dividing the

thalamic from the subthalamic region This line de-

fines the horizontal plane (Fig 4) (52)

2 VCA line

This line is a vertical traversing the posterior margin

of the anterior commissure This line is the basis for the vertical frontal plane (Fig 4) 3 Midline This is the interhemispheric, sagittal plane Figure 4 — CA-CP line (anterior commissure-posterior commissure) = horizontal plane

Basic Reference System The three dimensions are:

Distances from these planes may be measured in mil-

limeters Because of the individual variations in height,

length, and width of human brains, these measure- ments are only applicable to one individual This be-

comes increasingly true with greater distance from the

basal lines Millimetric measurements, in fact, can only

apply in a general population to the gray central nuclei,

whose dimensional variations remain moderate

For this reason, we are now presenting in three dimen-

sions the proportional grid system, which we had first pro- posed in 1967 (Fig 5) (55)

The three-dimensional proportional grid system is es- tablished according to the maximal dimensions of the

brain in the three planes of space This system adapts

itself to brains of all dimensions, and equally well to neuroradiologic images of all dimensions

This proportional localization system marks off the dis-

tances separating the basal lines and the cortical periphery defined by lines through:

— Vertical line VCA = verticofrontal plane

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6 2 Reference System: Basal Brain Line CA-CP

— The highest point of the parietal cortex This total volume is then divided (Fig 6):

— The most posterior point of the occipital cortex By horizontal lines:

— The lowest point of the temporal cortex Above the CA-CP line in eighths

— The most anterior point of the frontal cortex Below the CA-CP line in quarters

— The most lateral point of the parietotemporal cortex By vertical lines:

Anterior to the VCA line in quarters Posterior to the VCP line in quarters 1 1 iH 4 1 2 oy al | y< 1 +o 1 2 3 ?| ! ¡> , ! 4 hi † toy 1 —— 5 L1 rt 3 1 6 TT - 1 tol it 4 1 8 Đủ CAICP ot 1 9 i! ha ĩ my 1 4 oy my 11 ——†—— là TỶ) 5 1 12 2 1 1 H G F E D c B A

Figure 5 Proportional grid system Figure 6 The brain is divided into

orthogonal parallelograms, the di-

mensions of which vary with the

principal axes of the brain Each of

these volumes is defined by its three

dimensions (indicated by a capital

letter, a lower case letter, and a num-

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The space between the two perpendiculars erected

through the anterior and posterior commissures has been dealt with individually because, by dividing it in-

to three zones (E1, E2 and E3), a more precise localiza-

tion of the central gray nuclei can be obtained, and be-

cause it consistently defines the localization of the mo- tor cortex (Fig 7) (52)

Millimetric and Volumetric Readings 7

fulness of this possibility has been confirmed recently

by publications of Vanier and colleagues (59, 60)

The rectangles of the grid have been drawn in the three planes of space to divide the cerebral mass in as many

rectangular parallelograms (see Fig 6), which corre- spond: A B c D E F G H 1

Figure 7 Location of the Rolandic fissure according to analomic studies (20 brains stereotactically local- ized) using the normalized proportional grid system (Reprinted with permission from Talairach et al [55))

The proportional grid system allows localization of

cortical and subcortical structures with relative preci-

sion in all three planes of space whatever the shape and

size of the brain

This gridding has the merit of dividing the error It has been te object of anatomic and neuroradiologic stud-

ies pursued for a long time in the surgery of epilepsy and has proved to be much more reliable than a milli-

metric quantification, in particular in the statistical

study of anatomic electroclinical correlations after the placement of multiple depth electrodes

Using this proportional system basing the divisions of the brain on the individual brain proportions, one achieves a normalized system valid for all brains This

permits statistical studies, because each individual case can be reduced to a common scale (Figs 7, 8) The use-

— In the vertical direction to 12 horizontal sectors, des- ignated 7 to 12

- In the anteroposterior direction to nine verticofron- tal sectors designated A fo I

— In the transverse direction into four sagittal sections

designated a tod

To avoid creating volumes that would be too large, the

sectors are divided into intermediary sectors (a-b, 7-8,

H-I) For the sagittal sections, the intermediate sectors do not exceed 4mm on either side of the dividing lines

(see Fig 41)

This division of the brain in unitary volumes is the

road to a computerized atlas Such an atlas could em-

phasize for each unit all the structures that it contains

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8 2 Reference System: Basal Brain Line CA-CP d c b a a b c d

Figure 8 Intracerebral points stimulated at the level of the mesial cortex and transferred to the normal-

ized grid model presented sagittally and coronally (approximately 400 stimulations) The supplementary

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3 Cerebral Structures in Three-Dimensional Space

To facilitate the utilization of this book, we have not

used a different brain specimen for each of the planes of space, as is done in most classic anatomic atlases

The transition from one plane to another under such

conditions is far from easy Our original work was car-

ried out on a personal collection of brains on which

stereotaxic localization had been performed in situ

with placement of the CA-CP line in conformity with a

technique that we described in 1957 (52) Here we have

used one brain preparation (photographed and en- larged to real dimensions) in which the two hemis- pheres cut sagittally were anatomically satisfactory

From accurately outlined sagittal sections, a series of sections were extrapolated in the frontal and horizontal planes by point-to-point projection

Tracts

The number of bundles represented has necessarily been reduced in an arbitrary manner for clarity while preserving the documentation of these sections

Corticospinal Tract (Pyramidal Tract, PT) It is repre-

sented on the right and the left in a different manner On the left, dark green fibers extend from the motor cortex and follow its sinuous outlines At this level, if

one visualizes the sensory fibers in terms of the sinu-

osities and waves of the Rolandic fissure, one may ap-

preciate the different juxtapositions and superposi- tions of the sensory and motor fibers

On the right, the pyramidal tract (PT) is represented by

colored dots The apparent asymmetry between right

and left corresponds to the variations of the central sul-

cus in the two hemispheres (see Fig 12)

- Red dots: face cortex

~ Green dots: hand - upper extremity - shoulder

— Black dots: trunk - inferior extremity

These localizations are consistent with the work of Penfield (35) but have also become obvious to us through the results of stereoelectroencephalographic

explorations made in cases of epilepsy using the

CA-CP proportional grid system for the placement of

the electrodes In contrast to Penfield, the representa-

tion of the superior extremity is in our experience clos-

er to the midline, situated at 1 to 0.5cm from the medi-

al surface of the hemisphere, as we have marked it on the sections

Optic Pathway (Bo, Ro) This is represented in red One

might be surprised not to find Meyer's loop in the op-

tic radiations Experience with temporal corticectomies in epilepsy has shown that an excision passing 1cm in

front of the VCP line (which always passes through the

center of the lateral geniculate body) does not cause in- volvement of the visual field There is every reason to think that this loop does not exist, at least not in the

classically supposed magnitude, and that fibers ema- nating from the lateral geniculate body follow the sim-

plest trajectory from within outward, to pass around

the temporal horn of the lateral ventricle and then

spread out in a fanlike manner (45, 57, 64)

Auditory Fibers (Ra) These are represented in maroon

From the medial geniculate body, the radiation runs transversely through the posterior part of the sublen-

ticular region of the internal capsule and over the tem-

poral horn, then they diverge upward behind the insula in a large fan-shape to approach the transverse gyrus (area 41)

Olfactory Tract (Tol) It is represented in yellow Ac-

cording to the classic description, it divides into two

roots, medial and lateral The latter is preponderant in

man It ends in the piriform lobe, uncus, and in parts of

the amygdaloid complex Nevertheless, in our experi-

ence, with Dr Bancaud, extending over 20 years of stereoelectroencephalography investigations, the tem- poral electrical stimulations have rarely induced olfac-

tory responses Likewise, in the course of temporal lobe epilepsies, olfactory hallucinations were scarcely

ever noticed as a primary clinical sign They may ap-

pear in the terminal stage of a seizure and might be re-

lated to an activation of the postero-orbital part of the

frontal lobe through the uncinate fasciculus (6)

Large Association Bundles These fibers are colored in

violet, including the corpus callosum They have been entered by reason of the important role that they seem to play in the propagation of epileptogenic discharge, giving rise to characteristic symptom sequences As an

example, one may refer to a case of “perisylvian” ep-

ilepsy in which the fasciculus arcuatus appeared to

play a large role in the propagation of the discharge Likewise in occipital epilepsies spreading secondarily to the temporal lobe, the inferior longitudinal fascicu-

lus plays a role In various seizures of anterior tempo-

ral origin which exhibit electroclinical manifestations

of the frontal type in their later phases, the uncinate

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10 3 Cerebral Structures in Three-Dimensional Space

The general course of these fibers is influenced by the

meanderings of the cortex and the spatial distribution

of the interconnected cortical regions

Cortical Areas

The topography of the cortical areas does not have

absolute validity The brain presented here was not

subjected to histologic studies and the transfer of the

cartography of Brodmann usually pictured in two-di-

mensional projections sometimes possesses uncertain- ties

The brain presented in Figs 9, 10, 12-17 is a volumet- ric reconstruction made from the sections of the Atlas

It has been made taking into account stereotaxic data

from the original cadaveric brain The accurate recon-

struction of the two cerebral hemispheres as a solid

structure has facilitated the identification of anatomic

zones and the location on a curved rather than a plane surface of the cortical areas according to Brodmann’s

classification, which has remained the most widely uti- lized (9) (Figs 9, 10)

The subdivision of the cerebral cortex into cyto-archi- tectonic areas does not imply, it is hardly necessary to state, a parcellation of cerebral function, even if certain

cortical areas appear to correspond to a univalent neu-

ral activity accessible in its totality or partially to tech- niques of exploration in vivo; for example: sensory re-

ceiving areas (3, 2 and 1, visual and auditory areas)

17 and 41, primary motor area 4, supplementary motor

area 6 (mesial face of the hemisphere), oculomotor

area 8

It is helpful to keep in mind that all the regions of the

cortex are tightly associated through short fibers be-

tween neighboring areas and by homolateral and com- missural bundles Furthermore, the majority of the cor- tex is, to different degrees, connected with subcortical structures: central gray nuclei, brainstem systems,

cerebellum, and the spinal cord

To facilitate the reading of the sections, a brief survey

of the cortical areas and their principal connections fol-

lows

Frontal Lobe

Area 4 the primary somatomotor area contributes to the

formation of the corticospinal tract Intimate connec-

tions with areas 6 and 5 contralaterally (chimpanzee)

Efferent fibers to thalamus, lenticular nucleus, substan-

tia nigra, zona incerta

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nal tract Other efferents are to the putamen, globus pallidus, the subthalamic and diencephalic nuclei, the

brainstem in particular the pontine nuclei (corticopon- tine tract of Arnold), relaying to the neocerebellar cor- tex In primates, direct connections have been demon- strated to homolateral area 8, to contralateral areas 4

and 6, the gyrus cingularis, the parietal lobe

Area 8 represents a large portion of the frontal oculo- motor field for voluntary conjugate movements of the eyes and cephalogyria It is connected by long association

bundles with other cortical regions, in particular the

occipital lobe, and by projection fibers with the brain-

stem and the oculomotor nerves

Areas 9 and 10 belong to the prefrontal cortex Principal connections are with the thalamus (dorsomedian nu- cleus) and also the three other cerebral lobes, and the hypothalamus Efferent fibers, associated with others from areas 8 and 45, accompany the tract of Arnold to

the brainstem

Areas 44 and 45 cover approximately the cortical area of Broca (motor speech) in the lower frontal convolution They are directly connected by long tracts with area 10 and undoubtedly with the supplementary motor area

Cortical Areas 11

Area 47 is connected with the orbital portion of the

frontal convolutions by its thalamohypothalamic con- nections and has vegetative functions

Parietal Lobe

Areas 1, 2, 3, the primary somatosensory cortex, sends ef- ferent fibers to the red nucleus and, more particularly

for area 2, to the substantia nigra, the pontine nuclei, and central gray nuclei

Area 5 has contralateral connections with areas 1, 2, and 4, homolateral connections with area 22 in the superior temporal convolution and the gyrus cingula-

ris

Area 7 has contralateral connections with areas 1, 2, and 5 For areas 5 and 7, subcortical projections are to

the lenticular nucleus and the tegmentum (ansa lentic-

ularis and lenticular fasciculus)

Areas 39 and 40 are territories strongly linked with associative functions, consisting essentially of intracere-

bral connections to areas 18, 19, and 22, association bundles to the temporal pole and the frontal lobe, and commissural homotopic connections Area 39 corre- sponds more or less to the angular gyrus and area 40 to

the supramarginal gyrus

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120 3 Cerebral Structures in Three-Dimensional

Occipital Lobe

Area 17 is the primary visual sensory area macroscopically

identified by the striae of Gennari It is directly con- nected with area 18 and through it with area 19

Area 18 is the area of visual integration possessing recip- rocal connections with area 19 Efferent fibers travel

subcortically toward the brainstem of the superior

quadrigeminal colliculus

Area 19 is largely interconnected with the adjacent

areas and contralateral area 19 via callosal radiations The occipital oculomotor area on the external surface of the lobe spreads over areas 18 and 19 It is the seat of

vertical and oblique conjugate movements of automatic type

Areas 18 and 19 are connected to the frontal oculomo- tor center, to the sensorimotor cortex, and to the audi-

tory cortex by long association bundles

Temporal Lobe

Areas 41 and 42 lie on the transverse temporal convo-

lutions and represent the primary auditory receptive cortex (area 41) and auditory integration region (area 42) with bi-

lateral representation They are interconnected by com- missural fibers They have significant connections to areas 18 and 19, to the inferior portion of the postcen- tral convolution, to the insula, to areas 44 and 45, and the oculomotor fields Efferent fibers project to the medial geniculate body

Area 22 lies in the midportion of the superior temporal

convolution, surrounding the auditory area Area 22

constitutes an auditory association area related to the in- sular, parietal, and occipital cortex

Area 21 is the origin of the major portion of the bundle

of Turk, which also receives projection fibers from areas 20 and 22 and some parietal and occipital efferent fibers Parietal cortex areas areas Parieto-frontal cortex (40-42) areas 7 (40-31) Parietal cortex — E ——= =3 | cortex areas 18-19-7-38-37 (40-39) Postcentral cortex areas areas 4(6) 1-2 Space | Precentral cortex Area 37 is an auditory visual association area Cingulate Gyrus

The cingulate gyrus comprises areas 23, 24, 31 and 33

and 26, 29, and 30 in the region of the retrosplenial

isthmus In addition to important connections with the

thalamus, numerous connections have been described from area 24 to areas 6, 8, 9, 10, and 29, and other effer- ents principally from areas 11 and 12 Efferent fibers

with corticostriate, corticohypothalamic, and cortico-

tegmental subcortical targets have been demonstrated

in the monkey

Corticothalamic Connections

The thalamic connections to the cortex are particularly

rich These connections are often reciprocal and main-

tain a topographic relationship between histologic sub- divisions of the thalamus and a distinct cortical area

These corticopetal and corticofugal pathways are not macroscopically identifiable, but the:r trajectory can be

reasonably well placed in serial sections Thus, when,

for example, the slices involve area 10, the reader may

assume that the adjacent white matter is principally oc- cupied by fibers connected to the dorsomedial nucleus Since this work is not intended for stereotaxic surgery of the central gray nuclei, we have simply used a sche-

matic diagram of the principal nuclear masses of the

thalamus The limits therefore appear artificial, but

they preserve the topographic relationships The no-

menclature adopted here is taken from Walker, which

is still the most common in current literature (62)

Figure 11 summarizes the essential thalamocortical re-

lationships These have been demonstrated in smaller

laboratory mammals and in primates and are largely accepted as being applicable to man Frontal cortex 11-47 10-9-8 (44-45-46) Cingulate cortex areas 23-24 (32-29) Frontal cortex 6 areas (8-44) Figure 11 Connections of

Brodmann’s areas with

thalamic nuclei Paren-

theses indicate thalamo- cortical connections that

are accepted but not

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Cerebral Functions and Reference System Figures 12 and 13 demonstrate the entirety of the brain and its visible convolutions in relation to the basal

lines It is also useful to be able to localize the principal

cortical regions involved in the great cerebral functions

Figure 12 Visible convolutions and reference system

Cerebral Functions and Reference System 13

in relation to these same lines (Figs 14-17) It is self-

evident that this anatomic allocation of certain major

functions to different areas of the cerebral cortex is in-

complete and approximate and very likely will be sub-

jected to numerous changes with the advance of ana- tomoradiologic correlations

The right and left hemispheres of the reconstructed brain show the extent of variability of the sulci and gyri in the two hemispheres of the same brain Note the difference between the location of the right gyrus supramar-

ginalis on the right and on the left (in a right-handed person) Note also the variations of the central sulcus

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14 3 Cerebral Structures in Three-Dimensional Space

Figure 13 Visible convolutions and reference system Gyri and sulci of the same brain Above: right medial

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These functions are deduced from disturbances result-

ing from localized hemispheric lesions (difficulty with

reading, with writing, etc.) as well as data furnished by

basic and human neurophysiology (stimulation in the

course of stereoelectroencephalographic explorations, and study of ablation of epileptogenic cortex (3, 4, 57,

58)

Such data no not pretend to summarize a function or to

explain its inner mechanics in a normal subject This

would be confusing the localization of a function and the localization of lesions or stimulation

Region involved inthe organization of writing

Primary motor and sensory

areas (upper extremity, face) (contralateral) Region involved in the organization of articulated language (Broca) Region involved in the recognition of certain portions of the body: right/left discrimination digital agnosia Region involved in the organization of heard, spoken, written language 15 Cerebral Functions and Reference System

However, it seems to us that better knowledge of the

macroscopic anatomic organization of the human brain, which is the goal of this work, would permit a better decoding for the neurologist and neuro-psychol- ogist of the clinical syndromes and of their diversity,

and for the neuroradiologist and the neurosurgeon a

better appreciation of the relationships between a lesion and the structures involved by it

Region involved in the

manipulation of objects and

execution of gestures of

symbolic value (military

salute, sign of the cross)

Region involved in the organization of figure drawing

Region involved in the

organization of reading Region involved in the recognition of objects, images, and colors

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16 3 Cerebral Structures in Three-Dimensional Space

Primary visual areas Primary motor and sensory Region involved in the elaboration Region involved in the control (contra- and homolateral) areas Lower extremity (controlateral) of movement (in relation to language) and organization of gestural

instinctual and affective behavior

Region involved in Region involved in the organization Region involved in olfactory visual perception and integration of reading perception and integration (contro and homolateral)

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Cerebral Functions and Reference System 17

Region involved in visual Region involved in the recognition Primary motor and sensory area Region involved in Region involved in perception and integration of space and perception of body (upperextremily-face) sensory-motor integration _ the elaboration and

image and gestures (contralateral) control of higher

mental functions

(bilateral)

Region involved in Regioninvokedinthegrasp —_ Region involved in the integration of Region involvedinthe Region involved in auditory perception reflex and ability orient the sensation and of complex perceptions integration of gustatory _vegetative

and integration Position of the head in space Retention of experiences and acquisitions —_ functions (bilateral) functions (cardiac, (bilateral) touching on awareness of body and of respiratory) (bilateral)

surrounding space (bilateral)

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18 3 Cerebral Structures in Three-Dimensional Space

Region involved in the control_ Region involved in the Primary motor and Region involved in the control and organization of gesture and elaboration of movement sensory areas (knee, ankle, _ of visual, auditory, and tactile

instinctual affective behavior (supplementary motor area) _ toes) (contralateral) perceptions (bilateral) (bilateral) (contralateral) Region involved in the recognition of space

Region involved in olfactory Region involved in the organization Region involved in memory, Region involved in Primary visual areas

perception and integration and control of metabolism and regulation of sleep and visual perception and (contra-and homolateral) endocrine equilibrium homeostasis wakefulness, and mood integration

(hunger, thirst, sexuality) (bilateral) (contra- and homolateral) (bilateral)

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4 Practical Examples for the Use of the Atlas

19

in Neuroradiologic Examinations

In actual practice, the baseline CA-CP of this Atlas will only rarely coincide with the bony lines of orientation or the planes of section used by neuroradiologists in performing a computed tomography (CT) scan of the head The Atlas will, however, always be usable, taking

into account a larger or smaller loss in precision

At present, one can utilize this book starting with the

interhemispheric plane, which is habitually displayed

by standard radiologic examinations Starting from this

plane, as we will show in detail later, it will be easy to find the corresponding sagittal anatomic section and to pass easily with the aid of the proposed system to the other two planes, the verticofrontal and the horizontal

Even in dealing with an axial radiologic section taken at an angle in respect to the horizontal plane CA-CP, it

will be possible to apply the information from this

three-dimensional Atlas to the approximate region of

the point under consideration

Of course, if one were to utilize the magnetic reso-

nance (MR) images of the anterior and posterior com-

missures, and trace these on all other sections, the

Atlas would then place at the disposal of neuroradiolo-

gists the stereotaxic anatomic studies based on the

CA-CP baseline Such a procedure would allow the

neuroradiologist to situate with more precision within the involved sections all the normal structures that are not immediately identifiable visually and display their

relationship to the pathologic processes made evident

by the new imaging technology

First Example: CT Scan

Three-dimensional utilization of the Atlas with respect to a CT scanner image

obtained under usual conditions

In this example (Fig 18) the image of the ventricular

system is easily comparable with one of the horizontal sections parallel to the CA-CP line, here the section of

sector 6 (20mm) (Fig 19) Despite the probability of an

angular difference between the two planes, one notes a

certain degree of correlation in the sagittal and vertico- frontal planes for regions close to the lesion, especially

if, as is most often the case, the CT plane is approxi-

mately parallel to the orbitomeatal plane The lesion site (green dot) is clearly identified on the horizontal section (+20mm) by the coordinates 6, a—b, E1 (Fig 19, arrows) The same coordinates are seen on the later-

al view a-b, 6, E1 (Fig 20) and on the verticofrontal sec-

tion E1, 6, ab (Fig 21) One notes here:

Figure 18 Axial section of computed tomography scan 30mm above orbitomeatal line The green dot represents the location

of an imaginary lesion

— Involvement of the motor bundles of face and upper extremity, (dark green fibers) the occipitofrontal as- sociation bundle (FOF), the body of the caudate nu- cleus (NC, yellow)

— Contact of the lesional process with the body of the lateral ventricle (VI) and with radiations of the cor-

pus callosum

— The integrity of the thalamus (Th) and lenticular nu- cleus (NL), etc

Despite the imprecise orientation in this case, the

three-dimensional anatomic view may nonetheless

bring information much richer than the sole horizontal perspective of the CT scan to an understanding of the situation of a lesion and of the risks attendant on its

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20 4 Practical Examples for the Use of the Atlas in Neuroradiologic Examinations

Figure 19 Horizontal Atlas section Section of the Atlas 20mm from the CA-CP line

Figures 19, 20, 21 The lesion site (green dot) is defined PS: The list of the anatomic abbreviations can be found

by the following coordinates: 6—ab-E; on pp 111, 112, 113, and also on the inside of the front

— For the horizontal section: 6-ab-E, cover

— For the lateral section: ab—6-E,

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_First Example: CT Scan 21

Figure 20 Sagittal section of the Atlas corresponding to Fig 19

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22 4 Practical Examples for the Use of the Atlas in Neuroradiologic Examinations

Figure 21

Second Example:

MRI Without Reference System

Utilization of the Atlas with an MR image

in the absence of a precise reference system

other than the distance to the interhemispheric plane

This MR image demonstrates at approximately 50mm from the midline a lesion situated at the level of the green dot (Fig 22, above)

~ The first step consists of choosing the sections closest to the plane under consideration, here 47 and 51 mm

defined in our atlas as belonging to sector ¢ 47 and c 51, sagittal plane (Fig 23) They delimit a brain slice, which compensates, to a certain degree, for the indi- vidual variations

~ The second step consists of orienting the MR image

(Fig 22, below) identically with these sections ac- cording to an evident structure; here, the lateral sul- cus, the superior temporal sulcus, etc In another case, such a structure might be the shape or orienta-

tion of the ventricular cavities, etc

~ The third step consists of projecting the lesion onto

these sagittal sections (Fig 23, green dot) The coor- dinates that appear there localize the lesion to 7-8

10

Verticofrontal section of the Atlas corresponding to Figures 19 and 20

(horizontal plane) and H (verticofrontal plane), as shown by the arrows This lesion is thus situated in zone c, H, 7-8

~— The fourth step is to move te the verticofrontal sec- tion, sector H, in 7-8, ¢ (Fig 24, above), then to the

horizontal section sector 7-8 in H, ¢, (see arrows, Fig

24, below)

The lesion is defined by three coordinates (c, 7-8, H)

thus:

~ For the lateral plane: c, 7-8, H

— For the frontal plane: H, 7-8, c — For the horizontal plane: 7-8, c, H

Despite the absence here of stereotaxic precision, one

learns that area 19, considered visuopsychic, is in- volved as well as the association pathways; also that areas 37 and 39 will soon be involved with the implica-

tions for lexic functions of a left hemisphere lesion If the lesion extends medially, it will reach the inferior

longitudinal fasciculus (FLI) Then, a homonymous

hemianopsia would have to be expected due to damage

to the optic radiations (RO)

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Second Example: MRI Without Reference System 23 D0 ag abel a ld

Figure 22 Above: Nuclear magnetic resonance image, sagittal Below: Same image is moved to fit the anatomic drawings of the

section The supposed lesion is marked by a green dot Atlas

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24 4 Practical Examples for the Use of the Atlas in Neuroradiologic Examinations _

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Figure 24 Above: Ver-

ticofrontal section H

(from the Atlas)

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26 4 Practical Examples for the Use of the Atlas in Neuroradiologic Examinations

Third Example:

MRI With Reference System

Three-dimensional utilization of the Atlas

on MR images, on which the anterior and posterior commissures (arrows) can be localized

Some neuroradiologists have applied our reference

system and many investigations have been made in

this manner using the CA-CP line (Prof C Salamon,

CHU La Timone, Marseille; Prof D Fredy, CH Sainte Anne, CHU Cochin, Paris; Prof J Bories, CHU Salpê- triére, MRI Coordinator, Salpétriére, Paris)

The two commissures are easily identified on a sagittal

medial plane (Fig 25) It is more difficult on the other

two planes (horizontal, verticofrontal) For a specific

brain, each set of MR images issued exhibits the refer-

ence data in a defined location and the various brain

images at the same angle Therefore, it is possible to set

the basal lines for the section demonstrating the

CA-CP markers, then to superimpose the images of the

other, sagittal sections and transfer the basal lines to

them (Fig 26)

The orientation of the sagittal sections would then be

defined with precision and the two other planes would

be sufficiently defined

Thus, it will be easy to compare anatomic sections and

MR images:

Fig 26, above, and section a (9 mm) p.44

Fig 26, below, and section c-d (55mm) p.5ó

and, for example, to localize the central sulcus on these

images no matter what individual variations it may

have (Fig 26, Fig 27)

AP

Figure 25 Mid-sagittal MR section Construction of basal lines based on the anterior and

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Third Example: MRI With Reference System

Figure 26 Sagittal sections Each section has been superimposed on the midline section

and then the basal lines traced Arrows indicate the central sulcus

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28 4 Practical Examples for the Use of the Atlas in Neuroradiologic Examinations

Recently, progress has been achieved MR scan sec-

tions can be performed directly in orthogonal planes according to the basal line (Fredy D., Missir O., DiLou- ya O., Centre Hospitalier Sainte Anne) First the basal line CA-CP is determined on the midsagittal plane, and the midline on the anteroposterior view Subsequently, the machine draws the various levels of the desired

cerebral sections Therefore, the sagittal, frontal, and

axial sections form a coherent set (Figs 27, 28) corre-

sponding accurately to the three planes of the Atlas

sections

Figure 27 Above: Verticofrontal sections Numbered from an-

terior to posterior MR slice thickness, 7mm

Below: Horizontal sections Numbered from rostral to caudal

Magnetic resonance slice thickness, 7mm

In this manner, one uses a similar reference system for

each individual MR image as the corresponding ana-

tomic sections in the book Moreover, the comparison

is valid for the whole extent of the section, and patho- logic lesions can be precisely localized within the pro- portional grid

A basal line may also be transferred automatically to all

images of the sequence (Figs 29-32)

II 4000!

Figure 28 Sagittal sections Numbered from right to left Mag-

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Third Example: MRI With Reference System 29

Figure 29 Magnetic resonance imaging Three different sequences of the same patient Each sequence demonstrates only one

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30 4 Practical Examples for the Use of the Atlas in Neuroradiologic Examinations For an example we display a set of MR images, in three

orthogonal planes They could be compared despite in- dividual variations, to the anatomical sections of the

Atlas (Fig 30, 31, 32)

Sections (C) of MR images have been carried out and numbered like the MR images in the Fig 27 and 28 1° Sagittal image: section C9 corresponds to

sector A (9-13 mm)

pp 44-45

Sagittal image: section C14 corresponds to

sector C (47 mm) pp 54

2° Verticofrontal image: section C4 corresponds to

sector D and D-E (+4 to +8mm) pp.68-69 Verticofrontal image: section C12 corresponds to sector F-G and G (—45 to —50mm) p.75 section C5 corresponds to sector 5-6 (+ 28mm) p.92 section C9 corresponds to sector 8-9 and 9 (—2 to —4mm) pp 100-101 3° Horizontal image: Horizontal image:

As long as the sections are strictly obtained according to the reference lines (CA-CP, VCA, midline) the poten-

tially large number of MR investigations would result in valid statistical studies of anatomic data; for exam- ple: hemispheric symmetry, left-right asymmetry, nor- mal size of the subarachnoid space in the cerebral sulci,

normal ventricular size Criteria of pathologic change

could also be investigated, e.g., the initial signs of ven-

tricular dilation or the criteria of cerebral atrophy

Figure 30 Sagittal sections, left hemisphere Magnetic reso-

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Third Example: MRI With Reference System 31

Figure 31 Verticofrontal sections Magnetic resonance slice Figure 32 Horizontal section Magnetic resonance slice thick-

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Third Example: MRI With Reference System 33

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34 4 Practical Examples for the Use oí the Atlas in Neuroradiologic Examinations

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Therefore, more extensive use of the anatomic quality of MR images could also be developed These images supply specific information for each individual about

the cortex, white matter, subarachnoid spaces, etc of the greatest interest After appropriate magnification, it would be possible to superimpose them accurately on-

to the stereotaxic film radiographs taken according to

the same orthogonal projections (Fig 37)

The combined use of these images could soon lead to define not only the target, but also the trajectory of

multilead electrodes with increased accuracy

In conclusion, it should be envisaged that the MR scanner computer will in future be able to produce the

Third Example: MRI With Reference System 35

proportional grid system directly in accordance with the dimensions of the great axes of the brain (Fig 38)

Thus, the scanner would perform what we have been doing manually for 20 years to display statistically the location of cerebral electrodes, and of the epileptogenic

areas identified during the SEEG investigations If the

grid were applied to these images, we foresee that a le-

sion could be automatically located with reference to the triplanar grid, and correlated with a greater quantity of anatomic information stored in the computer memo- ry than we can display in the pictures of the Atlas with-

out altering their didactic clarity

Figure 37 Same patient - Combina- tion of arteriography, ventriculography and MRI

Above: Drawing of teleradiographic stereotaxic pictures with proportional grid: Ventriculography and arteriogra- phy Only anterior cerebral artery and

main veins are demonstrated

Below: MRI, Interhemispheric surface

White lines: horizontal sections level

and basal lines (CA-CP, VCA-VCP)

Black lines: proportional grid

Numbers: supposed position of 4

electrodes

| Supplementary motor area medially, area 6 laterally

2 Close to the dorsal corpus callo-

sum: area 24, area 33 and cingulum

callosal radiations

3 Anterior cingulate gyrus

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36 4 Practical | Examples fort the Use of the Atlas in Neuroradiologic Examinations =>S0 MONOD DAWN 12 d c b a a b c d Figure 38 Possible appearance of a proportional grid set on a magnetic resonance im- age

Above: Interhemispheric surface

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37

5 Three-Dimensional Atlas of a Human Brain

Study of both hemispheres of the same brain

situ

Female, European Age 60 years, right-handed Reference System

Basal line CA-CP: Horizontal plane

Vertical line VCA: Verticofrontal plane

Midline: Sagittal plane Millimetric reading Volumetric reading (proportional grid system) Demonstration of In the left hemisphere (G): ~ Cerebral cortex

— Central gray and subthalamic nuclei (dotted outline)

- Motor fibers (without distinction of role) — Visual, auditory, olfactory fibers

— Major association bundles (corpus callosum, cingu-

lum, occipito-frontal fasciculus, arcuate fasciculus, inferior longitudinal fasciculus, tapetum, uncinate fasciculus)

— Fields of Brodmann

In the right hemisphere (D):

— Simplified outline of the brain

~ Central gray and subthalamic nuclei (in color)

— Motor fibers (with functional distinctions: face,

upper extremity, lower extremity) — Infundibular nuclei (in color)

Color Code

— Ventricular cavities

On the right: small black crosses

On the left: small crosses on rose background ~ Cortex

On the left: light blue

- Pyramidal cortex: light blue with red striations and

dots

- Visual cortex: light blue and red striations

Brain sections in the three dimensions (sagittal-vertico-frontal-horizontal)

Reconstruction of the right and left hemispheres obtained under stereotaxic conditions (localization) and markings carried out in Abbreviations used in the Atlas figures are defined on the inside front cover of the book (see also p 111-113)

— Pyramidal pathways

On the left: green dashes On the right: colored dots

(red = face, tongue, pharynx, larynx) (black = lower extremity, trunk)

(green = upper extremity, shoulder)

— Optic pathways (chiasma, optic tract, optic radia- tions): red dashes

— Corpus callosum: crossed violet dashes

— Major association bundles: violet dashes

— Central structures

~ Ventricular atrium: blue on the right — Mammillary bodies: blue on the right — Thalamus: rose

— Caudate nucleus: yellow

— Lenticular nucleus (globus pallidus and putamen):

green

— Locus niger: blue and large crosses

— Corpus Luysii: blue and small crosses

— External geniculate body: red and small crosses

— Medial geniculate body: yellow and small crosses

— Ammon’s horn: large violet dashes

— Hypothalamic nuclei

— Preoptic medial (POM): maroon

— Lateral preoptic (POL): maroon striated — Supraoptic: maroon and dots

— Lateral hypothalamic (HL): red with crosses

— Dorsal hypothalamic (HD): green

— Ventro-medial (VM): green with crosses — Periventricular (PV): yellow

— Para-ventricular (PaV): green with crosses

~ Posterior hypothalamic nucleus (HP): violet with

crosses

— Tuberal nucleus (T): blue

The anatomic abbreviations used in the atlas can be

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38

Sag

5 Three-Dimensional Atlas of a Human Brain

ittal Sections 36 sections (right and left)

Millimetric Reading (level of sections)

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Sagittal Sections 39

Volumetric Reading (proportional grid system)

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