Article Figures & Data
Figures
- Fig 1.
Selected coronal, sagittal, and axial images of the postmortem basal forebrain illustrating the serial imaging planes for Fig 2 and On-line Figs 1 and 2, respectively. Table 1 provides a complete list of labeled anatomy for all figures, indicated by the numbers in parentheses in the legends. The familiarity of T2 contrast and multiple imaging planes provided in this study should help facilitate learning the complex neuroanatomy of the basal forebrain.
- Fig 2.
Serial inferior-to-superior axial images of the postmortem basal forebrain parallel to the commissural plane (A–F, −4, −2, 0, 2, 4, and 8 mm relative to the intercommissural plane, respectively). The globus pallidus internus (17) is a therapeutic DBS target for Parkinson disease and dystonia.18 The globus pallidus internus is separated from the externus (16) by a thin hypointense band, the internal medullary lamina (55 in On-line Fig 1). Note the 2 divisions of the globus pallidus internus (medial and lateral) separated by the accessory medullary lamina in B and C. Contrast is less conspicuous in the more superior thalamus.
- Fig 3.
Selected images illustrating the subthalamic nucleus (6) in the basal forebrain. Coronal, sagittal, and axial images show the subthalamic nucleus as a biconvex hypointense structure nestled along the medial margin of the internal capsule (26). B, The darkest portion of the internal capsule just anterior to the subthalamic nucleus represents the Edinger comb system (77) containing the pallidosubthalamic, pallidonigral, and nigrostriatal tracts. The small white circle represents the potential DBS electrode tip placement site (Table 2) in the inferior portion of the zona incerta (asterisk), which corresponds with a better therapeutic profile according to Plaha et al.22
- Fig 4.
Selected images illustrating the hippocampal-thalamic pathways. Coronal, sagittal, oblique axial (the dashed line in B represents the oblique imaging plane for C), and magnified coronal images of the fornix (9) and mammillothalamic tract (10). A and B, The decreased size of the postcommissural fornix as it approaches the mammillary bodies (56) is likely due, in part, to the direct hippocampal pathway (36) in C, which bypasses the mammillary bodies to reach the anterior thalamic nuclei (41). D, Just medial to the Fields of Forel (78) and pallidofugal tracts, the principal mammillary tract (80) gives rise to the ascending mammillothalamic tract. Note the subthalamic fasciculus (81) and zona incerta (asterisk).
- Fig 5.
Selected images illustrating the pallidothalamic tracts. Sagittal, oblique axial (the dashed line in A represents the oblique imaging plane for B), and coronal images illustrating the complex 3D shapes and spatial relationships of the ansa lenticularis (5), lenticular fasciculus (58), and thalamic fasciculus (27). B, The ansa lenticularis originates from the inferomedial globus pallidus internus (17) and joins the lenticular fasciculus (H2 field of Forel) in the very hypointense prerubral H Fields of Forel (78). These pallidal efferents then ascend as the thalamic fasciculus (H1 Fields of Forel) to the ventral thalamus. The zona incerta (asterisk) is the bright signal intensity region in between lenticular and thalamic fasciculi in B and C. The subthalamic nucleus (6) can be seen in relationship to these structures in A. Note the dark structure just inferior to the 44 label and the dashed line is a thalamic perforating vessel.
- Fig 6.
Coronal, axial, and sagittal images illustrating the superior ascent of the dentatorubrothalamic tract (19) to the Vim nucleus (75). A, Slight obliquity of the image allows depiction of the Vim and DRT on the left and the posterior aspect of the relatively more hyperintense nucleus ventrooralis (33) on the right (zona incerta labeled with asterisks). The relationship of the PLIC (26), nucleus ventrocaudalis anterior (28), and nucleus ventrocaudalis posterior (29) nuclei to the Vim is also illustrated. For completeness, the interested reader can find the proximal or prerubral component of the dentatorubrothalamic pathway also demonstrated in On-line Fig 3 of the previous report.57
Tables
Labeling Key 1) Putamen 2) Caudate nucleus 3) Anterior commissure 4) Ansa peduncularis (inferior thalamic peduncle) 5) Ansa lenticularis 6) Subthalamic nucleus 7) Cerebral peduncle 8) Lateral geniculate nucleus 9) Fornix 10) Mammillothalamic tract 11) Red nucleus 12) Medial lemniscus 13) Spinothalamic tract 14) Central tegmental tract 15) Inferior colliculus 16) Globus pallidus externus 17) Globus pallidus internus 18) Medial geniculate nucleus 19) Dentatorubrothalamic tract 20) Brachium of the inferior colliculus 21) Mesencephalic trigeminal nucleus 22) Habenulopeduncular tract (fasiculus retroflexus) 23) Posterior commissure 24) Anterior limb of the internal capsule 25) Genu of the internal capsule 26) Posterior limb of the internal capsule 27) Thalamic fasciculus (H1) 28) Nucleus ventrocaudalis anterior 29) Nucleus ventrocaudalis posterior 30) Pulvinar 31) Superior colliculus 32) Nucleus lateropolaris 33) Nucleus ventrooralis 34) External capsule 35) Retrolenticular internal capsule 36) Direct hippocampal tract 37) Habenular commissure 38) Brachium of the superior colliculus 39) Nucleus centralis 40) Nucleus habenularis 41) Anterior thalamic nuclear group 42) Nucleus medialis 43) External medullary lamina (thalamus) 44) Extreme capsule 45) Claustrum 46) Caudolenticular gray bridges (pontes grisei caudatolenticulares) 47) Olfactory tubercle 48) Accumbens area 49) Medial forebrain bundle 50) Optic tract 51) External medullary lamina (globus pallidus) 52) Diagonal band of Broca 53) Basal nucleus of Meynert 54) Hypothalamic nuclei 55) Internal medullary lamina (globus pallidus) 56) Mammillary body 57) Optic radiations 58) Lenticular fasciculus (H2) 59) Substantia nigra 60) Massa intermedia 61) Nucleus dorsalis superficialis 62) Nucleus dorsalis oralis 63) Internal medullary lamina (thalamus) 64) Auditory radiations 65) Periaqueductal gray matter 66) Supraoptic decussation 67) Optic chiasm 68) Superior cerebellar peduncle (crossed) 69) Decussation of the superior cerebellar peduncle 70) Medial longitudinal fasciculus 71) Splenium 72) Hypothalamic sulcus 73) Oculomotor nerve (cranial nerve III) 74) Stratum opticum 75) Nucleus ventrointermedius 76) Nucleus parafascicularis 77) Edinger comb system 78) Nucleus of field of Forel (H) 79) Internal capsule 80) Principal mammillary tract 81) Subthalamic fasciculus “*” Zona incerta - Table 2:
Measurements of the subthalamic nucleus in SUDC brains using TSE MRI contrast (n = 11)a
Measurement/Dimension/Plane Right Left Differenceb P Valuec COVd Lengthe (mm) Anteroposterior 9.6 ± 0.9 9.9 ± 0.8 −0.3 ± 0.6 .084 8.8% Mediolateral 4.2 ± 1.2 4.1 ± 1.0 0.0 ± 0.4 .910 26.0% Superoinferior 6.0 ± 0.6 5.8 ± 0.7 0.2 ± 0.3 .047 10.8% Anglef Coronal 58.7° ± 6.5° 58.0° ± 6.6° 0.7° ± 5.8° .414 10.9% Axial 135.5° ± 4.8° 131.6° ± 5.8° 3.8° ± 5.9° .590 4.1% Sagittal 26.5° ± 6.6° 28.5° ± 7.0° −1.9° ± 5.4° .188 24.3% Stereotactic coordinatesg (mm) Lateral 13.5 ± 1.0 13.5 ± 1.1 0.1 ± 0.5 1.000 7.8% Posterior 4.8 ± 0.6 4.7 ± 0.5 0.1 ± 0.3 1.000 11.1% Inferior 5.5 ± 0.9 5.4 ± 0.7 0.1 ± 0.5 1.000 14.7% Note:—COV indicates coefficient of variation.
↵a Data are means ± standard deviation unless otherwise indicated.
↵b Right-sided measurement minus left-sided measurement.
↵c Paired-sample Wilcoxon signed rank test.
↵d Global COV for right and left data combined (n = 22).
↵e Largest dimension in each plane.
↵f The angle formed by the long axis of the subthalamic nucleus relative to the orthogonal imaging plane where angulation is inferomedial to superolateral in the coronal plane, anteromedial to posterolateral in the axial plane, and anterosuperior to posteroinferior in the sagittal plane.
↵g Coordinates relative to the intercommissural point where the most inferior, lateral, and posterior point of the subthalamic nucleus forms a distinct border with the inferior portion of the zona incerta. This point will usually be inferior and lateral to the desired DBS electrode tip target but can be measured precisely to assess individual and right-left variation in the subthalamic nucleus position.
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