The surgical approaches to the cavernous sinus were examined in 50 adult cadaveric cavernous sinuses using magnification of ×3 to ×40. The following approaches were examined: 1) the superior intradural approach directed through a frontotemporal craniotomy and the roof of the cavernous sinus: 2) the superior intradural approach combined with an extradural approach for removing the anterior clinoid process and unroofing the optic canal and orbit; 3) the superomedial approach directed through a supraorbital craniotomy and subfrontal exposure to the wall of the sinus adjacent to the pituitary gland; 4) the lateral intradural approach directed below the temporal lobe to the lateral wall of the sinus; 5) the lateral extradural approach for exposure of the internal carotid artery in the floor of the middle cranial fossa proximal to the sinus; 6) the combined lateral and inferolateral approach, in which the infratemporal fossa was opened and the full course of the petrous carotid artery and the lateral wall of the sinus were exposed and; 7) the inferomedial approach, in which the medial wall of the sinus was exposed by the transnasal-transsphenoidal route. It was clear that a single approach was not capable of providing access to all parts of the sinus. The intracavernous structures best exposed by each route are reviewed. The osseous relationships in the region were examined in dry skulls. Anatomic variants important in exposing the cavernous sinus are reviewed.
The anterior perforating arteries, the group of arteries that enter the brain through the anterior perforated substance (APS), were examined using X 3 to X 40 magnification in 50 cerebral hemispheres obtained from 25 adult cadavers. These arteries arose from the internal carotid, middle and anterior cerebral, and the anterior choroidal arteries. The carotid branches to the APS arose distal to the origin of the anterior choroidal artery. The anterior choroidal artery branches arose from the main or superior branch of the artery. The middle cerebral artery branches to the APS (the lenticulostriate arteries) arose from the M1 and M2 segments and were divided into medial, intermediate, and lateral groups, each of which had a characteristic configuration. The anterior cerebral artery branches arose from the A1 segment and from the recurrent artery. The internal carotid and anterior choroidal artery branches entered the posterior half of the central portion of the APS. The lenticulostriate branches entered the middle and posterior portions of the lateral half of the APS. The A1 segment gave rise to branches which entered the medial half of the APS above the optic nerve and chiasm. The recurrent artery sent branches into the anterior two-thirds of the full mediolateral extent of the APS. The relationship of these branches to the cerebral structures above the APS and to the common aneurysm sites is reviewed.
The microsurgical anatomy of the superficial cortical veins was examined in 20 cerebral hemispheres. The superficial cortical veins are divided into three groups based on whether they drain the lateral, medial, or inferior surface of the hemisphere. The veins on the three surfaces are further subdivided on the basis of the lobe and cortical area that they drain. The superficial cerebral veins collect into four groups of bridging veins: a superior sagittal group, which drains into the superior sagittal sinus; a sphenoidal group, which drains into the sphenoparietal and cavernous sinuses on the inner surface of the sphenoid bone; a tentorial group, which converges on the sinuses in the tentorium; and a falcine group, which empties into the inferior sagittal or straight sinus or their tributaries. The superior sagittal group drains the superior part of the medial and lateral surfaces of the frontal, parietal, and occipital lobes and the anterior part of the basal surface of the frontal lobe. The sphenoidal group drains the parts of the frontal, temporal, and parietal lobes adjoining the sylvian fissure. The tentorial group drains the lateral surface of the temporal lobe and the basal surface of the temporal and occipital lobes. The falcine group drains an area that includes the cingulate and parahippocampal gyri and approximates the cortical parts of the limbic lobe of the brain. The relationship of these veins to the venous lacunae was also examined.
The microsurgical anatomy of the tentorial incisura was evaluated in 25 adult cadavers using X 3 to X 40 magnification. The area surrounding the incisura is divided into the anterior, middle, and posterior incisural spaces. The anterior incisural space is located anterior to the brain stem and extends upward around the optic chiasm to the subcallosal area; the middle incisural space is located lateral to the brain stem and is intimately related to the hippocampal formation in the medial part of the temporal lobe; and the posterior incisural space is located posterior to the midbrain and corresponds to the region of the pineal gland and vein of Galen. The neural, cisternal, ventricular, and vascular relationships of each space were examined. The arterial relationships in the anterior incisural space and the venous relationships in the posterior incisural space are extremely complex, since the anterior incisural space contains all the components of the circle of Willis and the bifurcation of the internal carotid and basilar arteries, and the posterior incisural space contains the convergence of the internal cerebral and basal veins and many of their tributaries on the vein of Galen. The discussion reviews tentorial herniation and operative approaches to the incisura.
The surgical approaches to the cavernous sinus were examined in 50 adult cadaveric cavernous sinuses using magnification of X3 to X40. The following approaches were examined: 1) the superior intradural approach directed through a frontotemporal craniotomy and the roof of the cavernous sinus; 2) the superior intradural approach combined with an extradural approach for removing the anterior clinoid process and unroofing the optic canal and orbit; 3) the superomedial approach directed through a supraorbital craniotomy and subfrontal exposure to the wall of the sinus adjacent to the pituitary gland; 4) the lateral intradural approach directed below the temporal lobe to the lateral wall of the sinus; 5) the lateral extradural approach for exposure of the internal carotid artery in the floor of the middle cranial fossa proximal to the sinus; 6) the combined lateral and inferolateral approach, in which the infratemporal fossa was opened and the full course of the petrous carotid artery and the lateral wall of the sinus were exposed and; 7) the inferomedial approach, in which the medial wall of the sinus was exposed by the transnasal-transsphenoidal route. It was clear that a single approach was not capable of providing access to all parts of the sinus. The intracavernous structures best exposed by each route are reviewed. The osseous relationships in the region were examined in dry skulls. Anatomic variants important in exposing the cavernous sinus are reviewed.
The anatomy needed to plan microoperative approaches to the lateral ventricles was examined in 20 cadaveric cerebral hemispheres. The neural, arterial, and venous structures in the walls of the lateral ventricles and the relationship of the lateral ventricles to the third ventricle and basal cisterns were examined. The operative approaches to the lateral ventricle are reviewed.
BACKGROUND The subthalamic nucleus (STN), globus pallidus internus (GPi), and pedunculopontine nucleus (PPN) are effective targets for deep brain stimulation (DBS) in many pathological conditions. Previous literature has focused on appropriate stimulation targets and their relationships with functional neuroanatomic pathways; however, comprehensive anatomic dissections illustrating these nuclei and their connections are lacking. This information will provide insight into the anatomic basis of stimulation-induced DBS benefits and side effects. OBJECTIVE To combine advanced cadaveric dissection techniques and ultrahigh field magnetic resonance imaging (MRI) to explore the anatomy of the STN, GPi, and PPN with their associated fiber pathways. METHODS A total of 10 cadaveric human brains and 2 hemispheres of a cadaveric head were examined using fiber dissection techniques. The anatomic dissections were compared with 11.1 Tesla (T) structural MRI and 4.7 T MRI fiber tractography. RESULTS The extensive connections of the STN (caudate nucleus, putamen, medial frontal cortex, substantia innominata, substantia nigra, PPN, globus pallidus externus (GPe), GPi, olfactory tubercle, hypothalamus, and mammillary body) were demonstrated. The connections of GPi to the thalamus, substantia nigra, STN, amygdala, putamen, PPN, and GPe were also illustrated. The PPN was shown to connect to the STN and GPi anteriorly, to the cerebellum inferiorly, and to the substantia nigra anteriorly and superiorly. CONCLUSION This study demonstrates connections using combined anatomic microdissections, ultrahigh field MRI, and MRI tractography. The anatomic findings are analyzed in relation to various stimulation-induced clinical effects. Precise knowledge of neuroanatomy, anatomic relationships, and fiber connections of the STN, GPi, PPN will likely enable more effective targeting and improved DBS outcomes.
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