Stereotactic Localization of the Monro Foramen and the Safest Stereotactic Interforniceal Approach to the Third Ventricle: A Neuroanatomical Study.

BACKGROUND AND OBJECTIVE: To localize the human foramen of Monro stereotactically, to define the anatomical parameters of the safest stereotactic transcallosal transseptal interforniceal approach to the third ventricle, and to show how neurosurgeons could use them in preoperative planning. MATERIAL AND METHODS: Our material consisted of 44 formalin-fixated human cerebral hemispheres. We found the location of the anterior (AC) and posterior commissure at the internal hemispheric surface. The posterosuperior border of the AC (point A) was our stereotactic reference point with coordinates (X, Y, Z) = (0, 0, 0). We found the Monro foramen location and measured the stereotactic coordinates of its anterior inferior border (point B). The safest trajectory to the third ventricle has to pass as far as possible from points A and B so as not to traumatize the choroid plexus of the Monro foramina or the AC. The midpoint of the AB distance (point M) is the stereotactic point that provides this safest trajectory. We also measured AB length and point M stereotactic coordinates. RESULTS: Mean stereotactic coordinates of the (midline projection of the) point B were (X, Y, Z) = (0, -0.6, 2.4). Point B was located averagely 3.2 mm far from point A. Mean stereotactic coordinates of the point M, a necessary component of the trajectory of the safest stereotactic interforniceal approach to the third ventricle, were (X, Y, Z) = (0, -0.3, 1.2). Point M was located 1.6 mm far from point A. CONCLUSIONS: The present study shows how neurosurgeons can localize and use crucial anatomical landmarks, namely the AC and foramen of Monro, to approach the third ventricle safely via a stereotactic interforniceal technique. This can be achieved during preoperative planning with simple identification of stereotactic points A, B, and M on preoperative median sagittal magnetic resonance images.

Bilateral asymmetry of the highly bifurcated brachial artery variation.

High bifurcation of the brachial artery seems to be a common variation, which can occur in many different forms, and some of them might be rather rare. We report an unusual case of bilateral high bifurcation of the brachial artery in a male cadaver. On the right arm, high origin of the ulnar artery as superficial ulnar artery was observed. The brachial artery continued and divided at the level of the elbow into radial and common interosseous artery. On the left arm, a high bifurcation of the common interosseous artery occurred, while the rest of the brachial artery continued and at the level of the elbow bifurcated into radial and superficial ulnar artery. In both arms, the common interosseous artery followed the branching pattern of the normal ulnar artery. The so formed superficial ulnar arteries gave each four common palmar digital arteries. This case is being reported for the bilaterally different variational anatomy of the upper limb arteries.

Stereotactic anatomy of the human subthalamic nucleus: providing coordinates for accurate electrode placement.

BACKGROUND AND STUDY AIMS: Stereotactic targeting of the subthalamic nucleus (STN) for insertion of deep brain stimulation (DBS) electrodes became popular in the last two decades. We present a study focused on the detailed stereotactic anatomy of the STN with respect to its targeting. MATERIAL AND METHODS: We used cerebral magnetic resonance (MR) images from 26 patients (50 STNs) for the imaging study. The material of the anatomical study consisted of 24 cerebral hemispheres (24 STNs) from 16 normal human brains. We measured and analyzed the X, X', Y, Y', and Z, Z' stereotactic coordinates of the STN at specific clinically important transverse, coronal, and sagittal planes. RESULTS: The STN extended almost 1.5 mm more lateral and almost 1 mm more posterior in patients < 60 years of age. The Y coordinate was more posterior and the X coordinate more lateral on MRI than in anatomical specimens. The left STN was located more lateral than the right STN. Analyzing our data we found a standard coronal zone 1.1 mm wide (zone T), a standard coronal plane (thus providing the most accurate Y target coordinate, plane M), and a standard transverse area (area C) for accurate right STN targeting. CONCLUSIONS: Our study offers new insights into the stereotactic anatomy of the human STN. These data should be taken into account if performing STN DBS.

Emerging patterns of the human superior thyroid artery and review of its clinical anatomy.

PURPOSE: There is wide variability of the location of the superior thyroid artery (STA). Our purpose was to describe variations of the STA origin, with great respect to different anatomical patterns which could be observed in humans. METHODS: The material was 68 formalin-embalmed adult cadavers of both sexes (45-70-year-old). Methodologically, we dissected the neck region bilaterally and focused on studying the external carotid artery (ECA) branches, especially the STA emerging pattern. We also measured the distance of the STA origin from the common carotid artery (CCA) bifurcation (using the latter as a landmark). RESULTS: Based on our results we categorized the STA emerging pattern into three major types A, B and C according to its origin (which was CCA, ECA and CCA bifurcation, respectively). Regarding type B, we found that the left STA arises approximately 2 mm closer to the CCA bifurcation compared to the right STA (p < 0.05). CONCLUSIONS: The STA is a carotid branch with variable origin, which can be CCA, ECA or CCA bifurcation. It is also an artery of great clinical importance in head and neck surgery. The present study provided data of the STA emerging patterns, as well as a review of its clinical anatomy.

Achilles' death: anatomical considerations regarding the most famous trauma of the Trojan War.

In Greek mythology, Achilles was a hero of the Trojan War, the central character and greatest warrior of Homer's Iliad. As Achilles died because of a small wound on his heel, the term "Achilles' heel" has come to mean a person's principal weakness. But is the human heel a really vulnerable part of our body? Could a non-poisonous arrow have caused Achilles' death? Should an arrow be necessarily poisonous in order to cause a lethal heel would? The purpose of this effort is to explain, from an anatomic point of view, how Achilles heel wounding could have led to his death. The Achilles tendon is the strongest, largest and thickest tendon in the human body and plays an important role in the biomechanics of the lower extremity. The blood supply of the tendon is from the peroneal and posterior tibial arteries. It is quite likely that the arrow which killed Achilles was poisoned. This supposition could be of course enough to cause his death. In case the arrow was not poisoned a rupture of the posterior tibial artery by the arrow could have caused a bleeding, but it seems unlikely for such a bleeding to be lethal. Moreover, a combination of these two theories could have also taken place, i.e. a poisoned arrow traumatizing the posterior tibial artery and hence causing rapid diffusion of the poison as well as bleeding. Furthermore, infectious and/or immunologic bases regarding Achilles' death could be considered. In our opinion, a poisoned arrow was probably the crucial factor leading to the famous inglorious death of this famous glorious Homeric hero.

Absent falx cerebelli: report of a rare case.

The falx cerebelli is a small crescentic fold of dura mater below the tentorium cerebelli, which projects forward into the posterior cerebellar notch. Its base is directed upwards and attached to the posterior part of the inferior surface of the tentorium cerebelli in the midline; its posterior margin is attached to the internal occipital crest and contains the occipital sinus; the apex frequently dividing into two small folds which disappear at the sides of the foramen magnum. The material of our neuroanatomic study consisted of formalin-embalmed cadavers that we had in the dissection room of our Department from cadaver donors for students education. We report a case of absence of this dura mater structure from a 91-year-old female cadaver. To our knowledge, this is the first report of absent falx cerebelli in a normal human brain. The review of the literature revealed a few reports of its multiplication.

Variations of the attachment of the superior head of human lateral pterygoid muscle.

INTRODUCTION: The superior head of the lateral pterygoid muscle (LPM), is closely related to the temporomandibular joint (TMJ) and plays a role in the aetiology of temporomandibular disorders. Increased activity of this muscle has been implicated in the anterior displacement of the TMJ disc. However, there is uncertainty about the manner of the LPM attachment to the disc-condyle complex. AIM: The aim of this study was to investigate the exact anatomy of the attachment of the superior head of the LPM (SLPM) to the disc-condyle complex of the TMJ. MATERIAL AND METHODS: Thirty-six TMJs were examined - both sides of 18 Greek cadavers (eight males and 10 females, mean age 79.6 years). Examination of the attachment of the SLPM was undertaken viewed under the dissecting microscope. RESULTS: Variation in the attachment of the SLPM was categorized into three types: in type I, the SLPM inserted into the condyle and the disc-capsule complex (55.5%). In type II, the SLPM only inserted into the condyle (27.8%). In type III, the SLPM inserted purely into the disc-capsule complex (16.7%). CONCLUSIONS: This study demonstrates that there are three different attachment types of the SLPM to the disc-condyle complex. The type III variation could be involved in the TMJ pathology. The knowledge of the variations of the SLPM attachment could be useful for precise surgical and pharmaceutical approaches.

Anatomy of the human subthalamic nucleus: a combined morphometric study.

Purpose. Our purpose was to provide a combined clinically oriented study focused on the detailed anatomy of the human STN, with great respect to its targeting. Methods. For our imaging study, we used cerebral magnetic resonance images (MRIs) from 26 neurosurgical patients and for our anatomic study 32 cerebral hemispheres from 18 normal brains from cadaver donors. We measured and analyzed the STN dimensions (based on its stereotactic coordinates). Results. At stereotactic level Z = -4, the STN length was 7.7 mm on MRIs and 8.1 mm in anatomic specimens. Its width was 6 mm on MRIs and 6.3 mm in anatomic specimens. The STN was averagely visible in 3.2 transverse MRI slices and its maximum dimension was 8.5 mm. The intercommissural distance was 26.3 mm on MRIs and 27.3 mm in anatomic specimens. We found statistically significant difference of the STN width and length between individuals <60 and ≥60 years old. Conclusion. The identification of the STN limits was easier in anatomic specimens than on MRIs and easier on T2 compared to T1-weighted MRIs sections. STN dimensions appear slightly smaller on MRIs. Younger people have wider and longer STN.

Anatomical variation and morphology in the position of the palatine foramina in adult human skulls from Greece.

OBJECTIVE: To investigate the anatomical variability of the palatine structures in Greek population. MATERIAL AND METHODS: 71 Greek adult dry human skulls were examined to detect the position of the greater palatine (GPF) and lesser palatine foramina (LPF) related to adjacent anatomical landmarks. RESULTS: The perpendicular distance of the GPF to the midline sagittal suture was 1.53 cm and 0.3 cm from the inner border of the alveolar ridge. The mean distance from the posterior palatal border was consistent 0.46 cm on the right and 0.47 cm on the left side of the skulls. In the greater majority of the skulls (76.2%), the GPF were between proximal-distal surfaces of the 3rd maxillary molar. A single LPF was observed in 53.45% of the skulls, two LPF were observed in 31% of the skulls bilaterally and five LPF were rare (2.1%). The commonest position of LPF was at the junction of the palatine bone and the inner lamella of the pterygoid plate (71.9%). CONCLUSION: Our results can help clinicians localize the palatine foramina in patients with and without maxillary molars and to predict the depth of a needle to anaesthetise the maxillary nerve with greater success when performing surgical procedures in the hard and soft palate.

The human nucleus accumbens suffers parkinsonism-related shrinkage: a novel finding.

PURPOSE: The human nucleus accumbens (NA) plays an important role in motivation and emotional processes and is involved in some of the most disabling neuropsychiatric disorders such as Parkinson's disease (PD). The purpose of our study was to check out the potential existence of a statistically significant difference in NA size between parkinsonian and non-parkinsonian individuals, through studying brain magnetic resonance images (MRIs). METHODS: For our study we used 52 NAs from 26 cerebral MRIs from neurosurgical patients. Of these MRIs, 15 were preoperative from patients with advanced PD who underwent bilateral deep brain stimulation of the subthalamic nucleus. The group of non-parkinsonian MRIs came from the rest 11 individuals. We measured the absolute and relative NA maximum transverse diameter (D (max)), and absolute and relative NA width at a specific transverse plane. RESULTS: We found a statistically significant difference of the mean value of the D (max) (absolute and relative) between the two groups. The mean percentage reduction of the NA size was 11.77% represented by the relative D (max). CONCLUSIONS: To our knowledge, this is the first report of parkinsonism-related shrinkage of the human NA. Further research is needed to identify whether a respective shrinkage is also observed in patients with early PD and whether this atrophy is correlated with dopaminergic neuropsychiatric symptoms (perhaps mediated by a malfunctioning NA) that occur in PD.

Stereotactic anatomy of the human nucleus accumbens: from applied mathematics to microsurgical accuracy.

PURPOSE: Stereotactic surgery of the human NA is a neurosurgical achievement of the twenty-first century. Our purpose was to provide a clinically oriented study focused on the detailed stereotactic anatomy of the NA, with great respect to its targeting. We tried to offer a guide of NA stereotactic targeting for neurosurgeons. METHODS: For our imaging study, we used cerebral magnetic resonance images (MRIs) from 26 neurosurgical patients (52 NAs). The material of our anatomic study consisted of 32 cerebral hemispheres (32 NAs) from 18 normal human brains, which we have in our Department (Department of Anatomy) from cadaver donors. We measured and analyzed the X, X', Y, Y', Z, Z' stereotactic coordinates of the NA at specific clinically important transverse, coronal and sagittal levels. RESULTS: Our principal findings contain a probability-based guide for in vivo (side depended) stereotactic localization of the human NA, a standard for the NA, specific stereotactic zone of the human brain (Z = -4), two specific standard NA areas (X = 7, X = 8) and the most reliable stereotactically standard area of the human NA (Y = 2). CONCLUSIONS: We provide a stereotactic anatomic guide for some common targeting necessities of the NA stereotactic surgery, resulted from detailed analysis and careful combination of the measured data of our clinically oriented study. We hope that our work will be a really useful guide for neurosurgeons applying deep brain stimulation of the NA.

Anatomy of the human nucleus accumbens: a combined morphometric study.

PURPOSE: The human nucleus accumbens (NA), which belongs to the basal ganglia of the brain, is the main part of the ventral striatum. The purpose of our clinically oriented anatomical-radiologic study was to provide anatomical and imaging data of the human NA, primarily useful to neurosurgeons. METHODS: For our imaging study, we used cerebral magnetic resonance images (MRIs) from 26 neurosurgical patients (52 NAs). The material for our anatomic study consisted of 32 cerebral hemispheres (32 NAs) from 18 normal human brains which we have in our department (Department of Anatomy) from cadaver donors. We measured and analyzed the dimensions of the NA at specific clinically important transverse, coronal and sagittal levels. RESULTS: The human NA suffers from age-related but no side- or sex-related morphometric changes. In surgically important stereotactic levels this nucleus is easily identifiable on MRIs. CONCLUSIONS: We present an anatomic guide of the NA from carefully measured data of our extensive and combined study and we hope that our work will be really helpful to neuroscientists interested in the NA.

Exploring the neurosurgical anatomy of the human insula: a combined and comparative anatomic-radiologic study.

PURPOSE: The human insula constitutes the invaginated portion of the cerebral cortex and is less well understood than other cortical areas because of its hidden location. Our purpose was to study the neurosurgical anatomy of the human insula via a combined and comparative study of its gross and imaging anatomy. METHODS: We totally studied the anatomy of 148 normal insulae in anatomic specimens and radiologic images. We evaluated the number of all insular gyri (short and long), we statistically analyzed our results, and we made comparisons among hemispheres and gender. We also compared the two studies. Finally, we searched in the literature to make comparisons with other authors and to add our experience to the today existing knowledge of the insular anatomy. RESULTS: We found a significantly greater value of the insular gyri number for males, potential underestimation of the real insular gyri number by MRI and that the classic insular gyri pattern can rarely be absent. The middle short insular gyrus can be indistinguishable more likely on MRIs than during surgery, the long insular gyri are less curved than the short gyri, and finally, the insular perforating vessels usually originate at the inferior insular part. CONCLUSIONS: Deep knowledge of the gross, imaging, and surgical anatomy of the insula is of paramount importance for neurosurgeons dealing with disorders in this area. The male insula is larger (increased gyri pattern) than the female. Moreover, the classic insular gyri pattern can rarely be absent, probably as a normal anatomic variation.

Thoracic paravertebral spread using two different ultrasound-guided intercostal injection techniques in human cadavers.

The continuity between the intercostal and paravertebral space has been established by several studies. In this study, the paravertebral spread of a colored dye was attempted with two different ultrasound-guided techniques. The posterior area of the trunk was scanned with a linear probe between the level of the fifth and the seventh thoracic vertebrae in eleven embalmed human cadavers. In the first technique, the probe was placed transversely below the inferior margin of the rib, and a needle was inserted between the internal intercostal membrane and the pleura. In the second technique, the probe was placed longitudinally at the intercostal space 5 cm lateral to the spinous processes, and the needle was inserted between the internal intercostal membrane and the pleura. In both techniques, 1 ml of methylene blue was injected, and both the intercostal and paravertebral spaces were prepared. In total, 33 injections were performed: 19 with the transverse technique and 14 with the longitudinal technique. Successful spread of the dye to the thoracic paravertebral space was recorded in 89.5% cases using the transverse technique and 92.8% cases using the longitudinal technique. No intrapleural spread of the dye was recorded in either technique. Ultrasound-guided injection into the intercostal space may offer an alternative approach to the thoracic paravertebral space.