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.

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.

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.

Thickness-based correlations of cortical areas involved in senses, speech and cognitive processes

AIM: To explore the existence of potential correlations of cortical thickness between different functional brain areas.

METHODS: Our material consisted of 38 formalin-fixated human cerebral hemispheres from twenty males and three females, cadaver donors for students’ education. We selected the following cortical areas at each hemisphere to examine: supramarginal gyrus (S), angular gyrus (A), area of colors recognition (F), area of names recognition (N), area of auditory attention (H), area of place memory (M), cortex of the superior wall of the calcarine sulcus (V1) and cortex of the inferior wall of the calcarine sulcus (V2). We measured the thickness of each cortical area and statistically analyzed our data.

RESULTS: We found a significant difference of the mean value of the V1 (P < 0.05) between right and left hemispheres, as well as very significant correlations (P < 0.001) between the following cortical areas: N and F, A and F, S and F, A and S, A and N, S and N. We also found significant correlations (P < 0.01) between the following areas: S and M, S and H, N and H, as well as between the following areas (P < 0.05): V1 and V2, M and F, M and N, A and H.

CONCLUSION: Our results suggest that there could be a potentially stronger impact for objects placed in the left inferior quarter of the visual field. Our study revealed several thickness-based correlations among different functional cortical areas. Most of them seem to have a more or less rational explanation.

Human obturator nerve: Gross anatomy

AIM: To study the anatomy (formation, course, relationships and branching pattern) of the obturator nerve in detail.

METHODS: The study was based on 500 adult human formalin-embalmed cadavers, 342 males and 158 females. We studied the anatomical formation, course and relationships of the obturator nerve within the lesser pelvis before the obturator canal. Finally, the whole course of the obturator nerve was examined.

RESULTS: We found numerous anatomical variations about the formation of the obturator nerve, its division into two main branches, its articular branches, its intrapelvic branches for the periosteum of the pubic bone, and also the number of its muscular divisions and its anatomical relationship to the obturator externus muscle and obturator artery. We found that fibers from the L3 and L4 spinal nerves are standard components of the obturator nerve. The main trunk of the obturator nerve divides into anterior and posterior branches, within the pelvis in 23.30%, within the obturator canal in 52.30% and extrapelvic in 24.35% of cases. The anterior branch of the obturator nerve supplies three muscular branches in 67.10%, two muscular branches in 28.94% and four muscular branches in 3.94% of the cases. The posterior branch of the obturator nerve supplies two muscular branches in 60.52%, three muscular branches in 19.07%, one muscular branch in 14.47% and four muscular branches in 5.92% of cases.

CONCLUSION: We present a gross anatomical study of the human obturator nerve based on a remarkably large number of cases as well as potential clinical applications of our findings.

Anterior communicating artery aneurysm associated with duplicated hypoplastic right A1 segment

Variations of the anterior cerebral artery (ACA)-anterior communicating artery (ACoA) complex are commonly observed when associated with a symptomatic intracranial aneurysm. We report an asymptomatic ACoA aneurysm associated with duplicated hypoplastic A1 segment of the right ACA, observed in a 70-year-old female cadaver. Furthermore, the aneurysm, practically substituting the ACoA, caused a remarkable depression on the internal surface of the right frontal lobe, anterior to the optic chiasm. Aneurysms and other anomalies of the ACA and ACoA are common and their microvascular surgical management requires sound knowledge of the normal and variant vascular anatomy. Persistence of some embryonic vessels that normally disappear, disappearance of vessels that would normally persist or sprouting of new vessels due to hemodynamic and genetic factors are the usual causes for such anomalies. The high incidence of coexisting vascular anomalies and aneurysm suggests that such abnormalities predispose to aneurysm formation due to changes in the regional blood flow. A1 segment duplication has been reported to occur in 4% of subjects in cadaveric studies and in up to 0.5%-9.7% of cases of ACoA aneurysm surgery. Angiographic hypoplasias and aplasias of the A1 segment have been also correlated with ACoA aneurysm patients.

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.

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.

Idiopathic temporal bone encephalocele

Meningoencephaloceles are herniations of brain tissue through dehiscences of the skull base. These skull defects are either acquired (otologic infection, trauma, surgery, neoplasia) or spontaneous. Spontaneous temporal bone meningoencephaloceles are quite rare conditions, usually congenital in origin presenting during childhood, and only occasionally idiopathic presenting during adulthood. We present a case of temporal bone meningoencephalocele of adult onset. The patient was treated with exploratory mastoidectomy, amputation of the herniated cele and closure of the defect with temporalis fascia and an inferiorly based pedicled muscular flap. No reconstruction of the bony defect was performed, as the layered closure was considered adequate. Twelve months' follow-up revealed no relapse of the condition or postoperative complications.

High bifurcation of the brachial artery

Variations of the arterial pattern in the upper limb are quite common in humans. In the present study, we describe two cases of high bifurcation of the brachial artery. In the first cadaver both branches run superficially along the arm and were also located superficially at the antecubita fossa. In the second cadaver the branch that continues as the radial artery in the forearm run superficially and was located also superficially at the antecubita fossa, while the second branch had a more or less normal distribution. The embryological basis and clinical significance are discussed.

The safest electrode trajectory for deep brain stimulation of the human nucleus accumbens: a stereotactic anatomic study

BACKGROUND

The primary purpose of our stereotactic anatomic study was to determine the safest electrode trajectory for deep brain stimulation (DBS) of the human nucleus accumbens (NA). Considering NA DBS together with the complications related to surgical implantation and based on methods for assessing the electrode trajectory we tried to reveal the secret of a trajectory for targeting the NA with the highest possible level of safety.

MATERIAL AND METHODS

Our material consisted of 30 cerebral hemispheres we have in our Department from cadaver donors for students' education. We identified the electrode's target point in coronal sections. As safe we considered a trajectory from the cerebral cortex to the NA, which traverses the anterior limb of the internal capsule (AIC) without passing through either the caudate nucleus or putamen. We measured the minimum, maximum and safest coronal angles of the electrode trajectory (between the trajectory and the midline), as well as the AIC angle and width of the trajectory angle. We also measured trajectory projection length from the cerebral surface to the superior (d1) and inferior (d2) margins of the NA.

RESULTS

The safest trajectory angle for NA DBS was found to have a mean value of 29.10 degrees, ranging from 23.80 to 35.40 degrees. The mean AIC angle was 33.78 degrees. We found no statistically significant difference between right and left hemispheres and a strong statistical relation between the safest electrode trajectory and AIC angle. Mean values of d1 and d2 were found to be 53.57 mm and 60.86 mm respectively. The mean value of the length of the electrode trajectory in coronal projection within the NA (d2-d1) was found to be 7.29 mm.

CONCLUSION

The new knowledge that our stereotactic anatomic study offers is a definition of the safest electrode trajectory for NA DBS, its coronal angle width, as well as an estimation of its length.

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.

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.

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.

The human nucleus accumbens as a target for deep brain stimulation: anatomic study of electrode's target point and stereotactic coordinates

INTRODUCTION

The nucleus accumbens (NA), a "pleasure center", is the most inferior part of the ventral striatum. NA, related to the limbic and extrapyramidal motor system, is involved in some of the most common neuropsychiatric disorders. Nowadays it is a target for deep brain stimulation (DBS), in some carefully selected patients. Our purpose was to evaluate the accuracy of its position within the NA, in relation to the stereotactic target point that is today used.

METHODS AND MATERIALS

We identified, studying 25 cerebral hemispheres, the target point of the NA DBS electrode, at a specific level that is important for its imaging. We also identified the stereotactic coordinates of the NA and made a statistical analysis and comparisons.

RESULTS

We found that in 3 out of 25 cases, the used stereotactic coordinates fail to offer a target point within the limits of the NA.

DISCUSSION

We present the first stereotactic anatomic study evaluating the precise position where the electrode for human NA DBS is to be placed and the only anatomic study of the human NA performed on such a large number of cases. The stereotactic coordinates used for NA DBS are accurate. However, we suggest that the electrode's final position should be considered to be slightly less deep.

A rare variation of the axillary artery combined contralaterally with an unusual high origin of a superficial ulnar artery: description, review of the literature and embryological analysis

During anatomical dissection of a female Caucasian cadaver in our department we observed a combination of two rare arterial patterns of the upper limb bilaterally; a superficial ulnar artery of high origin in the right upper limb and some rare variations of the left axillary artery: Right arm: The superficial ulnar artery originated from the second part of the axillary artery, before the origin of the subscapular artery. It proceeded superficially in the forearm. The axillary artery continued normally in the arm as brachial artery, and finally divided into the radial and the common interosseous artery. The normal ulnar artery was absent. The presence of the superficial ulnar artery is a rare variation given that its total incidence ranges from 0.67% to 9.38%, with only 0.17% to 2% originating from the axillary artery. Left arm: The second part of the axillary artery gave rise to a first common trunk (named A), lying between the two roots of the median nerve, which divided in two new common trunks (B and C). One of these gave origin to the subscapular and the posterior circumflex humeral artery while the other gave rise to the anterior circumflex humeral artery, two muscle twigs and then continued as profunda brachii artery. The incidence of anatomic variations of the major arteries of the upper extremities ranges from 11% to 24%. Nevertheless a pattern with three common trunks comprising the origin of the profunda brachii has not yet been cited in the literature.

Eagle's syndrome: a review of the literature

Eagle's syndrome represents symptoms brought on by compression of regional structures by elongation of the styloid process or ossification of the stylohyoid or stylomandibular ligaments. Watt Eagle described it for the first time in 1937, dividing it into two subtypes: the "classic syndrome" and the "stylo-carotid artery syndrome." Many theories have been put forth regarding its pathogenesis. Depending on the underlying pathogenetic mechanism and the anatomical structures compressed or irritated by the styloid process, symptoms vary greatly, ranging from cervicofacial pain to cerebral ischemia. The syndrome generally follows tonsillectomy or trauma. Diagnosis is confirmed by radiological findings. Palpation of the styloid process in the tonsillar fossa and infiltration with anesthesia are also used in making the diagnosis. The treatment is primarily surgical; however, some conservative treatments have also been used. The current literature on Eagle's syndrome is reviewed, highlighting its often underestimated frequency and its clinical importance.

Sectioning of filum terminale externum using a rigid endoscope through the sacral hiatus. Cadaver study

AIM

Tethered cord syndrome (TCS) is a stretch-induced functional disorder of the spinal cord, which is directly related to filum fixation. Classic surgical approaches to the filum involve open surgery and include varying amounts of spinal bone removal. In an effort to reduce the morbidity and mortality of these procedures, the authors explored a less invasive method. They evaluated the ability, safety and feasibility for endoscopic sectioning of the filum terminale externum by performing upward orientated navigation in the extradural sacral spinal canal through the sacral hiatus using a rigid endoscope.

METHODS

Four adult, phenol-formalin embalmed cadavers were used for endoscopic section of the filum terminale externum at the tip of thecal sac. After preparing the anatomical area of sacral hiatus, a rigid endoscope (Storz, of 3.8 mm external diameter with two working channels, of 1 mm each, one for suction-irrigation and one as working) was inserted into the extradural sacral spinal canal and the filum terminale externum was identified and cut easily at the distal end of thecal sac at the level of S2. In all cases, it was possible to manipulate the rigid endoscope and inspect the full length of the extradural sacral spinal canal, especially at the S1-S2 level.

RESULTS

The results indicate that the tested transhiatal approach for upward orientated extradural endoscopy represents a minimally invasive procedure that provides an appropriate and feasible route to the extradural sacral spinal canal.

CONCLUSION

Such approach is an attractive alternative for filum terminale externum sectioning in cases where tethered cord syndrome is not accompanied by any other pathology. Moreover if filum terminale internum sectiong is indicated, it can be performed in second stage.

Bilateral fistulas: a rare cause of chest pain. Case report with literature review

A coronary artery fistula is a direct communication between a coronary artery and one of the cardiac chambers or vessels around the heart. These fistulas are usually diagnosed by coronary arteriography. Clinical presentations are variable depending on the type of fistula, shunt volume, site of the shunt, and presence of other cardiac conditions. Bilateral coronary fistulas between coronary arteries and the pulmonary artery are very rare. This report describes a 51-year-old man without any previous medical history, who presented to our hospital one hour after the acute onset of severe substernal chest pain associated with shortness of breath and nausea. Coronary angiography revealed two fistulas arising from the left anterior descending and right coronary arteries and draining at exactly the same site in the pulmonary artery. There was no evidence of atherosclerotic coronary artery disease in either the left or right coronary arterial tree.

Dolichoectatic Cervical Arteries (Carotid and Vertebral Arteries) Heralded by Recurrent Cerebral Ischemia: Case Illustration

A case of a 61-year-old man with recurrent episodes of cerebral transient ischemic attacks is reported. The patient had a history of cigarette smoking, hypertension, hypercholesterolemia, and diabetes mellitus. Before these episodes, the patient had no clinical symptoms and signs of cerebral pathology. Brain magnetic resonance imaging revealed microvascular lesions in the white matter of the cerebral hemispheres. Digital subtraction arteriogram revealed the aortic arch dolichoic shape and course of the great vessels originating from it, whereas there were no pathological findings from the intracranial vessels. This study describes a case of the existence of distal dolichoectasia of the vertebral and carotid arteries without intracranial dolichoectasia. It seems that such a type of dolichoectasia does not influence the performance status of a patient, but when a critical point is crossed, patients suffer from cerebrovascular disease.

Middle cranial fossa endoscopy using a rigid endoscope

Trigeminal neuralgia (TN), also known as tic douloureaux, is a craniofacial pain disorder which is typically associated with acute-onset severe pain on one side of the face usually. The condition is characterized by intermittent unilateral pain affecting the lower face and jaw. Although many potential causes have been implicated, in many patients the etiology remains obscure. Initially, patients with trigeminal neuralgia should be offered conservative medical management. If surgery is necessary, the simplest and least hazardous procedure should be chosen. The goals of modern surgical therapy are: Long-term pain control, minimal to no morbidity, and as low a mortality risk as possible. In this study, we attempted to perform middle cranial fossa endoscopic exploration in four adult phenol-formalin embalmed cadavers, using a rigid endoscope with 3.8 mm external diameter and two working channels of 1 mm in diameter each (Karl Storz, Tuttlingen, Germany), inserted through a burr-hole centered at the base of the middle cranial fossa, 1 cm in front and 1 cm upwards of the tragus. Our objective was to determine if this approach provides adequate access to the trigeminal ganglion for possible dissection of V2 and V3 trigeminal roots, the two typically radiating sites of TN. In all four cadavers, middle cranial fossa exploration was possible without difficulties. We offer this approach as a minimally invasive surgical procedure to access the trigeminal ganglion, for potential use as another alternative for the surgical management of medically refractory trigeminal neuralgia.

Endoscopic anatomy of the thecal sac using a flexible steerable endoscope

In this study the ability for upward-orientated endoscopic visualization of thecal subarachnoid space using a flexible steerable endoscope was evaluated in order to compare endoscopic anatomical findings with the already known macroscopic ones of the incontained structures and to test the approach for clinical employment. For this purpose, four adult phenol-formalin embalmed cadavers were used and the approach selected was through a laminectomy window at the S1-S2 level. The dura mater was opened and a flexible steerable endoscope (Storz, of 2.8 mm external diameter with one working channel) was inserted subarachnoidally for upward-orientated observation of the content of thecal sac. By using this approach filum terminale, lower lumbar, sacral and coccygeal nerve rootlets were identified and observed in detail. By moving the endoscope even more upwards, inspection of the upper part of the thecal subarachnoid space and conus medullaris was also possible. The findings collected from the study indicate that this approach for upward-orientated intradural subarachnoid endoscopy gives an appropriate working and inspecting window to the lower, as well as to the upper part of the thecal subarachnoid space and even of the conus medullaris. Furthermore, inspection and identification of lower lumbar, sacral and coccygeal nerve rootlets is possible and efficient and the endoscopic anatomical observations coincide with the already known gross-anatomical ones.

Temporal bone study of development of the organ of Corti: correlation between auditory function and anatomical structure

OBJECTIVE

To study the development of the organ of Corti in the human cochlea, and to correlate our findings with the onset of auditory function.

MATERIAL AND METHODS

Step sections of 81 human fetal temporal bones were studied, from eight weeks of gestation to full term.

RESULTS

By the end of the 10th week, the tectorial membrane primordium could be traced even in the most apical turns. Individual hair cells became identifiable at the basal turn at 14 weeks. At the same time, a small but well formed oval space was observed between the inner and outer hair cells in the basal turn. This does not correspond to the tunnel of Corti, as is erroneously quoted in the literature, as the individual pillar cells develop at later stages. Between 14 and 15 weeks, Hensen's cells were recognised for the first time. Individual pillar cells were identifiable at 17 weeks and the tunnel of Corti opened at 20 weeks. By 25 weeks, the cochlea had reached its adult size, but continued to develop until full term.

DISCUSSION AND CONCLUSIONS

A temporal coincidence of different developmental events is responsible for early fetal audition at 20 weeks, including growth of pillar cells, opening of the tunnel of Corti and regression of Kollicker's organ, with the subsequent formation of the inner spiral sulcus and then separation of the tectorial membrane. The fine structures of the organ of Corti continue to develop well after the 25th week, and this may well alter the mechanical properties of the vibrating parts of the cochlea, which may in turn account for the frequency shift observed in preterm infants. These changes will have to be taken into account in the development of prenatal hearing screening tests.

Anomalous origin of circumflex artery from right sinus of Valsalva: a rare cause of non-ST elevation syndrome

We present a case with anomalous origin of the left circumflex artery from the right coronary artery ostium, which caused a non-ST elevation coronary syndrome. A review of the literature indicates this to be an extremely rare case.

14C-Lidocaine Disposition in Serum and Tissues of Normal and Liver Diseased Rats

PURPOSE

This study was designed to investigate the disposition of (14)C-lidocaine in serum and tissues in rats with liver dysfunction.

MATERIALS AND METHODS

Eighteen male rats were randomly divided into 2 groups. Group A was considered as control while group B underwent liver damage by administrating CCl(4) 0.4 mg/kg twice a week for 6 weeks. Both groups received 5 doses of 2.5 mg/kg lidocaine mixture (labeled (14)C-lidocaine and nonlabeled). The rats were killed 2 hours after the last dose. Total lidocaine levels ((14)C-lidocaine and (14)C-lidocaine metabolite concentrations) as well as the percent of total lidocaine-bound fractions in tissues were measured.

RESULTS

(14)C-lidocaine concentrations were significantly increased in the serum (9.4+/-0.4 microg/mL), heart (7.8+/-2 microg/gL), and mandible (0.97+/-0.01 microg/g) in diseased rats as compared with normal rats (serum, 5.3+/-1.7 microg/mL; heart, 4.2+/-0.9 microg/g; mandible, 0.68+/-0.02 microg/g, respectively). (14)C-lidocaine bound fractions in the mandible and heart did not show any significant differences between the 2 groups. Instead, (14)C-lidocaine bound fractions in serum were significantly reduced in diseased animals as opposed to normal ones.

CONCLUSION

We concluded that liver dysfunction can modify (14)C-lidocaine concentrations in the serum and tissues without altering the lidocaine binding properties in the mandible and heart.