Intracranial primary synovial sarcoma mimicking a spontaneous cerebral hematoma-a case report and review of the literature

BACKGROUND

Synovial sarcoma is a soft tissue sarcoma, of uncertain histological origin, usually located near large joints and concerning mainly young adults. Intracranial presentation in the form of metastasis from a primitive body sarcoma has been rarely reported. However, intracranial primitive synovial sarcoma (IPSS) is extremely rare and only a few cases have been reported in the literature.

CASE DESCRIPTION

We present the case of a 48-year-old man, with no particular medical history, that was referred to our hospital for severe headache with a normal neurological exam and a CT cerebral scan showing a left frontal lobe hematoma. The initial cerebral CT scan didn't show any vascular malformation and the body CT scan was negative for a primitive lesion. A close follow-up with a cerebral MRI three months later, demonstrated a T1 enhanced lesion with an important volume progression. The patient underwent a complete surgical removal of this lesion and the first pathology diagnosis was compatible with a meningioma. After further proofreading by an expert and molecular analysis, the diagnosis of monophasic synovial sarcoma was confirmed. Nine months after the first surgery, the follow-up MRI showed the progressive recurrence of the lesion and in this context the patient underwent a second surgery with total resection of the tumor and frontal thin margin excision. Afterwards, the patient was treated with adjuvant radiotherapy, with a good clinical evolution, and till now the follow-up shows no recurrence.

CONCLUSION

IPSS is an extremely rare sarcoma, with challenging diagnosis and difficult management. Specific molecular analysis is necessary. Complete resection followed by radiotherapy seem to be the most appropriate therapeutic approach. However, the prognosis is still poor. Our case is even rarer because of the initial presentation as a cerebral hematoma.

Long term surgical results of 154 petroclival meningiomas: A retrospective multicenter study

BACKGROUND

Outcomes of petroclival meningiomas (PCM) (morbidity, permanent cranial nerves deficit, tumor removal and recurrence) are inconsistent in the literature, making it a challenge to predict surgical morbidity.

METHODS

A multicenter study of patients with PCMs larger than 2.5cm between 1984 and 2017 was conducted. The authors retrospectively reviewed the patients' medical records, imaging studies and pathology reports to analyze presentation, surgical approach, neurological outcomes, complications, recurrence rates and predictive factors.

RESULTS

There were 154 patients. The follow-up was 76.8 months on average (range 8-380 months). Gross total resection (GTR) was achieved in 40 (26.0%) patients, subtotal resection (STR) in 101 (65.6%), and partial resection in 13 (8.3%). Six (2.6%) perioperative deaths occurred. The 5-year, 10-year and 15-year progression-free survival (PFS) of GTR and STR with radiation therapy (RT) was similar (100%, 90% and 75%). PFS of STR without adjuvant radiation was associated with progression in 71%, 51% and 31%, respectively. Anterior petrosectomy and combined petrosectomy were associated with higher postoperative CN V and CN VI deficits compared to the retrosigmoid approach. The latter had a significantly higher risk of CN VII, CN VIII and LCN deficit. Temporal lobe dysfunction (seizure and aphasia) were significantly associated with the anterior petrosectomy approach.

CONCLUSIONS

Our study shows that optimal subtotal resection of PCMs associated with postoperative RT or stereotactic radiosurgery results in long-term tumor control to equivalent radical surgery. Case selection and appropriate intraoperative judgement are required to reduce the morbidity.

From Vesalius to tractography

The description of an anatomical specimen may look straightforward, but it appears that it depends in fact on several intermingled factors: technical methods for conservation, dissection and vascular injection and the anatomist skills are of course important. This is especially true when the studied organ, as for instance the brain, is subject to rapid putrefaction after death without any preservation technique. Nevertheless the possibility to reject, or at least criticize, the dominant paradigm is probably as important as these technical considerations: important changes occurred in brain representation between the early Middle Ages and the Early Modern Times, without major improvements of cadaveric preservation or dissection methods; Vesalius rejected the existence of the rete mirabile in human not only because he was a talented anatomist but also because he accepted and had the courage to fight the dominant tradition inherited from Galen. Such difficulties in the scientific approach obviously remain vivid, and should not be forgotten despite the development of modern tools for studying brain morphology and function.

Anterior fossa schwannoma mimicking an olfactory groove meningioma: case report and literature review

Intracranial schwannomas not associated with cranial nerves account for less than 1% of surgically treated schwannomas of the central and peripheral nervous system. With only 45 cases reported to date, subfrontal schwannomas are very rare tumors, leaving the issue of their origin controversial. A 66-year-old woman presented with a 1-year history of progressive headaches. Clinical examination revealed hypoesthesia of the nasal tip. CT-scan and MRI studies revealed a large subfrontal tumor thought preoperatively to be a meningioma. Intraoperatively, a large extra-axial tumor arising from the floor of the right frontal fossa was encountered. Histopathology identified the tumor as a schwannoma. This current case gives strong clinical presumption of an origin from the anterior ethmoidal nerve. We reviewed the literature in order to establish the epidemiology of these tumors, from which there appear to be divergent profiles depending on tumor origin and histology. Despite close similarities with olfactory groove meningiomas, patient history and radiological findings provide substantial evidence for differential diagnosis.

The choroidal fissure: anatomy and surgical implications

The choroidal fissure (CF) is an important landmark that allows approaches to the deepest aspects of the brain. It is the C-shaped site of attachment of the choroid plexus in the lateral ventricles, which runs between fornix and thalamus. The thinness and the absence of neural tissue between the ependyma and pia matter of this part of the medial wall of the lateral ventricles provides a surgical pathway to the third ventricle and perimesencephalic cisterns. A precise knowledge of the microsurgical anatomy of the region, particularly vascular relationships, is essential to consider surgery through the CF. We decided to present the anatomy of the CF in three distinct chapters, corresponding to three compartments of the C-shaped structure of the CF. In each compartment - rostral, dorsal and caudal - we developed the neurovascular anatomy and then discussed the clinical and surgical applications.

Cemento-ossifying fibroma involving paranasal sinuses and skull base

INTRODUCTION

Ossifying fibroma is a rare benign fibro-osseous lesion that usually affects mandible and maxillary bone. Their localisation to paranasal sinus and skull base is uncommon.

MATERIAL AND METHOD

We report a huge recurrence of ossifying fibroma of the ethmoid paranasal sinus involving the skull base.

CASE REPORT

Ten years after the removal of ossifying of the ethmoid 34 year old man presented headache with diplopia. Computed tomography (CT) and magnetic resonance imagery (MRI) showed a recurrent tumour witch extended to the nasal cavity, the sphenoid and the posterior ethmoid sinuses, and the skull base. The tumour was totally removed using an anterior subcranial approach with removal of the orbital rim. Histopathology confirmed an ossifying fibroma. Two years later a subdural empyema with frontal suppuration necessited to remove the frontal bone flap, which was re-constructed 12 months later using a synthetic material.

CONCLUSION

Ossifying fibroma is a rare, benign tumour witch may recur if incomplete resection is performed. A long follow up with CT scan and MRI is required.

The dural sheath of the optic nerve: descriptive anatomy and surgical applications

The aim of this work was to clarify the descriptive anatomy of the optic dural sheath using microanatomical dissections on cadavers. The orbit is the rostral part of the extradural neural axis compartment; the optic dural sheath forms the central portion of the orbit.In order to describe this specific anatomy, we carefully dissected 5 cadaveric heads (10 orbits) up to the meningeal structure of the orbit and its contents. 1 cadaveric head was reserved for electron microscopy to add to our knowledge of the collagen structure of the optic dural sheath.In this chapter, we describe the anatomy of the interperiostal-dural concept and the anatomy of the orbit. The optic dural sheath contains three portions: the intracranial, the intracanalicular and the intraorbital segment. Each one has specific anatomic relations which result in particular surgical considerations.

A cultivation technique for E. coli fed-batch cultivations operating close to the maximum oxygen transfer capacity of the reactor

A cultivation strategy combining the advantages of temperature-limited fed-batch and probing feeding control is presented. The technique was evaluated in fed-batch cultivations with E. coli BL21(DE3) producing xylanase in a 3 liter bioreactor. A 20% increase in cell mass was achieved and the usual decrease in specific enzyme activity normally observed during the late production phase was diminished with the new technique. The method was further tested by growing E. coli W3110 in a larger bioreactor (50 l). It is a suitable cultivation technique when the O2 transfer capacity of the reactor is reached and it is desired to continue to produce the recombinant protein.

[Duplication of the inferior vena cava: anatomical dissection and clinical implications]

The duplication of the inferior vena cava is often incidentally discovered during radiological studies. The presence of this anomaly can be mistaken for retroperitoneal adenopathy. Its knowledge allows to avoid hemorrhagic complications during retroperitoneal surgery. An anatomical dissection of a duplication of the inferior vena cava is presented. Embryogenesis and variations are described. Radiological and clinical implications are discussed.

The persistent left superior vena cava: anatomical study, pathogenesis and clinical considerations

The persistence of a left superior vena cava (LSVC) is an intrinsically cardiac anomaly, which can lead to serious complications during catheterization via the subclavian or internal jugular vein. We found this anomaly during dissection associated with an abnormal origin of the vertebral artery originating from the aortic arch between the left common carotid and subclavian arteries. The LSVC coursed towards the right atrium through a very dilated coronary sinus ostium. No abnormality of the azygos system was found. A thorough anatomic description was then made with external and internal morphology. The embryonic development and variations are described. Radiological and clinical implications are discussed.

Intra-operative mapping of the subcortical visual pathways using direct electrical stimulations

Despite the risk of postoperative visual field defect following surgery within the temporo-parieto-occipital region, visual mapping has rarely been described, in particular at the subcortical level. In this report, we successfully performed a subcortical mapping of the visual pathways using intra-operative electrical stimulations (IES), during surgery under local anesthesia for a low-grade glioma invading the whole temporal lobe and the temporo-occipital junction. The optic radiations then constituted the posterior and deep functional boundary of the resection, avoiding the occurrence of a post-operative hemianopsia, in spite of an asymptomatic quadrantanopsia. This preliminary experience illustrates the possibility to use intra-operative direct electrical stimulation during surgery of lesions involving the posterior afferent visual system, in order to identify and then preserve the visual pathways, as previously reported for sensorimotor and language subcortical fibers.

Production of heterologous thermostable glycoside hydrolases and the presence of host-cell proteases in substrate limited fed-batch cultures of Escherichia coli BL21(DE3)

Metabolic stress is a phenomenon often discussed in conjunction with recombinant protein production in Escherichia coli. This investigation shows how heterologous protein production and the presence of host cell proteases is related to: (1) Isopropyl-beta- D-thiogalactopyranoside (IPTG) induction, (2) cell-mass concentration at the time of induction, and (3) the presence of metabolites (glutamic acid or those from tryptone soy broth) during the post-induction phase of high cell density fed-batch cultivations. Two thermostable xylanase variants and one thermostable cellulase, all originating from Rhodothermus marinus, were expressed in E. coli strain BL21 (DE3). A three-fold difference in the specific activity of both xylanase variants [between 7,000 and 21,000 U/(g cell dry weight)], was observed under the different conditions tested. Upon induction at high cell-mass concentrations employing a nutrient feed devoid of the metabolites above, the specific activity of the xylanase variants, was initially higher but decreased 2-3 h into the post-induction phase and simultaneously protease activity was detected. Furthermore, protease activity was detected in all induced cultivations employing this nutrient feed, but was undetected in uninduced control cultivations (final cell-mass concentration of 40 g/l(-1)), as well as in induced cultivations employing metabolite-supplemented nutrient feeds. By contrast, maximum specific cellulase activity [between 700 and 900 U/(g cell dry weight)] remained relatively unaffected in all cases. The results demonstrate that detectable host cell proteases was not the primary reason for the decrease in post-induction activity observed under certain conditions, and possible causes for the differing production levels of heterologous proteins are discussed.

Anatomical study of the length of the human intestine

Although preoperative assessment of the length of the intestine may be of interest to avoid postoperative consequences of large intestinal resection, measurements of the intestine are quite rare and results variable in the literature. This anatomical study aimed to assess the length of the different intestinal segments, their variation and their correlation with sex, age, weight and height. Two hundred non-fixed adult cadavers (100 men, 100 women) who willingly gave their bodies for scientific purposes were studied. The post mortem average length of the whole intestine was 795.5+/-129 cm and was significantly longer in men and in young subjects. It was correlated with the subject's weight but not height. Multivariate analysis demonstrated that the factor showing the strongest correlation with intestinal length was body weight. This latter parameter may be useful in the preoperative assessment of intestinal length.

[Hemangiopericytoma of the infratemporalis fossa: a multi-operated patient]

Hemangiopericytoma (HPC) was diagnosed in a 65-year-old man in 1991. Initially the tumor was located in the maxillary sinus. Resection was followed by multiple recurrences involving the infratemporalis fossa (ITF), the nasopharyngeal region, and the right tonsillar region. Over a 10-year-old period, the histology pattern remained unchanged. Multiple approaches, as described in the literature, were used for resection depending on the site of the recurrence. To data, no malignant structure has been identified. Pain and cranial nerve deficits (V2, V3) have been the main squeleae. This case points out the limitations of radical resection because of the difficulty of the approach to this anatomic region. CT scan must be performed to choose the best access route depending on the primary site of the tumor and its extension.

Microanatomy of the pericallosal arterial complex

OBJECT

The pericallosal arterial complex supplies the callosal and pericallosal regions, as well as the anterior two thirds of the medial and superomedial aspects of both hemispheres. It is composed of the pericallosal artery (that is, the segment of the anterior cerebral artery located distal to the anterior communicating artery [ACoA]) and the median callosal artery (or third pericallosal artery), which originates from the ACoA. This system was studied in 46 specimens (23 human cadaver heads) injected with colored latex.

METHODS

After being injected with colored latex, embalmed, and bleached, the specimens were studied with the aid of optic magnification. The pericallosal artery was found to be divided into four segments (A2-A5 in the proximodistal direction). After giving rise to central, callosal, and cortical branches, it terminated near the splenium of the corpus callosum as the posterior pericallosal artery, or on the precuneus as the inferomedial parietal artery.

CONCLUSIONS

The authors propose a logical classification of the different variations in the pericallosal arterial complex based on embryological development. This complex can be considered a hemodynamic solution to an abnormal regression of one of its parts, which is balanced by the development of supplemental channels from other parts.

[Cerebro-meningeal hemorrhage secondary to ruptured vascular malformation during pregnancy and post-partum]

Thirty two new cases of vascular malformations discovered during pregnancy were reviewed in a multicentric retrospective study and compared to the literature. The authors studied both the influence of pregnancy and post-partum on cerebral vascular malformations and the corresponding neurosurgical and obstetrical management. The relative frequencies of arteriovenous malformations (AVMs) and arterial aneurysms (AAs) is the same for pregnant and non-pregnant women. Pregnancy does not increase the risk of first bleeding of vascular malformations but the risk of re-bleeding is increased for AVMs. The bleeding of a vascular malformation is more strongly correlated to age than to parity. The mean maternal age at the time of rupture is greater for AAs than for AVMs, as it is in the general population. The bleeding of a vascular malformations occurs more frequently during the second and third trimesters of pregnancy than in the first one and in the post-partum. Labor and delivery are not great-risk-periods. Management of vascular malformation in pregnant woman is proposed as follow : --a ruptured AA or AVM is managed as it is in non-pregnant woman, whatever the gestational age; no fetal extraction needs to be performed except ed if the rupture occurs at the very end of the pregnancy;--an non-ruptured AVM discovered during pregnancy is treated after delivery; an non-ruptured AVM that never bled before pregnancy is managed in the same way that an non-ruptured AA.

[Surgical approaches to the corpus callosum]

There are no dedicated approaches to the corps callosum itself. The different approaches, subcallosal, supracallosal and posterior to the splenium are usually used to reach neighboring structures such as third ventricle or pericallosal arteries. MRI is the best guideline to reach a specific position in the corps callosum and must imperatively contribute to the choice of the type of approach. During the procedure, it is necessary to take great care to protect the vessels, arteries and veins especially, to avoid ischemic damage which is the main complication of these approaches.

[Development of the corpus callosum (CC)]

Corpus callosum embryology can be divided into three parts: during "commissuration", a cellular mass develops between the two telencephalic vesicles. The primitive lamina terminalis corresponds to the closing point of the anterior neuropore. Its dorsal part grows and forms the lamina reunions (6-8 intra uterine weeks, IUW). From ventral to dorsal, this lamina reunions gives rise to the area praecommissuralis (origin of the anterior commissure), to the primordium hippocampi (10 I.U.W., fornix), and to the massa commissuralis (10 S.I.U., corpus callosum). Fibers arising from the developing hemispheres run through this primitive corpus callosum. The growth of the corpus callosum follows the expansion of the hemispheres, in a rostro-caudal and then dorso-ventral circular movement. The last part of the corpus callosum to form is the rostrum. Maturation occurs postnatally, and corresponds to axonal elimination, and myelination, progressively changing the callosal connection pattern of the newborn and infant into the adult pattern.

[Morphologic anatomy of the corpus callosum]

The corpus callosum is a neopallial commissure. In inferior vertebrates, the pallial commissures are essentially represented by the anterior commissure. The corpus callosum appears in mammals only. Eutherians alone have a corpus callosum, the other mammals have an anterior commissure and hipocampal commissure. In humans, the different portions of the corps callosum are described on a median sagittal slice: rostrum, genu, body, isthmus, splenium. Klingler method allows to dissect fibers of each of these portions and their relationship with the corona radiata and optic radiations. These latter are separated from the ventricular ependyme by callosal radiations. Finally, each part of the corpus callosum participates in lateral ventricle wall formation.

[Arterial and venous vascularization of the corpus callosum]

Blood supply of the corpus callosum is assured by two arterial systems, the carotid system mainly and the vertebrobasilar system accessorily. The carotid system intervenes via the pericallosal artery, portion of the anterior cerebral artery distal to the anterior communicating artery. This pericallosal artery can be bihemispheric in 4 to 12% of the cases or azygos in 0.26% of cases. In 20 to 80% of cases, the median callosal artery arises from the communicating artery. The vertebrobasilar system intervenes in splenium vascularization by its terminal branches. These two carotid and vertebrobasilar systems give rise to perforating arteries that assure intrinsic vascularization of the corpus callosum creating a system of regular vascular stitches around the fibers of the corpus callosum. The venous drainage of the corpus callosum is essentially via callosal veins and callosocingulate veins towards the deep venous system of the brain.

Microanatomy of the hypophyseal fossa boundaries

OBJECT

The authors studied the heads of 17 adult cadavers and one fetus to clarify the anatomy of the sellar region, particularly the lateral boundaries of the hypophyseal fossa.

METHODS

Vascular injections and microdissection or histological techniques were used in this study. The roof of the cavernous sinuses and diaphragma sellae were part of a single horizontal dural layer that joined the two anterior petroclinoid folds. Laterally, the direction of this layer changed; it became the lateral wall of the cavernous sinus and joined the dura mater of the middle cerebral fossa. On the midline, this layer ballooned toward the sella through the diaphragmatic foramina, created a dural bag containing the hypophysis, and attached to the inferior aspect of the diaphragma sellae. As a consequence, no straight sagittal dural wall existed between the pituitary gland and cavernous sinus; the lateral border of the hypophyseal fossa was part of this anteroposterior and superoinferior convex bag. The authors stress the importance of the venous elements of the region and discuss the structure of the cavernous and coronary sinuses.

CONCLUSIONS

Invasion of the cavernous sinus makes surgery more risky and difficult and may necessitate modification of the surgical treatment plan. The preoperative diagnosis of cavernous sinus invasion is thus of great interest, but the possibility of normal lateral expansions of the pituitary gland must be kept in mind. A lateral expansion of this gland into the cavernous sinus was encountered in 29% of the specimens, and an adenoma that developed in such an expansion could easily mimic cavernous sinus invasion.

A new concept in Dorello's canal microanatomy: the petroclival venous confluence

The so-called Dorello's canal was studied in 32 specimens (16 human cadaver heads) injected with colored latex and fixed in formalin (28 specimens) or studied with microscopic and ultrastructural methods (four specimens). To avoid the differences usually encountered in the description of this area, the authors preferred to consider a larger space that they have named the petroclival venous confluence (PVC). It was located between two dural layers: inner (or cerebral) and outer (or osteoperiosteal). The PVC was quadrangular on transverse section. The posterior petroclinoid fold and the axial plane below the dural foramen of the abducent nerve (sixth cranial nerve) limited the PVC at the top and bottom, respectively. Its anteroinferior limit was the posterosuperior aspect of the upper clivus and outer layer of the dura mater. Its anterior limit was the vertical plane containing the posterior petroclinoid fold, and its posterior limit was the inner layer of the dura. The PVC was limited laterally by the medial aspect of the petrous bone apex and medially by the virtual sagittal plane extending the medial limit of the inferior petrosal sinus upward. The PVC was a venous space bordered by endothelium and continuous with the cavernous sinus, the basal sinus of the clivus, and the inferior petrosal sinus. There were trabeculations between the two dural layers. The petrosphenoidal ligament of Gruber may be regarded as a larger trabeculation, and it divided the PVC into a superior and an inferior compartment. The abducent nerve generally ran through the inferior compartment, where it was fixed to the surrounding dura mater. This nerve was only separated from venous blood by a meningeal sheath of varying thinness lined with endothelium. The clinical implications of these findings are discussed.

Surgical anatomy and dissection of the petrous and peripetrous area. Anatomic basis of the lateral approaches to the skull base

The purpose of this study is to review the topographic anatomy of the petrous and peripetrous structures, with emphasis on the relationships important to the lateral approaches to the posterior and lateral skull base. Surgical exposure of the clivus, the posterior aspect of the petrous bone, the ventral aspect of the brain stem, and of all the intradural structures in the area, remains difficult because of the presence of the so-called "petrous and peripetrous complex". However, the lateral approach to the skull base is the most suitable approach if the lesion lies lateral to the cavernous portion of the internal carotid artery, and of course if the lesion develops laterally behind the petrous apex. Consequently, neurosurgeons should be familiar with the anatomy of the intrapetrous cavities and their contents, and with the relationships in the area. Middle cranial fossa dissections (dry and fresh specimens) allow us to study the anatomical relationships between the intrapetrous carotid artery, the facial nerve, the porus, the cochlea, the geniculate ganglion and the petrosal nerves, the trigeminal ganglion and nerve, the auditory tube and the middle ear. While briefly reviewing some approaches (anterior petrosectomy, sub-temporal preauricular infratemporal fossa approach, pre-sigmoid approach), we explore the concept of the approach and the limitations of surgical technique and exposure.

Smooth pursuit eye movement deficits after pontine nuclei lesions in humans

Eye movements were recorded electroculographically in four patients with basal pontine lesions, demonstrated by MRI. The most prominent eye movement abnormality observed was mild to severe impairment of smooth pursuit and optokinetic nystagmus, mainly ipsilateral to the lesion. This abnormality is thought to result from damage to the pontine nuclei, which form a crucial relay between the cerebral cortex and the cerebellum controlling smooth pursuit. Abnormalities of saccades and the vestibulo-ocular reflex in one patient are also discussed.

Progressive necrosis of the conus medullaris: magnetic resonance imaging and surgical findings

A 67-year-old man with non-insulin-dependent diabetes mellitus progressively developed, over a 2-year period, lower extremity sensory and motor defects associated with impaired bladder function and perineal and perianal sensation related to a disease of the conus medullaris extending from T12 to S5. The magnetic resonance imaging scan suggested myelomalacia and the diagnosis of progressive necrotic myelopathy was confirmed by surgical intervention.

Colloid cyst of the fourth ventricle: diagnostic problems and pathogenic considerations

The authors report the case history of a patient with a colloid cyst of the 4th ventricle. The clinical history of slow intracranial hypertension, homogeneous hyperdensity with contrast enhancement on computed tomographic, scan, and the gelatinous aspect of the cyst at surgery are characteristic of colloid cysts. The diagnosis was made, however, only at the time of histological examination. A common neuroepithelial origin with 3rd ventricle cysts would be explained by similar embryological developments of the prosencephalic and the rhombencephalic roofs.

A rare embryologic variation: carotid-anterior cerebral artery anastomosis or infraoptic course of the anterior cerebral artery

Carotid-anterior cerebral artery anastomosis constitutes an anomaly of the anterior part of the arterial circle of the brain. The anterior cerebral a. arises a few millimeters above the emergence of the internal carotid from the cavernous sinus, at the usual level of origin of the ophthalmic a. It travels medially, beneath the optic n., and then describes a curve with a superolateral concavity to arrive at the anterior part of the optic chiasma, where it anastomoses with the anterior communicating a. This asymptomatic variant of course is often associated with other cerebral vascular anomalies, especially arterial aneurysms. On the basis of 2 new cases discovered by chance, together with a review of the literature, various hypotheses capable of explaining the embryologic origin of these anomalies are discussed.

Anatomical basis of the microsurgical approach to the pineal gland

The microanatomic study of the pineal region was made from 18 cadaver brains. The purpose of this paper is to describe the surgical anatomy needed to approach this area, which is deeply located and in the midline, by analysing the different methods of approach.