Validation of reference genes in human chordoma

Background:

Chordoma are rare slow-growing tumors of the axial skeleton, which are thought to arise from remnants of the notochord. Little is known about the underlying mechanisms that drive this tumor. However, the assessment of gene expression levels by quantitative real-time polymerase chain reaction (qRT-PCR) is hampered due to a lack of validated reference genes. Using an unstable reference gene in qRT-PCR may lead to irreproducible results.

Methods:

The expression of 12 candidate reference genes (ACTB, B2M, T, EF1a, GAPDH, HPRT, KRT8, KRT19, PGK1, RS27a, TBP, and YWHAZ) was analyzed by qRT-PCR in flash frozen chordoma samples from 18 patients. GeNorm and NormFinder algorithms were used to rank the stability of the genes.

Results:

From most to least stably expressed, the top six genes found by geNorm were PGK1, YWHAZ, ACTB, HPRT, EF1A, and TBP. When analyzed by NormFinder, the top six genes were ACTB, YWHAZ, PGK1, B2M, TBP, and HPRT. GAPDH alone, which is often used as a reference gene in chordoma gene expression studies, is not stable enough for reliable results.

Conclusion:

In gene expression studies of human chordomas, PGK1, ACTB, and YWHAZ are more stably expressed, and therefore, are preferred reference genes over the most often used reference gene so far, GAPDH.

Protocol for intraoperative assessment of the human cerebrovascular glycocalyx

INTRODUCTION

Adequate functioning of the blood-brain barrier (BBB) is important for brain homoeostasis and normal neuronal function. Disruption of the BBB has been described in several neurological diseases. Recent reports suggest that an increased permeability of the BBB also contributes to increased seizure susceptibility in patients with epilepsy. The endothelial glycocalyx is coating the luminal side of the endothelium and can be considered as the first barrier of the BBB. We hypothesise that an altered glycocalyx thickness plays a role in the aetiology of temporal lobe epilepsy (TLE), the most common type of epilepsy. Here, we propose a protocol that allows intraoperative assessment of the cerebrovascular glycocalyx thickness in patients with TLE and assess whether its thickness is decreased in patients with TLE when compared with controls.

METHODS AND ANALYSIS

This protocol is designed as a prospective observational case-control study in patients who undergo resective brain surgery as treatment for TLE. Control subjects are patients without a history of epileptic seizures, who undergo a craniotomy or burr hole surgery for other indications. Intraoperative glycocalyx thickness measurements of sublingual, cortical and hippocampal microcirculation are performed by video microscopy using sidestream dark-field imaging. Demographic details, seizure characteristics, epilepsy risk factors, intraoperative haemodynamic parameters and histopathological evaluation are additionally recorded.

ETHICS AND DISSEMINATION

This protocol has been ethically approved by the local medical ethical committee (ID: NL51594.068.14) and complies with the Declaration of Helsinki and principles of Good Clinical Practice. Informed consent is obtained before study enrolment and only coded data will be stored in a secured database, enabling an audit trail. Results will be submitted to international peer-reviewed journals and presented at international conferences.

TRIAL REGISTRATION NUMBER

NTR5568.

A vertebral extra dural chordoma at C5, possibly deriving from a clival chordoma

Background:

Clival chordomas are a rare type of cancer with low metastatic potential and primary metastasize to the lung or bones.

Case Description:

This case report describes a possible metastatic, paravertebral chordoma at level C4-C5 in a patient with a past medical history of a clival chordoma.

Conclusion:

Chordomas are unpredictable and may metastasise.

The impact of auditory feedback on neuronavigation

OBJECT

We aimed to develop an auditory feedback system to be used in addition to regular neuronavigation, in an attempt to improve the usefulness of the information offered by neuronavigation systems.

INSTRUMENTATION

Using a serial connection, instrument co-ordinates determined by a commercially available neuronavigation system were transferred to a laptop computer. Based on preoperative segmentation of the images, the software on the laptop computer produced an audible signal whenever the instrument moved into an area the surgeon wanted to avoid.

METHODS

To evaluate the impact of our setup on volumetric resections, phantom experiments were conducted. CT scans were acquired from eight blocks of floral foam. In each of these scans, a target-volume was segmented. This target-volume was subsequently resected using either regular neuronavigation or neuronavigation extended with auditory feedback. A 'postoperative' CT scan was used to compare the resection cavity to the preoperatively planned target-volume.

FINDINGS

The resemblance between the resection cavity and the target-volume was greater each time auditory feedback had been used. This corresponded with more complete removal of the target-volume. However, it also corresponded with the removal of more non-target 'tissue' in two out of four cases.

CONCLUSIONS

The usefulness of auditory feedback was made plausible and the use of a new type of navigation phantom was illustrated. Based on these results, we recommend incorporation of auditory feedback in commercially available neuronavigation systems, especially since this is relatively inexpensive.

Subtyping of oligo-astrocytic tumours by comparative genomic hybridization

Oligo-astrocytic tumours (OAs) histologically show both oligodendroglial and astrocytic differentiation. Unequivocal criteria for delineation of OAs from pure oligodendroglial (Os) and astrocytic (As) tumours and for grading of OAs are lacking. Molecular genetic analysis may allow for a better characterization of OAs and thereby guide prognostic and therapeutic decisions. Comparative genomic hybridization (CGH) was performed on 39 gliomas with variable phenotypic expression of histological features characteristic of both astrocytic and oligodendroglial differentiation. The results show that OAs are genetically more heterogeneous than Os. In addition to the "-1p/-19q" and "+7/-10" subtypes that have been previously recognized, two additional genetic subtypes, "intermediate" and "other", were identified in the present study. "Intermediate" OAs likely represent progression from "-1p/-19q" tumours. The "other" subtype appears to represent an additional, heretofore unrecognized, genetic pathway(s). Application of rigorously "strict" histopathological criteria, as opposed to "relaxed" criteria, for the selection of oligo-astrocytic tumours resulted in a higher percentage of "-1p/-19q" tumours, but some "-1p/-19q" tumours might be missed. The results suggest that molecular genetic analysis is a useful and valid additional tool for the classification of gliomas, particularly for the significant subset of tumours in which subjective histopathological criteria are insufficient for an unequivocal distinction between Os, As, and mixed OAs.

PTEN mutation analysis in two genetic subtypes of high-grade oligodendroglial tumors. PTEN is only occasionally mutated in one of the two genetic subtypes

We recently identified two genetic subtypes of high-grade oligodendroglial tumors (HG-OT): 1p-/19q- HG-OT are characterized by a loss of chromosome 1p32-36 (del(1)(p32-p36) and/or a del(19)(q13. 3); whereas +7/-10 HG-OT harbor a gain of chromosome 7 (+7) and/or a -10 without a loss of 1p32-36 and 19q13.3. Because a -10 and a +7 are most frequently detected in glioblastomas (GBM), the genotype of +7/-10 HG-OT suggests that these tumors are GBM with a prominent oligodendroglial phenotype rather than anaplastic oligodendrogliomas. PTEN is a tumor suppressor gene, located at 10q23.3, which is involved in tumor progression of GBM and other neoplasms. In this study, we screened for PTEN mutations in six low-grade oligodendroglial tumors (LG-OT), five 1p-/19q- HG-OT, seven +7/-10 HG-OT, and nine xenografted GBM. PTEN mutations were detected in none of the LG-OT and 1p-/19q- HG-OT, once in +7/-10 HG-OT, and frequently in GBM. As one of the +7/-10 HG-OT harbored a PTEN mutation, this demonstrates that PTEN can be involved in the oncogenesis of this genetic subtype of HG-OT. The lower frequency of PTEN mutations in +7/-10 HG-OT compared to GBM suggests that these tumors are of a distinct tumor type rather than GBM. Published by Elsevier Science Inc.

Genetic reflection of glioblastoma biopsy material in xenografts: characterization of 11 glioblastoma xenograft lines by comparative genomic hybridization

OBJECT

Human tumors implanted as subcutaneous xenografts in nude mice are widely used for the study of tumor biology and therapy. Validation of these models requires knowledge of the genetic makeup of the xenografts. The aim of this study was to establish whether chromosomal imbalances in 11 xenograft lines derived from human glioblastomas multiforme (x-GBMs) are similar to those found in GBM biopsy samples. The authors also studied genetic stability during serial passaging of three xenograft lines.

METHODS

Chromosomal imbalances in x-GBMs were detected using comparative genomic hybridization (CGH). The authors compared the CGH results in x-GBMs with those in the original GBMs (o-GBMs) that were used to establish three of the xenograft lines and with the GBM biopsy results reported in the literature (1-GBMs). In three xenograft lines two different passages were analyzed.

CONCLUSIONS

The results show that the chromosomal imbalances in x-GBMs are similar to those in o-GBMs and 1-GBMs, indicating that the GBM xenograft lines used were valid models from a genetic point of view. The CGH analysis of two different passages of three xenograft lines indicates that x-GBMs (like 1-GBMs) show intratumoral genetic heterogeneity and do not acquire chromosomal imbalances as a result of serial passaging.

[Cavernous sinus syndrome]

A clear and concise description and clinical interpretation of the cavernous sinus syndrome are lacking. Pathological changes in or around the cavernous sinus may lead to failure of eye muscle nerves and of one or more branches of the trigeminal nerve. The clinical signs of the cavernous sinus syndrome are combinations of failure of these cranial nerves sometimes with exophthalmus. Because many nerves can be wholly or partially involved in the syndrome, there is no clinical uniformity and the cavernous sinus syndrome has never been well defined. A neurotopographical classification is proposed in order to simplify the multiple interpretations of the cavernous sinus syndrome. The classical cavernous sinus syndrome is divided into three syndromes: the syndrome of the superior orbital fissure, the syndrome of the lateral wall of the cavernous sinus and the central cavernous sinus syndrome.

Surgical approach and histoanatomical aspects of the oculomotor nerve in rats

The surgical approach and some histoanatomical characteristics of the intracavernous portion of the oculomotor nerve are described. Moreover, some perioperative precautions for intracranial surgical procedures in the rat are reported and the suitability of the rat as a model for studying intracranial nerve regeneration is discussed. With the data provided, this model of oculomotor nerve approach can be used to study various aspects of intracranial nerve regeneration.

End-to-end versus peripheral nerve graft repair of the oculomotor nerve in rats: A comparative histological and morphometric study

A comparative study was undertaken to evaluate end-to-end versus peripheral nerve graft repair in cranial nerve reconstruction. In 14 rats, the oculomotor nerve was sharply transected in the cavernous sinus and repaired either by end-to-end coaptation (n = 7) or by interposition of a peripheral nerve graft (n = 7). The results were evaluated 16 weeks after surgery by light and transmission electron microsurgery and by morphometric analysis. The degree of neuroma formation, fibrosis, and axonal disorganisation at the repair site was the same for both groups. Histologically, both end-to-end and graft repair groups revealed various degrees of axonal regeneration with myelinated nerve fibres in the distal nerve segments. In both groups, the number of nerve fibres distal to the repair site was increased compared to proximal to the repair (P < 0.001) but myelinated axon diameter was significantly less than that of control nerves (P < 0.001). No difference existed between the two repair groups in terms of mean myelinated axonal diameter. However, the number and density of myelinated axons was statistically greater in the graft group (P < 0.05). In conclusion, despite the disadvantage of two repair sites, peripheral nerve grafting results in equal or slightly superior axonal regeneration compared to an end-to-end repair in the rodent model of intracranial oculomotor nerve reconstruction. We speculate that this may be due to the structure of the peripheral nerve graft.

Effect of a modified Nd:YAG laser technique on neuroma formation: An experimental study in rat sciatic nerve

BACKGROUND AND OBJECTIVES

Traumatic transection of a peripheral nerve is inherently associated with the development of neuroma at the end of the proximal stump, often leading to therapy-resistant pain. This study was designed to evaluate whether the neodymium:yttrium aluminum garnet (Nd:YAG) laser could prevent neuroma formation after neurectomy.

STUDY DESIGN/MATERIALS AND METHODS

The sciatic nerves of 14 rats were diffuse coagulated by defocused Nd:YAG laser (12 W power), and subsequently transected with additional focused laser energy. The control group consisted of contralateral nerves transected by microscissors. The nerves were reexposed at different time intervals up to 9 weeks after surgery, and evaluation consisted of macroscopy, and light and transmission electron microscopy.

RESULTS

True neuroma formation could not be observed after laser transection, and only five nerves formed a neuromatous bulb, with minimal adhesions to surrounding tissue. Microscissor transection resulted in widespread amputation neuromas, consisting of regenerating axons and connective tissue, and nervous tissue regenerating into surrounding tissue. Laser-transected nerves showed degenerative changes of the axons and myelin, while proliferation of Schwann cells could not be observed. No outgrowth of axons could be observed outside the coagulated proximal stump. An epi/perineurial layer was present, covering the nerve stumps. Microscissor-transected nerves showed proliferation of fibroblasts and Schwann cells, forming minifascicles, and vigorous outgrowth of axons into the tissue and even into the distal nerve stump.

CONCLUSIONS

Within the limitations of this study it is concluded that the formation of amputation neuromas is suppressed by Nd:YAG laser application by thermal coagulation of the nerve and suppression of Schwann-cell proliferation.

Identification of subgroups of high-grade oligodendroglial tumors by comparative genomic hybridization

In contrast to astrocytic tumors, approximately two thirds of anaplastic oligodendrogliomas are reported to be chemosensitive. Relatively little is known about the genetic aberrations in oligodendroglial tumors (OTs). In order to elucidate oligodendroglial oncogenesis and to find specific genetic aberrations that may have prognostic and therapeutic implications, we performed comparative genomic hybridization (CGH) to detect chromosomal copy number changes in 17 low-grade OTs (LG-OTs) and 12 high-grade OTs (HG-OTs) lacking a prominent astrocytic component. Loss of chromosome 1p (79%) and 19q (76%) were most frequently detected by CGH, all LG-OTs and 50% of the HG-OTs contained -1p (including 1p36-32), -19q (including 19q13.3), or both, and the rest of the HG-OTs showed +7, -10, or both. Since losses of 1p36-32 and 19q13.3 were mutually exclusive with +7 or -10, the HG-OTs could be divided in -1p/-19q and +7/-10 tumors. While the -1p/-19q tumors can be considered as pure anaplastic oligodendrogliomas, the +7/-10 tumors may rather be glioblastomas with prominent oligodendroglial differentiation. We conclude that CGH is a powerful tool to assist in the identification of 2 major subgroups of HG-OTs with prognostic and possibly therapeutic relevance.

On the mechanism of transient postoperative deficit of cranial nerves

BACKGROUND

Transient cranial nerve deficit is a common postoperative complication after surgery at the cranial base. In this type of surgery, the cranial nerves are often not macroscopically damaged or transected, but more or less manipulated during surgery. In this article, the cellular mechanisms of postoperative cranial nerve deficit are reviewed.

METHODS

Experimental and clinical papers concerning cranial and peripheral nerve damage during surgery were critically reviewed.

RESULTS

There are definite differences in the anatomical and histological structure between peripheral and intracranial nerves, which make the latter much more prone to intraoperative damage. Several pathological mechanisms are responsible for postoperative deficit, such as segmental demyelination of the nerve, comprised microcirculation within the nerve, postoperative edema, and "synaptic stripping" around the cell bodies of the affected neurons, which can be regarded as a regenerative response of the nervous system.

CONCLUSIONS

Several cellular mechanisms are responsible for postoperative cranial nerve deficit after skull base surgery. Understanding these mechanisms is important for all surgeons involved in the treatment of skull base lesions.

Protective coating of cranial nerves with fibrin glue (Tissucol) during cranial base surgery: technical note

OBJECTIVE

Cranial nerve deficit, either transient or permanent, is a common postoperative complication after cranial base surgery. Frequently, this occurs because intracranial nerves are directly involved in the cranial base lesion. However, any cranial nerve adjacent to the lesion can be damaged because of direct or indirect manipulation during surgery, leading to severe morbidity. We describe a new technique in which the adjacent intracranial nerves are protected from surgical trauma by coating the nerves with a biological two-component fibrin glue (Tissucol; Immuno A.G., Vienna, Austria).

SURGICAL TECHNIQUE

The technique was performed in patients who underwent cranial base surgery for different types of lesions. After exposure of the operating field, the cranial nerves that were at risk of operative trauma were coated with a thin layer of fibrin glue using a double lumen catheter within a traditional suction device.

RESULTS

With the application of fibrin glue, a protective layer of a rubbery consistency is formed around the nerve. No intraoperative complications or adverse effects of the application were noted. Moreover, no surgical injury of the nerves occurred and no or minimal postoperative cranial nerve deficit was noted in the coated nerves.

CONCLUSION

Although it is difficult to compare the postoperative cranial nerve deficit in the coated nerves with a control group, we think that this technique is a valuable method to minimize or avoid intraoperative cranial nerve injury during cranial base surgery.

Falcine sinus and occipital encephalocele: a magnetic resonance venography study

OBJECT

Occipital encephaloceles are relatively frequently encountered. Many investigators have addressed the embryogenesis of these formations, but the dural system has never before been studied. In this retrospective analysis the authors sought to gain a better understanding of the origins of these defects.

METHODS

The charts and radiological examinations, especially the magnetic resonance venography studies, were reviewed in seven patients. In six patients the straight sinus was absent. Drainage of the galenic system took place through a sinus within the falx, also known as a falcine sinus. The tentorium was not seen in five patients.

CONCLUSIONS

The combination of an absent straight sinus and dysplastic tentorium is no coincidence: both develop within the same mesenchyme in the mesencephalic flexure. Distortion of the mesenchyme by a neural tube defect, causing an occipital encephalocele, will lead not only to disorders of the tentorium but also of the straight sinus.

Intracranial repair of a divided trochlear nerve. Case report

The authors report the case of a 37-year-old woman in whom the trochlear nerve was transected during removal of a meningioma in the cavernous sinus and subsequently repaired by using microsurgical techniques. This patient presented with a tumor in the posterior part of the right cavernous sinus with expansion over the tentorium. Preoperatively, she suffered from partial deficit of the right trochlear nerve. Intraoperatively, the trochlear nerve was noted to be completely encased by the tumor and was totally divided during removal of the lesion. After tumor resection, the trochlear nerve was repaired by using a sural nerve fascicle secured with sutures and fibrin glue. Six months after the operation, trochlear nerve regeneration became evident as the patient's binocular vision gradually improved. The patient regained normal functioning of the superior oblique muscle 3.5 years after surgery. It is concluded that repair of a divided trochlear nerve is worthwhile and can be followed by successful regeneration and an excellent functional recovery of the superior oblique muscle.

Cerebral arteriovenous malformations in childhood: state of the art with special reference to treatment

In this state of the art paper, the clinical and diagnostic features of cerebral arteriovenous malformation (AVM) in childhood are outlined and special attention is paid to the treatment. Several options exists for the treatment of an AVM, consisting of surgery, endovascular embolization, stereotactic radiosurgery, or a combination of these treatments.

Charles Labbé (1851-1889)

The vein of Labbé is a very important structure and every neurosurgeon is acquainted with its anatomy. Because of the recent increasing interest and experience in skull base surgery, the vein of Labbé has received a great deal of attention. Intraoperative damage to this vein should be avoided and several methods to prevent this have been described. Despite these developments, nothing is written in the neurosurgical literature about the man who described this vein for the first time: Charles Labbé. The authors therefore conducted an extensive search of the literature and uncovered several public records in France to learn more about Charles Labbé.

Lumbar cerebrospinal fluid drainage for symptomatic sacral nerve root cysts: an adjuvant diagnostic procedure and/or alternative treatment? Technical case report

OBJECTIVE AND IMPORTANCE

The treatment of symptomatic sacral nerve root cysts is difficult and challenging. A major role has been ascribed to the hydrostatic and pulsatile forces of cerebrospinal fluid (CSF) for the symptomatology of sacral nerve root cysts. Theoretically, lowering those pressures should have a beneficial effect on the symptoms. Lowering the hydrostatic and pulsatile pressures may be achieved by lumbar CSF drainage. The effect of lumbar CSF drainage on the symptomatology of sacral nerve root cysts is described.

CLINICAL PRESENTATION

Three patients suffered from leg and/or low back pain as a result of sacral nerve root cysts.

INTERVENTION

First, CSF was drained through an external lumbar drain that was connected to a CSF bag. Mobilization was not restricted. All patients became free of symptoms. Eventually, a lumboperitoneal shunt was inserted in two patients. Those two patients remained free of complaints for 11 and 9 months, respectively.

CONCLUSION

To our knowledge, this is the first report that clearly establishes the role of CSF forces in the symptomatology of sacral nerve root cysts. Lumbar external CSF drainage is a diagnostic tool to investigate the clinical significance of sacral nerve root cyst(s). Lumboperitoneal CSF shunting is a promising alternative in the treatment of symptomatic sacral nerve root cysts.

Intracranial nerve repair: a review of experimental and clinical studies

With recent developments in neurosurgery and related disciplines, more aggressive approaches are being made for various lesions of the skull base, and, as a consequence, cranial nerves are more frequently damaged, which causes significant morbidity. The authors review experimental and clinical studies involving surgical repair of severed cranial nerves and provide evidence that some degree of functional regeneration occurs. Functional recovery after repair is mainly dependent on the preoperative function of the muscle-nerve unit and the morphological organization of the nerve; the more complex the organization, the lesser the degree of functional recovery. The beneficial effect of surgical repair on postoperative morbidity is outlined together with suggestions for future research.

The Dutch 'Benefit-II' project: do physicians benefit from using an electronic medical dossier?

In 1992 the Dutch College of General Practitioners (NHG) started a project, which lasted until May 1994. The project had three major objectives: establishing as exactly as possible what benefits we gain from using an Electronic Medical Dossier (EMD) can we find an influence on the quality of care? Which drawbacks or problems are there, advising on the optimal use of an EMD; What is the best place to record certain data? advising the Working Committee on Informatics (WCIA), of Dutch National Association of General Practitioners (LHV) and NHG on the directions for the new Reference Model 1995. To obtain these goals panel discussions and a questionnaire were used. The project resulted in advice on how to use the EMD in the most efficient way. Also we have learned about the use of GP-information systems and the perception about this usage by the Dutch GPs.

Polyposis coli, craniofacial exostosis and astrocytoma: the concomitant occurrence of the Gardner's and Turcot syndromes

BACKGROUND

Up to 60% of the patients with known adenomatous polyposis coli may present hyperostosis of the skull and facial bones, and/or a susceptibility to fibromas. This is known as the Gardner's syndrome, and is considered as an allelic variant of familial adenomatous polyposis (FAP). Also, although very rare, an adenomatous polyposis coli may occur with malignant tumors of the central nervous system, known as Turcot syndrome. If both syndromes are different phenotypic presentation of FAP, this would explain a simultaneous occurrence.

METHOD

We report the history of a patient who showed clinical signs of the simultaneous occurrence of both Gardner's and Turcot syndromes. The syndromes are compared, and in view of the literature, a genetic explanation for the concomitant occurrence is discussed.

RESULTS

Evidence obtained from the literature to consider Turcot syndrome as a phenotype of FAB is as follows: (1) The occurrence of Gardner's and Turcot syndromes in one family, but in different members; (2) The presence of congenital hypertrophic retinal pigmented epithelium (CHRPE), which correlates with the expression of polyps in FAP patients, in both syndromes; (3) Linkage of the Turcot phenotype to the adenomatous polyposis coli locus by genetic markers. Evidence obtained from this case report indicates that there is a manifestation of both syndromes in one patient together with a positive family history for FAP.

CONCLUSION

This concomitant occurrence of both Gardner's and Turcot syndromes in one patient clinically supports genetic and ophthalmic investigation to consider Turcot syndrome (like Gardner's syndrome) as a phenotypic variant of FAP. Patients with FAP should be examined for the presence of Gardner's syndrome. In case a Gardner's syndrome is suspected, a computed tomography scan of the brain is recommended because of the possible existence of a simultaneous Turcot syndrome.

Anatomy of the sympathetic pathways in the cavernous sinus

We studied sympathetic fibres in the cavernous sinus in 40 unfixed specimens obtained from human cadavers. Sympathetic fibres in the cavernous sinus are understood to be grouped in a plexiform configuration surrounding the internal carotid artery and have a diffuse distribution among the sympathetic nerves. Our study, however, suggests that a more systematic arrangement of sympathetic pathways exists in the cavernous sinus. A detailed anatomical description of intracavernous sympathetic fibres contributes to academic anatomical knowledge and may have practical applications for 1. diagnostic interpretation of pathologic conditions involving the cavernous sinus, 2. recognition and orientation of anatomical structures during intracavernous surgical procedures, and 3. a deeper understanding of the sympathetic nerve supply to cerebral vasculature.

The arterial pattern at the base of arhinencephalic and holoprosencephalic brains

The mechanisms by which the anatomical variations of the circle of Willis develop is considered to be related to haemodynamic factors, i.e. the differential growth of the various parts of the brain will continuously change the haemodynamic demands and consequently the flow patterns in the cerebral arteries. It is therefore to be expected that, if a selected part of the brain does not develop, the change in the haemodynamic demand will affect the development of some cerebral arteries. Consequently the arteries at the base of 2 arhinencephalic and 8 holoprosencephalic brains were studied in conjunction with the brain malformations. The defects of holoprosencephaly are believed to arise from a failure of the prosencephalon to separate fully into the telencephalon and diencephalon and become manifest at the time that the prosencephalon normally starts to separate into the hemispheres, i.e. 28-34 d p.c. Arhinencephalic brains are fully diverticulated. There is only a partial or complete agenesis of the olfactory tracts and bulbs. The defect causing arhinencephaly starts at 43 d p.c. In the arhinencephalic brains no particular vascular abnormalities were found. However, at the base of the holoprosencephalic brains no complete circle of Willis was present; the anterior part was lacking and was replaced by anterior branches which emerged unilaterally or bilaterally from the internal carotid artery. The choroidal arteries were of very large calibre and ran to the highly vascularised wall of the dorsal cyst which is usually present in holoprosencephalic brains. In contrast to the anterior part, the posterior arterial pattern was almost identical to the posterior part of the circle of Willis of normal brains. The basic vascular patterns found in the holoprosencephalic brains displayed the features of Padget's developmental stages 2 and 3 of the cerebral vasculature, i.e. the pattern that has normally developed within 28-40 d p.c. The further modification of this pattern could largely be understood from the functional demand imposed on the circulation by the enlarged anterior choroidal arteries. Because the development of the anterior part of the circle of Willis precedes the developmental derangement causing arhinencephaly, a complete circle was found in these brains.

Surgical repair of a cranial meningocele in a calf

A meningocele at the anterior fontanelle was diagnosed in a two-and-a-half month old Meuse-Rhine-Yssel calf. After radiographic and ultrasonographic evaluation, the meningocele was successfully repaired surgically.

The cavernous sinus syndrome. An anatomical and clinical study

The cavernous sinus is often involved pathologically, which can cause ocular motor nerve palsies with or without facial sensory disturbances. Consequently several clinical features of ocular motor nerve palsies have been described. In this article we present a study of the cavernous sinus syndrome, and compare this syndrome with other nerve palsy syndromes caused by lesions in or adjacent to the cavernous sinus. The clinical features are explained by means of an anatomical study of the cavernous sinus.