[Microsurgical anatomy of perforating branches of anterior communicating artery]. / Anatomie microchirurgicale des branches perforantes de l'artère communicante antérieure.

INTRODUCTION: The anterior communicating artery (ACoA) gives perforating branches to the optic chiasma, the hypothalamus and the corpus callosum. Perforating branches are variable (number, direction). Nevertheless, their knowledge is crucial during surgery of this area to spare injuries leading to ischemic post-operative complications. OBJECTIVE: The objective was to update the anatomical knowledge about perforating branches of the ACoA. METHODS: The study was led on a series of seven brains taken from human cadavers. An injection of latex neoprene was performed for every case. The region of interest was observed under operating microscope. Were examined: the length of the ACoA, its diameter, its orientation, its configuration and perforating branches (number and areas). RESULTS: Three cases on five presented with an anatomical variation at the level of the ACoA. The average length of AcoA was 2.1 millimeters (min: 2, max: 2.2). The average diameter of the ACoA was 1.67 mm (min: 1.1, max: 2.1). The average number of perforating branches was 4.2 (min: 2, max: 6). The presence of a median artery of the corpus callosum seemed to correlated with a low number of perforating branches. Branches supplying the optic chiasma seemed to be more numerous.

[The occipital sinus: a radioanatomic study]. / Étude radioanatomique du sinus occipital.

INTRODUCTION: The aim of this study was to assess the presence of an occipital sinus in both children and adults, and to detail its main associated anatomical characteristics. METHODS: One hundred of patients' MRI (3D T1 EG) between 0 and 86 years old were studied, in sagittal and axial sections, with the software DxMM. Occipital sinus length, perimeter, and cerebellar falx length measurements were performed with the software's tools. RESULTS: Forty-three percent of patients had an occipital sinus (average perimeter was 3.02 mm, average length was 19.85 mm), and 23.26% of these patients had a cerebellar falx, 30.23% of these patients had one vein or more draining into the occipital sinus. Sixty-two percent of children had an occipital sinus (average perimeter was 2.87 mm, average length was 21.63 mm), and 29.03% of them had a cerebellar falx. Twenty-four percent of adults had an occipital sinus (average perimeter was 3.4mm, average length was 15.28 mm), and 8.33% of them had a cerebellar falx. CONCLUSION: This work highlights a link between the age and the occipital sinus existence. The perimeter of this sinus seems to be superior for adults, but its length seems to be superior for children. A cerebellar falx with the occipital sinus was found more frequently for children.

Targeting the red nucleus for cerebellar tremor.

Deep brain stimulation of the thalamus (and especially the ventral intermediate nucleus) does not significantly improve a drug-resistant, disabling cerebellar tremor. The dentato-rubro-olivary tract (Guillain-Mollaret triangle, including the red nucleus) is a subcortical loop that is critically involved in tremor genesis. We report the case of a 48-year-old female patient presenting with generalized cerebellar tremor caused by alcohol-related cerebellar degeneration. Resistance to pharmacological treatment and the severity of the symptoms prompted us to investigate the effects of bilateral deep brain stimulation of the red nucleus. Intra-operative microrecordings of the red nucleus revealed intense, irregular, tonic background activity but no rhythmic components that were synchronous with upper limb tremor. The postural component of the cerebellar tremor disappeared during insertion of the macro-electrodes and for a few minutes after stimulation, with no changes in the intentional (kinetic) component. Stimulation per se did not reduce postural or intentional tremor and was associated with dysautonomic symptoms (the voltage threshold for which was inversed related to the stimulation frequency). Our observations suggest that the red nucleus is (1) an important centre for the genesis of cerebellar tremor and thus (2) a possible target for drug-refractory tremor. Future research must determine how neuromodulation of the red nucleus can best be implemented in patients with cerebellar degeneration.

[Relationships between piriformis muscle and sciatic nerve: radioanatomical study with 104 buttocks]. / Les rapports entre le muscle piriforme et le nerf ischiatique : étude radioanatomique de 104 régions glutéales.

OBJECTIVE: The relationships between the piriformis muscle and the sciatic nerve are close and may be changing. In some cases, these relationships are the cause of a piriformis syndrome, an under-diagnosed etiology of non discal sciatica. The aim of the study was to explore, by the MRI, the sciatic nerve and the piriformis muscle. MATERIELS AND METHODS: One hundred and four buttocks were explored by MRI for 52 randomly selected patients. RESULTS: In 59.6% of cases, no variation of the piriformis muscle and sciatic nerve were found. In 26% of cases, the sciatic nerve was divided into the pelvis. In 9.6% of cases, it was divided into the pelvis, the piriformis muscle was bifid and the common peroneal nerve ran between both heads. The piriformis muscle was bifid in 10.6% of cases, hypertrophic in 13.5% of cases and atrophic in 2.9% of cases.

[The conflict between obturator nerve and ovary: a cadaveric and radioanatomic study]. / Le conflit ovaro-obturateur : une étude cadavérique et radio-anatomique.

The aim of this study was to describe the anatomical relationships between the ovary and the obturator nerve in its intrapelvic portion. Seven embalmed cadavers were dissected; 20 MRIs were then analyzed. The main distance between the lateral pole of the ovary and the obturator nerve was 29 mm. The authors describe various etiologies responsible for obturator neuralgia. An underdiagnosed cause is gonadal hypertrophy.

Perfusion MRI as a neurosurgical tool for improved targeting in stereotactic tumor biopsies.

OBJECTIVE: Stereotactic biopsies are subject to sampling errors (essentially due to target selection). The presence of contrast enhancement is not a reliable marker of malignancy. The goal of the present study was to determine whether perfusion-weighted imaging can improve target selection in stereotactic biopsies. METHODS: We studied 21 consecutive stereotactic biopsies between June 2009 and March 2010. Perfusion-weighted magnetic resonance imaging (MRI) was integrated into our neuronavigator. Perfusion-weighted imaging was used as an adjunct to conventional MRI data for target determination. Conventional MRI alone was used to determine the trajectory. RESULTS: We found a linear correlation between regional cerebral blood volume (rCBV) and vessel density (number of vessels per mm(2); R = 0.64; p < 0.001). Perfusion-weighted imaging facilitated target determination in 11 cases (52.4%), all of which were histopathologically diagnosed as glial tumors. For glial tumors, which presented with contrast enhancement, perfusion-weighted imaging identified a more precisely delimited target in 9 cases, a different target in 1 case, and exactly the same target in 1 other case. In all cases, perfusion-selected sampling provided information on cellular features and tumor grading. rCBV was significantly associated with grading (p < 0.01), endothelial proliferation (p < 0.01), and vessel density (p < 0.01). For lesions with rCBV values ≤1, perfusion-weighted MRI did not help to determine the target but was useful for surgical management. CONCLUSIONS: For stereotactic biopsies, targeting based on perfusion-weighted imaging is a feasible method for reducing the sampling error and improving target selection in the histopathological diagnosis of tumors with high rCBVs.

Robotic implantation of deep brain stimulation leads, assisted by intra-operative, flat-panel CT.

BACKGROUND: There are two mandatory skills in deep brain stimulation (DBS) neurosurgery: accuracy and control. METHOD: Frame-based robotic registration was performed. Prior to insertion into the skull, the guide tube's position was checked with flat-panel computed tomography (fpCT). After registration against the pre-operative plan, we measured and corrected the robotic arm's position so that the guide tube with the micro-electrode would follow the planned trajectory exactly. We then used fpCT again to check the DBS lead's final position. CONCLUSION: The combination of intra-operative fpCT with robotised surgery provides an appropriate, user-friendly solution to the key technical challenges in DBS lead implantation.

Dual, minimally invasive fixation in acute, double, thoracic spine fracture.

BACKGROUND: We report on a dual percutaneous fixation in 2 patients with a double thoracic spine fracture. The advantages and limitations of this new approach for treating traumatic spinal fractures are reviewed. CLINICAL PRESENTATION: A 67-year-old male was admitted following a fall from a height of 3 m. A neurological examination revealed sub-T11 motor and sensory paraparesis. There were a T6 vertical body and bi-articular fracture and a T11 vertebral burst fracture with > 75% posterior wall damage. A 40-year-old male was admitted after a suicide attempt. A neurological examination revealed sub-T11 paraplegia. There were a T7 vertebral body fracture with intact posterior wall and a T11 burst fracture with > 75% posterior wall damage. SURGICAL TECHNIQUE: The same technique was used in both cases. 2 minimally invasive percutaneous fixations of the 2 fractures were performed. In a third step, we performed a T10-T12 open laminectomy. This technique helped to limit blood loss and avoid an over-long fixation. Pedicle screw targeting was optimal. 16 months later, the neurological status was normal in patient 1 and there was neurological improvement in patient 2. No secondary segmental kyphotic deformities appeared.Percutaneous fixation enables the treatment of an acute thoracic spine fracture. With appropriate presurgical planning, this technique can be applied to all thoracic vertebrae. Spinal cord injuries justify the use of laminectomy together with percutaneous fixation, in order to limit erector muscle injury and blood loss.

Surgical anatomy and surgical approaches to the lateral ventricles.

This study focuses on the surgical approaches to intraventricular tumors which have developed within the cavity of the lateral ventricle. The first section is dedicated to embryology and describes the wrapping of the telencephalic vesicles around the thalamus and the morphogenesis of basal nuclei and commissures. In the second section, the anatomy of the lateral ventricles is described, along with their arterial and venous vasculature, their relationship with the eloquent cortical areas and cortical sulci, and their relationship with white matter fascicles, especially the optic radiations. In the third part, the main surgical approaches to the frontal horn, to the ventricular atrium and to the temporal horn are detailed.

[Acute CSF changes in the mesencephalon aqueduct after subarachnoid hemorrhage as measured by PC-MRI]. / Caractérisation des perturbations du flux de LCS dans l'aqueduc du mésencéphale par IRM-CP à la phase aiguë de l'hémorragie méningée.

PURPOSE: Determining acute intracranial hydrodynamic changes after subarachnoid hemorrhage through an analysis of the CSF stroke volume (SV) as measured by phase-contrast MRI (PC-MRI) in the mesencephalon aqueduct. METHOD: A prospective study was performed in 33 patients with subarachnoid hemorrhage. A PC-MRI imaging study was performed n the acute phase (< 48 hours). CSF flow was measured in the aqueduct. The appearance of acute hydrocephalus (HCA) was then compared with data on CSF flow, and the location of the intraventricular and perimesencephalic bleeding. RESULTS: CSF analysis was performed on 27 patients, 11 of whom presented with an acute HCA. All 11 patients had an abnormal SV in the aqueduct: patients with a communicating HCA had an increased SV (n=8); and patients with a noncommunicating HCA had a nil SV (n=3). Patients with a normal SV in the aqueduct did not develop an acute HCA. Intraventricular bleeding significantly led to HCA (P=0.02), which was of the communicating type in 70% of cases. CONCLUSION: Subarachnoid hemorrhage leads to intracranial CSF hydrodynamic modifications in the aqueduct in the majority of patients. CSF flow can help us to understand the mechanism of the appearance of acute HCA. Indeed, hydrocephalus occurred - of the communicating type in most cases - even in the presence of intraventricular bleeding.

Tension pneumocephalus and rhinorrhea revealing spontaneous cerebrospinal fluid fistula of the anterior cranial base.

Spontaneous cerebrospinal fluid fistulas (CSFFs) of the anterior skull base are extremely rare. We report a case of spontaneous CSFF of the ethmoid cribriform plate presenting with rhinorrhea and tension pneumocephalus. We discuss the physiopathology, the radiological management, and the treatment of spontaneous CSF fistulas related to the anterior skull base. A 58-year-old woman was admitted to our institution for headaches with clear rhinorrhea persisting over several days. Antecedents were unremarkable. An episode of epistaxis three days before was reported. Clinical examination showed clear rhinorrhea, headaches, and anosmia. The CT scan showed voluminous epidural and subdural pneumocephalus with mass effect on both frontal and temporal lobes. A high-resolution CT scan with bone reconstruction showed a 2-mm bony defect of the cribriform plate. Surgery consisted of epidural frontal anterior skull base repair. Postsurgery follow-up was uneventful. At one year, the patient was asymptomatic apart from the persistence of anosmia. Spontaneous CSF fistulas are uncommon and can be associated with tension pneumocephalus. The physiopathology remains unclear. Their treatment by complete exclusion of the fistula is necessary because of the lethal risk of pneumococcus meningitis.

[Follicular dural lymphoma. Case report]. / Lymphome folliculaire méningé. A propos d'un cas.

A case of a meningeal B-cell lymphoma is described. A 48-year-old man presented with an episode of grand mal seizure following a brain injury. An initial diagnosis of extradural hematoma was made based on the results of the cerebral computerized tomography scan. Magnetic resonance images demonstrated an enhanced mass with a dural tail attached to the meningeal layer of the temporal bone, suggesting a meningioma "en plaque". The mass was surgically excised. Tumoral removal was subcomplete (Simpson 2). Operative inspection also suggested a meningioma, but histological analysis and electron microscopy revealed a grade IV follicular B-cell lymphoma. Biological studies were normal. An extensive workup found an external iliac adenopathy with several osseous locations on PET. The patient underwent chemotherapy and radiotherapy. Three years after the first symptoms appeared, the patient is alive and free of symptoms. The clinicopathological features and treatments were discussed.

[Giant prebulbomedullary arachnoid cyst. Case report and review of the literature]. / Kyste arachnoïdien géant prébulbomédullaire. Cas clinique et revue de la littérature.

Usual locations of arachnoid cyst are the middle cranial fossa in 50-60%, cerebellopontine angle (10%) and suprasellar area (10%). Most of these malformations are asymptomatic. Premedullar arachnoid cysts are extremely rare. All previous cases reported were operated. We report a case of an asymptomatic giant craniocervical junction arachnoid cyst with a follow up of five years. In 2002, an adolescent consulted for persistent cervical pain. Encephalic MR showed a giant ventral craniocervical junction arachnoid cyst. Neurologic examination was normal. Conservative treatment was decided with a clinical follow up and repeated MR in case of persistent cervicalgia. Craniocervical junction arachnoid cysts are anecdotic. Medical care cannot be standardized. Pathogenesis and management are discussed.

[Giant cystic widening of Virchow-Robin spaces, case report]. / Dilatations géantes des espaces de Virchow-Robin.

INTRODUCTION: Virchow-Robin spaces are very well-known anatomical and radiological entities. However, the observation of giant cystic widening of Virchow-Robin spaces is anecdotic. We report herein the case of a patient presenting with giant cystic widening of Virchow-Robin spaces located in both cerebral hemispheres. OBSERVATION: A 26-year-old female presented with numbness of left arm and then, of both arms. CT scan showed many hypodensities located in the two hemispheres. Neurologic examination was normal. MR imaging allowed the diagnosis of giant cystic widening Virchow-Robin spaces in T2, T2*, T1 gadolinium and Flair weighted images. Neuropsychological investigations were normal. CONCLUSION: Giant cystic widening of Virchow-Robin spaces are extremely rare entities. MR imaging helps the diagnosis. Only extreme dilatation of Virchow-Robin perivascular spaces close to ventricular system must be watched and treated in case of an obstructive hydrocephalus risk. When located in cerebral hemispheres, these dilatations are mostly asymptomatic and must not be confused with a cystic tumoral disease.

[Endoscopic anatomy of the terminal portion of the basilar artery and its distal perforating branches]. / Anatomie endoscopique de la terminaison de l'artère basilaire et de ses perforantes distales.

The aim of this study was to describe and highlight the endoscopic anatomy of the tip of the basilar artery and its perforating branches. Knowledges of the anatomy are crucial for neurosurgeons to avoid pitfalls during endoscopic third ventriculostomy.

[Primary intramedullary lymphoma. Case report]. / Lymphome primitif intramédullaire. A propos d'un cas.

A 66-year-old female presented primary intramedullary spinal cord lymphoma. This patient was referred for lower limbs weakness, which had developed six weeks earlier and right C5 radiculalgia. Physical examination revealed a medullary syndrome with Claude-Bernard-Horner syndrome. The diagnosis was established after MRI and biopsy (dorsal myelotomy). The patient was given chemotherapy and craniospinal adjuvant radiotherapy (30 Grays). The clinical, radiological and therapeutic features are discussed.

[Paraganglioma of the cavernous sinus. Case report]. / Paragangliome du sinus caverneux. A propos d'un cas.

A case of paraganglioma arising from the cavernous area is presented. A 51-year-old woman presented with a parasellar mass causing decreased visual acuity, oculomotor nerve paresis and retro-orbital headaches without endocrinological dysfunction. Diagnosis was confirmed by histological appearance and electron microscopy. The patient was treated with surgery followed by radiation therapy consisting of 45 Gy. The clinicopathological features and the possible pathogenesis are discussed.

[Biometric and histological study of human, porcine and sheep internal thoracic arteries (reflections on their use in revascularization of arteries of less than four millimetres diameter)]. / Etude biométrique et histologique comparative des artères thoraciques internes de l'homme, du porc et du mouton (application en chirurgie de revascularisation des artères de moins de quatre millimètres de diamètre).

In order to enhance the knowledge of the internal thoracic arteries of pig, sheep, and man, allowing to constitute a fundamental basis as for the current and later applications in the interventions in surgery of revascularization of the arteries of less than four millimetre of diameter, a biometric and histological comparative study of these arteries was carried out. Forty human corpses, 27 men and 13 women (mean age 75+/-6 years) were dissected, alike with three pigs respectively weighing 80 kg, 80 kg and 84 kg and four sheep weighing 70 kg each. The left and right internal thoracic arteries were harvested: exposure over the entire length and remote dissection before excision. At the same time their internal lengths and gauges were measured. The internal thoracic artery (ITA) of human has an average useful length of 18 cm and an average internal gauge close to 1.5 mm. ITA of the pig has an average length of 27 cm and an average internal gauge close to 2.8 mm. The ITA of the sheep has an average length of 18 cm with an average internal gauge close to 1 mm. The porcine Internal Thoracic Artery is an elastic artery like its human counterpart. Many elastic fibres and few smooth muscle cells are present in the media. On the other hand, the internal thoracic artery of the sheep has a mixed structure. Its media contains more smooth muscle cells than elastic fibres.

[Surgical anatomy of spinal cord tumors]. / Anatomie chirurgicale des tumeurs de moelle épinière.

In this article, we respectively describe the morphology of the spinal cord, spinal meningeal layers, main fiber tracts, and both arterial and venous distribution in order to explain signs of spinal cord compression. We will then describe a surgical technique for spinal cord tumor removal.

Value of phase contrast magnetic resonance imaging for investigation of cerebral hydrodynamics.

OBJECTIVE: Phase Contrast Magnetic Resonance Imaging (PCMRI) is a noninvasive technique that can be used to quantify variations of flow during the cardiac cycle. PCMRI allows investigations of blood flow dynamics in the main arteries and veins of the brain but also the dynamics of cerebrospinal fluid. These cerebral flow investigations provide a description of the regulation mechanisms of intracranial pressure during the cardiac cycle. The objective of this paper is to describe the contribution of this technique in diseases related to disorders of cerebral hydrodynamics in the light of 5 clinical cases. METHOD: Flow measurements were performed using PCMRI sequences on a 1.5 Tesla MR imager in 4 patients with symptomatic ventricular dilation and 1 patient with a syringomyelic cavity. RESULTS: Flow quantification in these 5 patients, representative of the diseases mainly concerned by cerebral hydrodynamics, is useful to guide the indication for ventricular shunting in patients with hydrocephalus, to demonstrate obstruction of the cerebral aqueduct, to demonstrate recirculation of ventricular CSF after ventriculostomy and to characterize the dynamic features of CSF inside a spinal cavity. CONCLUSION: PCMRI, now available to neurosurgeons, is complementary to morphological MR and provides quantitative information on cerebral hydrodynamics. This information is mainly used to confirm alteration of CSF flow in the cerebral and spinal compartments. PCMRI is also a functional tool to better understand the pathophysiology of hydrocephalus and syringomyelia.