[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.

[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.

[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.

Should we fear cement leakage during kyphoplasty in percutaneous traumatic spine surgery? A single experience with 76 consecutive cases.

OBJECTIVE: Although kyphoplasty is widely used to repair osteoporotic and pathologic vertebral fractures, balloon kyphoplasty and vertebral body stenting are new treatment options in cases of traumatic spinal injury. To our knowledge, there are no literature data on the incidence of cement leakage whereas these two percutaneous techniques are commonly used to repair non-pathologic fractures. The aim of this study was to evaluate and compare the clinical characteristics and the incidence of cement leakage associated with balloon kyphoplasty and vertebral body stenting in the percutaneous treatment of traumatic spinal injury. METHODS: A series of 76 consecutive kyphoplasties (50 with vertebral body stenting and 26 balloon kyphoplasties) were retrospectively reviewed. Preoperative and postoperative computed tomography scans were analyzed in order to detect cement leakage and grade it as minor, moderate or major. RESULTS: The overall leakage rate was 50%. None of the leakages gave rise to clinical symptoms. Although balloon kyphoplasty and vertebral body stenting did not differ in terms of the leakage rate, the latter technique was associated with a lower leakage volume. The Magerl type, fracture level and use of concomitant osteosynthesis did not appear to significantly influence the leakage rate. CONCLUSION: Vertebral body stenting can reduce the amount of cement leakage due to a better cohesion of the bone fragments after kyphosis correction and maintenance.

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.

[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.

[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.

[Type II proatlantal artery with unusual origin of the occipital artery feeding of a type IV dural arteriovenous fistula: case report]. / Artère proatlantale de type II avec origine atypique d'une artère occipitale alimentant une fistule artérioveineuse durale de type IV : cas clinique.

CASE REPORT: We report the case of a 49 year-old woman, who presented with an intracranial haemorrhage. During cerebral angiography investigations, we observed an unusual vertebral artery that originated from the external carotid artery and an uncommon origin of the occipital artery from the vertebral artery feeding a dural arteriovenous fistula grade IV. This rare vertebral artery origin is probably the remnant of a type II proatlantal artery. In addition, the origin of the occipital artery evoked a vascular development disease including a dural arteriovenous fistula which may be the result. These multiple vascular abnormalities could be explained by embryologic disorders.

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.

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.

[Brown-Sequard syndrom complicating a C6 teardrop fracture associate with an occult vertebral artery dissection: case report]. / Syndrome de Brown-Séquard compliquant une fracture teardrop de C6 associée à une dissection d'une artère vertébrale asymptomatique : à propos d'un cas.

CASE REPORT: We report the case of a 27-year-old man, presenting a C6 tear-drop fracture associated to medullar contusion with a Brown-Sequard syndrome. An asymptomatic right vertebral artery dissection in its V2 portion was also discovered by the radiologic investigations. A surgical treatment and antiplatelet therapy were performed. The patient outcome was quite satisfactory.

[Surgical anatomy of the lateral ventricles]. / Anatomie chirurgicale des ventricules latéraux.

The lateral ventricle is a deep-seated cavity, overlayed by a cortical mantle which contains eloquent areas, especially on the dominant hemisphere, and surrounded by the optic radiations. The surgical approach requires a thorough preoperative reflexion based on magnetic resonance imaging, in order to understand the site of origin and the vascular pedicles of the tumor. Surgical approaches to the frontal horn, temporal horn and atrium are successively described.

[Subependymomas of lateral ventricle. Analysis of our series and review of literature]. / Les subépendymomes (astrocytomes subépendymaires) du ventricule latéral. Analyse de notre série et revue de la littérature.

Subependymoma is a benign lesion, slow-growing neoplasm, representing 0.2 to 0.7 % of intracranial tumors. They are often clinically silent, incidentally discovered at autopsy. These symptoms are related to big volume. They are attached to the septum pellucidum, leading to hydrocephalus by Monro foramen obstruction. Overall mean age at diagnosis is 39 years with more males than females. At CT-scan, subependymoma shows a slightly low attenuation compared to gray matter. There is no or mild enhancement following contrast injection. On MR T1-weighted imaging, subependymoma is isointense and hyperintense on MR T2-weighted imaging. Intramural calcifications and cystic components are noted in 20 to 30 % of patients. Peritumoral oedema is absent. Immunohistochemicals studies show intense positivity for S-100 and GFAP. The treatment is surgical with an excellent prognosis.

[Meningiomas of the lateral ventricle. A series of 40 cases with analysis of the literature]. / Les méningiomes du ventricule latéral. Analyse d'une série de 40 cas et revue de la littérature.

This series reports 40 cases of meningiomas of the lateral ventricle treated in France between 1995 and 2010. The mean age was 52 years. The revelation was incidental in 23% of cases. 36 patients underwent surgery with uneventful postoperative course in 75% of them. Visual field deficits were the most frequent sequelae. In six cases, recurrences occurred during the follow-up period. The relevant series of the literature were discussed in order to precise the therapeutic strategies and the outcome.

[Rare tumors of the lateral ventricle. Review of the literature]. / Les tumeurs rares du ventricule latéral. Revue de la littérature.

Metastases of lateral ventricle (LV) are attached to choroidal plexus. Primary source is cancer of kidney. Two thirds of patients are male. Oligodendrogliomas occur in young females. Signs of increased intracranial pressure are a constant feature. These tumors are found in anterior portion of the LV with severe enhancement and clumped calcifications. Treatment is surgical. Cavernomas have a preponderance of rapid growth with a bleeding revelation. Seizures are rare. Rebleeding is frequent and justifies a surgical treatment. Schwannomas are a rare entity in which the majority of patients are very young. MRI shows calcifications, cystic components and a strong enhancement. They are limited to sporadic cases, never associated with neurofibromatosis. Arachnoid cysts are located in the atrium and/or in the occipital horn. Patients are young (mean age < 40 years). MRI demonstrates an intracystic lesion with signal intensity similar to the CSF. Best treatment is an endoscopic fenestration. Epidermoid cysts occur in third decade. These pearly tumors appear isointense or a little hyperintense on T1-weighted imaging, very characteristic. They are enhanced after gadolinium injection and appear strongly hyperintense on T2-weighted imaging. An incomplete removal with a thorough long-term follow-up is necessary. Cavernomas of LV are hyperintense on T1- and T2-weighted imaging. They have a bleeding risk of 25 to 45%. Therefore, they must be operated.

[Fundamental embryology and anatomy of the lateral ventricle]. / Embryologie et anatomie fondamentale du ventricule latéral.

The lateral ventricles are the C-shaped cavities of the telencephalon. Embryology of theses cavities is recalled as well as the immediate relationship of the frontal horn, the body, the atrium and the temporal and occipital horns.

[Ependymomas of the lateral ventricle. A series of 27 cases with review of the literature]. / Les épendymomes du ventricule latéral. Analyse de 27 cas et revue de la littérature.

Twenty-seven cases of ependymoma were collected in the French multicentric study dedicated to lateral ventricle tumors. The mean age of patients was 31,5 years. All patients underwent surgery, with complete resection of the tumor in 76% of cases. Histologic examination disclosed 23 grade 2 ependymomas and four grade 3 ependymomas. Postoperative mortality was 7%. Four patients underwent radiotherapy, and five chemotherapy. Local recurrence of the tumor occurred in seven cases, with a mean delay of 48 months. Disseminated disease within the central nervous system was found in only one patient. Median survival in all the 27 patients was 181 months, and median progression-free survival was 106 months. The relevant series of the literature are reviewed in order to precise the prognostic factors of ependymomas and therapeutic strategies.

[Arteries and veins of the lateral ventricle]. / Vascularisation des ventricules latéraux.

Tumors of the frontal horn of the lateral ventricle (LV) are only supplied by the posteromedial choroidal artery. Tumors of the body of the LV are supplied by the same artery. Tumors of the atrium of the LV with anterior extension are supplied by both posteromedial choroidal and posterolateral arteries. Tumors of the atrium with inferior extension are supplied by both anterior choroidal artery and posterolateral choroidal arteries. Tumors of the inferior horn are only supplied by anterior choroidal artery. The tumoral venous drainage is organized with three main groups of veins: a medial group, a lateral group and a choroidal group.

[Central neurocytomas of the lateral ventricle. A series of 35 cases with review of the literature]. / Les neurocytomes centraux du ventricule latéral. Analyse d'une série de 35 cas et revue de la littérature.

Central neurocytoma is the second most frequent tumor in our series of 284 lateral ventricle tumors (12%). Mean age was 32.6 years. There was a male predominance (20/35). Most frequent clinical signs were neuropsychological disturbances and intracranial hypertension. On imaging, these tumors concentrate central calcifications in more than half of cases. Main locations were frontal horn and corpus of lateral ventricle (82%). Uneventful postoperative course was recorded in 52% of cases. Immunoreactivity against neuron-specific enolase (NSE), synaptophysin, S100 protein, Microtubul Associated Protein de type 2 (MAP2) and calcineurin confirms the neuronal nature of the neoplasm. This tumor has a good prognosis. Local control after surgery is obtained in 68% of cases. Gamma knife surgery seems to be useful in cases of little volume with tumoral remnants or recurrence, when radiological appearance is well circumscribed and round-shaped.