[Craniopharyngioma in children: MRI study of 43 cases]. / Les crAniopharyngiomes de l'enfant.

BACKGROUND AND PURPOSE: Craniopharyngiomas are intra-cranial tumors, relatively frequent in children, expanding in the pituitary stalk axis, from the third ventricle to the sphenoid body. Plain films and CT scan generally show a calcified lesion, deforming the sella turcica. MRI improves tumor description and topographic and structural analysis of the lesion. The aim of this study is to analyze the MRI aspect of craniopharyngiomas in a pediatric population and to correlate findings with surgical data. METHODS: MR and CT studies of 43 pediatric cases of histology-proven craniopharyngiomas were reviewed retrospectively. Tumor emergence, extensions and signal on different sequences were recorded. We searched for radio-surgical correlations. RESULTS: Craniopharyngiomas can be classified into two groups: intra-sellar tumors and third ventricle floor tumors (infundibulum and tuber cinereum). Preferential routes of extension are observed in each group correlated with consistency (cystic and/or solid). Surgical data confirmed these results. CONCLUSIONS: MRI is crucial for the pre-therapeutic evaluation of craniopharyngiomas allowing not only a detailed description of the tumor but also guiding therapeutic decisions. This series demonstrated that craniopharyngiomas exhibit two different types of localization and behavior. Embryonic development of the tumor explains the topographical differences.

Schizencephaly: correlation between the lobar topography of the cleft(s) and absence of the septum pellucidum.

The bipolar defects observed in schizencephalies-clefts in the hemispheric mantle on the one hand, absent septum pellucidum on the other--without any anatomic or functional continuity suggest that there is some sort of common specific vulnerability of both structures. A study of the correlation between lobar location of the clefts and involvement of the septum pellucidum was undertaken, considering the hypothesis that the septum pellucidum is the portion of a "medial medullary velum" that corresponds to the frontal lobe, while the psalterium would correspond to the parieto-occipital lobe and the fimbria corresponds to the temporal lobe. This retrospective study of 16 cases of schizencephaly properly investigated by MR discloses a perfect correlation, all cases with absent septum pellucidum having clefts into the frontal lobe, all cases with present septum pellucidum having clefts in the parietal, temporal, and occipital lobes, and only the few instances (3 cases) of overlapping findings being characterized by clefts in the central area, where the distinction between posterior frontal and anterior parietal lobes is uncertain because of the cortical dysplasia related to the clefts. Partial defects of the septum also proved to correlate closely, topographically, with the location of the clefts. Therefore, the facts confirm a segmental organization of the mantle and septal defects, suggesting a developmental rather than a destructive mechanism, which could at least be related to a segmental pattern of selective vulnerability.

[Advances in the contributions of imaging to stereotaxic localization of cerebral arteriovenous malformations for radiosurgery ]. / Evolution des données d'imagerie dans le repérage stéréotaxique pour la radiochirurgie des malformations artério-veineuses cérébrales.

Historically, angiography was one of the first diagnostic methods to allow for visualization of neurovascular structures. It has been and still is very useful for precise evaluation of vascular pathology and is one of the main elements in treatment planning for radiosurgical targets. It is the only imaging method that gives insight into the angioarchitecture of a cerebral arteriovenous malformation, possibly reducing the target volume. Construction of frames (Leksell, Fisher) that are compatible with cross-sectional imaging methods, such as CT and MRI allowed there use for planning of stereotactical treatment for brain cerebral arteriovenous malformations. The advantages of these methods are given by the fact, that they are less invasive and that they allow visualization of neurovascular structures and surrounding cerebral structures. Further evolution of the cross-sectional imaging techniques allowed reconstruction of the image data in different planes and segmentation of structures such as vessels. Use of special algorithms allow visualization of the image data, i.e. surface rendering with 3D images of vascular structures. However, such images allow no detailed insight into the angioarchitecture of a cerebral arteriovenous malformation and give rather a view of the whole volume, i.e. a "tumor" aspect of the cerebral arteriovenous malformation. Similar images are currently also obtained with digital substraction angiography using rotational image acquisitions and image postprocessing allowing 3D reconstruction of angiographical image data. The different image evaluation methods are thus complementary all giving useful information for treatment planning. Therefore it would be useful to develop the possibility to integrate the information obtained by these modalities. Image fusion require identification of fiducial marks, what can be performed with application of external marks or by using internal anatomical marks. Recent developments allow now use of vascular structures as fidiucial marks to obtain image fusion. This paper reports on the evolution of stereotactical planning, performed on 541 patients over a period of eight years.

[Gamma-knife radiosurgery for brainstem arteriovenous malformations. Preliminary results]. / Traitement radiochirurgical gamma-knife des malformations artério-veineuses du tronc cérébral. Résultats préliminaires.

BACKGROUND AND PURPOSE: Microsurgical resection have the advantage to be immediately effective according to bleeding risk and is the reference treatment for cerebral arteriovenous malformations. For cerebral arteriovenous malformations located in the brainstem gamma-knife radiosurgery due to its low invasivity is classically a first line treatment. We reviewed the Marseilles experience to assess the efficacy and safety of gamma-knife radiosurgery for brain stem arteriovenous malformations. METHODS: We analyzed retrospectively data of 45 patients with an arteriovenous malformation located in the brain stem treated in Marseilles by gamma-knife radiosurgery by between 07/92 and 12/99. Mean age was 42 years, there were 5 children. Arteriovenous malformations were located in the pons or midbrain for the majority of the patients. Intraaxial lesion was found in 82% of patients. Hemorrhage prior to radiosurgery occurred in 75% of the patients. Gamma-knife procedure was the first treatment of the arteriovenous malformations for 29 patients (65%); previous surgery was performed in 34 patients (15%). Mean nidus volume was 550 mm(3) (32-14 196 mm(3)). Mean margin dose was of 23 Gy (range 15-30 Gy). Follow up was available for 25 patients (mean 18 months). RESULTS: One patient presented a transient worsening of his neurological status, and 2 patients developed a fixed deficit. Two patients underwent rebleeding at an interval of 12 to 36 months after the gamma-knife procedure. At last angiographic follow-up (13 patients), the obliteration rate was 82% of the arteriovenous malformations. A second procedure was proposed to a patient with only partial occlusion at 3 years. CONCLUSIONS: Gamma-knife radiosurgery can achieve good obliteration rate of brain stem arteriovenous malformations with low morbidity and may be a valuable first-choice therapy for such arteriovenous malformations. A larger population and longer follow up are mandatory in order to confirm these preliminary results.

Developmental dyslexia: atypical cortical asymmetries and functional significance.

Using brain magnetic resonance imaging, we measured in 16 young developmental dyslexic adults and 14 age-matched controls cortical asymmetries of posterior language-related areas, including Planum temporale and parietal operculum cortical ribbon, and of the inferior frontal region related in the left hemisphere to speech processing. In addition, we assessed the sulcal morphology of the inferior frontal gyrus in both groups according to a qualitative method. The dyslexic subjects also performed specific tasks exploring different aspects of phonological and lexical-semantic processes. Results showed that: (1) contrary to most results reported in the literature, there is a lack of any morphological difference relative to Planum temporale asymmetry between the two groups; (2) there are significant differences between dyslexic and control subjects relative to frontal areas; (3) concerning the parietal region, there is a more asymmetrical pattern towards the left side in dyslexic subjects than in controls; and (4) relations in dyslexic subjects between parietal asymmetry coefficient and the level of performance in a phonological task have a particular reliance on verbal short-term memory, frontal asymmetry and performance in a non-word reading task. Considering these results it is suggested that phonological segmentation skills may relate to frontal lobe morphology, while phonological memory-based impairment in people with dyslexia may rather relate to parietal lobe morphology.

Pineal region tumors: the role of stereotactic radiosurgery.

Between July 1992 and August 1995, 11 patients with pineal region tumors (PRTs) were treated at our center. Ages ranged from 8 to 72 years (median 21). Diagnosis was confirmed by histological examination in 7 patients. The remaining cases had strong neuroradiological and marker evidence of the diagnosis, so that a stereotactic biopsy could be avoided. The pathological diagnoses were pinealocytoma (n = 1), tectal astrocytoma (n = 1), germinoma (n = 2), pinealoblastoma (n = 2), and meningioma (n = 3). The marginal dose of these tumors ranged from 12 to 18-20 Gy. Conventional external radiotherapy was never used in this series. With a median follow-up of 12.3 months (range 2-34), all tumors responded to treatment and disappeared or ceased growing. We observed no mortality or major morbidity. One patient (tectal astrocytoma) had a mild radiation-induced reaction, with headache and transient worsening of an abducent nerve palsy, which were controlled with steroids. In germinomas and pinealoblastomas, recovery of normal cerebrospinal fluid circulation was observed in less than 7 days, in parallel with major tumor shrinkage. In this study we confirm that radiosurgery can be an effective and safe alternative for the treatment of pinealocytomas and low-grade tectal gliomas. Moreover, we consider that the characteristics of the radiosurgery technique suggest the method should be evaluated for the treatment of malignant PRTs.

[Paralytic pontine exotropia disclosing endocarditis]. / Exotropie pontique paralytique révélatrice d'une endocardite.

A case of bacterial endocarditis complicated by paralytic pontine exotropia is reported. Magnetic resonance imaging clearly showed a rostral lesion of the paramedial pontine reticular formation and the medial longitudinal fasciculus. The occurrence of paralytic pontine exotropia is suggestive of ischaemia, and patients with this so-called "one-and-a-half syndrome" associated with signs of infection should be investigated for endocarditis.

Value of MRI in the morphological evaluation of tumors of the third ventricle.

The detection or suspicion of a tumoral expansive process in the third ventricule is usually performed by MRI. The contribution of MRI to the diagnosis is unquestionable in view of its accuracy in the topographical characterization of these lesions and in the detection of small formations. The great histological variety of tumours in that region may result in different treatments which can be associated. MRI, therefore, plays an important role in pretherapeutic morphological evaluation. Fifteen patients with tumour of the third ventricle were examined by MRI before treatment. The results of these examinations were compared with the pathological data and the therapeutic procedures: ventricular shunting, stereotactic needle biopsy, radio- or chemotherapy and surgery. MRI cannot provide a formal histological characterization, but it can individualise some categories of tumours, give details on the walls of the third ventricle (notably in the case of bifocal pineal and suprassellar lesions), visualize the paths of CSF flow and predict the need for cisternoventriculostomy, and detect venous structures in the vicinity of the great cerebral vein which might result in post-biopsy and post-surgery complications.

Embolization of an intraparotid false aneurysm of the external carotid artery: case report.

A case of posttraumatic false aneurysm of the terminal part of the main external carotid artery involving the entire parotid gland is presented. Embolization with two microcoils allowed immediate thrombosis of the false aneurysm. The lumen of the external carotid artery remained open. Facial paralysis resolved. The atypical clinical presentation and the therapeutic steps in such a case are described.

[Hemichorea in acquired immunodeficiency syndrome. Toxoplasmosis abscess in the striatum]. / Hémichorée au cours du syndrome d'immunodéficience acquise. Abcès toxoplasmiques dans le striatum.

Three HIV seropositive patients presented with cerebral toxoplasmosis which was treated by anti-infectious agents. After partial improvement, they developed hemichorea related to striatal infectious lesions. In AIDS patients with cerebral toxoplasmosis, autopsy series have reported a high incidence of basal ganglia abscesses, explaining the occurrence of involuntary movements such as hemichorea.

[Colloid cysts of the third cerebral ventricle. Computed x-ray tomography, MRI and stereotaxic puncture. Apropos of 9 cases]. / Kystes colloïdes du 3e ventricule. Scanner, I.R.M. et ponction stéréotaxique. A propos de 9 observations.

The authors report their experience with Colloid Cysts of the third ventricle (9 cases treated between 1983 and 1989). Eight of them were punctured using stereotactic approach; five cysts were completely evacuated and the patients are free of recurrence. In three cases, tapping was impossible or the cyst insufficiently evacuated and the patients were secondary operated on (open microsurgical approach). The last case was directly operated on. Colloid cysts cured by stereotactic puncture were all hypo or iso-dense at C.T. scan and had a diameter of more than 1 cm. All these cases have had a M.R.I. exploration and the image of the cyst was always the same increased T1 and T2 signal. Unfortunately, we did not have the opportunity to realize M.R.I. in colloid cysts of a small size and hyperdense at C.T. scan. These results can help to the indication of a stereotactic puncture at the first attempt in some well defined colloid cysts.

[Stereotaxic guidance in open surgery of the brain]. / Guidage stéréotaxique de certaines interventions à crâne ouvert.

The authors describe the technique used to precisely locate, before surgical ablation, small superficial or deep seated intracerebral lesions. When they are superficial, a burrhole is placed above the lesional site, that is reconstructed by superimposing the CT image onto a plain film radiogram taken during stereotaxy. Deep seated lesions are localized by inserting a guide under stereotaxy, prior to open surgery, which will lead the neurosurgeon without error from the cortex to the lesion. 37 observations are reported where this technique lead to a greatly simplified intervention with minimal cortical damage.

[Modern imaging and stereotaxy]. / Imagerie moderne et stéréotaxie.

The authors present their technique of utilization in stereotaxic neurosurgery of CT and IRM documents realized in standard condition. Besides, they present an original apparatus that allows to combine the advantages of Leksell and Talairach's stereotaxic system.

[Stereotaxic biopsies (SB) of intracranial neoplasms. Considerations apropos of 3,052 cases]. / Les biopsies stéréotaxiques (BS) des néoformations intra-crâniennes. Réflexions à propos de 3 052 cas.

On May 12th 1984 a meeting on stereotactic biopsies of intraencephalic lesions has been held in Marseilles. All French Neurosurgeons and Neuropathologists involved with this technique were present. This report presents, in one hand, the result of an investigation on 3 052 BS and, in the other hand, the synthesis of discussions held on the limits and dangers of the BS, morphology of the biopsy instrument, means of the definition of the target and the microscopic histologic technics and results.

[The role of stereotaxic biopsy in the therapeutic approach to malignant gliomas (author's transl)]. / Place de la biopsie en condition stéréotaxique dans la tactique thérapeutique des gliomes malins.

Analysis of 770 biopsies of intra-cerebral neoplasms under stereotaxic conditions and performed in Bordeaux, Rennes and Marseilles. The study emphasized the relative benign nature of this examination (1% deaths, 1.4 % severe sequellae) bearing in mind the severity of the underlying disease. In a very large number of cases (from 7 to 38% according to Schools) the diagnosis made before biopsy was fundamentally altered by this examination. The quasi-certitude of the nature of the lesion, and the possible facilitation of surgery by the precision of the lesional topography, and finally the possibility of a therapeutic gesture of evacuation in certain cases, is felt to justify intra-cranial biopsy performed under stereotaxic conditions.

Prolactin secreting adenoma in 22 men.

The authors report on 22 men with a prolactin secreting adenoma. Clinical symptomatology included associated signs of tumoral compression with varying degrees of hypogonadism. Endocrinological evaluation disclosed hyperprolactinemia in all cases but one, and hypopituitarism in 10 of 22 cases. Of the 22 patients, 21 underwent transsphenoidal microsurgery (two of whom underwent a second procedure by the infrafrontal approach) and in one case surgery was performed by the infrafrontal route. Diagnosis was confirmed by immunocytochemical evaluation of tumoral tissue. Prolactin levels returned to normal in 32% of cases after operation and became normal after complementary bromocriptine therapy in 54.5% of cases. However, normal prolactin secretion was not consistently accompanied by a return to normal of gonadotropin regulation. In three patients radiotherapy was not effective. The latter treatment should be limited to the very rare cases of postoperative resistance to bromocriptine.