Optimizing the Detection of Subtle Insular Lesions on MRI When Insular Epilepsy Is Suspected.

Insular epilepsy is underdiagnosed and accounts for a number of failed operations. Identifying insular target lesions on MR imaging can help guide intracranial electroencephalography and improve the outcome of surgery. In this study, we present a novel method of exploring the insular region for subtle lesions on 3D MR imaging by MPR postprocessing of slices in oblique reference planes. Using this method, we retrospectively reviewed presurgical MRIs that were initially considered to have normal findings in 7 pediatric patients with intractable insular epilepsy. Insular epilepsy was confirmed in these patients on stereo-electroencephalography and histopathology. The MPR postprocessing method we describe helped detect subtle insular lesions in all 7 patients.

Tumor pathology of the orbit.

The term orbital tumor covers a wide range of benign and malignant diseases affecting specific component of the orbit or developing in contact with them. They are found incidentally or may be investigated as part of the assessment of a systemic disorder or because of orbital signs (exophthalmos, pain, etc.). Computed tomography, MRI and Color Doppler Ultrasound (CDU), play a varying role depending on the clinical presentation and the disease being investigated. This article reflects long experience in a reference center but does not claim to be exhaustive. We have chosen to consider these tumors from the perspective of their usual presentation, emphasizing the most common causes and suggestive radiological and clinical presentations (progressive or sudden-onset exophthalmos, children or adults, lacrimal gland lesions, periorbital lesions and enophthalmos). We will describe in particular muscle involvement (thyrotoxicosis and tumors), vascular lesions (cavernous sinus hemangioma, orbital varix, cystic lymphangioma), childhood lesions and orbital hematomas. We offer straightforward useful protocols for simple investigation and differential diagnosis. Readers who wish to go further to extend their knowledge in this fascinating area can refer to the references in the bibliography.

Olfactory anomalies in CHARGE syndrome: imaging findings of a potential major diagnostic criterion.

BACKGROUND AND PURPOSE: CHARGE syndrome is a genetic disorder resulting in the association of multiple congenital anomalies. Although a high prevalence of olfactory anomalies in CHARGE syndrome has been reported in autopsy and functional studies, to our knowledge, such anomalies have not been included among the diagnostic criteria, and their radiographic prevalence has not been assessed. The purpose of this research was to determine the radiographic prevalence of olfactory anomalies in a small sample of subjects with diagnosed CHARGE syndrome. MATERIALS AND METHODS: The medical records and high-resolution MR images (section thickness < or =3 mm and in-plane resolution < or =1 mm) in 10 patients with clinically proved CHARGE syndrome were retrospectively reviewed by 3 neuroradiologists who consensually evaluated the status of the olfactory bulbs and sulci as either normal, hypoplastic, or absent. The prevalence (p) of congenital anomalies found in the medical records and of the olfactory structures was calculated with a 95% confidence interval (CI). RESULTS: MR imaging demonstrated olfactory anomalies in all 10 patients, including either absence or hypoplasia of the olfactory bulbs and olfactory sulci (p, 100%; CI, 0.65-1.00). CONCLUSION: These findings suggest that olfactory abnormalities detectable on high-resolution MR imaging are among the most prevalent features of CHARGE syndrome.

CHARGE syndrome includes hypogonadotropic hypogonadism and abnormal olfactory bulb development.

CONTEXT: CHARGE (coloboma, heart defect, choanal atresia, retarded growth and development, genital hypoplasia, ear abnormalities, and/or hearing loss defect) syndrome consists of a combination of congenital malformations including genital hypoplasia and retarded growth. OBJECTIVE: The objective of the study was to study gonadotropic axis function and growth parameters in CHARGE syndrome. DESIGN: This was a retrospective study. PATIENTS: The study included 32 children with CHARGE syndrome. RESULTS: Nineteen of 20 affected boys had micropenis and/or cryptorchidism, consistent with hypogonadotropic hypogonadism during fetal life. None of the boys was of pubertal age. Seven of nine boys tested before the age of 5 months during the neonatal peak period had extremely low testosterone levels. LH response to GnRH stimulation was variable during the first year of life and not correlated with existing clinical abnormalities. None of the girls over the age of 12 yr (n = 7) had begun puberty spontaneously, and a lack of response to GnRH stimulation was documented in five of them. Olfactory evaluation (n = 10) and magnetic resonance imaging (n = 18) of the forebrain revealed defective sense of smell and abnormal olfactory bulbs in all cases. Cardiorespiratory and nutritional problems were corrected, but the mean height of the 25 children who had reached 5 yr of age was -2 +/- 0.2 sd score. Height was not correlated with birth length or body mass index. GH deficiency was diagnosed in only three children. CONCLUSION: These findings suggest that CHARGE syndrome includes the main features of Kallmann syndrome, which is defined by hypogonadotropic hypogonadism combined with a defective sense of smell and abnormal olfactory bulb development. This forebrain abnormality, if confirmed in a larger group of patients, could serve as a major new criterion for the diagnosis of CHARGE syndrome.

Radiographic findings in 37 cases of primary CNS lymphoma in immunocompetent patients.

Because of the increasing incidence of primary central nervous system lymphoma (PCNSL), it is essential to recognize this disease in order to start appropriate treatment. We present the characteristic CT and MRI features of this tumour. The findings of 32 CT and 31 MR of 37 immunocompetent patients with biopsy-proved PCNSL are reviewed. The main features are presented and analysed, and are discussed in comparison with proven literature data. Primary central nervous system lymphoma presents as supratentorial solitary lesions in approximately 80% of the patients and multiple lesions in 20%. In contrast to classical data, the lesions are located in deep structures only in one-third of the cases, and involve posterior fossa in 10% of cases. Most of the lesions are hyperdense or isodense (92%) on CT, hypointense or isointense on T1-weighted images, and only about 40% are hyperintense on T2-weighted images. Nearly all the lesions enhance, except after corticosteroid administration. They produce mild oedema and mass effect. Meningeal or ventricular enhancement are rare but suggestive. Calcification, haemorrhage or necrosis are scarce. Although PCNSL in immunocompetent patients have a variable CT and MR appearance, the imaging data often suggest the diagnosis.

[Atypical cerebral lymphoma with ocular onset: report of a case]. / Lymphome cérébral atypique à révélation oculaire: à propos d'un cas.

A 72 year-old woman is hospitalized and explored in the neurological department because of dementia discovered after a vitrectomy performed to treat a relapsing chronic uveitis. MRI examination shows atypical hyperintense white matter lesions on T2 weighted images related to Lyme disease. Worsening of clinical status, despite appropriate medical treatment and apparition of enhanced nodules MR images rules out the diagnosis of lyme disease and is attributed to brain metastases. The search for primitive tumor is not contributive and a brain biopsy is performed. It discloses a B cells non-hodgkin lymphoma. This case report stresses two points: first, a lymphoma must be one of the diagnosis to evocate if imaging shows an enhancing nodule, or extensive hypersignal of the white matter, second: it emphasizes the value of vitreous analysis searching for lymphoma during chronic uveitis associated to neurological symptoms.

Angiitis of the central nervous system.

Angiitis of the central nervous system is a rare disease which may result from numerous causes responsible for the presence of inflammatory lesions of the vascular wall. These inflammatory lesions may sometimes be associated with necrosis. Cerebral vessels of all sizes may be involved. The clinical presentation is highly variable, with focal to diffuse manifestations and acute to chronic evolution. Angiography is the cornerstone diagnostic procedure, showing multiple segmental stenoses of the cerebral arteries sometimes separated by fusiform dilatations. Although suggestive, this angiographical pattern is not unequivocal and other causes must be carefully ruled out. Only cerebral and/or leptomeningeal biopsy can provide a definite diagnosis of cerebral angiitis but this invasive diagnostic procedure is not performed in the majority of cases. Among the numerous causes of cerebral angiitis, one can individualize infectious diseases, primary systemic angiitis with cerebral involvement, angiitis secondary to various systemic diseases and other miscellaneous causes such as drug abuse or neoplasm.

Dysgenesis of the internal carotid artery associated with transsphenoidal encephalocele: a neural crest syndrome?

We describe two original cases of internal carotid artery dysgenesis associated with a malformative spectrum, which includes transsphenoidal encephalocele, optic nerve coloboma, hypopituitarism, and hypertelorism. Cephalic neural crest cells migrate to various regions in the head and neck where they contribute to the development of structures as diverse as the anterior skull base, the walls of the craniofacial arteries, the forebrain, and the face. Data suggest that the link between these rare malformations is abnormal neural crest development.

Radiosurgery of cerebral arteriovenous malformations: is an early angiogram needed?

BACKGROUND AND PURPOSE: Radiosurgical treatment of arteriovenous malformations (AVMs) has slow and progressive vasoocclusive effects. We sought to determine if early posttherapeutic angiography provides relevant information for the management of radiosurgically treated AVMs. METHODS: Between 1990 and 1993, the progress of 138 of 197 cerebral AVMs treated by linear accelerator (Linac) was regularly followed by angiographic study. On each posttherapeutic angiogram ("early," 6-18-month follow-up; "intermediate," 19-29-month-follow-up; and "late," > 30-month follow-up), the degree of reduction across the greatest diameter of the nidus and hemodynamic modifications were analyzed. Each cerebral AVM was qualitatively classified into one of the following categories after early angiographic study: 0%-reduced, 25%-reduced, 50%-reduced, 75%-reduced, and 100%-reduced or "complete obliteration." Vasoocclusive progress for each category was then studied over time. RESULTS: Three (10%) of the 30 0-25%-reduced, eight (38%) of 21 50%-reduced, and 27 (84%) of 32 75%-reduced cerebral AVMs showed complete obliteration after further follow-up. The three 0-25%-reduced AVMS that went on to complete obliteration underwent very early angiography (6-7 months). Fifty-five cerebral AVMs showed complete obliteration on early angiograms (40%). In this group, more follow-up, when performed, confirmed complete obliteration in all cases (n = 17). CONCLUSION: An early angiogram is needed to predict the effectiveness of radiosurgery. Important AVM changes seen on early angiograms are highly correlated with treatment success. Moreover, no or minor changes seen on early angiograms are highly predictive of radiosurgical failure. For these patients, further treatment should be discussed promptly.

Rupture during treatment of recently ruptured aneurysms with Guglielmi electrodetachable coils.

BACKGROUND AND PURPOSE: We describe four cases of aneurysmal rupture during embolization with Guglielmi electrodetachable coils (GDCs) in an attempt to identify those aneurysms whose rupture during embolization represents a life-threatening risk; our emphasis is on emergency management, in particular, ventriculostomy. METHODS: Medical records were reviewed retrospectively for 91 aneurysms treated with GDCs 0 to 21 days after subarachnoid hemorrhage. Rupture was ascertained by the presence of extravascular effusion of contrast medium. RESULTS: Of the perforated aneurysms, two involved the anterior communicating artery, one the posterior inferior communicating artery, and one the basilar artery. Only two patients, whose aneurysms were located in the posterior fossa, had major complications (arterial hyperpressure, mydriasis, angiographically documented circulatory arrest or slowing). One of these patients died and the other improved after emergency ventriculostomy. CONCLUSION: Aneurysmal perforation during embolization may be accompanied by severe intracranial hypertension, which causes either a decrease or arrest of cerebral perfusion, the duration of which determines clinical outcome. Emergency ventriculostomy (which should be performed in the angiographic suite) is an effective means to reduce intracranial pressure. Recognition of aneurysms associated with a high risk of mortality by rupture in the course of embolization (recently ruptured small aneurysms, posterior fossa aneurysms, associated ventricular dilatation, massive cisternal hemorrhage) and use of proper logistics should ensure the effective management of this devastating complication.

Magnetic resonance angiography of giant intracranial aneurysms.

3D time-of-flight magnetic resonance angiography (3D TOF MRA) and 2D MRA with presaturation were evaluated in 18 patients with 21 giant intracranial aneurysms. 3D TOF MRA gave optimal images of proximal unruptured and nonthrombosed aneurysms. 2D MRA with presaturation was more informative in cases of distal, haemorrhagic or thrombosed aneurysms and in assessment of their components (thrombus, haemorrhage, patent residual lumen).

Cerebral arteriovenous malformations: the value of radiologic parameters in predicting response to radiosurgery.

PURPOSE: To define the morphological patterns of cerebral arteriovenous malformations (AVMs) that influence their response to radiosurgery at 2 years. METHODS: We retrospectively reviewed the yearly MR and angiographic follow-up studies in 102 patients who had radiosurgical treatment for cerebral AVMs between 1990 and 1992. Parameters studied were maximum length and volume of the nidus, position relative to the midline, anatomic structures involved, sectional anatomic location (depth within the brain tissue), angioarchitecture, and Spetzler and Martin grading. Statistical analysis determined their influence on treatment results at 2 years. RESULTS: Parameters that correlated with obliteration at 2 years were maximum length less than 25 mm, small volume, sectional location deep within brain tissue, and plexiform angioarchitecture. Ventricular and paraventricular locations correlated with nonobliteration at 2 years. CONCLUSION: This study highlights the role of two new morphological parameters in predicting the efficiency of radiosurgery in the treatment of cerebral AVMs: depth within the parenchyma and angioarchitecture. It also emphasizes the usefulness of sectional imaging in the work-up before radiosurgery.

Transient global amnesia after cerebral angiography. A case report.

We report on a case of transient global amnesia after cerebral angiography in which a nonionic contrast medium was used. The complication observed showed no evidence of any definite cause.

Measurement of liver blood volume using a macromolecular MRI contrast agent at equilibrium.

Liver regional blood volume (LRBV) is altered by several disease states and various drugs. Preliminary studies in the rat, using research MR imaging instruments at 2T and vascular contrast agents, have suggested that MRI may be used to measure LRBV. Our goal was to develop a technique for measuring LRBV using a clinical machine at 1.5 T. This study was performed in the rabbit, using CarboxyMethylDextran Gd-DTPA, a macromolecular contrast agent with a molecular weight of 158 kDa. MRI was performed at 1.5 T, in the plane of the inferior vena cava, with and without flow compensation, before contrast injection and in the steady state after injection. Accuracy and stability of LRBV measurement, over 2 h and with various doses (0.01-0.05 mmol/kg), was tested against a standard Evan's Blue dye-indicator technique. LRBV was 28 +/- 2 mL/100 g when measured by MRI with flow compensation, which is in good agreement with the literature and with the 26 +/- 6 mL/100 g, measured by the Evan's Blue dilution technique. Measurements varied less than 7% over time and less than 9% over the range of doses. LRBV was overestimated using a sequence without flow compensation especially when large doses of contrast agent were injected. This noninvasive MRI technique provides a simple method for measuring liver LRBV and offers new prospects for future physiological and pathological studies.

Radiologic anatomy of segmental agenesis of the internal carotid artery.

We report six cases of segmental agenesis of the internal carotid a. discovered in adult patients: one case of cervical segmental agenesis (no. 1), one case of cervical and petrosal segmental agenesis (no. 2), two cases of vertical cavernous segmental agenesis (nos. 3 and 4) and two cases of distal segmental agenesis, one unilateral (no. 5) and the other bilateral (no. 6). The collateral pathways observed were: the ascending pharyngeal a. which constitutes an "intratympanic course" of the internal carotid a. (no. 1), an intercarotid anastomosis (no. 2), an arterial network at the base of the skull, the so-called "rete mirabile" (nos. 3 and 4) and the posterior communicating a. (nos. 5 and 6). Recognition of these rare dysgenesis relies upon the following radio-anatomic characteristics: reduced caliber of the a., inconsistent sparing of the carotid body, reduced diameter or even absence of the carotid canal and above all, the presence of collateral pathways. The collateral pathways allow an understanding of the segmental nature of carotid a. development and a distinction between congenital and acquired stenoses.

Angioarchitecture associated with haemorrhage in cerebral arteriovenous malformations: a prognostic statistical model.

The overall haemorrhagic risk of a cerebral arteriovenous malformation (cAVM) is 2-4% per year. However, the individual risk of haemorrhage has never been determined. This study was undertaken to assess the haemorrhage risk of an individual cAVM. Neuroangiographic findings of 160 cAVM were analysed retrospectively, looking at 30 angiographic features. A statistical model was established by logistic regression to evaluate the risk of an individual cAVM. We statistically correlated 15 parameters with the haemorrhage risk. The statistical model includes five independent parameters. Four are unfavourable: exclusively deep drainage, venous stenoses, venous reflux and the radio of afferent to efferent systems; one is favourable: venous recruitment. This model quantifies the individual risk of haemorrhage. When this model is applied to the population studied, the error rate is 5%. This model can contribute to therapeutic strategy, and to a better understanding of the natural history of cAVM.

Ruptured fusiform aneurysm of the superior third of the basilar artery associated with the absence of the midbasilar artery. Case report.

A case involving the absence of the midthird portion of the basilar artery (BA) associated with a ruptured fusiform aneurysm of the superior third of the basilar artery discovered after a subarachnoid hemorrhage is reported. Surgical clipping was precluded by the anatomical conditions. The aneurysm was treated by occlusion (surgical clipping and balloon occlusion) of both posterior communicating arteries to decrease the hemodynamic stress on the aneurysm wall. The pericerebellar arterial network was allowed to supply the distal BA and its collateral vessels indirectly. This treatment proved to be efficient; angiography and magnetic resonance imaging demonstrated shrinkage of the aneurysm cavity. The absence of the midthird of the BA is usually associated with a persisting trigeminal artery (nonexistent in this case) or disclosed in cases of acute BA occlusion in dramatic clinical conditions. A similar anatomical feature has been described only once before. There may be a segmental maldevelopment of the longitudinal neural arteries during embryogenesis or a defect in fusion of these paired structures during the development of the BA itself.