Applications de l’arm dynamique dans la pathologie vasculaire du système nerveux central

Conventional catheter angiography (CCA) remains the gold standard for the evaluation of most intracranial vascular malformations. MRA techniques such as Time of Flight, Phase Contrast or 3D contrast-enhanced MRA, provide anatomic evaluation but without hemodynamic information. Recently developed, dynamic MRA is based on dynamic acquisition of images and image subtraction; these two principal characteristics produce images comparable to those obtained by CCA. The purpose of this review is to explain the principles, advantages and drawbacks of this technique in the evaluation of arteriovenous malformations, arteriovenous fistulas, aneurysms and venous thrombosis.

IRM des malformations de l’hippocampe dans l’épilepsie temporale réfractaire

OBJECTIVE

In some patients with temporal lobe epilepsy, recent MRI studies have revealed several morphological features indicative of discrete hippocampal malformation (HM). Its prevalence is unknown and the relationship between the HM and the origin of seizures has never been investigated. Our purpose is to define the MRI findings of this new entity and to determine its incidence in a group of patients and in a control group in order to evaluate its clinical significance.

MATERIALS AND METHODS

MR imaging findings in 97 patients suffering from medically intraceable temporal epilepsy were prospectively evaluated during the preoperative evaluation of surgical candidates. The MR-imaging protocol included oblique coronal slices perpendicular to the temporal lobes using high resolution T2 weighted (HR TSE T2), Fluid attenuated inversion recovery (FLAIR) and inversion-images. This protocol has been completed by axial FLAIR images and axial and sagittal IR images of the whole brain. Coronal HR TSE T2 images were performed in 50 healthy control subjects. Cerebral lesion and hippocampal morphology were evaluated in both groups.

RESULTS

Fourteen patients (14%) showed hippocampal morphological modification. The most frequent and specific findings were lack of visualization of the internal hippocampal (lack of linear T2 hypointensity within the hippocampus) and the abnormal shape (pyramidal, vertically oriented or globular-shaped). Other signs were: abnormal position of the hippocampus (medically located hippocampus) and vertical collateral sulcus. Cases without visualization of the internal structure of the hippocampus were considered as a complete form of HM and were correlated with temporal epilepsy. A vertical collateral sulcus was observed in some control group subjects.

CONCLUSION

Complete forms of HM could be considered as epileptogenic lesions. Nevertheless, interpretation of the incomplete form is delicate: the abnormal angle of the collateral sulcus can be encountered in healthy subjects and could therefore be considered a normal variant.

Supratentorial functional disturbances in two children with cerebellar cortical dysplasia

When evaluating children with mental retardation, subtle cerebral and cerebellar morphologic anomalies are often noted at Magnetic Resonance Imaging (MRI). Some, such as cerebellar cortical dysplasia (CCD), have been considered as subtle markers of cerebral dysgenesis. Their functional significance and their effect on brain function, remain unknown. To study supratentorial functional disturbances related to CCD we performed Positron-Emission-Tomography (PET) studies in two children with isolated CCD, in order to investigate the degree of involvement of supratentorial structures. One had developmental delay, motor disturbances and ataxia, and the other one only had mental retardation. PET studies revealed hypoperfusion and hypometabolism within the vermis, thalamus and the right striatum in one case, and hypometabolism in the basal ganglia and cerebellar deep grey nuclei in the other case. Our results could lead to a hypothesis explaining motor disturbances as well as cognitive impairment, and could suggest a pathological functional significance of CCD. Nevertheless, the relationship between these findings and mental retardation needs further investigation.

Imagerie vasculaire non invasive et malformations artérioveineuses cérébrales

Imaging evaluation of cerebral arteriovenous malformations (AVM) requires selective visualization of the different compartments of the malformation in order to select the therapeutic management. Conventional angiography remains the reference to analyze intracranial vessel conspicuity but non-invasive methods constitute an excellent alternative. Among these techniques, CT angiography is rarely used because of the need to inject iodinated contrast material and because of irradiation. MR angiography provides useful information and can be performed using several techniques: time of flight with or without contrast material injection, phase contrast, three-dimensional (3D) gradient echo acquisition after contrast material injection and, more recently, MR digital subtraction angiography. The purpose of this review article is to summarize the different non-invasive techniques for vascular imaging and to analyze the usefulness of these techniques for the assessment of brain AVMs.

Spinal cord infarction: clinical and magnetic resonance imaging findings and short term outcome

BACKGROUND

Most studies on spinal cord infarction have been conducted in single centres; they usually consisted of case reports, or of larger series of patients recruited over a large period of time, with heterogeneous diagnostic procedures. Therefore, the clinical and radiological presentation of spinal cord infarcts and their short term outcome remain poorly understood.

OBJECTIVE

To define clinical and magnetic resonance imaging (MRI) findings, and short term outcome in patients with spinal cord infarcts.

METHODS

The authors prospectively included patients within 10 days of onset. An MRI scan was required and repeated when initially normal.

RESULTS

Twenty eight consecutive patients were included over a 24 month period in 16 neurological centres. The infarct was cervical in seven patients, thoracic in three, thoracolumbar in 15, and restricted to the conus in three. On axial MRI scans the infarct was located in the central territory of the anterior spinal artery in 21 patients, and in the peripheral arterial territory in three. At month two, 15 patients had a good outcome and 13 had a poor outcome, including three deaths. Patients who, at onset, could not walk, had bladder dysfunction, or proprioceptive deficits were more likely to have a poor outcome. At month two, pain had occurred in 10 of the 25 survivors and was associated neither with the initial severity, nor the extent of the infarct on MRI.

CONCLUSION

The two month outcome mainly depends on the initial severity of the neurological deficit; however, a few patients with a severe impairment at onset had a good outcome, especially when proprioception remained normal at onset. The study does not support the hypothesis that pain occurs more frequently in small spinal infarcts.

Les urgences neurologiques

Neurological symptoms are a very frequent cause of consultation in emergency units and require consultation with neurologists and neuroradiologists. The most frequent diagnoses are stroke syndrome, seizure, headache, confusion, meningitis and meningo-encephalitis, and facial palsy. The morbidity and mortality of neurological emergencies are strongly related to prompt medical management of the patients which often requires neuroimaging studies. The most common neurological emergencies will be reviewed.

Céphalées dans un contexte d’urgence

Headaches constitute one of the most frequent reason of consultation. Their causes are extremely varied. The first step consists in the analysis of the characteristics of the pain and the associated signs in order to distinguish primary and secondary headaches. Primary headaches, including migraines and tension-type headaches are the most frequent types and do not require imaging evaluation. Secondary headaches are related to an organic cause and require specific investigations. In case of suspected symptomatic or secondary headaches, brain imaging plays an important role in the etiologic work-up. The main purpose of imaging in an emergency setting is to diagnose a life-threatening disease.

Dysplasie du cortex cérébelleux : aspects en IRM et signification

Because it is now possible to obtain high-resolution multiplanar MR imaging of the cerebellum and because of the developing interest on the role of the cerebellum on higher brain functions, we have decided to study the process of cerebellar fissuration. All brain MRI examinations performed in children for varied neurological and neurosurgical indications, especially children with non-specific mental retardation and patients with cerebral malformation detected at initial imaging work-up, were reviewed. Fissuration and lobulation anomalies (abnormal orientation of fissures, pseudopolymicrogyria, cortical thickening, subcortical cysts and heterotopia) were identified that we called cerebellar cortical dysplasia (CCD). In order to better understand the origin of this malformation, current data on cerebellar embryogenesis and histogenesis will be reviewed, and the pathological and radiological features will be illustrated. Milder forms of CCD represent a distinct group of anomalies that should be distinguished from other types of cerebellar dysplasia (agenesis, hypoplasia or complex dysplasia with involvement of the cerebellar vermis (rhombencephalosynapsis)) or combined cerebellar and cerebral dysplasia (muscular dystrophies and lissencephaly). Recognition of cerebellar cortical dysplasia could be a first step towards a broader understanding of its pathogenesis and significance.

[Neuromeningeal tuberculosis: the contribution of genetic amplification to diagnosis]

Neurological manifestations of tuberculosis are rare, especially in immunocompetent subjects. The heterogeneity of clinical and radiological features induces frequently a delay for diagnosis. The aim of the study was to describe clinical and radiological presentation of 11 cases of neuro-tuberculosis and to evaluate clinical outcome. We performed clinical, CSF, MRI and outcome evaluation in all patients. We also performed a mycobacterium analysis by polymerase chain reaction (PCR). Patients were 6 men and 5 women with a mean age of 45.4 years. Clinical presentations were meningeal symptoms in 9 cases and focal manifestations in 4 cases. CSF was abnormal in 82 p.cent of cases (protein increase in 73 p.cent, pleiocytosis in 73 p.cent, hypoglycorrhachia in 45 p.cent and hypochlorrhachia in 36 p.cent). The best diagnostic test was PCR (positive in 45 p.cent of cases). CSF cultures were positive in only 2 cases (18 p.cent). Only 2 patients had chest involvement. MRI was abnormal in 64 p.cent of cases showing pseudo-tumor, arachnoiditis, vascular lesions or medullar involvement. Outcome was good in all cases but two (one patient died and one patient had paraplegia possibly related to late diagnosis). Neurological manifestations of tuberculosis are extremely various in terms of clinical and radiological presentation. The best diagnostic test seems to be tuberculosis PCR. Outcome is frequently favorable if late diagnosis is avoided.

Endovascular treatment of remnants of intracranial aneurysms following incomplete clipping

We report clinical and angiographic findings in eight patients treated by the endovascular approach for an intracranial aneurysm remnant after incomplete surgical clipping. They were seven women and one man, mean age 38 years (range 14-50 years). In three, the remnant was responsible for a recurrent subarachnoid haemorrhage. All were treated by embolisation of the remnant using Guglielmi detachable coils. In two, a nondetachable balloon was inflated in front of the remnant during coil detachment because of a wide neck. Mean clinical and imaging follow-up was 19 months (range 12-24 months). Immediate angiography showed complete occlusion of the remnant and follow-up clinical examination showed good or excellent recovery in all patients. Imaging follow-up confirmed persistent occlusion of the remnant in all cases.

[A critical appraisal of diagnostic imaging techniques in asymptomatic carotid stenosis]

Asymptomatic stenosis of the internal carotid artery requires a non-invasive imaging work-up. The objectives include the quantification of the degree of stenosis, the analysis of the atherosclerotic plaque and the consequences of this stenosis on the brain tissue. Previous studies showed the reliability of MR angiography and spiral CT for the assessment of the arterial lumen. However, the consensus is based on the association of ultrasonography and MRA because of the non-invasive approach of these examinations that allow a complete evaluation of both the extracranial and the intracranial vessels. Recent advances in MRI will probably allow to simultaneously analyze the arterial wall in order to detect the plaques at risk and to optimize the therapeutic approach.

Ischémie médullaire

Traditional data and recent advances in the field of spinal cord ischemia are reviewed, with special attention to clinical and radiological features, as well as underlying etiology, outcome, and pathophysiology. Acute spinal cord ischemia includes arterial and venous infarction and global ischemia resulting from cardiac arrest or severe hypotension. MRI has become the technique of choice for the imaging diagnosis of spinal cord infarction. Correlation of clinical and MRI data has allowed diagnosis of clinical syndromes due to small infarcts in the central or peripheral arterial territory of the spinal cord. Diffusion-weighted MR imaging may increase the sensitivity and specificity for diagnosis of acute spinal cord infarction. Diagnosis of venous spinal cord infarction remains difficult. As for global ischemia, neuropathological studies demonstrated a great sensitivity of spinal cord to ischemia, with selective vulnerability of lumbosacral neurons. Chronic spinal cord ischemia results in a syndrome of progressive myelopathy. The cause is usually an arteriovenous malformation. Most often, diagnosis may be suspected on MRI, leading to diagnostic, and eventually therapeutic, spinal angiography.

Angioplasty and stenting for high-grade internal carotid artery stenosis: safety study in 39 selected patients

BACKGROUND

Carotid angioplasty and stenting (CAS) is sometimes used as an alternative to surgery, despite the lack of evidence for its safety and efficacy.

METHOD

Over a 33-month period, 39 consecutive patients with a stenosis >/=70% underwent CAS (4 in a randomized trial and 35 because of contra-indications for surgery).

RESULTS

In 5 patients (13%; 95% CI: 3-23), a major complication occurred (3 disabling ischaemic strokes, 1 myocardial infarction, 1 acute interstitial nephropathy). In 7 patients (18%; 95% CI: 6-30), a minor complication occurred (5 transient ischaemic attacks, 1 transient confusional state, 1 non-disabling ischaemic stroke).

CONCLUSION

CAS cannot be considered as a routine procedure and should be restricted to high-risk patients unfit for surgery.

Percutaneous transluminal angioplasty of proximal vertebral artery stenosis: long-term clinical follow-up of 16 consecutive patients

We report long-term (average 30 months) clinical and radiological follow-up of 16 consecutive patients with uni- or bilateral proximal vertebral artery stenosis who underwent percutaneous transluminal angioplasty (PTA), without stenting, between 1995 and 1998. Assessment was performed by an independent neurologist. All patients but one remained asymptomatic during follow-up; moderate restenosis was observed in four. PTA of the proximal vertebral artery is safe but in the absence of knowledge of the natural history of atherosclerotic vertebral artery stenosis, whether it is beneficial or not remains unproven. The decision as to whether to perform this procedure is individual.

[Imaging of non-traumatic intracerebral hematoma]

Intracerebral hematoma is mainly due to the spontaneous rupture of small vessels damaged by chronic hypertension or amyloid angiopathy. In some cases, intracerebral hemorrhage may be associated with a vascular malformation, a tumor, venous thrombosis or hemorrhagic transformation of a cerebral infarct. The objective of brain imaging is to identify the hematoma according to its different stages and to find a potential underlying cause because of the risk of recurrence and the possibilities of treatment. In emergency, a diagnosis of hematoma may be obtained by CT scan or MRI but the etiologic work-up requires early MRI. According to the patient's age, the medical history and the location of the hematoma, it may be necessary to perform conventional angiography in order to exclude an intracranial vascular malformation. The aim of this review is to detail the different aspects of intracerebral hemorrhages and to discuss the main causes that can be found at brain imaging.

Prospective study of patients presenting with acute partial transverse myelopathy

BACKGROUND

The clinical and radiological characteristics of myelopathy in multiple sclerosis (MS) are relatively well known. Nevertheless, it remains difficult for the clinician to ascertain conversion to MS after a first episode of acute partial transverse myelopathy (APTM).

OBJECTIVE

The aims of this study were to define predictive factors for conversion to clinically definite MS after an APTM and to define predictive factors for disease severity.

PATIENTS AND METHODS

Between 1994 and 2001, we prospectively included 55 patients presenting with a first episode of APTM. Three patients were lost during the follow-up. We evaluated clinical signs, spinal cord and brain MRI, cerebrospinal fluid (CSF) and visual evoked potentials on admission. After a mean followup of 35 months (range 12-86), we evaluated the diagnosis and, among the MS group, the severity of the disease.

RESULTS

Of the 52 APTM patients who completed the study, 30 became clinically definite MS. The predictive factors for conversion to MS were: initial sensory symptoms, latero-posterior spinal cord lesion, abnormal brain MRI and oligoclonal bands in CSF. In the MS group, the number of spinal cord lesions on MRI was the only predictive factor for a poor outcome, being statistically correlated with a higher number of relapses.

CONCLUSION

On the basis of our results, we propose that, in patients with APTM, sensory symptoms, oligoclonal bands and brain MRI are predictive factors for subsequent conversion to clinically definite MS and that within the latter patients the number of spinal cord lesions on MRI is the only predictive factor for a poor outcome.

[Subdural hematomas in children: role of cerebral and spinal MRI in the diagnosis of child abuse]

PURPOSE

To determine if the presence of multiple subdural hematomas (SH) of varying signal intensities at MRI was suggestive of repeated injuries allowing a diagnosis of non accidental head injury (NAHI).

MATERIAL AND METHODS

We included 13 patients (9 boys/4 girls; mean age 15.3 weeks) with suspected NAHI and bilateral SH. Six patients had MRI during acute admission (first week) and seven patients between 10 and 30 days after head trauma (mean 12.6 days). A total of 8/13 patients had spinal MRI. We assessed the distribution and signal intensity of SH, brain, epidural and spinal cord abnormalities. Our findings were compared to medico-legal investigations in 7/13 patients to evaluate the correlation between the age of SH on MRI and the date of injuries.

RESULT

Lesions detected included cerebral edema, ischemia, contusions and cranio-cervical axonal injury and 2/8 patient had spinal epidural hematomas. Multiple SH with varying signal intensities were seen. The commonest location was the frontoparietal areas (100%) and suboccipital region (77%). In 5/6 cases, MRI during the acute admission revealed multiple and small SH having the same signal intensity. When MRI was performed later multiple SH of varying signal intensity were found in 54% of cases. We found a good correlation between the age of the SH and the date of suspected injuries in all cases. Nevertheless, in 5 patients, other SH of various ages were present suggesting rebleeding.

CONCLUSION

Our findings confirm the value of MRI in the detection of brain and spinal cord lesions and SH of varying signal intensities in non accidental head injury. MRI is not able to predict whether different signal intensities correspond to spontaneous repeated bleedings or repeated injuries. The presence of these lesions without clinical evidence of accidental trauma justifies a medico-legal evaluation to confirm the diagnosis of child abuse and to protect these patients.

Giant aneurysms of the internal carotid artery: endovascular treatment and long-term follow-up

We report the long-term follow-up of 18 patients with giant aneurysms of the internal carotid artery (ICA) referred for endovascular occlusion of the parent vessel. There were 10 aneurysms involving the infra- and/or supraclinoid cavernous segment, six the ophthalmic segment, one the petrous segment and one the bifurcation. One patient who did not tolerate test occlusion was treated medically. Clinical and imaging follow-up were obtained in 16 patients for a mean of 30 months, range 6-80 months. Endovascular treatment led to excellent clinical outcome in 16 patients. One 34-year-old woman, who presented with subarachnoid haemorrhage (SAH), died from bilateral middle cerebral artery infarcts due to severe vasospasm 4 days after treatment. The patient treated medically died from SAH. Long-term imaging follow-up in 16 patients revealed a markedly smaller aneurysm sac in all cases.

[Neurenteric cyst: an unusual congenital malformation of the spinal canal]

Neurenteric cyst is a rare congenital anomaly, which is included in the split notochord syndrome. The cyst arises from abnormal persistence of the neurenteric canal at about three weeks of gestation. The most common locations are extramedullary intradural. They can extend anywhere along the neuraxis. The intermittent, polymorphic and misleading clinical symptoms may result in a delay in diagnosis. Magnetic resonance imaging is the gold standard in the diagnosis of this anomaly. Surgical treatment allows total recovery in most cases.