Cerebellar cortical dysplasia: MR findings in a complex entity

BACKGROUND AND PURPOSE

MR imaging findings of cerebellar cortical dysplasia have been described as a new cerebellar malformation. The purpose of this study was to assess the association of cerebellar cortical dysplasia with other cerebral malformations.

METHODS

We retrospectively reviewed 46 MR examinations of patients presenting with developmental delay, hypotonia, and facial deformities to identify abnormal folia or fissures or both within cerebellar hemispheres or vermis suggesting cortical dysplasia.

RESULTS

Cerebellar cortical dysplasia was diagnosed in 17 patients. In two patients, it was isolated. In the remaining 15 patients, the malformation was associated with vermian malformation (n=11), cerebral cortical dysplasias (n=8), dysplasia of corpus callosum (n=6), and heterotopia (n=5). A widespread malformation of the posterior fossa was observed in eight patients (Dandy-Walker, Chiari II and III, and hypoplasia of brain stem). One patient with hypertrophied cerebellar hemisphere had minor enlargement of the right cerebral hemisphere and lateral ventricle. He also had nodular heterotopia, suggesting unilateral megalencephaly.

CONCLUSION

Our study suggests that cerebellar cortical dysplasias are common in cases with more widespread cerebral malformations. Technical progress providing high-quality tridimensional MR imaging of the cerebellum may explain its recent descriptions.

Cardiac repolarization abnormalities in multiple sclerosis: spinal cord MRI correlates

Ventricular repolarization dysfunction has recently been reported in multiple sclerosis (MS). We evaluated ventricular repolarization dysfunction in 52 MS patients and looked for a relationship between corrected QT (QTc) abnormalities (i.e., abnormalities of QT intervals corrected for rate) and spinal cord magnetic resonance imaging (MRI) findings. QTc intervals were increased in MS patients compared with controls (P < 0.01) and were correlated with a reduction of spinal cord area (P < 0.01). QTc abnormalities in MS were thus associated with axonal loss, reflected by spinal cord atrophy, rather than demyelination.

[Paraplegia episodes revealing tuberculous myelitis]

A 38 year-old woman, without previous medical history, presented, since 1993, several paraplegic fits carrying herself progressively through to a severe paraplegia. Diagnoses successively proposed were spinal cord compressions by slipped discs, spinal cord infarct and multiple sclerosis. In November 1998, the patient presented back pain and fever. Spinal cord magnetic resonance imaging (MRI) revealed a mildly enlarged dorsal cord with signal abnormalities. The lesions were isointense on T1-weighted images, hyperintense on T2-weighted images and showed a ringlike contrast enhancement. A lumbar puncture showed a trouble cerebrospinal fluid (CSF) with leucocytes 600/mm(3) (85 p.100 polynuclear), protein 6.7 g/l, glucose 0.26 g/l, chloride 109 mmol/l. The patient was first treated with parenteral unspecific antibiotherapy. Microbiological studies of blood and CSF were negative. CSF examination with polymerase chain reaction (PCR) was positive for Mycobacterium tuberculosis. Clinical (pain and fever) symptoms and CSF abnormalities decreased after antituberculous treatment. However, paraparesis remain severe. Spinal tuberculous localizations often lead to diagnostic and therapeutic errors. Improvement of spinal cord MRI sequences and using of PCR technics in CSF would contribute to reduce these difficulties.

Contrast-enhanced MR angiography of supraaortic vessels: the effect of voxel size on image quality

BACKGROUND AND PURPOSE

Several acquisition strategies may be used for imaging supraaortic vessels by using contrast-enhanced MR angiography. The purpose of this study was to assess the effect of voxel size on image quality of MR angiograms.

METHODS

Fourty-four patients underwent 3D MR angiography in the coronal plane. Patients were randomly assigned into two groups according to the voxel size of MR angiograms: group 1 referred to a 1.3 x 1.29 x 1.25-mm voxel size and group 2 to a 0.95 x 0.76 x 0.82 mm voxel size. Signal-to-noise ratios (SNRs) were measured and image artifacts were analyzed by consensus between observers. The delineation of the arterial lumen was independently ranked on a four-point scale (1 = not assessable; 2 = poor delineation; 3 = fair delineation; 4 = optimal delineation).

RESULTS

The overall interobserver agreement for the delineation of the arterial lumen was good (K = .84, P < .0001), with a rank significantly higher in group 2 (68% of arteries graded as 4) compared with group 1 (76% graded as 3). SNRs were significantly higher by using the conventional resolution technique, with a negative correlation between SNRs and artery delineation (P < .0001). Image artifacts, however, were more frequent with the high-resolution technique, including wrap-around artifacts and signal fall-off at the origin of the great vessels.

CONCLUSION

MR angiograms with a decreased voxel size improve the delineation of cervical carotid and vertebral arteries, despite reduced SNRs and additional artifacts.

The anatomy of aphasia revisited

OBJECTIVE

To determine lesion locations associated with the various types of aphasic disorders in patients with stroke.

BACKGROUND

The anatomy of aphasia has been challenged by several recent studies. Discrepancies are likely to be due to methodologic issues.

METHODS

We examined 107 patients with a standardized aphasia battery and MRI. Three examiners blinded to the clinical data rated signal abnormalities in 69 predetermined regions of interest. The statistical procedure used classification tree testing, which selected regions associated with each aphasic disorder.

RESULTS

1) Nonfluent aphasia depended on the presence of frontal or putaminal lesions; 2) repetition disorder on insula-external capsule lesions; 3) comprehension disorder on posterior lesions of the temporal gyri; 4) phonemic paraphasia on external capsule lesions extending either to the posterior part of the temporal lobe or to the internal capsule; 5) verbal paraphasia on temporal or caudate lesions; and 6) perseveration on caudate lesions. These analyses correctly classified 67% to 94% of patients.

CONCLUSIONS

Lesion location is the main determinant of aphasic disorders at the acute stage. Most clinical-radiologic correlations supported the classic anatomy of aphasia.

Unusual MR findings of the brain stem in arterial hypertension

MR imaging findings have been reported in only a few cases of severe arterial hypertension. We report two cases of severe paroxysmal arterial hypertension associated with unusual brain stem hyperintensity. The lesions improved dramatically after stabilization of blood pressure, suggesting that edema could be the main cause of the MR imaging-observed hyperintensity.

Recent advances in magnetic resonance angiography of carotid and vertebral arteries

New magnetic resonance angiographic sequences using gadolinium infusion allow high-quality images of supra-aortic vessels. Raw data may be obtained in a short scan time of less than 30 s, with a large acquisition volume from the aortic arch to the circle of Willis. After computed reconstruction of the vascular tree, angiograms appear similar to those obtained with conventional catheter angiography. Parameters of the sequence must be carefully chosen, however, with trade-offs between spatial resolution, scan time, acquisition volume and contrast of image. New developments have been proposed to improve the image quality with different acquisition strategies. These recent advances will probably be useful to assess the carotid and the vertebral arteries with more accuracy. They will require high-performance gradient systems and sophisticated software that is not yet available on all machines, however.

Contrast-enhanced MR angiography of the craniocervical vessels: a review

The use of MR angiography (MRA) with injection of contrast medium enables imaging of a large volume with a very short acquisition time, providing angiographic images similar to those obtained with catheter angiography. This makes possible investigation of patients in the acute phase of stroke, with examination of the entire length of the cervical arteries from the aortic arch to the circle of Willis. However, the parameters of the sequence must be carefully chosen to optimise image quality, with a compromise between spatial resolution, acquisition time and image contrast. An overview of the technical aspects is presented, including current developments. Different protocol strategies are discussed, including their advantages and limits. Finally, we review the preliminary results of contrast-enhanced MRA for assessment of atherosclerotic lesions of supra-aortic vessels.

[Clinical aspects and treatment of dural-spinal arteriovenous fistulas with perimedullary venous drainage. 10 cases]

BACKGROUND AND PURPOSE

Spinal dural arteriovenous fistulas (SDAVF) are rare but represent the most frequent spinal arteriovenous malformation. Their clinical manifestations are well known, but their management can still be discussed between surgery and endovascular treatment. The purpose of this study is to emphasize the pre-eminence of surgical management for posterior and postero-lateral fistulas, which are the most common location of the malformation.

METHODS

We report a consecutive series of 10 patients with SDAVF treated between July, 1995 and July, 1997. Results are compared with other series of the literature.

RESULTS

Clinical manifestations were not specific and the diagnosis was established in most cases only one year after the onset of symptoms, as a progressive myelopathy. Low back pain was present in 4 patients, with pseudo-radicular pain in the lower limbs suggesting spinal degenerative disease in 3 cases. At the time of diagnosis, 8 patients had permanent motor weakness of the lower limbs, usually associated with hypesthesia and sphincterial dysfunction (7 cases). In all cases, the diagnosis was established using MRI. In most cases, the intradural draining spinal veins were also visible on MRI images. The location of the SDAVF was always precised by angiography, and was located between T5 and L1 in our series. Seven patients were successfully operated on, with surgical interruption of the intradural draining vein. Three patients underwent an endovascular treatment, but two of them were operated on later, as control angiography showed recurrence of the SDAVF. The clinical status of patients always improved after treatment, but recovery was incomplete in patients with severe and long lasting neurological deficit.

CONCLUSIONS

Surgical interruption of the intradural draining vein is a safe and effective method of treatment of SDAVF, especially for posterior and postero-lateral fistulas. Endovascular treatment is recommended for anterior locations of SDAVF.

[MRI imaging in cortical laminar necrosis]

PURPOSE

The goal of this study was to follow over time the MR imaging features of cortical laminar necrosis.

PATIENTS AND METHODS

Six patients with cortical laminar necrosis were included. There were two women and four men aged 54-84 years, with a mean age of 68 years. In four patients, cortical laminar necrosis was caused by ischemic stroke, one case occurred after a cardiac arrest and the last patient had a meningoencephalitis. The time delay from insult to the first MR study varied between one week and 3 months.

RESULTS

The MRI showed hyperintense lesions in the cerebral cortex on T1W and T2W images. The high intensity signal was still observed a few months after the insult. Cortical laminar necrosis lesions did not demonstrate hemorrhage on CT and MRI studies.

CONCLUSION

MRI allowed detection of cortical laminar necrosis and could differentiate it from hemorrhage.

Preliminary experience using contrast-enhanced MR angiography to assess vertebral artery structure for the follow-up of suspected dissection

BACKGROUND AND PURPOSE

Important advances have been made recently in MR angiography with the use of contrast medium injection, which has proved valuable for the imaging of vertebral arteries (VAs) obtained during short scanning times. Our purpose was to assess the feasability of contrast-enhanced fast 3D MR angiography for imaging VAs and to evaluate the long-term follow-up of VA dissections.

METHODS

Sixteen consecutive patients with 18 angiographically documented VA dissections (seven occlusive dissections and 11 stenotic dissections, including two each with a pseudoaneurysm) were followed up using both contrast-enhanced 3D MR angiography and cervical T1-weighted MR imaging at a median delay of 22 months. Ten patients underwent MR imaging at the acute phase as well, and nine underwent early follow-up angiography at a median delay of 3 months. MR angiographic findings were determined by consensus, focussing on image quality, presence of residual stenosis, luminal irregularities, and occlusion.

RESULTS

Of the 32 VAs, a segment of the artery was not assessable on contrast-enhanced MR angiography in each of four small VAs. A central signal void artifact of cervical arteries was seen in one patient and motion artifacts were seen in two, but images could be interpreted. A venous enhancement was detected in 10 of 16 examinations, but this did not prevent image analysis. Ten of 11 stenotic dissections returned to normal, whereas one stenotic dissection progressed to occlusion. Two pseudoaneurysms detected by initial angiography resolved spontaneously; one was revealed only by delayed MR angiography, and one was detected on an early MR angiogram and proved resolved on a late MR angiogram. Of the seven initially occluded VAs, five reopened, with a hairline residual lumen in each of three.

CONCLUSION

This preliminary experience showed that contrast-enhanced MR angiography is a promising tool for imaging VAs; it allows the assessment of VA dissection changes over time. Most lesions tended to heal spontaneously, but persisting occlusion or pseudoaneurysm could be detected during the late course.

[Cerebral angiography: a study of complications in 450 consecutive procedures]

PURPOSE

To evaluate all types of complications, both minor and major, associated with modern cerebral angiography.

MATERIALS AND METHODS

A prospective study of 450 consecutive cerebral angiographic procedures is reported.

RESULTS

One patient (0.2%) died from a cholesterol embolus. In seven patients (1.6%), thromboembolic events occurred within 24 hours after the procedure, leading to transient ischemic symptoms in six and permanent hemiplegia in one. Two patients suffered from acute renal failure (0.4%). Transient cardiac arrhythmias were observed in three patients without consequence on the clinical outcome. Most complications of angiography occurred in patients referred from the neurology department for work-up of stroke syndrome.

CONCLUSION

Our results show that morbidity and mortality rates related to the angiographic procedure did not decrease in spite of major improvement of angiographic materiel. Atherosclerosis is the main risk factor for complication. Most of the complications could be avoided by appropriate selection of indications and by using non-invasive techniques such as magnetic resonance angiography or helical CT angiography.

[Neurological examination and brain computed tomography in the initial staging of non-small-cell lung cancer: a prospective study]

Brain metastases occur in 17 to 40% of lung carcinoma and 30 to 60% of brain metastases originate from a lung carcinoma. Brain metastasis directly influences prognosis and treatment of lung cancer. The aim of this study was to prospectively compare the findings of the neurological examination performed by a neurologist and results of double dose delayed computed tomography (CT DDD). The neurologist and radiologist were blinded to each other's results. Patients included had non-small-cell lung cancer (NSCLC) and were neurologically asymptomatic with no other cancer. From November 1993 to May 1996, 135 patients were included (126 men and 9 women). Ninety neurological examinations were normal, 34 suggested brain metastasis and 11 were abnormal but did not suggest brain metastasis. One hundred thirteen CTs were normal, 1 showed a brain metastasis and 11 were abnormal but did not evidence brain metastasis. The sensitivity, specificity, positive predictive value and negative predictive value of the neurological examination were 73, 79, 23 and 97% respectively. The presence of brain metastasis was directly related to tumor stage but not to age or histology. We suggest that brain CT DDD should be performed in stage IIIA, IIIB, IV whereas in stage I or II, the neurological examination is sufficient. However, a larger number of patients would be required to confirm these findings.

Endovascular treatment of ruptured intracranial aneurysms

The Guglielmi detachable coil (GDC) is an important tool for the treatment of ruptured intracranial aneuryms by an endovascular approach. This new device may be introduced under fluoroscopy into the aneurysmal sac through a microcatheter. When the coil is judged well positioned, it can be detached with accuracy by electrolytic breakdown. The procedure is completed when a dense coil packing is obtained. When vasospasm is present, papaverin infusion or angioplasty may be used by the endovascular approach as well. Best results are achieved in cases of small aneurysm with small neck. The morbidity and mortality rates in the first 200 patients treated by GDC for a ruptured intracranial aneurysm were 4% and 1.5%, respectively. Complications are generally related to rupture of the malformation by the endovascular device or to thromboembolic events. Despite these promising results, further studies using larger numbers of patients are required to determine the exact role of these procedures in patient care.

Internal carotid arterial stenosis: CT angiography with volume rendering

PURPOSE

To determine the reliability of helical computed tomography (CT) with volume rendering for evaluation of internal carotid arterial stenosis.

MATERIALS AND METHODS

In 22 patients, 44 carotid arteries were evaluated with helical CT and selective conventional angiography. CT data were displayed on volume-rendered and maximum intensity projection (MIP) images. Stenoses were measured separately on axial, volume-rendered, and MIP images and on conventional angiograms. Each artery was then graded as having no stenosis, mild (< 30%) stenosis, moderate (30%-70%) stenosis, severe (> 70%) stenosis, near occlusion, or occlusion.

RESULTS

One case of stenosis was not assessable at axial CT because of an inappropriate scanning plane; four cases were not assessable at MIP CT because of mural calcifications. All carotid arteries were assessable on volume-rendered images despite no depiction of the residual lumen at the site of narrowing in three cases of near occlusion. Correlations between angiography and helical CT were good. Axial, volume-rendered, and MIP images enabled correct classification of stenosis in 88%, 89%, and 90% of arteries, respectively. CT with volume rendering was slightly more sensitive for determining candidates for endarterectomy (i.e., those with > 70% stenosis and near occlusion); sensitivity was 100% and specificity, 92%.

CONCLUSION

CT angiography with volume rendering enabled accurate evaluation of carotid disease, even when dense calcifications were present. However, no definite advantage over currently available techniques for CT measurement of stenosis severity was found.

Gadolinium-enhanced fast three-dimensional angiography of the neck: technical aspect

RATIONAL AND OBJECTIVES

This study sought to assess the feasibility of a contrast-enhanced three-dimensional (3D) magnetic resonance (MR) angiographic sequence for imaging the cervical arteries.

METHODS

Ninety-eight consecutive patients underwent contrast MR angiography using a 3D sequence in the coronal plane, including both carotid and vertebral arteries. Gadolinium was injected at the beginning of the sequence. When the contrast was not optimal, a second injection was performed 5 to 10 minutes later. Qualitative assessment was performed for each arterial portion in a consensus manner by three radiologists who judged contrast enhancement, imaging coverage, and artifacts.

RESULTS

A second injection was required in 11 patients, and two examinations were not assessable because of motion artifacts. Among the vessels analyzed, 19% were not assessable owing to the limited coverage in 11% and to the low contrast in 9%. Carotid bifurcations were assessable in 95%, whereas vertebral arteries were visualized from their origins to their intradural portions in only 82% of cases. A longitudinal signal-void artifact was found in the center of the arterial lumen of carotid arteries in six patients.

CONCLUSIONS

Contrast MR angiography constitutes a promising tool to assess cervical arteries. Some limitations including spatial resolution, timing of injection, and imaging coverage should be overcome in the near future.

Control functions of the frontal lobes. Modularity of the central-supervisory system?

Lesions of the prefrontal cortex result in a wide variety of neuropsychological disorders. Despite recent advances, the executive processes and their functional architecture remain poorly specified. This study assessed control processes operating in novel, conflicting and combined tasks in patients with lesion of the prefrontal or posterior cortices. Experiments used two-choice reaction time tests with similar perceptuo-motor and decision processes. It mainly showed (1) impaired short term memory in posterior patients, and (2) impairment of response inhibition and tasks combination in some frontal patients. Selective deficits with double dissociations were evidenced on novel, conflicting and combined tasks. This study provides additional evidence for the prominent role of the frontal lobes in control processes. The demonstration of selective deficits of specific control processes suggests that executive functions depend on multiple separable control processes, and that their operations can be specified in cognitive terms.

Dystonia after striatopallidal and thalamic stroke: clinicoradiological correlations and pathophysiological mechanisms

OBJECTIVE

To establish the pathophysiological mechanisms of striatopallidal and thalamic dystonia.

METHODS

Five patients from among 26 who presented (between March 1987 and July 1996) with focal dystonia, segmental dystonia, or hemidystonia caused by a single localised vascular lesion, were selected. Patients with lesions with indefinite boundaries, and diffuse, or multiple, or large brain lesions were excluded. Three dimensional T1 weighted MRI (1.5 tesla) was performed to determine the topography of the lesions. The atlas of Hassler allowed the stereotactic localisation of the lesions to be specified exactly.

RESULTS

Three patients had dystonic spasms associated with striatopallidal lesions and one with a thalamic and striatopallidal lesion. One other patient presented with a myoclonic dystonia related to a thalamic lesion. The striatopallidal lesions were located in the sensorimotor area with a somatotopical distribution. The pure thalamic lesion involved the centromedian nucleus, the sensory nuclei, and the pulvinar whereas the thalamic and striatopallidal lesion was located in the pallidonigral thalamic territory, which receives pallidonigral inputs.

CONCLUSION

The striatopallidal dystonia might be the consequence of the interruption of the cortico-striato-pallido-thalamo-cortical loop induced by lesions located within the sensorimotor part of the striatopallidal complex. By contrast, it is suggested that thalamic dystonia might be caused by lesions located in the centro-median or the ventral intermediate nuclei, outside the pallidonigral territory, but leading also to a dysfunction of the cortico-striato-pallido-thalamo-cortical loop.

Medial temporal lobe atrophy in stroke patients: relation to pre-existing dementia

OBJECTIVE

The links between stroke and Alzheimer's disease seem to be closer than expected by chance. In a previous study it was shown that up to 16% of patients admitted for stroke had pre-existing dementia. Medial temporal lobe atrophy (MTLA) is strongly associated with Alzheimer's disease. The aim of this study was to determine the prevalence of MTLA and its relation with pre-existing dementia.

METHOD

The study was conducted on 170 consecutive stroke patients (87 women; median age 75 years; 152 infarcts), who underwent non-contrast CT with temporal lobe oriented 2 mm contiguous slices at admission. A cut off point of 11.5 mm was used to differentiate patients with and without MTLA. Pre-existing dementia was assessed using the informant questionnaire on cognitive decline in the elderly (IQCODE) with a cut off score of 104.

RESULTS

Ninety four patients (55.3%) had MTLA, of whom 23 (24.5%) had pre-existing dementia; of 76 patients without MTLA, only four (5.3%) had pre-existing dementia (p=0.0007). The logistic regression analysis with MTLA as dependent variable found the following independent variables: increasing age (p<0.05), and global cerebral atrophy scores (p<0.01). The IQCODE scores just reached significance (p=0.05).

CONCLUSION

Stroke patients with MTLA are more likely to have pre-existing dementia; this suggests that Alzheimer's disease might contribute to the dementia syndrome. A longitudinal follow up is now necessary to determine whether stroke patients with MTLA and without pre-existing dementia are at increased risk of Alzheimer's disease over subsequent years.