Biomedical subjects
Publications and source records attributed to M G Bousser.
In the past ten years, migraine has really entered the field of science, with a number of major advances Despite theses advances, a lot has still to be done to understand what migraine really is and to improve the management of migraine sufferers.
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Recently identified in a french family, CADASIL (Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy) is a generalised disease of small arteries, largely predominating in the brain. Its clinical manifestations start during mid-adulthood and include recurrent ischaemic subcortical events, attacks of migraine with aura, severe mood disorders, subcortical dementia, and, at magnetic resonance imaging, widespread leuko-encephalopathy. There is so far no specific treatment and the mean duration of the disease is 20 years. CADASIL is most frequently a familial disorder with an autosomal dominant mode of transmission. Its responsible gene, Notch 3, is located on Chromosome 19. By the identification of its gene, CADASIL, (which is now known to affect over 400 families worldwide) is a unique variety of cerebro-vascular disease, affecting mainly the subcortical white matter.
CADASIL, an autosomal dominant adult onset arteriopathy causing stroke and dementia in humans, is underlaid by a non atherosclerotic non amyloid angiopathy involving mainly the media of small cerebral arteries; it is characterized by major lesions of vascular smooth muscle cells. Using a positional cloning approach, we mapped CADASIL locus on chromosome 19 and identified the mutated gene as being Notch3. This gene, previously unknown in humans, encodes for a large transmembrane receptor belonging to the Notch/lin12 gene family which are known to be involved in cell fate specification during development. Genetic analysis of more than 120 CADASIL unrelated families allowed us to show that these mutations are highly stereotyped and affect only the extra cellular domain of the protein. On the basis of these data, a molecular diagnostic test has been set up and is now widely required by clinicians involved in the diagnosis of vascular leukoencephalopathies. Using this test, we recently showed that CADASIL can also occur in patients who do not have any affected relative due to the existence of notch3 de novo mutations. As a first step to investigate the molecular and cellular mechanisms leading from Notch3 mutations to CADASIL phenotype, we analyzed by in-situ hybridization and immunohistochemistry the pattern of expression of this gene. Notch3 expression is highly restricted to the vascular smooth muscle cell in normal human adults. In CADASIL tissues there is a dramatic accumulation of the extracellular domain of the protein which suggests that one of the main mechanisms of CADASIL involves anomalies in the proteolytical cleavage and clearance of this protein. These data provide important clues to the mechanisms of this condition and current work should lead in the next future to a complete understanding of CADASIL and set up the basis of a rational therapeutical approach of this condition.
BACKGROUND: Cerebral venous thrombosis (CVT) is often overlooked when intracranial hypertension (ICH) is isolated, hence mimicking idiopathic intracranial hypertension (IIH). OBJECTIVE: To describe the characteristics of patients with CVT and ICH. METHODS: We examined 160 consecutive patients with CVT between 1975 and 1998. They were separated into two groups according to their clinical presentation--isolated ICH and other neurologic symptoms and signs. RESULTS: Fifty-nine patients with CVT (37%) presented with isolated ICH. Neuroimaging showed involvement of more than one sinus in 35 patients (59%). Brain CT was normal in 27 of 50 patients (54%). Lumbar puncture was performed in 44 patients and showed elevated opening pressure in 25 of 32 (78%) and abnormal CSF content in 11 (25%). Etiologies and risk factors included local causes in 7 of 59 (12%), surgery in 1, inflammatory diseases in 18 (30.5%), infection in 2, cancer in 1, postpartum state in 1, coagulopathies in 11 (19%), oral contraception in 7 (12%), and remained unknown in 11 (19%). Anticoagulants were used in 41 of 59 patients (69.5%), steroids or acetazolamide in 26 (44%), therapeutic lumbar puncture in 44 (75%), and surgical shunt in 1. Three patients had optic atrophy with severe visual loss, 1 died from carcinomatous meningitis, and 55 (93%) had complete recovery. CONCLUSIONS: Central venous thrombosis (CVT) can present with all the classical criteria for idiopathic intracranial hypertension (IIH), including normal brain CT with normal CSF content. Because the recognition of CVT has crucial prognostic and therapeutic implications, MRI, with magnetic resonance venography when necessary, should be performed in patients with isolated intracranial hypertension. The outcome of CVT is unpredictable, and management of patients with CVT should not differ whether they present with isolated raised intracranial pressure or with other neurologic symptoms and signs. Therefore, isolated raised intracranial pressure from CVT differs in management from IIH and should be classified neither as "IIH" nor "pseudotumor cerebri."
OBJECTIVE: To evaluate the clinical course of aneurysms developed during extracranial internal carotid artery (ICA) dissection. BACKGROUND: Aneurysms developed during extracranial ICA dissection are detected angiographically in 5 to 40% of cervical artery dissections. The clinical and radiologic course of these aneurysms is not known, and it is not known how they should be treated. METHODS: Fifty-eight consecutive patients with extracranial ICA dissection were reviewed, and those with radiographically detectable dissecting aneurysm at the acute stage or during early follow-up were included in this study. All patients had regular clinical and MR angiography examinations. Sixteen patients (27.5%) with a total of 20 ICA dissecting aneurysms were followed for a mean period of 36.9+/-21 months (range, 10 to 93 months). RESULTS: No clinical symptoms suggestive of aneurysmal rupture or embolization from the aneurysm were identified. Extracranial ICA aneurysms remained unchanged in 65% of patients, were resolved in 5% of patients, and decreased in size in 30% of patients. CONCLUSIONS: The clinical course of dissecting aneurysms was benign, although spontaneous radiologic resolution occurred rarely. Medical management with antiplatelet therapy alone (after early anticoagulation) is generally sufficient, and surgical management was seldom required.
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INTRODUCTION: Cervicocranial arterial dissection is a major cause of cerebral infarction in young subjects. Traumatic and infectious factors are frequently suspected to be at the origin of cervicocranial artery dissection. However, they are usually too minor or too common to explain the vessel wall split-off. Underlying arteriopathy predisposing to dissections is therefore often suspected. CURRENT KNOWLEDGE AND KEY POINTS: The hypothesis of an underlying arteriopathy is based in certain cases on either the discovery of hereditary connective tissue disorders (or secondary signs of these diseases) or their frequent association with vascular and cardiac morphological abnormalities, thus suggesting extracellular matrix abnormalities. Current histological and biochemical data do not suggest the existence of a unique form of the disease but rather indicate the presence of various matrix abnormalities that could involve one of the fibrillar components or its enzymatic regulation. FUTURE PROSPECTS AND PROJECTS: Classification of dissections according to the various vascular wall alterations would therefore permit to better define recurrence and familial risks and to improve overall management of the patients.
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OBJECTIVE: To emphasize the diagnostic importance of change in the headache pattern which pointed to cerebral venous thrombosis in two patients after lumbar puncture and high-dose intravenous methylprednisolone for suspected multiple sclerosis. RESULTS: Both patients had a diagnostic lumbar puncture for suspected multiple sclerosis and were treated with high-dose intravenous methylprednisolone. Both developed a postlumbar puncture headache that was initially postural, typical of low cerebrospinal fluid pressure. Three days later, the headache became constant, lost its postural component, and was associated with bilateral papilledema. Magnetic resonance imaging of the brain disclosed superior sagittal and lateral sinuses thrombosis. The diagnostic difficulties of such cases and the potential role of lumbar puncture and corticosteroids as risk factors for cerebral venous thrombosis are discussed. CONCLUSIONS: When a typical postdural puncture headache loses its postural component, investigations should be performed to rule out cerebral venous thrombosis, particularly in the presence of other risk factors.
Over a period of ten years, a boy had several episodes of coma, lasting three to five days. Each episode was preceded by hemiparesis or paresthesias, aphasia, headaches and behavioural changes, with subsequent loss of consciousness. Partial seizures occurred during the first episode. A history of migraine or hemiplegic migraine was found in several members of the family. Linkage to chromosome 1q21-23, where a gene for familial hemiplegic migraine has been mapped, was shown in this family.
Familial hemiplegic migraine (HM) is an autosomal dominant migraine with aura. In 20% of HM families, HM is associated with a mild permanent cerebellar ataxia (PCA). The CACNA1A gene encoding the alpha1A subunit of P/Q-type voltage-gated calcium channels is involved in 50% of unselected HM families and in all families with HM/PCA. Four CACNA1A missense mutations have been identified in HM: two in pure HM and two in HM/PCA. Different CACNA1A mutations have been identified in other autosomal dominant conditions: mutations leading to a truncated protein in episodic ataxia type 2 (EA2), small expansions of a CAG trinucleotide in spinocerebellar ataxia type 6 and also in three families with EA2 features, and, finally, a missense mutation in a single family suffering from episodic ataxia and severe progressive PCA. We screened 16 families and 3 nonfamilial case patients affected by HM/PCA for specific CACNA1A mutations and found nine families and one nonfamilial case with the same T666M mutation, one new mutation (D715E) in one family, and no CAG repeat expansion. Both T666M and D715E substitutions were absent in 12 probands belonging to pure HM families whose disease appears to be linked to CACNA1A. Finally, haplotyping with neighboring markers suggested that T666M arose through recurrent mutational events. These data could indicate that the PCA observed in 20% of HM families results from specific pathophysiologic mechanisms.
BACKGROUND AND PURPOSE: CADASIL is a newly recognized cause of subcortical ischemic strokes that progressively leads to dementia associated with pseudobulbar palsy and severe motor disability. This deleterious progression and the severity of clinical presentation are widely variable among affected subjects. The exact role played by MRI white-matter abnormalities, a hallmark of the disease, in the severity of the clinical phenotype remains poorly understood. METHODS: To address this issue, we used diffusion tensor imaging (DTI), a new MRI technique highly sensitive to white-matter microstructural changes, in 16 symptomatic patients and 10 age-matched controls. Mean diffusivity and anisotropy of diffusion were measured within hyperintensities identified on T2-weighted images (T2WI) and outside these lesions on 4 slices at the level of centrum semiovale. RESULTS: We found a 60% increase of water mean diffusivity and a parallel loss of diffusion anisotropy in hyperintensities identified on T2WI. The same pattern of diffusion changes, but of lesser intensity, was found in the normal-appearing white matter on T2WI. Mean diffusivity in regions with increased signal on T2WI was higher in patients with severe clinical disability compared with those with no or mild deficit (1.33+/-0.11 versus 1.13+/-0.11 10(-3) mm(2)/s, P<0.01). Furthermore, diffusion measured within T2 hyperintensities correlated with both the Mini-Mental State Examination and Rankin scale scores. In patients with a severe clinical status, the increase of water diffusion in these regions exceeded 70% in comparison with values obtained in the normal white matter in control subjects. CONCLUSIONS: These results indicate that DTI is able to detect important ultrastructural changes in regions with increased signal on T2WI and within the normal-appearing white matter in CADASIL. The diffusion changes might be related to both neuronal loss and demyelination. The degree of the underlying ultrastructural alterations is related to the severity of the clinical status with a possible threshold level of white-matter damage above which severe neurological impairment may occur in this disease. DTI appears to be a promising technique for monitoring disease progression in CADASIL.
BACKGROUND: We recently showed that the severity of MRI signal abnormalities increases with age in CADASIL, an arteriopathy due to mutations of notch 3 gene on chromosome 19. Previous results also suggest that the various hemispheric subcortical areas have a different vulnerability to ischemia in this disease. The distribution of the lesions at the brain stem level has not yet been reported. CASE DESCRIPTIONS: We reviewed the MRIs of 68 affected patients having signal abnormalities in the hemispheric white matter to assess the distribution and clinical consequences of brain stem signal abnormalities in CADASIL. We found hypersignals on T2-weighted images in the brain stem in 45% of the subjects. The pons was more frequently involved (100%) than the mesencephalon (69%) and the medulla (35%). Hyposignals on T1-weighted images, at the brain stem level, were observed only in two thirds of these subjects. The lack of signal abnormalities reaching the brain stem surface and the absence of cerebellar lesions were noteworthy. CONCLUSIONS: Brain stem signal abnormalities observed in CADASIL are found in regions irrigated only by perforating arteries. These results support parallel observations made for CADASIL-associated signal abnormalities in the cerebral hemispheres and emphasize the importance of the angioarchitecture of the cerebral vasculature to explain why a condition characterized by a systemic vessel wall pathology is manifested only as a brain disease.
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Antiplatelet (AP) drugs play a major role in stroke prevention. Aspirin (50-1300 mg), ticlopidine (500 mg), clopidogrel (75 mg) and dipyridamole (400 mg) are effective in secondary prevention of atherothrombotic brain infarcts. Aspirin has been the most extensively studied drug and remains the most cost-effective one. The optimal dose is still debated; doses between 100 and 300 mg are the most widely used. The preventive efficacy of aspirin is already present at the acute phase of cerebral infarct. In primary prevention, aspirin nearly halves the risk of myocardial infarction but does not reduce that of stroke. Cardiac diseases with a high embolic risk require the use of oral anticoagulation. In non valvular atrial fibrillation, the choice of antithrombotic drugs depends on risk stratification: oral anticoagulants are indicated in high risk subjects whereas aspirin is recommended in low risk subjects and when oral anticoagulants are contraindicated. Studies with new associations of AP and with new drugs are required to increase the yield of the antiplatelet approach in high risk subjects; this should be done in parallel with efforts to detect and to treat the vascular risk factors associated with the development of a mass approach for stroke primary prevention.
Therapeutical trials in the acute phase of stroke have showed a moderate benefit of administration of aspirin in prevention of death or recurrent cerebral events. This benefit was obtained despite a small increase in systemic and cerebral haemorrhages. Heparin used at high dosage, without any control of coagulation test, induces an excess of cerebral and systemic haemorrhage which overset its benefit in prevention of recurrent cerebral events. Similar results have been observed with heparinoid and nadroparine used at high dosage. The only benefit of anticoagulation is the prevention of total and fatal pulmonary embolism which has been observed in all recent studies. The antithrombotic treatment which offers the best ratio benefit-risk in the acute phase of stroke is aspirin at a minimum dosage of 160 mg by day and, if risk factors are present, heparin at an adequate dosage to prevent venous thrombo-embolism. Explicative studies are required to explore the potential benefit of heparin in patients with a high risk of recurrent cerebral ischemic events.