Biomedical subjects
Publications and source records attributed to P Niclot.
We report water diffusion abnormalities in periventricular areas in a patient with Wernicke's encephalopathy. The reduction in diffusion disappeared after 2 weeks of treatment with intravenous thiamine. We suggest that the restricted mobility of cerebral water is related to inflammatory lesions.
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Cerebral venous thrombosis is a rare disorder with highly variable and nonspecific clinical presentations. For these reasons, specific treatment should be given only when the diagnosis has been firmly established. Etiologic diagnosis should begin in the emergency department to identify underlying conditions that require specific treatment. The mainstay of treatment is anticoagulation with heparin, even in the case of cerebral hemorrhage, followed as soon as possible by oral anticoagulant administration. The optimal duration of oral anticoagulation has not been established. By analogy with systemic venous thrombosis, it should be prolonged 3 to 6 months. When a high risk of recurrence is present, treatment should be continued until the risk disappears. In contrast to arterial stroke, complete recovery of prolonged or severe neurologic deficit is possible, justifying initiation of anticoagulation even when the clinical situation seems desperate. For the same reason, aggressive treatment of intracranial hypertension and seizures or status epilepticus is warranted. Screening for extraneurologic venous thrombosis should be done by means of clinical examination and, if necessary, specific imaging procedures. Local thrombolysis is not yet of proven efficacy and safety. It can be used in patients with clinical worsening related to documented extension of the venous thrombosis despite anticoagulation and in the absence of cerebral hematoma. Surgical treatment is limited to external ventricular drainage and suboccipital craniotomy in the very rare cases of cerebellar vein thrombosis with edematous cerebellar infarct.
At the acute phase of cerebral infarction, two recent large studies found that the use of aspirin reduces both mortality and the risk of the recurrence of stroke. In primary prevention, aspirin nearly halves the risk of myocardial infarction but does not reduce that of stroke. Concerning the secondary prevention of atherothrombotic brain infarcts, aspirin has been the most extensively studied drug, and is efficient between 50 mg and 1.3 g. In spite of the efficacy of other antiplatelets in this indication--ticlopidine (500 mg), clopidogrel (75 mg) and dipyridamole (400 mg)--aspirin remains the most cost-effective, doses between 100 and 300 mg being the most widely used. Cardiac diseases with a high embolic risk require the use of oral anticoagulation. In nonvalvular 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 associations of aspirin and other antiplatelets are required to increase the yield of this medication in high-risk subjects, in parallel with efforts to detect and to treat the vascular risk factors.
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.
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Thalamotomy in the ventrolateral thalamic nucleus is a common treatment of severe parkinsonian or essential tremor. Although results are often satisfactory, complications may occur and alter the success of the operation. High frequency stimulation of the target before thalamotomy leads to transitory abolition of the tremor. Therefore, a chronic stimulation device was developed and its use produced results similar to those of thalamotomy for parkinsonian tremor. Unwanted side-effect can be reduced by changing the parameters of the stimulation. Improvements in multiple sclerosis and post-traumatic tremors may be expected. We present a review of the indications and results of both technics.