Regressive dystonia and cerebellar ataxia: two unusual symptoms in central pontine myelinolysis.

Two patients with central pontine myelinolysis who presented with dystonia are described. In one, it was associated with cerebellar ataxia which spontaneously improved. In the second, dystonia progressively disappeared 6 months later. In both cases magnetic resonance imaging (MRI) revealed characteristic pontine lesions. Extrapontine myelinolysis involving the putamen was also observed in one patient. Even when the basal ganglia seem to be spared on MRI, dystonia is probably due to their involvement by myelinolysis. Cerebellar ataxia may be related to peduncular or cerebellar lesions or both.

Impairment of the supervisory attentional system in early untreated patients with Parkinson's disease.

The aim of this study was to specify the frontal type dysfunction widely reported in Parkinson's disease (PD) early in the course of the disease and before dopaminergic therapy. Seventeen "de novo" PD patients and 17 healthy control subjects performed modified versions of the Stroop word-color test and the Brown Peterson paradigm. A dissociation between results on the two tasks was observed in PD patients. They had difficulties in inhibiting a strong habitual response and establishing a new, better adapted pattern of response; but they performed as well as controls in a dual-task paradigm requiring correct allocation of the processing resources of working memory. Early in the course of the disease, untreated PD patients suffer from dysfunction of the supervisory attentional system. However, the present findings suggest that this system is not a single unit but rather could be composed of multiple subsystems whose sensitivity depends on the origin of frontal dysfunction. Indeed, only a few of these subsystems seemed to be impaired in de novo PD patients. It can be hypothesized that those involved in the phenomena of adaptation and consolidation of currently appropriate responses depend on the dorsolateral prefrontal loop, which is affected by the dopaminergic innervation of the caudate nucleus.

[Cerebrotendinous xanthomatosis. 2 cases with magnetic resonance imaging]. / Xanthomatose cérébro-tendineuse. Deux cas avec imagerie par résonance magnétique.

A 40-year-old woman presented with bilateral juvenile cataract, tendinous xanthomas, intellectual deterioration, spastic tetraparesis, proprioceptive deficit and parkinsonian syndrome. A younger sister's clinical picture differed by the absence of xanthomas and the presence of a cerebellar syndrome. The diagnosis of cerebrotendinous xanthomatosis was confirmed by a high concentration of plasma cholestanol and by urinary chromatography. Magnetic resonance imaging displayed some abnormalities in the hemispheric and cerebellar white matter. Under chenodesoxycholic therapy the biological abnormalities decreased while the clinical disturbances were unchanged.

[Peripheral haemosiderosis of the central nervous system]. / Hémosidérose marginale du névraxe.

We report 2 cases of patients with hemosiderosis of the central nervous system. The diagnosis was made in 1999 in a stroke unit. The patients had both deafness, but their clinical presentation was different, due to heterogeneous features of this pathology. Hemosiderosis of the central nervous system is due to chronic subarachnoidal hemorrhage. Magnetic resonance imaging is extremely sensitive to the presence of hemosiderin and is the investigation of choice enabling diagnosis and sometimes bleeding source (50 p. cent). The interest of our observations concerned the source of bleeding. In the first patient, diagnostic work-up was negative. For the second one, the deposition of hemosiderin was explained by 3 possible sources. If a bleeding source can be identified, surgery is the optimal treatment. Copper chelation, like Trientine can be used, but there is no evidence-based for using this treatment.

[Cognitive functions and the basal ganglia: the model of Parkinson disease]. / Fonctions cognitives et noyaux gris centraux: le modèle de la maladie de Parkinson.

Cognitive changes have long been observed in patients with degenerative diseases or focal lesions that involve primarily subcortical structures. Generally speaking, the deficits that have been reported in these diseases are similar and include: slowing of central processing; defective use of memory stores; impaired behavioural regulation in sorting tasks; disorders of plaining in tower-related tasks; and impaired manipulation of internal representation of visuo-spatial stimuli. Given the modulatory role of the basal ganglia and related structures, these disorders might result from more fundamental deficits concerning the allocation of attentional resources, the temporal organization of behaviour, the maintenance of representations in working memory or the self-elaboration of internal strategy, all of which resemble dysfunctions of processes that are commonly considered to be controlled by the frontal lobes. This suggests a functional continuity between the basal ganglia and association areas of the prefrontal cortex. The recent description in primates of parallel, segregated loops that interconnect well-defined subregions of the basal ganglia to discrete areas of the prefrontal cortex via the thalamus may give some support to this hypothesis.

[Bilateral cavernous sinus syndrome: Burkitt's lymphoma]. / Syndrome du sinus caverneux bilatéral: lymphome de Burkitt.

Bilateral cavernous sinus syndrome is usually due to a vascular disease, such as thrombophlebitis or arteriovenous malformation. In a 29-year old woman this syndrome revealed a malignant non-Hodgkin's lymphoma of the Burkitt type. In this case, the physiopathological mechanism was metastatic extension to the dura mater of a systemic lymphoma. The contribution of MRI to the diagnosis is emphasized.