Déficit du rappel verbal par infarctus thalamique dorso-latéral gauche [Deficit of verbal recall caused by left dorso-lateral thalamic infarction]

A case of amnesia with preferential disorder of verbal recall, associated to a limited infarct of the left superior, external and anterior thalamus, is reported. This lesion involved the anterior and middle dorso-lateral nuclei and the centrolateral nucleus, sparing most of the structures classically incriminated in diencephalic amnesia. At the initial stage, the patient presented discrete language impairment and severe deficit of semantic processing, which later recovered. At the late stage, the anterograde and retrograde amnesia principally concerned the recall of verbal information used in daily life, verbal learning using short-term and long-term recall, questionnaires evaluating retrograde memory and requiring the evocation of proper names. Verbal priming was also affected. Verbal recognition was preserved. Evocation of the most recent events of the personal life was also impaired. Confrontation of this case with others previously reported suggests that various thalamic amnesias may be described, associated to different cognitive deficits, in relation with the preferential situation of lesions

Cerebral blood flow in lateral medullary infarcts.

The aim of this study was to evaluate the diaschisis phenomenon in patients presenting with lateral medullary infarct (Wallenberg's syndrome). We examined all patients admitted between 1991 and 1993. The localization of lesions was evaluated by MRI. Single-photon emission computed tomographic technique was used to assess cerebral blood flow by two methods (133Xe and hexamethylpropyleneamine oxime) on five slices of brain tissue. Flow values were calculated in 11 regions of interest in each cerebral hemisphere and in the cerebellum and were compared with those obtained in 20 control subjects. Three patients had selective lateral medullary infarct: Relative reduction of flow (133Xe) and of tracer uptake (HMPAO) were observed in one patient in the ipsilateral cerebellum and contralateral hemisphere; in two patients, hemispheric flow values were relatively low, without significant asymmetry. Two patients also presented with cerebellar infarct: Flow drop was severe in the ipsilateral cerebellum, and contralateral reduction in the brain hemisphere was observed in both cases. Lateral medullary infarct can be associated with ipsilateral reduction of flow in the cerebellum, but this phenomenon is inconstant. Severe flow drop suggests infarction in the territory of the posterior inferior cerebellar artery. Contralateral hemispheric flow reduction can also be observed. These phenomena of cerebellar and crossed hemispheric diaschisis are probably related to lesions of tracts from the olivary and reticular nuclei

Dystonie et tremblement dans une lésion bilatérale du mésencéphale postérieur et du vermis [Dystonia and tremor in bilateral lesion of the posterior mesencephalon and the vermis]

The aim of this study is to report the association of diffuse dystonia and tremor in a bilateral and extended lesion of the posterior mesencephalon. After surgery on a meningioma of the upper part of the fourth ventricle, this patient presented with facial dystonia, predominating on orbicularis muscles and peribuccal area, and limb dystonia, with tonic extension of fingers and first toes. The tremor was associated with a rhythmic and most often alternate agonist-antagonist muscular activation, whose frequency varied from 3 to 7 Hz. These disorders were increased by the standing position, voluntary movement, somatosensory stimulations, stress or emotion. Pyramidal and somatosensory tracts were spared. Therapeutic trials showed that both the dystonia and tremor were improved by subcutaneous injection of apomorphine, the dystonia by trihexyphenidyle, and the tremor by carbamazepine and propranolol, but not by levodopa and benserazide. The cerebral blood flow study using HMPAO showed a relatively important activity on the cerebellum, which could play a role in the onset of these disorders

Cerebral blood flow in major depression and dysthymia.

International audienceUsing single photon emission computerized tomography (SPECT) with a 99mTc-HMPAO perfusion technique, we studied the regional cerebral blood flow (rCBF) of 42 drug-free inpatients suffering from Major Depression' (n = 21) or dysthymia with the super-imposed diagnosis of a major depressive episode (n = 21). The patients with Major Depression had a significantly lower frontal and posterior rCBF ratio than those with Double Depression. Left frontal region indices showed a slight overlap between the two groups. There was no correlation between the severity of the illness and the rCBF indices. Different qualitative cerebral dysfunctions may be implicated in these two affective disorder sub-types