[Technical considerations on scintigraphies with radioactive mercury 197].
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Biomedical subjects
Publications and source records attributed to C Raynaud.
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Visual behavior is frequently impaired at onset of West syndrome (WS). We studied the neuropsychological outcome of eight children who had cryptogenic WS and moderate to severe visual impairment at the onset of epilepsy. At the last examination, a regional cerebral blood flow study using SPECT (single photon emission computed tomography) was performed. The behavior abnormalities observed initially evolved to various defects of cognitive function. Three patients had severe mental retardation with autistic features. Two had marked speech disorders but one had global cognitive impairment. Three patients had specific visual-spatial deficits. SPECT showed perfusion defects involving the parieto-occipital areas in 6 of 8 patients. These abnormalities were restricted to parieto-occipital regions in the three patients with selective visual-spatial deficits, whereas they were associated with other perfusion defects in the three remaining patients. This study demonstrates that the visual inattention observed at the onset of WS is frequently associated with long-term cognitive and/or perfusion defects involving the parieto-occipital regions.
Focal cortical disturbances are frequent sequelae in West syndrome (WS) even though it is a generalized epileptic syndrome. Functional neuroimaging was used to determine whether focal perfusion abnormalities exist at WS onset and change during evolution. We studied regional cerebral blood flow (rCBF) at different stages of WS. Mean CBF (mCBF) and rCBF were measured using SPECT (single photon emission computed tomography) and 133Xe in 13 WS patients: at onset (20 cases), just after steroids (17 cases), and after a mean follow-up of 2 years (26 cases). At WS onset, interictal mCBF was increased as the result of foci of hyper- and hypoperfusion, which were, respectively, mainly located in the frontal and posterior cortex. Just after steroid therapy, mCBF decreased without any focal predominance. During follow-up, hypoperfused foci remained unchanged whereas the frontal hyperperfused foci decreased after spasm control. Our results show that focal abnormalities are present at WS onset. Focal hypoactivity could reflect a cortical lesion responsible for WS and focal hyperactivity could play a role in the persistence of generalized epilepsy.