Voxel-based mapping of brain hypometabolism in permanent amnesia with PET.

In this study, we used voxel-based mapping methods to compare the resting cerebral metabolic rate of glucose (CMRglc) measured with PET in five patients with permanent amnesia (three with chronic Wernicke-Korsakoff and two with postanoxia syndrome) to that of nine healthy age-matched subjects. We assessed (i) a group pattern of relative hypometabolism; and (ii) the consistency of this group pattern, if any, in individual subjects, according to etiology. The results from the group analysis documented that permanent amnesia is associated with hypometabolism in the thalamus, posterior cingulate cortex, and mesial prefrontal cortex (near the anterior cingulate gyrus), bilaterally, as well as in the left supramarginal and middle temporal gyri. The individual analysis showed that this group pattern was found in essentially each patient, regardless of the cause of amnesia. Thus, permanent amnesia is subtended by dysfunction in structures belonging to Papez/limbic circuits as well as in left-hemisphere areas typically concerned with verbal functions, probably through a mechanism of thalamo-cortical disconnection and possibly involved in retrograde amnesia. The use of a voxel-based method allowed us to map a common network of synaptic dysfunction in a neuropsychological syndrome regardless of etiology. Our results indicate that this should be a powerful method in functional neuropsychology.

[Celiac disease in adults revealed by sensory-motor neuropathy]. / Maladie coeliaque de l'adulte révélée par une neuropathie sensitivo-motrice.

Central or peripheral nervous system complications are occasionally observed in adult patients with celiac disease. Several mechanisms have been proposed including vitamin deficiency, vascular inflammation and a direct effect of gluten intolerance. Typical nerve fiber damage due to demyelinization has been suggested. We observed a 65-year old woman with a right peroneal nerve palsy superimposed on a diffuse peripheral neuropathy who was found to have folic acid deficiency which in turn led to the diagnosis of adult celiac disease. Electrophysiological and histological studies demonstrated a predominantly demyelinating peripheral neuropathy which responded first to parenteral folic acid supplementation and second to a gluten-free diet. The mechanisms of peripheral nerve damage in adult celiac disease are briefly discussed and the possible role of folic acid deficiency is emphasized.

[Accidental poisoning with podophyllin: a case with study of peripheral nerve]. / Intoxication accidentelle à la podophylline: un cas avec étude du nerf périphérique.

A 53 year-old veterinary surgeon accidentally ingested 0.8 g of podophyllin. Twelve hours later, he was deeply comatose, with clinical and EMG signs of extensive axonal sensorimotor and autonomic peripheral neuropathy. In addition, transient bone marrow and hepatic toxicity occurred. The coma lasted 2 weeks. Systemic and neurological disturbances started to improve at 3 months post-onset, but the patient died four months later from gastro-intestinal bleeding. Sural nerve biopsy showed loss of myelinated fibers and signs of axonal degeneration with type E teased fibers. The cytoplasm of Schwann and endothelial cells was vacuolated and swelled. Diffuse interstitial aedema was noted. Podophyllin acts as a spindle poison, binds microtubular proteins and inhibits axoplasmic flow.

Subcortical neglect.

The unilateral neglect syndrome is defined as a lack of directed attention to one half of the space or the body. It has been reported mainly after cortical lesions of the right parietal or frontal lobe in man. However, there is strong experimental and clinical evidence for the existence of neglect syndromes of subcortical origin. The unilateral neglect syndrome is not the result of elementary sensory deficits. The failure in directed attention is dependent on an imbalance of hemispheric activation.

[Thalamic neglect]. / Négligence thalamique.

Thalamic lesions can provoke negligence behavior with various, sometimes dissociated manifestations: motor negligence or reduction in use of one half of the body whatever the direction of the gesture or the half-space in which it occurs; extinction phenomena demonstrated without difficulty for visual, somatesthetic and auditory modalities; spatial negligence involving attentional and intentional components, often difficult to distinguish. Negligence of this type is mainly the result of right sided lesions, with several non-exclusive explanations: natural predominance of the left hemisphere, activating role of language with respect to the left hemisphere, capacity of the right hemisphere to be "attentive" to bath half-spaces in contrast to the left hemisphere, attentive to the right half-space only.