Functional recovery after surgical resection of low grade gliomas in eloquent brain: hypothesis of brain compensation

OBJECTIVES: To describe functional recovery after surgical resection of low grade gliomas (LGG) in eloquent brain areas, and discuss the mechanisms of compensation. METHODS: Seventy-seven right-handed patients without deficit were operated on for a LGG invading primary and/or secondary sensorimotor and/or language areas, as shown anatomically by pre-operative MRI and intraoperatively by electrical brain stimulation and cortico-subcortical mapping. RESULTS: Tumours involved 31 supplementary motor areas, 28 insulas, 8 primary somatosensory areas, 4 primary motor areas, 4 Broca's areas, and 2 left temporal language areas. All patients had immediate post-operative deficits. Recovery occurred within 3 months in all except four cases (definitive morbidity: 5%). Ninety-two percent of the lesions were either totally or extensively resected on post-operative MRI. CONCLUSIONS: These findings suggest that spatio-temporal functional re-organisation is possible in peritumoural brain, and that the process is dynamic. The recruitment of compensatory areas with long term perilesional functional reshaping would explain why: before surgery, there is no clinical deficit despite the tumour growth in eloquent regions; immediately after surgery, the occurrence of a deficit, which could be due to the resection of invaded areas participating (but not essential) to the function; and why three months after surgery, almost complete recovery had occurred. This brain plasticity, which decreases the long term risk of surgical morbidity, may be used to extend the limits of surgery in eloquent areas.     

Per and neuropeptide expression in the rat suprachiasmatic nuclei: compartmentalization and differential cellular induction by light

Per1 and Per2, two clock genes rhythmically expressed in the suprachiasmatic nucleus (SCN), are implicated in the molecular mechanism of the circadian pacemaker and play a major role in its entrainment by light. To date, it is not known if every cell of the SCN, a heterogeneous structure in respect of neuropeptide content, expresses clock genes equally. The aim of this study was to identify, by single and double non-radioactive and/or radioactive hybridizations, the cell types (AVP, VIP and GRP) expressing Per1 or Per2 in the SCN of rats, (1) when Per are highly expressed during the daytime, and (2) after induction of Per expression by a light pulse at night. Our results indicate that, during the daytime, Per1 and Per2 genes are both mainly expressed in the AVP cells of the dorso-median part of the SCN, whereas only a few VIP cells in the ventral part of the SCN exhibit Per gene expression. In contrast, following a light pulse at night, there is differential induction of the two Per genes. Per1 expression essentially occurs in the ventro-lateral GRP cells, while Per2 expression is not restricted to the retinorecipient part of the SCN as it also occurs in AVP cells. Altogether, our results suggest that Per1 and Per2 are mainly expressed in AVP cells during the daytime and suggest that GRP cells play an important role in resetting of the clock by light.     

Acute effects of intravenous glutamine supplementation on protein metabolism in very low birth weight infants: a stable isotope study.

Although very low birth weight infants are subjected to severe stress and glutamine is now considered a conditionally essential amino acid that may attenuate stress-induced protein wasting in adults, current amino acid solutions designed for neonatal parenteral nutrition do not contain glutamine. To determine whether a short-term supplementation with i.v. glutamine would affect protein metabolism in very low birth weight infants, 13 preterm neonates (gestational age, 28-30 wk; birth weight, 820-1610 g) receiving parenteral nutrition supplying 1.5 g x kg(-1) x d(-1) amino acids and approximately 60 nonprotein kcal x kg(-1) x d(-1) were randomized to receive an i.v. supplement made of either 1) natural L-glutamine (0.5 g x kg(-1) x d(-1); glutamine group), or 2) an isonitrogenous glutamine-free amino acid mixture (control group), for 24 h starting on the third day of life. On the fourth day of life, they received a 2-h infusion of NaH(13)CO(3) to assess the recovery of (13)C in breath, immediately followed by a 3-h L-[1-(13)C]leucine infusion. Plasma ammonia did not differ between the groups. Glutamine supplementation was associated with 1) higher plasma glutamine (629 +/- 94 versus 503 +/- 83 microM, mean +/- SD; p < 0.05, one-tailed unpaired t test), 2) lower rates of leucine release from protein breakdown (-16%, p < 0.05) and leucine oxidation (-35%, p < 0.05), 3) a lower rate of nonoxidative leucine disposal, an index of protein synthesis (-20%, p < 0.05), and 4) no change in protein balance (nonoxidative leucine disposal - leucine release from protein breakdown, NS). We conclude that although parenteral glutamine failed to enhance rates of protein synthesis, glutamine may have an acute protein-sparing effect, as it suppressed leucine oxidation and protein breakdown, in parenterally fed very low birth weight infants.     

Functional recuperation following lesions of the primary somatosensory fields. Study of compensatory mechanisms

During a long time, lesions of the primary somatosensory area (S I) were considered as generating severe and definitive neurological sequelae. However, recent reports described a recovery following stroke and resective surgeries (for epilepsy or tumor). On the basis of these observations, of experimentations in animals, and of studies of the (re)organization of eloquent areas in man using new methods of functional mapping, brain plasticity phenomena underlying the recovery were analyzed. They seems to implicate the recruitment of local areas (sensory redundancies within S I), regional areas (primary motor area, secondary somatosensory area, posterior parietal cortex, insula), controlateral eloquent regions, and even learning of new compensatory strategies. Such data could allow us to extend surgical indications of resection of lesions located within S I. An improvement of our knowledge of these functional reshaping phenomena (unmasking of latent networks and/or participation of eloquent homologous and/or sprouting) and then their prediction remains mandatory, with the goal to optimize the surgical preplanning in functional regions, taking account of the individual dynamic spatiotemporal cortical organization. This better knowledge seems to be obtained by studying the correlations between pre- and post-operative functional neuroimaging (fMRI, MEG) data, and the intraoperative functional mapping results.     

Fever caused by metapramine. Diagnosis of fever caused by psychotropic drugs

Because of two hyperthermias, due to metapramine a french antidepressives of the tricyclic family, international literature concerning drug fever induced by psychotropics was reviewed. This study stresses the fact that apart from neuroleptics which are frequently involved in that type of accident, other psychotropics are very rarely responsible of hyperthermia. One hundred and five cases published since 1970 and sufficiently well documented to be analysed according to Dangoumeau's french method of imputation of side effects of drugs, were reviewed. Among these cases, one hundred (95%) corresponded to malignant syndrome of neuroleptics, 89 concerned neuroleptics alone, and 11, neuroleptics associated with other psychotropics. Regarding the different mechanisms which can explain drug fever as described by Lipsky, it seems that concerning psychotropics two types may be retained: Fever due to central dysregulation directly induced by drugs, and mainly, immunoallergic fever, the most frequently seen as described in our two cases.