[A clinical study of the number processing system: decimal size effects on reading numbers in patients with left parieto-occipital gliomas]. / Effet de la grandeur décimale sur la lecture de chiffres dans les gliomes du carrefour gauche.

An increasing number of studies are focusing on the anatomo-functional organisation of number processing and some cognitive models have been recently developed. Nevertheless, relationships between areas implicated in number processing, and language areas and circuits remain unclear. Recently, Dehaene and Cohen, in their "triple-code model of number processing", (Dehaene and Cohen, 1995) distinguished two alternative number representation and processing systems: one depending on verbal processes, the other representing a quantity manipulation. According to this model, the retrieval of "arithmetical facts" (AF), learned by rote at school and memorised in a verbal form (such as the multiplication table or simple addition problems) can be considered as a verbal automatism; conversely, subtraction problems, which require mental manipulation of the quantities, represent an abstract, semantic elaboration: "Actual Calculation" (AC). The anatomical correlate of the retrieval of AF (depending on automatic verbal associations) seems to correspond to the left-hemispheric perisylvian areas, while impairment of the actual calculation (AC) depends on the intraparietal region, particularly in the left dominant hemisphere. The present study describes the neuropsychological assessment of three patients, tested after surgery for left parieto-occipital tumors. Two of them were affected by an anaplasic glioma, the third by a low-grade glioma. The cognitive evaluation included: words of Rey, numeral (directed and reversed) span, reading of "simple" numbers (from 1 to 10) and of "complex" numbers (many decimals), writing (dictation) and reading a standard text, finger denomination and right-left distinction. All patients showed language disturbances, dysgraphia and severe dyslexia. In reading numbers, we identified two types of errors: lexical and syntactic. "Lexical errors" consisted in a wrong choice among words in the number's lexicon. For instance, all patients made errors in reading "complex" numbers composed by many decimals, switching single numbers but respecting the decimal size and the structure of the whole number (such as 69107 instead of 68107). On the other hand, only one patient committed syntactic errors, misunderstanding the decimal size and the structure of the number. We considered lexical errors as verbal errors, and syntactic errors as semantic errors, affecting the notion of quantity. We tried to explain verbal disturbances as well as lexical errors as a consequence of lesion of the left-hemispheric perisylvian areas, while syntactic errors as a consequence of impairment of the intraparietal region.

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.

Intraoperative mapping of the cortical areas involved in multiplication and subtraction: an electrostimulation study in a patient with a left parietal glioma.

OBJECTIVES: Advances in neuroimaging studies have recently improved the understanding of the functional anatomy of the calculation processes, having in particular underlined the central role of the angular gyrus (AG). In this study, the authors applied this knowledge to the surgical resection of a glioma invading the left AG, by localising and sparing the cortical areas involved in two different components of calculation (multiplication and subtraction), using direct electrical stimulations. METHODS: A calculation mapping was performed in a patient without deficit except a slightly impaired performance for serial arithmetic subtraction, during the resection under local anaesthesia of a left parieto-occipital glioma invading the dominant AG. After somatosensory and language mappings, cortical areas involved in single digit multiplications and subtractions of seven were mapped using the method of electrostimulation, before glioma removal. RESULTS: Distinct sites specifically involved in multiplication or subtraction were detected within the left AG, with a precise spatial distribution and overlapping. All the eloquent (somatosensory, language, and calculation) areas were surgically spared. Postoperatively, the patient had a transient complete deficit for arithmetic subtraction, without either multiplication or language disturbance. The tumour removal was complete. CONCLUSIONS: These findings suggest: firstly, the usefulness of an intraoperative calculation mapping during the removal of a lesion involving the left dominant AG, to avoid permanent postoperative deficit of arithmetic processes while optimising the quality of tumour resection; secondly, the possible existence of a well ordered and dynamic anatomo-functional organisation for different components of calculation within the left AG.

Long term reshaping of language, sensory, and motor maps after glioma resection: a new parameter to integrate in the surgical strategy.

OBJECTIVES: To describe cortical reorganisation and the effects of glioma infiltration on local brain function in three patients who underwent two operations 12-24 months apart. METHODS: Three patients who had no neurological deficit underwent two operations for low grade glioma, located in functionally important brain regions. During each operation, local brain function was characterised by electrical mapping and awake craniotomy. RESULTS: Language or sensorimotor areas had been invaded by the tumour at the time of the first operation, leading to incomplete glioma removal in all cases. Because of a tumour recurrence, the patients were reoperated on between 12 and 24 months later. Functional reorganisation of the language, sensory, and motor maps was detected by electrical stimulation of the brain, and this allowed total glioma removal without neurological sequelae. CONCLUSIONS: These findings show that surgical resection of a glioma can lead to functional reorganisation in the peritumorous and infiltrated brain. It may be that this reorganisation is directly or indirectly caused by the surgical procedure. If this hypothesis is confirmed by other studies, the use of such brain plasticity potential could be used when planning surgical options in some patients with low grade glioma. Such a strategy could extend the limits of tumour resection in gliomas involving eloquent brain areas without causing permanent morbidity.

Delayed onset of the supplementary motor area syndrome after surgical resection of the mesial frontal lobe: a time course study using intraoperative mapping in an awake patient.

Although the occurrence of the supplementary motor area (SMA) syndrome has been extensively reported following mesial lobe surgery, to our knowledge the time course of disease onset was never accurately documented. We describe a patient without deficit, despite harboring a glioma invading the left SMA. This patient was operated under local anesthesia, to perform intraoperative online sensorimotor and language mapping using electrical stimulations throughout the resection. No deficit was noted at the end of the tumor and SMA removal. The patient was maintained awake to perform an immediate control MRI. Aphasia and right hemiplegia occurred 30 min after the SMA resection. Total recovery was observed within 2 months. This work shows that the SMA syndrome may not occur immediately after SMA resection. We suggest that the transient compensation of the SMA function is likely due to residual activity of an oscillatory loop and/or short-term plasticity (rapid unmasking of parallel networks), with final recovery occurring due to long-term plasticity (neosynaptogenesis).

[Acute spongiform leucoencephalopathy with selective intramyelinic involvement of U fibers associated with an ovarian carcinoma. Syndrome of disconnection of U fibers (author's transl)]. / Leucoencéphalopathie aiguë spongiforme intra-myélinique limitée aux fibres en U chez une femme atteinte d'un cancer de l'ovaire. Syndrome de disconnexion des fibres en U.

Case report of clinical, pathological and ultrastructural features in an acute spongiform leucoencephalopathy with selective involvement of U fibers. A 52 years old woman exhibited an acute encephalopathy of 2 months duration, with dementia and multifocal impairment of cortical functions. The cerebral cortex was normal. This acute dementia resulted from a diffuse intercortical disconnection. Spongy degeneration was only found in U fibers. No other changes were noted especially in basal ganglia, optics tracts, and spinal cord. The white matter status spongious was related to an intramyelinic oedema. Such intramyelinic oedema is known only in Van Bogaert and Bertrand and Canavan disease, which is quite different, and in toxic encephalopathies, especially those induced by the hexachlorophene and triethyltin. In the present case no drugs or toxins were found. An ovarian carcinoma was found at post-mortem examination.

[Chronic inflammatory neuromyopathies in adults treated for gluten-sensitive enteropathy. A report on three cases with microvascular nerve and muscle lesions (author's transl)]. / Les neuromyopathies inflammatoires chroniques de l'entéropathie gluten-sensible traitée de l'adulte. Trois observations avec lésions de micro-vascularité du nerf et du muscle.

Neuromyopathies developed in three patients with gluten-sensitive enteropathy, a long time after they had been cured of their digestive disease by following a gluten-free diet. These cases differed radically from typical deficiency neuropathies by the presence of microvascular inflammatory lesions in nerves and muscles. The semiological findings were similar in all 3 cases, and were distinguished by the association of signs eveking lesions of the largest myelinated nerves fibers to the posterior rami with lesions in the muscles. Corticotherapy improved the condition but did not affect its chronic course. Nerve and muscle biopsies revealed the presence of segmentary microrascularitis, mainly lymphohistiocytic. The probable mechanism of these histological changes is alterations in the circulating immune-complexes, usually found in gluten-sensitive enteropathy, producing various types of associated disorders. Some of these immune-complexes would not be related straight to digestive intolerance to gluten, but would persist during the gluten-free diet period, and could be responsible for the micro-angiitis.

[Nondeficiency chronic polyneuropathies in celiac disease in adults (2 cases with inflammatory neuromuscular vascularitis)]. / Polyneuropathies chroniques non carentielles au cours de la maladie coéliaque de l'adulte. (2 observations avec lésions neuro-musculaires inflammatoires de vascularite)

The neurological and muscular complications seen in coeliac disease in adults are usually attributed to deficiency secondary to malabsorption. Amongst them, however, there exists a very rare cateogory, described by Cooke et al. (1966) taking the form of a chronic myeloneuropathy which cannot be explained in terms of the malabsorption syndrome. Our two cases of gluten intolerance enteropathy, confirmed by biopsy before and after diet, fell into this group of polyneuropathies. The patients, both women, suffered from an essentially sensory ataxic polyneuropathy with accessory motor component with pyramidal and posterior column signs. CSF findings showed a meningeal inflammatory reaction in one of the two cases. These neurological signs, appearing paradoxically during a digestive disease cured by diet, evolve chronically but become stabilised with corticosteroid therapy. Any vitamin deficiency may be excluded in the aetiology of these problems. Neuropathological study of neuromuscular biopsies in very fine serial sections confirmed the mild peripheral nervous involvement but revealed identical inflammatory lesions in the nerve and muscle which were remarkable by virtue of their very highly segmentally selective micro-vasculitis appearance. In these two cases, general, clinical and biological arguments, as well as the type of histological lesion, make it possible to exclude monoclonal gammapathies, malignant haemopathies, amyloidosis and the major collagen diseases. This micro-vasculitis, having transient forms with P.A.N. is no less distinctive, and may be integrated into the provisional group of "allergic angeitis", related to physiopathology of circulating immune complexes and very fashionable in theories as to the mechanism of gluten-sensitive enteropathies. The exact nature of the link between the latter and these types of polyneuropathy remains unknown.