Learning to read requires the acquisition of an efficient visual procedure for quickly recognizing fine print. Thus, reading practice could induce a perceptual learning effect in early vision. Using functional magnetic resonance imaging (fMRI) in literate and illiterate adults, we previously demonstrated an impact of reading acquisition on both high-and low-level occipitotemporal visual areas, but could not resolve the time course of these effects. To clarify whether literacy affects early vs. late stages of visual processing, we measured event-related potentials to various categories of visual stimuli in healthy adults with variable levels of literacy, including completely illiterate subjects, early-schooled literate subjects, and subjects who learned to read in adulthood (ex-illiterates). The stimuli included written letter strings forming pseudowords, on which literacy is expected to have a major impact, as well as faces, houses, tools, checkerboards, and false fonts. To evaluate the precision with which these stimuli were encoded, we studied repetition effects by presenting the stimuli in pairs composed of repeated, mirrored, or unrelated pictures from the same category. The results indicate that reading ability is correlated with a broad enhancement of early visual processing, including increased repetition suppression, suggesting better exemplar discrimination, and increased mirror discrimination, as early as ∼100-150 ms in the left occipitotemporal region. These effects were found with letter strings and false fonts, but also were partially generalized to other visual categories. Thus, learning to read affects the magnitude, precision, and invariance of early visual processing.reading | brain plasticity | education R eading is a cultural activity in which contemporary humans have considerable training. Fluently accessing the sounds and meanings of written words requires very fast and efficient visual recognition of letter strings, at rates exceeding 100 words/ min. Neuroimaging studies have begun to show how learning to read modulates the functioning of the visual system, from early retinotopic areas (1, 2) to extrastriate occipital and temporal cortex (1, 3, 4). In particular, a restricted region of the left occipitotemporal cortex, the visual word form area (VWFA), is robustly activated when orthographic stimuli are presented to literate subjects.This VWFA activation is reproducible across participants and writing systems (5, 6), even when orthographic stimuli are flashed unconsciously (7). Orthographic processing in the VWFA is thought to be very fast, peaking at ∼170-200 ms (8-10), and is colateralized to the dominant hemisphere for language (11,12). Reading practice enhances activation of the VWFA (1, 13, 14), even in dyslexic children (15). Reading also modulates nonvisual circuits, such as the spoken language network (1,14,16,17).In addition to these positive effects of learning to read, the theory of neuronal recycling (18) proposes that literacy acquisition also may have a negative "unlearning" e...

Approximately half of childhood leukoencephalopathies remain unclassified despite extensive investigation 1 . Recently, some of them have been identified and categorized based on their distinct abnormalities detected on magnetic resonance imaging (MRI) [2][3][4][5][6] . A novel distinct leukoencephalopathy was described in 2003 by Van der Knaap et al. 7 Symptoms begin during childhood, with slow progression. Distinctive clinical findings include cerebellar, pyramidal and dorsal column dysfunction. Laboratory investigation is unrevealing. Typical findings on MRI and proton magnetic resonance spectroscopy ( H-MRS typically show abnormalities within cerebral and cerebellar white matter, a characteristic involvement of brainstem and spinal cord tracts and elevated lactate in the abnormal white matter. We present three cases with characteristic clinical and neuroimaging findings of this disorder. Some additional unique findings of our patients are discussed, like distal motor neuropathy and elevated creatine kinase in the serum.KEY WORDS: leukoencephalopathy, brainstem, spinal cord, lactate.Leucoencefalopatia com envolvimento do tronco cerebral e da medula espinal e elevação do lactato cerebral: relato de três casos brasileiros RESUMO -Uma nova leucoencefalopatia foi recentemente descrita com base em achados característicos de ressonância magnética e espectroscopia de prótons por ressonância magnética. Leucoencefalopatia com envolvimento do tronco cerebral e da medula espinal e elevação do lactato cerebral é uma doença autossômica recessiva de aparecimento precoce e evolução lenta, caracterizada por disfunção cerebelar, piramidal e das colunas dorsais da medula. Ressonância magnética e espectroscopia de prótons tipicamente demonstram anormalidades na substância branca cerebral e cerebelar, com envolvimento característi-co de tratos no tronco encefálico e na medula espinhal e aumento de lactato na substância branca cerebral anormal. Relatamos três casos com achados clínicos e de neuroimagem característicos. Achados adicionais peculiares aos nossos pacientes são discutidos, como a elevação da creatina-quinase sérica e a presença de neuropatia motora distal. PALAVRAS-CHAVE: leucoencefalopatia, tronco cerebral, medula espinal, lactato.

The limb-girdle muscle dystrophy (LGMD) represents a heterogeneous group of muscular diseases with dominant and recessive inheritance, individualized by gene mutation. A group of 56 patients, 32 males and 24 females, with suggestive LGMD diagnosis were submitted to clinical evaluation, serum muscle enzymes, electromyography, muscle biopsy, and the immunoidentification (ID) of sarcoglycans (SG) alpha, beta, gamma and delta, dysferlin and western blot for calpain-3. All the patients had normal ID for dystrophin (rod domain, carboxyl and amine terminal). The alpha-SG was normal in 42 patients, beta-SG in 28, beta-SG in 45, delta-SG in 32, dysferlin in 37 and calpain-3 in 9. There was a reduction in the alpha-SG in 7 patients, beta-SG in 4, gamma-SG in 2, and delta-SG in 8. There was deficiency of alpha-SG in 7 patients, beta-SG in 6, gamma-SG in 9, delta-SG in 5, dysferlin in 8, and calpain-3 in 5. The patients were grouped according the ID as sarcoglycans deficiency 18 cases, dysferlin deficiency 8 cases and calpain-3 deficiency 5 cases. Only the sarcoglycans deficiency group showed calf hypertrophy. The dysferlin deficiency group was more frequent in females and the onset was later than sarcoglycan and calpain-3 deficiency groups. The calpain-3 deficiency group occurred only in males and showed an earlier onset and weaker muscular strength.

-Myasthenic crisis (MC) is a life-threatening complication of myasthenia gravis (MG) with a high mortality rate. The aim of our study was to review the different therapeutics approaches in the treatment of MC and their impact in the final outcome. We reviewed the medical files of patients diagnosed with MG admitted between February 1993 and October 1997, who developed MC. Sex, mean age, disease's duration, functional scale, symptoms preceding the crisis, crisis therapy in each set and mortality were then analysed. There were 24 patients who developed MC, 21 females and 3 males, with 1 neonatal, 1 congenital sporadic, 17 juvenile/adult, 3 over 50 years and 2 with thymoma. Dysphagia, dysphonia and dysartria were the most common symptoms preceding the crisis. A precipitating factor was elicited in 8 cases and the most common was infection (upper airway infection, urinary tract infection and pneumonia). 16 patients needed a nasogastric tube and 9 had a tracheostomy performed. 24 patients used anticholinesterase drugs, 21 prednisone, 7 immunosuppressive agents, 5 plasmapheresis, 3 human hyperimune gamma immunoglobulin and 12 had thymectomy. A good response was obtained in 13, satisfactory in 7 and there were 4 deaths. We concluded that in spite of all the therapeutics options, there were non statistically significant differences in the outcome of patients that underwent thymectomy and those who did not.KEY WORDS: myasthenia gravis, myasthenic crisis, thymectomy, neuromuscular disorders, muscle diseases.Crise miastênica: relato de 24 casos Crise miastênica: relato de 24 casos Crise miastênica: relato de 24 casos Crise miastênica: relato de 24 casos Crise miastênica: relato de 24 casos RESUMO -A crise miastênica (CM) é uma complicação preocupante da miastenia grave (MG) que apresenta altos índices de mortalidade. Neste estudo revisamos as diferentes abordagens no tratamento da CM e seu impacto no resultado final. Levantamos os dados dos pacientes com MG que desenvolveram CM admitidos entre fevereiro de 1993 e outubro de 1997. Foram analisados as interrelações do sexo, idade media, duração da doença, escala funcional, sintomas e procedimentos precedendo as crises, terapêutica empregada e mortalidade. Foram encontrados 24 casos que desenvolveram CM, sendo 21 do sexo feminino e 3 do masculino. Em relação à apresentação clínica, 1 era da forma neonatal, 1 congênita esporádica, 17 juvenil/adulta, 3 acima de 50 anos e 2 com timoma. Os sintomas principais que precederam a CM foram disfagia, disfonia e disartria. Foi possível identificar um fator desencadeante em 8 casos e o mais comum foi infecção (vias aéreas, pneumonia e trato urinário). Necessitaram de sonda nasogastrica 16 casos e a traqueostomia, 9. Usaram medicações anticolinesterásicas todos os 24 casos, prednisona 21, imunossupressivos 7, plasmaferese 5, gamaglobulina hiperimune 3 e foram submetidos a timectomia 12 casos antes ou após a CM. Obtivemos bom resultado em 13, satisfatório em 7 e ocorreram 4 óbitos, sendo 3 não relacionados com a CM. Concluímos que...

RESUMO -Relatamos três casos de síndrome de Isaacs, que apresentavam mioquímia clínica, cãibras, dificuldades para o relaxamento muscular, hipertrofia muscular e aumento da sudorese. A eletromiografia de agulha mostrou atividade muscular contínua involuntária, caracterizada como descargas mioquímicas. Os estudos da condução nervosa foram normais. Biópsia de músculo, realizado nos três casos, mostrou atrofia de fibras do tipo 2. Dois casos apresentaram melhora clínica com a utilização de carbamazepina e um com prednisona. PALAVRAS-CHAVE: atividade muscular contínua involuntária, mioquímia, descarga mioquímica Isaacs' syndrome: report of three cases ABSTRACT -We report two females, and one male with Isaacs' syndrome. The patients presented with clinical myokymia activity, muscle cramps, delayed relaxation, and muscle hypertrophy and increased sweating. Needle electromyography in several muscles showed generalized continuous motor unit discharges, myokymic discharges, and normal nerve conduction studies. Muscle biopsy showed type two fiber atrophy. Treatment with carbamazepine was effective in two cases and prednisone in one.KEY WORDS: continuous motor fiber activity, myokymia, myokymic discharge.A síndrome de Isaacs caracteriza-se pela atividade muscular contínua involuntária (mioquímia clínica), atraso do relaxamento muscular, rigidez e aumento da sudorese 1-5 . Descargas espontâneas de potenciais de unidade motora (PUM) são os principais achados da eletromiografia (EMG) de agulha, observados como descargas mioquímicas ou neuromiotônicas generalizadas [6][7][8][9][10][11] . As descargas dos PUM ocorrem por alterações do estado de excitabilidade das porções terminais dos axônios motores, devido a ação de anticorpos, contra canais de potássio voltagem dependente (CKVD) [12][13][14][15][16] . Pela raridade desta doença relatamos os achados clínicos, laboratoriais, eletroneurofisioló-gicos de três casos de síndrome de Isaacs, afim de contribuir para a melhor compreensão dos fenômenos fisiológicos. RELATO DOS CASOSCaso 1. OVN, 40 anos, branca, iniciou os sintomas há 4 anos, durante o terceiro trimestre de gestação, com fraqueza da musculatura proximal de membros inferiores (MMII), cãibras e contrações musculares involuntárias contínuas generalizadas. Nega quadros semelhantes na família, contato com substâncias tóxicas e uso de medicações. Ao exame apresentava atrofia da musculatura distal, força muscular proximal de MMII e distal de membros superiores (MMSS) grau 4 + (Medical Research Council-MRC), hipertonia global, hiporreflexia profunda, fasciculações Serviço de Neurologia (Doenças

We report three siblings of a family with hereditary motor and sensory polyneuropathy (HMSN) and buphthalmos. Electrophysiological studies showed a demyelinating neuropathy and pathological findings showed severe loss of myelinated fibers (MF), thin myelin sheaths and myelin infoldings in a few remaining MF. The presumed mode of inheritance is autosomal recessive. This family probably represents an unique form of CMT4 that may be related to one of the congenital glaucoma genic locus, particularly GLC3A and GLC3B, described in Turkish families.

We report the case of a 37‐year‐old man with clinical and electrophysiological features of hereditary slow‐channel syndrome (SCS) and antibodies against acetylcholine receptors (AChR‐Abs). He presented with weakness of shoulder and hand muscles. A supramaximal single stimulus to the motor nerves disclosed a double compound muscle action potential (CMAP). Repetitive stimulation of ulnar, suprascapular, and median nerves showed a CMAP decrement greater than 10%. The patient responded to pyridostigmine. This report confirms the importance of AChR‐Ab titers in suspected cases of hereditary SCS because patients with positive AChR‐Abs may have a better response to available treatments. © 2000 John Wiley & Sons, Inc. Muscle Nerve 23: 1582–1585, 2000

Objective: Our objective was to compeer the accuracy between two warning criteria during the intraoperative neurophysiologic monitorization for spine/spinal cord surgery. Method: We used two different warning criteria to detect neurological damage. The first criterion was the amplitude reduction of the somatossensory-evoked potentials (SEP) or motor-evoked potentials (MEP) greater than 50% at least in one limb and the second criterion was the complete loss of one of the same potentials. These results were compared with the neurological examination and the sensitivity, specificity, positive likelihood ratio (PLR) and negative likelihood ratio (NLR) was calculated for each criterion. Results: The sensitivity, specificity, PLR and NLR were respectively for criterion 1 and 2 (0,92/0,58; 0,96/0,99; 24/46 and 0,09/0,57). Conclusion: The first criterion suggests a better sensitivity and accuracy as a warning criterion to avoid central neurological damage.