RESUMEN
Cortical electrical stimulation mapping was used to study neural substrates of the function of writing in the temporoparietal cortex. We identified the sites involved in oral language (sentence reading and naming) and writing from dictation, in order to spare these areas during removal of brain tumours in 30 patients (23 in the left, and 7 in the right hemisphere). Electrostimulation of the cortex impaired writing ability in 62 restricted cortical areas (.25 cm2). These were found in left temporoparietal lobes and were mostly located along the superior temporal gyrus (Brodmann's areas 22 and 42). Stimulation of right temporoparietal lobes in right-handed patients produced no writing impairments. However there was a high variability of location between individuals. Stimulation resulted in combined symptoms (affecting oral language and writing) in fourteen patients, whereas in eight other patients, stimulation-induced pure agraphia symptoms with no oral language disturbance in twelve of the identified areas. Each detected area affected writing in a different way. We detected the various different stages of the auditory-to-motor pathway of writing from dictation: either through comprehension of the dictated sentences (word deafness areas), lexico-semantic retrieval, or phonologic processing. In group analysis, barycentres of all different types of writing interferences reveal a hierarchical functional organization along the superior temporal gyrus from initial word recognition to lexico-semantic and phonologic processes along the ventral and the dorsal comprehension pathways, supporting the previously described auditory-to-motor process. The left posterior Sylvian region supports different aspects of writing function that are extremely specialized and localized, sometimes being segregated in a way that could account for the occurrence of pure agraphia that has long-been described in cases of damage to this region.
Asunto(s)
Escritura Manual , Lóbulo Parietal/fisiología , Lóbulo Temporal/fisiología , Adulto , Anciano , Agrafia/etiología , Agrafia/psicología , Mapeo Encefálico , Neoplasias Encefálicas/cirugía , Estimulación Eléctrica , Electrodos , Femenino , Lateralidad Funcional/fisiología , Humanos , Procesamiento de Imagen Asistido por Computador , Individualidad , Trastornos del Lenguaje/etiología , Trastornos del Lenguaje/psicología , Masculino , Persona de Mediana Edad , Procedimientos Neuroquirúrgicos/efectos adversos , Complicaciones Posoperatorias/etiología , Complicaciones Posoperatorias/psicología , Desempeño Psicomotor/fisiología , Lectura , Adulto JovenRESUMEN
Direct cortical electrostimulation was used to study cortical areas hypothetically involved in translation in bilinguals during brain tumour resections, with a view to sparing these functional areas. A series of seven proficient bilingual patients was studied: two left-handed and five right-handed individuals with no pre-existing language deficit. Hemispheric cortex (on the side contralateral to the patient's hand-dominance) was directly stimulated whilst the patient performed naming and reading tasks in both languages and a translation task (of a written text from their second 'learned' language to their first or 'native' language). Of the 147 different cortical sites studied, 26 'language functional sites' were detected, where electrostimulation affected reading and/or naming in the patient's native and/or second learned language. Of these, 8 sites (in 4 patients) were "task-specific" and "language-specific" i.e., affecting only naming or reading in only one of the patient's languages. Of the 26 "language sites", only 3 produced any interferences in translation. All of these were located in frontal regions. Electrostimulation at these sites caused the patient to stop translating abruptly, but no language switching or other translation-related phenomenon was observed. No site was found that was involved only in translation and not other language tasks. Overall, in contrast to other language tasks, cortical structures of the convexity were rarely involved in translation. We suggest that translation interference could be more readily detected by subcortical stimulations. This spatial dissociation within the brain of translation function versus other language functions could explain the cases of dissociated language impairments observed in some bilingual patients with brain lesions. On a practical level, because the cortical sites found by translation tasks are few and related with other cortical language sites, we think that translation tasks provide little additional helpful information for cortical brain mapping in bilingual neurosurgical patients.
Asunto(s)
Mapeo Encefálico/métodos , Neoplasias Encefálicas/fisiopatología , Encéfalo/fisiología , Lenguaje , Multilingüismo , Adulto , Encéfalo/fisiopatología , Encéfalo/cirugía , Neoplasias Encefálicas/cirugía , Estimulación Eléctrica , Femenino , Humanos , Masculino , Persona de Mediana Edad , TraduccionesRESUMEN
BACKGROUND: Cortical and subcortical electrostimulation mapping during awake brain surgery for tumor removal is usually used to minimize deficits. OBJECTIVE: To use electrostimulation to study neuronal substrates involved in spatial awareness in humans. METHODS: Spatial neglect was studied using a line bisection task in combination with electrostimulation mapping of the right hemisphere in 50 cases. Stimulation sites were identified with Talairach coordinates. The behavioral effects induced by stimulation, especially eye movements and deviations from the median, were quantified and compared with preoperative data and a control group. RESULTS: Composite and highly individualized spatial neglect maps were generated. Both rightward and leftward deviations were induced, sometimes in the same patient but for different stimulation sites. Group analysis showed that specific and reproducible line deviations were induced by stimulation of discrete cortical areas located in the posterior part of the right superior and middle temporal gyri, inferior parietal lobe, and inferior postcentral and inferior frontal gyri (P < .05). Fiber tracking identified stimulated subcortical areas important to spare as sections of fronto-occipital and superior longitudinal II fascicles. According to preoperative and postoperative neglect battery tests, the specificity and sensitivity of intraoperative line bisection tests were 94% and 83%, respectively. CONCLUSION: In humans, discrete cortical areas that are variable in location between individuals but mainly located within the right posterior Sylvian fissure sustain visuospatial attention specifically toward the contralateral or ipsilateral space direction. Line bisection mapping was found to be a reliable method for minimizing spatial neglect caused by brain tumor surgery.
Asunto(s)
Mapeo Encefálico , Encéfalo/patología , Estimulación Eléctrica/métodos , Lateralidad Funcional/fisiología , Trastornos de la Percepción/patología , Adolescente , Adulto , Anciano , Encéfalo/fisiopatología , Encéfalo/cirugía , Neoplasias Encefálicas/complicaciones , Neoplasias Encefálicas/cirugía , Femenino , Estudios de Seguimiento , Humanos , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Pruebas Neuropsicológicas , Trastornos de la Percepción/etiología , Trastornos de la Percepción/cirugía , Desempeño Psicomotor/fisiología , Reproducibilidad de los Resultados , Estadísticas no Paramétricas , Adulto JovenRESUMEN
OBJECT: Frontoethmoidal mengingoencephaloceles (fMECs) are frequently observed in Cambodia, especially in poor families. The authors describe issues related to the surgical treatment of fMECs in Cambodia at the end of a humanitarian program that provided surgery free of charge to patients and their families. METHODS: The authors reviewed 257 cases of fMEC involving patients who presented to their institution, the Children's Surgical Center in Phnom Penh, between 2004 and 2009. They treated 200 of these patients surgically (108 males, 92 females; 89% younger than 18 years) using a "low-cost" management plan with no routine pre- or postoperative investigations. Initially, surgery was performed by visiting foreign surgeons who taught the procedures to resident surgeons. Patients were not charged for consultations or treatment and received at least 1 follow-up examination 6 months postoperatively. RESULTS: The nasoethmoidal type was the most frequent fMEC encountered (69%). Many patients had associated ophthalmological issues (46% of cases). Only 1 familial case was detected. Combined neurosurgical and facial procedures were successfully standardized and learned by surgeons initially unfamiliar with fMEC management. A neurosurgical approach avoided the need for a facial incision in 42 cases, improving cosmetic results. The most common postoperative issues were a temporary CSF leak (24 cases [12%]) and/or infection (28 cases [14%]). There were 3 deaths directly related to the operations. Cosmetic results were good in 145 cases, average in 27, poor in 7, and worse than preoperative appearance in 6 patients. Fifteen patients were lost to follow-up. The parents of 87% of the children were rice farmers. Questionnaire results confirmed that fMEC has important social and educational consequences for the affected children and that these consequences can be partially improved by fMEC correction. CONCLUSIONS: This experience in fMEC management demonstrates that local surgeons can treat these malformations with limited surgical materials and in a nonspecialized infrastructure after principles of treatment have been learned and if they are carefully respected. Surgery for fMEC can thus be more accessible to a larger number of patients in developing countries. Moreover, local treatment facilitates better postoperative and follow-up care.
Asunto(s)
Encefalocele/mortalidad , Encefalocele/cirugía , Meningocele/mortalidad , Meningocele/cirugía , Complicaciones Posoperatorias/mortalidad , Adolescente , Cambodia/epidemiología , Niño , Preescolar , Encefalocele/psicología , Esófago/anomalías , Esófago/cirugía , Hueso Etmoides/cirugía , Femenino , Estudios de Seguimiento , Hueso Frontal/cirugía , Humanos , Hipertelorismo/mortalidad , Hipertelorismo/psicología , Hipertelorismo/cirugía , Hipospadias/mortalidad , Hipospadias/psicología , Hipospadias/cirugía , Lactante , Recién Nacido , Masculino , Meningocele/psicología , Complicaciones Posoperatorias/psicología , Calidad de Vida , Estudios Retrospectivos , Ajuste Social , Factores Socioeconómicos , Cirugía Plástica/mortalidad , Encuestas y Cuestionarios , Resultado del Tratamiento , Adulto JovenRESUMEN
We have translated the most famous text of Sigmund Exner (1846-1926), which relates to the existence of a localised "writing centre" in the brain. We discuss its relevance to modern studies and understanding of writing and agraphia. In Exner's most famous text, he hypothesised about the eponymous "Exner's Area", a discrete area within the brain that was located in the left middle frontal gyrus, which was dedicated to the function of writing. This text in German, included in a book published in 1881 "Untersuchungen über die Lokalisation der Functionen in der Grosshirnrinde des Menschen" (Studies on the localisation of functions in the cerebral cortex of humans), lent itself to passionate debates during the following decades on the possibility of finding a specific writing centre in left middle frontal gyrus. Modern authors still refer back to the evidence cited in this seminal text. However, over the 281 pages of Exner's book, only a few chapters dealt with agraphia. Only four of the 167 case reports in the book explicitly mention agraphia. Although Exner describes the anatomical details of these lesions (from autopsies), no patient had pure agraphia, and only one case had an isolated lesion of the posterior part of the middle frontal gyrus. The small number of patients, the absence of pure agraphia symptoms, and the variation in the anatomy of these lesions are the main reasons why Exner's hypothesis of a writing centre in left middle frontal gyrus has been continually debated until now. More than the seminal publication of Sigmund Exner on agraphia, we think that the diffusion of his hypothesis was partly due to the influence that Exner and his family had within the scientific community at the turn of the 20th century.
Asunto(s)
Agrafia/historia , Lóbulo Frontal , Escritura Manual , Agrafia/patología , Agrafia/fisiopatología , Austria , Lóbulo Frontal/anatomía & histología , Lóbulo Frontal/patología , Lóbulo Frontal/fisiología , Lóbulo Frontal/fisiopatología , Historia del Siglo XIX , Historia del Siglo XX , Humanos , Libros de Texto como Asunto/historiaRESUMEN
OBJECTIVE: Surgical resection of mass lesions in Broca's area is controversial. To demonstrate that pathology may influence the localization of functional areas and language performance, we reviewed our experience of awake craniotomies in Broca's area. METHODS: Sixteen consecutive patients who underwent awake craniotomy and direct brain mapping for resective surgery in Broca's area were analyzed. Six patients had well-circumscribed lesions, whereas 10 patients had infiltrative gliomas. A short version of the Boston Diagnostic Aphasia Examination test was used for language assessment. RESULTS: Inferior frontal language sites were found in all but 4 patients. In patients with cavernomas or well-circumscribed tumors, 9 of 9 (100%) of the positive sites were located in the classic Broca's area (BA 44/45). By contrast, in those patients with gliomas, only 5 of 20 (25%) of the positive sites were located in BA 44/45. Patients with infiltrative gliomas demonstrated more deficits in the pre and postoperative periods than those with well-circumscribed mass lesions. All patients returned to their baseline abilities within 6 months. CONCLUSION: Intraoperative language maps generated in cases with well-circumscribed lesions are different from those generated in cases with infiltrative gliomas. This supports the view that interindividual language variability and displacement of critical structures by mass effect should first be considered for circumscribed lesions, whereas reshaping should largely be attributed to brain plasticity in gliomas. Surgery in Broca's area can be safely conducted using awake craniotomy and brain mapping.
Asunto(s)
Mapeo Encefálico/métodos , Neoplasias Encefálicas/cirugía , Lóbulo Frontal/cirugía , Monitoreo Intraoperatorio/métodos , Procedimientos Neuroquirúrgicos/métodos , Adolescente , Adulto , Anciano , Sedación Consciente , Femenino , Humanos , Masculino , Persona de Mediana Edad , Adulto JovenRESUMEN
Cervical spine injuries after diving into private swimming pools can lead to dramatic consequences. We reviewed 34 patients hospitalized in our center between 1996 and 2006. Data was collected from their initial admission and from follow-up appointments. The injuries were sustained by young men in 97% (mean age 27) and the majority happened during the summer (88%). Fractures were at C5-C7 in 70%. American Spinal Injury Association class (ASIA) on admission was A for 8 patients, B for 4, C for 4, D for 1, and E for 17. There were 23 surgical spine stabilizations. Final ASIA class was A for 6 patients, B for 1, C for 3, D for 5, and E for 18. The mean duration of hospitalization was 21.3 days in our neurosurgical center (mean overall cost: 36,000 Euros/patient) plus 10.6 months in rehabilitation center for the 15 patients admitted who had an ASIA class A to C. Mean overall direct cost for a patient with class A is almost 300,000 Euros, compared to around 10,000 Euros for patients with class D and E. In addition, a profound impact on personal and professional life was seen in many cases including 11 divorces and 7 job losses. Dangerous diving into swimming pools can result in spinal injuries with drastic consequences, including permanent physical disability and a profound impact on socio-professional status. Moreover, there are significant financial costs to society. Better prevention strategies should be implemented to reduce the impact of this public health problem.
Asunto(s)
Accidentes/economía , Vértebras Cervicales/lesiones , Buceo/lesiones , Traumatismos Vertebrales/cirugía , Piscinas , Adolescente , Adulto , Descompresión Quirúrgica , Buceo/economía , Femenino , Francia , Humanos , Masculino , Persona de Mediana Edad , Calidad de Vida , Estudios Retrospectivos , Factores de Riesgo , Fusión Vertebral , Traumatismos Vertebrales/economía , Columna Vertebral/cirugía , Resultado del TratamientoRESUMEN
OBJECT: Frontoethmoidal meningoencephalocele (fMEC) is relatively common in many Southeast Asian countries, with devastating aesthetic and social consequences for affected children. No cause has been detected to date. Among other factors, the authors of this paper attempt to identify a statistically significant difference in the spread of fMEC births throughout the year compared with other births. This seasonal variation in the incidence of fMEC births may provide clues to the causes of this condition. METHODS: From a group of 175 children with fMEC who underwent surgery at the authors' humanitarian institution (Children's Surgical Centre) in Phnom Penh between 2004 and 2008, 86 children were studied. These children were born at full term and had an accurately recorded date of birth. The birth dates of this fMEC group were compared with a group of > 15,000 other live births at one of the main maternity units in Phnom Penh in 2005 and 2006. RESULTS: Seasonal variation in incidence of fMEC by month of birth was highly statistically significant (p < 0.001), with the peak of births occurring in the dry season (between March and May). This is in contrast to the control group, in which there was an equal distribution of births throughout the year. More than 85% of the parents of children with fMEC who the authors treated were farmers, but this figure reflects the composition of the Cambodian population. CONCLUSIONS: Uneven spread in the incidence of fMEC births throughout the year suggests that a seasonal factor during the wet season may be suspected in the pathogenesis of fMEC in Cambodia.
Asunto(s)
Tasa de Natalidad , Encefalocele/epidemiología , Hueso Etmoides , Hueso Frontal , Meningocele/epidemiología , Estaciones del Año , Cambodia/epidemiología , Niño , Preescolar , Encefalocele/etiología , Femenino , Humanos , Incidencia , Masculino , Meningocele/etiologíaRESUMEN
OBJECTIVE: In 1881, Exner first described a "graphic motor image center" in the middle frontal gyrus. Current psycholinguistic models of handwriting involve the conversion of abstract, orthographic representations into motor representations before a sequence of appropriate hand movements is produced. Direct cortical stimulation and functional magnetic resonance imaging (fMRI) were used to study the human frontal areas involved in writing. METHODS: Cortical electrical stimulation mapping was used intraoperatively in 12 patients during the removal of brain tumors to identify the areas involved in oral language (sentence reading and naming) and writing, and to spare them during surgery. The fMRI activation experiment involved 12 right-handed and 12 left-handed healthy volunteers using word dictation (without visual control) and 2 control tasks. RESULTS: Direct cortical electrical stimulation of restricted areas rostral to the primary motor hand area (Brodmann area [BA] 6) impaired handwriting in 6 patients, without disturbing hand movements or oral language tasks. In 6 other patients, stimulation of lower frontal regions showed deficits combining handwriting with other language tasks. fMRI also revealed selective activation during word handwriting in left versus right BA6 depending on handedness. This area was anatomically matched to those areas that affected handwriting on electrical stimulation. INTERPRETATION: An area in middle frontal gyrus (BA6) that we have termed the graphemic/motor frontal area supports bridging between orthography and motor programs specific to handwriting.
Asunto(s)
Mapeo Encefálico/métodos , Corteza Motora/fisiología , Adulto , Estimulación Eléctrica/métodos , Femenino , Lóbulo Frontal/fisiología , Escritura Manual , Humanos , Imagen por Resonancia Magnética/métodos , Masculino , Persona de Mediana Edad , Adulto JovenRESUMEN
OBJECT: A naming task has been used to spare cortical areas involved in language. In the present study, a calculation task was combined with electrostimulation mapping (awake surgery) to spare cortical areas involved in calculation in patients undergoing surgery for brain lesions. The organization of language and calculation areas was analyzed in relation to these surgical data. METHODS: Twenty patients with brain lesions close to areas possibly involved in calculation (dominant parietal lobe and F2) were prospectively studied over a 4-year period. Four patients had preoperative symptoms of acalculia and therefore were not included in the brain mapping procedure. RESULTS: In 16 patients, direct electrostimulation caused calculation interferences in localized small cortical areas (< 2 cm(2)). Of the 53 calculation interferences found, 23 were independent of language areas, especially those in the inferior left parietal lobule. Various patterns of interference were observed (11 complete acalculia, 5 acalculia with wrong answers, 2 hesitations, and 5 mixed responses), although error patterns were fairly similar across angular, parietal, and frontal stimulation sites. Calculation areas in 4 patients could not be spared for oncological reasons; postoperatively, 3 of these patients showed significant acalculia symptoms. In contrast, none of the patients whose calculation areas were spared had arithmetic difficulties 1 month after surgery. Improvements in acalculia symptoms after surgery were also found in 3 of the 4 patients with preoperative calculation difficulties. CONCLUSIONS: To limit the risk of personal and professional disturbances caused by acquired anarithmetia in patients undergoing surgery for brain tumors or epilepsy, the authors think it is necessary to use a calculation task during brain mapping, especially when operating in the dominant parietal lobe.