RESUMO
Focal atonic seizures are recognized rarely as ictal phenomena, they can correspond to both generalized epilepsy and focal epilepsy. The areas of the brain involved in the management of this type of seizure are: the negative motor area and the primary motor and primary somatosensory cortices, although the neurophysiology that generates them is still unclear. We present the case of a patient with focal atonic seizures in the left upper limb, refractory to drug treatment. Neuroimaging was performed, a parietal cortical lesion was diagnosed. A scalp Video EEG and then a Stereo EEG was performed, defining the epileptogenic area and its relationship with eloquent areas. Surgical resection of the lesion was performed, achieving complete seizure control.
Las crisis atónicas focales son poco reconocidas como fenómenos ictales, pueden corresponder tanto a una epilepsia generalizada como a una epilepsia focal. Las áreas del cerebro implicadas en la gestión de este tipo de crisis son: el área motora negativa y las cortezas motora primaria y somatosensitiva primaria, aunque aún la neurofisiología que las genera no está aclarada. Presentamos el caso de un paciente con crisis atónicas focales farmacorresistentes en miembro superior izquierdo. Se realizó resonancia de cerebro con diagnóstico de displasia cortical parietal, se monitoreó con video EEG de scalp y luego a video EEG con electrodos profundos. Se definieron el área epileptógena y su relación con áreas elocuentes, se realizó resección quirúrgica de la lesión, logrando el control completo de las crisis.
Assuntos
Epilepsias Parciais , Epilepsia Generalizada , Malformações do Desenvolvimento Cortical , Humanos , Epilepsias Parciais/etiologia , Epilepsias Parciais/cirurgia , Epilepsias Parciais/diagnóstico , Convulsões/etiologia , Convulsões/cirurgia , Encéfalo , Malformações do Desenvolvimento Cortical/complicações , Malformações do Desenvolvimento Cortical/diagnóstico por imagem , Malformações do Desenvolvimento Cortical/cirurgia , Eletroencefalografia , Imageamento por Ressonância MagnéticaRESUMO
BACKGROUND: Intraoperative stimulation of the posterior inferior frontal lobe (IFL) induces speech arrest, which is often interpreted as demonstration of essential language function. However, prior reports have described "negative motor areas" in the IFL, sites where stimulation halts ongoing limb motor activity. OBJECTIVE: To investigate the spatial and functional relationship between IFL speech arrest areas and negative motor areas (NMAs). METHODS: In this retrospective cohort study, intraoperative stimulation mapping was performed to localize speech and motor function, as well as arrest of hand movement, hand posture, and guitar playing in a set of patients undergoing awake craniotomy for dominant hemisphere pathologies. The incidence and localization of speech arrest and motor inhibition was analyzed. RESULTS: Eleven patients underwent intraoperative localization of speech arrest sites and inhibitory motor areas. A total of 17 speech arrest sites were identified in the dominant frontal lobe, and, of these, 5 sites (29.4%) were also identified as NMAs. Speech arrest and arrest of guitar playing was also evoked by a single IFL site in 1 subject. CONCLUSION: Inferior frontal gyrus speech arrest sites do not function solely in speech production. These findings provide further evidence for the complexity of language organization, and suggest the need for refined mapping strategies that discern between language-specific sites and inhibitory motor areas.
Assuntos
Mapeamento Encefálico/métodos , Lobo Frontal/fisiologia , Lobo Frontal/cirurgia , Monitorização Neurofisiológica Intraoperatória/métodos , Movimento/fisiologia , Fala/fisiologia , Adulto , Estudos de Coortes , Craniotomia/métodos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Córtex Motor/fisiopatologia , Estudos Retrospectivos , Vigília/fisiologiaRESUMO
Inhibition is a central component of motor control. Although current models emphasize the involvement of frontal networks [1, 2], indirect evidence suggests a potential contribution of the posterior parietal cortex (PPC). This region is active during inhibition of upper-limb movements to undesired targets [3], and its stimulation with single magnetic pulses can depress motor-evoked potentials [4, 5]. Also, it has been speculated that alien hand movements caused by focal parietal lesions reflect a release of inhibition from PPC to M1 [6]. Considering these observations, we instructed 16 patients undergoing awake brain surgery to perform continuous hand movements while electrical stimulation was applied over PPC. Within a restricted dorsoposterior area, we identified focal sites where stimulation prevented movement initiation and instantly inhibited ongoing responses (which restarted promptly at stimulation offset). Inhibition was selective of the instructed response. It did not affect speech, hand movements passively generated through muscle electrical stimulation, or the ability to initiate spontaneous actions with other body segments (e.g., the feet). When a patient inadvertently performed a bilateral movement, a bilateral inhibition was found. When asked to produce unilateral movements, this patient presented a contralesional but not ipsilateral inhibition. This selectivity contrasted sharply with the unspecific inhibitions reported by previous studies within frontal regions, where speech and all limbs are typically affected (as we here confirm in a subset of patients) [7-10]. These results provide direct evidence that a specific area in the dorsoposterior parietal cortex can inhibit volitional upper-limb responses with high selectivity.
Assuntos
Mãos , Movimento/fisiologia , Lobo Parietal/fisiologia , Desempenho Psicomotor/fisiologia , Volição/fisiologia , Adolescente , Adulto , Estimulação Elétrica , Feminino , Lateralidade Funcional/fisiologia , Humanos , Masculino , Pessoa de Meia-Idade , Adulto JovemRESUMO
Resumen Las crisis atónicas focales son poco reconocidas como fenómenos ictales, pueden corresponder tanto a una epilepsia generalizada como a una epilepsia focal. Las áreas del cerebro implicadas en la gestión de este tipo de crisis son: el área motora negativa y las cortezas motora primaria y somatosensitiva primaria, aunque aún la neurofisiología que las genera no está aclarada. Presentamos el caso de un paciente con crisis atónicas focales farmacorresistentes en miembro superior iz quierdo. Se realizó resonancia de cerebro con diagnóstico de displasia cortical parietal, se monitoreó con video EEG de scalp y luego a video EEG con electrodos profundos. Se definieron el área epileptógena y su relación con áreas elocuentes, se realizó resección quirúrgica de la lesión, logrando el control completo de las crisis.
Abstract Focal atonic seizures are recognized rarely as ictal phenomena, they can correspond to both generalized epilepsy and focal epilepsy. The areas of the brain in volved in the management of this type of seizure are: the negative motor area and the primary motor and primary somatosensory cortices, although the neurophysiology that generates them is still unclear. We present the case of a patient with focal atonic seizures in the left upper limb, refractory to drug treatment. Neuroimaging was performed, a parietal cortical lesion was diagnosed. A scalp Video EEG and then a Stereo EEG was performed, defining the epileptogenic area and its relationship with eloquent areas. Surgical resection of the lesion was performed, achieving complete seizure control.
RESUMO
OBJECTIVE: The lateral and mesial aspects of the central and frontal cortex were studied by direct electrical stimulation of the cortex in epilepsy surgery candidates in order to determine the localization of unilateral and bilateral negative motor responses. METHODS: Results of electrical cortical stimulation were examined in epilepsy surgery candidates in whom invasive electrodes were implanted. The exact localization of subdural electrodes was defined by fusion of 3-dimensional reconstructed MRI and CT images in 13 patients and by analysis of plane skull X-rays and intraoperative visual localization of the electrodes in another 7 patients. RESULTS: Results of electrical stimulation of the cortex were evaluated in a total of 128 patients in whom invasive electrodes were implanted for planning resective epilepsy surgery. Twenty patients, in whom negative motor responses were obtained, were included in the study. Bilateral upper limb negative motor responses were more often elicited from stimulation of the mesial frontal cortex whereas stimulation of the lateral central cortex leads to contralateral upper limb negative motor responses (p<0.0001). Bilateral negative motor responses were exclusively found in the superior frontal gyrus whereas contralateral negative motor responses localized predominantly in the anterior part of the precentral gyrus (p<0.0001). CONCLUSIONS: Exact localization using 3-D fusion methods revealed that negative motor areas are widely distributed throughout the precentral gyrus and the mesial fronto-central cortex showing functional differences with regard to unilateral and bilateral upper limb representation. SIGNIFICANCE: The lateral fronto-central negative motor area serves predominantly contralateral upper limb motor control whereas the mesial frontal negative motor area represents bilateral upper limb movement control.