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Results for “Subdural Space”

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At least 865 records · Page 48Linked to original sources
PubMed2004

Evidence of basal temporo-occipital cortex involvement in stereoscopic vision in humans: a study with subdural electrode recordings.

Stereoscopic vision is based on small differences in both retinal images known as retinal disparities. We investigated the cortical responses to retinal disparities in a patient suffering from occipital epilepsy by recording evoked potentials to random dot stereograms (RDS) from subdural electrodes placed in the parieto-occipito-temporal junction, medial surface of the occipital lobe (pericalcarine cortex) and basal surface of the occipital and temporal lobes (fusiform gyrus). Clear responses to disparity present in RDS were found in the fusiform cortex. We observed that the fusiform responses discriminate the onset from the offset of the stimulus, correlation from uncorrelation, and they show a longer latency than responses found in the pericalcarine cortex. Our findings indicate that the fusiform area is involved in the processing of the stereoscopic information and shows responses that suggest a high level of stereoscopic processing.

Brain Mapping↗
PubMed2006

Epileptogenic neocortical networks are revealed by abnormal temporal dynamics in seizure-free subdural EEG.

Long-term video electroencephalographic (EEG) recording is currently a routine procedure in the presurgical evaluation of localization-related epilepsies. Cortical epileptogenic zone is usually localized from ictal recordings with intracranial electrodes, causing a significant burden to patients and health care. Growing literature suggests that epileptogenic networks exhibit aberrant dynamics also during seizure-free periods. We examined if neocortical epileptogenic regions can be circumscribed by quantifying local long-range temporal (auto-)correlations (LRTC) with detrended fluctuation analysis of seizure-free ongoing subdural EEG activity in 4 frequency bands in 5 patients. We show here with subdural EEG recordings that the LRTC are abnormally strong near the seizure onset area. This effect was most salient in neocortical oscillations in the beta frequency band (14-30 Hz). Moreover, lorazepam, a widely used antiepileptic drug, exerted contrasting effects on LRTC (n = 2): lorazepam attenuated beta-band LRTC near the epileptic focus, whereas it strengthened LRTC in other cortical areas. Our findings demonstrate that interictal neuronal network activity near the focus of seizure onset has pathologically strong intrinsic temporal correlations. The observed effect by lorazepam on beta-band activity suggests that the antiepileptic mechanism of benzodiazepines may be related to the normalization of LRTC within the epileptic focus. We propose that this method may become a promising candidate for routine invasive and noninvasive presurgical localization of epileptic foci.

Adult↗
PubMed2001

Does the pre-frontal cortex contribute to movement-related potentials? Recordings from subdural electrodes.

The contribution of the pre-frontal cortex to movement-related potentials (MRPs) is unclear. We recorded MRPs from six subdural electrode strips placed over the frontal cortex in a 13-year-old girl being monitored prior to surgery for intractable epilepsy. MRPs were recorded prior to two types of movement: self-paced random joystick movements which involve 'what to do' and 'when to do' decision making on every trial and prior to joystick movements in a fixed forward direction triggered by a tone which does not involve any trial-by-trial decision making. Self-paced random joystick movements were associated with an increased subdural positivity starting from 1000 ms prior to onset of joystick movement at electrodes over the pre-motor cortex (BA 6) and dorsolateral and inferior pre-frontal cortex (BA 46/45/10), as evident from a magnetic resonance imaging scan. These results suggest that in addition to the pre-motor area, the pre-frontal cortex also contributes to the generation of MRPs in conditions involving decision making about the precise nature ('what to do') and timing ('when to do') of the movement. These preliminary results require replication in a larger series of patients.

Adolescent↗
PubMed1976

Complications of surgery for subdural hematoma.

In this report we have discussed the complications of surgery for subdural hematoma. The complications are varied and many depend primarily on the type of treatment required by the patient. We have considered the problems associated with: percutaneous tap in infants, subdural shunts in infants and children, craniotomy for membranectomy, twist-drill drainage, and burr holes, craneictomy, and/or craniotomy. Infection, epilepsy, and reaccumulation of the subdural hematoma are common to all forms of therapy, while other complications are related to the specific form of subdural hematoma treatment. In addition, significant serum and electrolyte abnormalities which may occur as a consequence of subdural hematoma surgery have been reviewed. In general, the over-all complication rate of surgery for subdural hematoma is low in relationship to the morbidity and mortality associated with this lesion. Because of the frequency of subdural hematoma, the neurosurgeon should be ever vigilant in the prevention, recognition, and management of these complications.

Acute Disease↗