Partial Drug-resistant Epilepsy Clinical Trial
Official title:
ULtrasound Imaging in Focal Cortical dYSplasia: a New Approach to Delineating the Dysplastic Cortex During Neurosurgery
High Resolution Imaging of Cerebral Vasculature by Functional Micro-Doppler Sonography During Brain Surgery (ULYS)
Three decades since its comprehensive description (Taylor et al., 1971), focal cortical
dysplasia (FCD) remains an enigmatic condition. FCD may cause severe refractory epilepsy that
can be directly life threatening. Preoperative neuroimaging usually includes high-resolution
MR imaging, which can reveal only 60 to 80% of cortical abnormalities in patients with FCD.
When antiepileptic drugs fail to bring complete seizure freedom in FCD patients, surgical
resection of the FCD is inevitable. Many patients, especially those with normal MR imaging
results, undergo additional diagnostic procedures. Scalp EEG is frequently used and was one
of the more important modalities during early surgical series. Approximately one half to two
thirds of patients with abnormal EEG findings have a regional ictal abnormality. In some
cases, intracranial electrophysiological recordings, most commonly with grid arrays, are
used. Chronic recording allows identification of eloquent cortex areas, in addition to
defining the epileptogenic region. The "eloquent brain" refers to the parts of the brain that
allows the interaction with and the process of surrounding environment, via the senses,
motion, language, memory and the purposeful use of tools. Nevertheless, all these techniques
are either invasive or have a spatiotemporal resolution too poor to identify precisely the
epileptic lesion deep in the brain. Hence, large resection of lesion areas, such as
lobectomies and even hemispherectomies, are performed with a high risk of side effects
including aphasia, partial face paralysis and hemiplegia depending on the localization of the
lesion.
Navigable three-dimensional (3D)-MRI (based on Neuronavigation system) is currently used at
the Sainte Anne hospital for planning and guiding during resection but neurosurgeons often
complains about poor resolution and non-real-time imaging. While the use of surgical
navigation has been an important advance in brain surgery, its utility is limited by the
phenomenon known as brain shift. Whenever the brain is exposed, cerebral spinal fluid (CSF)
is lost. Additionally, after the start of resectioning, the position of the surgical field
can shift by centimeters, compared to the pre-surgery position. Brain shift makes it
potentially hazardous to rely on preoperative images to determine the location of residual
tumors. The only way to deal with brain shift and maintain accurate neuronavigation is with
intraoperative imaging to enhance resection of the pathologic tissue in FCD.
Previously, the investigators demonstrated the feasibility of their approach by monitoring
the hemodynamic responses during drug-induced epileptic seizures in preclinical models using
functional micro-Doppler Sonography (fmDS).
The investigators are now developing this new tool combining a navigable three-dimensional
(3D)-ultrasound interface to correct in real-time the brain shift (B-mode) with the
near-real-time identification with unprecedented resolution of the dysplasia foci based on
the specific hemodynamic signature of abnormal neurons.
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