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We report the case of a patient with nonlesional, pharmacoresistant epilepsy. Bilateral synchronous discharges as well as focal discharges were identified on electroencephalogram (EEG). After non-invasive and invasive presurgical evaluation, a probable epileptogenic zone was identified with concordant results of focal origin involvement of the left temporal pole. Resective epilepsy surgery provided seizure freedom (last follow-up at 12 months). The case nicely illustrates that bilateral synchronous discharges or/and a lack of lesions on neuroimaging are not contraindications to presurgical evaluation of epilepsy, which on the contrary should be offered to all patients with pharmacoresistant epilepsy. The case also illustrates the importance of combining electrophysiological, imaging, and neuropsychological information to guide intracranial EEG placement and improve postsurgical outcome.

Chronic epilepsy has rarely been reported after posterior reversible encephalopathy syndrome (PRES) and the association with hippocampal sclerosis has been suggested only once before. We report the case of a girl admitted at the age of 8 years with idiopathic nephrotic syndrome. On the second day of admission, she presented with focal complex seizures and cerebral MRI showed posterior encephalopathy and no hippocampal sclerosis. MRI after one month confirmed the diagnosis of PRES. The seizures recurred and the girl developed pharmacoresistant epilepsy and was admitted to our hospital for further investigation. Cerebral MRI three years after the diagnosis of PRES showed hippocampal sclerosis which was not present on the initial MRI. We conclude that there is a triggering role of PRES in the development of hippocampal sclerosis. Hippocampal sclerosis may have resulted from seizure-associated damage, alternatively, hypertensive encephalopathy may have led to hippocampal damage viaa vascular mechanism.

Chronic epilepsy has rarely been reported after posterior reversible encephalopathy syndrome (PRES) and the association with hippocampal sclerosis has been suggested only once before. We report the case of a girl admitted at the age of 8 years with idiopathic nephrotic syndrome. On the second day of admission, she presented with focal complex seizures and cerebral MRI showed posterior encephalopathy and no hippocampal sclerosis. MRI after one month confirmed the diagnosis of PRES. The seizures recurred and the girl developed pharmacoresistant epilepsy and was admitted to our hospital for further investigation. Cerebral MRI three years after the diagnosis of PRES showed hippocampal sclerosis which was not present on the initial MRI. We conclude that there is a triggering role of PRES in the development of hippocampal sclerosis. Hippocampal sclerosis may have resulted from seizure‐associated damage, alternatively, hypertensive encephalopathy may have led to hippocampal damage viaa vascular mechanism.

The surgical treatment of pharmaco-resistant focal epilepsy has increased dramatically in recent years. This evolution is undoubtedly due to an improvement of electrophysiological and neuroradiological investigations to localize the epileptic focus. Temporal lobe epilepsy is the most frequent pharmaco-resistent epileptic syndrome in adults and responds better to surgery than the so-called extratemporal epilepsy. Apart from the history and the clinical semiology, the investigations for temporal lobe epilepsy are based on core investigations, including electroencephalography (long-term video-EEG recordings) and MRI. Additional noninvasive imaging techniques to improve the localization of the epileptic focus include PET ictal and interictal SPECT, electric source imaging and magnetic source imaging, and simultaneous EEG and functional MRI. Advanced sequences and analysis of structural MRI data allow us to map subtle structural abnormalities as well as important white matter tracts, while functional MRI of language/memory helps to identify eloquent cortical area and estimate the risk of postoperative deficits. Our aim is to review the current literature and summarize all available data on these validated imaging techniques for the assessment of focal temporal lobe epilepsy.

ABSTRACT.Objective:To demonstrate a subdermal wire electrode technique for establishing a ground (GND) and reference (REF) during long-term EEG monitoring (LTM) with intracranial electrodes. Usually, a separate GND and REF are required and this GND&REF pair can be selected contacts in the invasive electrode arrays themselves, special invasive electrodes, or Standard surface disc electrodes which require frequent maintenance. We investigated the use of a pair of chronic Subdermal Wire Electrodes (SWE) for use as GND&REF. Methods:A pair of SWEs as GND&REF was tested in nine patients undergoing invasive EEG monitoring. SWE impedances were monitored in two patients and compared to disc electrode impedances. Results:Without maintenance, SWE impedances remained low and stable during the entire recording period (up to 20 days), whereas disc electrodes showed rapid impedance increase όfter the first day. In all nine patients, the consistent and durable integrity of the GND&REF pair of SWE allowed for a good quality EEG recording. No local skin complications were observed. Conclusions:A pair of SWE electrodes provides a GND&REF system that is easy to place, maintain, and provides a high quality recording with long-term stability when couplecl with referential based EEG recording system from invasive electrodes. Significance:A more efficient means of establishing a GND&REF pair during the monitoring of patients with invasive electrodes is described.