Successful stereoelectroencephalography re-evaluation in epilepsy patients after failed initial subdural grid evaluation.

OBJECTIVE: Epilepsy surgery success is dependent on accurate localization of the epileptogenic zone. Despite the use of invasive EEG using subdural grids and strips, surgical failures can occur. In this series, we explore the utility of a second evaluation with stereoelectroencephalography in patients whose initial invasive evaluation with subdural grid electrodes was unsuccessful in localizing seizure origin. METHODS: We conducted a retrospective review of patients who underwent subdural grid evaluation (SDE) at our center and identified patients who underwent a re-evaluation with stereoelectroencephalography (SEEG). RESULTS: We identified three patients who had both subdural and SEEG electrodes in the region of the identified epileptogenic zone in whom the initial SDE evaluation failed to make the patients seizure-free. Two of these patients underwent a second resection and became seizure-free. SIGNIFICANCE: Stereoelectroencephalography can be useful in the re-evaluation and re-operation of patients who previously had surgical failure using SDE.

Investigating the Precise Localization of the Grasping Action in the Mid-Cingulate Cortex and Future Directions.

Objective: To prospectively study the cingulate cortex for the localization and role of the grasping action in humans during electrical stimulation of depth electrodes. Methods: All the patients (n = 23) with intractable focal epilepsy and a depth electrode stereotactically placed in the cingulate cortex, as part of their pre-surgical epilepsy evaluation from 2015 to 2017, were included. Cortical stimulation was performed and examined for grasping actions. Post-implantation volumetric T1 MRIs were co-registered to determine the exact electrode position. Results: Five patients (male: female 4:1; median age 31) exhibited contralateral grasping actions during electrical stimulation. All patients had electrodes implanted in the ventral bank of the right cingulate sulcus adjacent to the vertical anterior commissure (VAC) line. Stimulation of other electrodes in adjacent regions did not elicit grasping. Conclusion: Grasping action elicited from a localized region in the mid-cingulate cortex (MCC) directly supports the concept of the cingulate cortex being crucially involved in the grasping network. This opens an opportunity to explore this region with deep brain stimulation as a motor neuromodulation target for treatment in specific movement disorders or neurorehabilitation.

Localisation and stimulation of the parietal eye field.

Localisation of the human parietal eye fields (PEF) has not been as well studied as the human frontal eye fields (FEF). Stimulation studies in rhesus monkeys have suggested the localisation of the PEF to be within the intraparietal sulcus. Functional MRI studies have demonstrated this region to be highly active and potentially connected in saccadic and gaze shifting tasks. Here, we present a case of a patient with left versive seizures evaluated with SEEG, in whom electrical stimulation within the right intraparietal sulcus resulted in horizontal and downward conjugate eye movements contralateral to stimulation. We illustrate clinical differences between the FEF and PEF on cortical stimulation. In addition to the frontal eye field, it is important to recognise other cortical regions involved in eye movement which can cause conjugate contralateral eye movement.

A study of perfusion changes with Insula Epilepsy using SPECT.

PURPOSE: The non-invasive localisation of insular lobe epilepsy is a challenge. We aimed to determine if ictal SPECT is a reliable adjunctive test in insular cases and to explore its role in the tailoring of intracranial strategies. METHOD: From a dataset of patients who underwent SEEG between December 2012 and December 2016, we collected patients with focal insular onset epilepsy. We examined semiology, EEG, PET and SPECT hyperperfusion pattern with SISCOM. We also reviewed relevant literature. RESULTS: 5 patients were identified, 4 females, from a dataset of 51 patients. Median age of seizure onset was 8 years old (8 months to 10 years). All patients had an ictal SPECT during pre-surgical work-up: median injection time was 7 s (3-17 sec) from clinical onset, and median seizure duration was 42 s (11-85 sec). Insula cortex showed focal hyperaemia in four patients, all bilateral, with the greatest hyperperfusion contralateral to the ictal onset in two cases, using SISCOM threshold at 1.5 standard deviation. Other sites with hyperaemia included basal ganglia and middle temporal gyrus. The SEEG confirmed insular onset seizures in all the cases. All patients had epilepsy surgery and were seizure free at 21 to 50 months follow up. The results from the literature review showed frequent hyperperfusion in structures outside insula and frequently over the contralateral hemisphere. CONCLUSIONS: This study highlights the technical limitations of SPECT when attempting to assess seizures arising from the insula. Our findings and the literature show ictal SPECT can be localising but falsely lateralising in seizures arising from the insula.

Reduced complications from intracranial grid insertion by using a small grid size and a precise protocol during monitoring.

BACKGROUND: A study of the risk factors associated with complications during intracranial EEG monitoring led to a change in protocol for monitoring and implantation at our centres. We conducted a study to identify any reduction in complications following the changed protocols involving the use of smaller subdural electrode arrays, continuous ICP monitoring, use of a central line, and intake of prophylactic antibiotics and dexamethasone. METHODS: We prospectively collected data on patient outcomes between 2005 and 2012 (group B) compared with patients between 1988 and 2004 (group A) before the protocol changes. RESULTS: Seventy-one patients in group A and 58 patients in group B underwent intracranial electrode implantation. Complications directly related to grids occurred in 25 % of group A vs. 8.6 % in group B (p < 0.05) and those indirectly related to grids were 11.2 % in group A vs. none in group B. The rate of transient complications requiring no treatment was 12.5 % in group A versus 1.7 % in group B. The rate of transient complications requiring treatment was 10 % in group A and 6.9 % in group B. There were two deaths in group A. The infection rate was higher in group B than group A (5.2 % vs. 2.8 %; p = 0.90). Since 2008 there have been no infective complications. Complications directly related to intracranial EEG monitoring were significantly reduced using the revised protocol (p < 0.05). Regression analysis identifying only the size of the grids (≤4 × 8 grid arrays) implanted was an independent predictor of more complications in group A (P < 0.05). CONCLUSIONS: Complication rates following intracranial implantation decreased following the use of a small grid size and adherence to a stringent protocol.

Myoclonic status epilepticus as a presentation of caspr2 antibody-associated autoimmune encephalitis.

We present a case of autoimmune encephalitis associated with antibodies targeting contact in-associated protein-like 2. This case is notable because of the presentation with myoclonic status epilepticus and the prolonged clinical course of refractory seizures, which are demonstrated in the accompanying videos, and not previously associated with this condition. Treatment with prednisone, intravenous immunoglobulin, plasma exchange, rituximab, cyclophosphamide, and mycophenolate mofetil resulted in significant functional improvement. Historically, myoclonic status epilepticus is associated with a grave prognosis and minimal chance of meaningful recovery. This case demonstrates that autoimmune encephalitis remains an important differential diagnosis in patients with such a presentation, and that early recognition and the appropriate institution of immunotherapy can result in seizure control and functional recovery. [Published with video sequences].

The yield and clinical utility of outpatient short-term video-electroencephalographic monitoring: a five-year retrospective study.

Outpatient short-term video-electroencephalographic monitoring (OVEM) is recognized as a useful tool in the diagnosis of epilepsy and other paroxysmal disorders. The aim of this retrospective study was to determine the diagnostic yield of OVEM. We analyzed 175 OVEM records of adults (111 females and 64 males) referred over a period of 5 years. The mean length of recording was 3.8 h. The highest yield was found in psychogenic nonepileptic seizures (PNES) (37.1%), followed by interictal epileptiform discharges (17.2%), and epileptic seizures (6.9%). The provisional diagnosis was epilepsy in 77.7% and PNES in 22.3% before the test. Outpatient short-term video-electroencephalographic monitoring changed the pre-test diagnosis in 30.9% of patients. Outpatient short-term video-electroencephalographic monitoring is a useful diagnostic test for PNES. It has a higher yield for PNES than epilepsy.