Cheolsu Shin

Routine EEG and temporal lobe epilepsy: Relation to long-term EEG monitoring, quantitative MRI, and operative outcome

Summary: Purpose: To investigate the relation among routine EEG, long‐term EEG monitoring (LTM), quantitative magnetic resonance imaging (MRI), and surgical outcome in temporal lobe epilepsy (TLE).

Electrocorticography and Temporal Lobe Epilepsy: Relationship to Quantitative MRI and Operative Outcome

Summary: We investigated the relationship between electrocorticography (ECoG), quantitative magnetic resonance imaging (MRI), and surgical outcome in 165 patients with intractable nonlesional temporal lobe epilepsy (NLTLE). A standard mesial temporal resection was performed in all patients. Patients with an operative follow‐up <1 year were excluded from the study. The extent of the lateral temporal neocortex resection (LCR) was guided by ECoG and the side of surgery. The extent of the LCR was not predictive of seizure outcome in patients with or without hippocampal formation atrophy (p > 0.5). Patients undergoing a right anterior temporal lobectomy had a larger LCR (p < 0.000l), but the side of surgery was not of predictive value in determining seizure outcome (p > 0.1). The topography of the acute intracranial spikes did not correlate with operative outcome (p > 0.5) and was independent of hippocampal volumetric studies (p > 0.5). The postexcision ECoG was also shown not to be of prognostic importance (p > 0.5). Our results indicates that the extent of the lateral temporal cortical resection and the ECoG findings are not important determinants of surgical outcome in patients with NLTLE.

Utility of an immunotherapy trial in evaluating patients with presumed autoimmune epilepsy.

Objective: To evaluate a trial of immunotherapy as an aid to diagnosis in suspected autoimmune epilepsy. Method: We reviewed the charts of 110 patients seen at our autoimmune neurology clinic with seizures as a chief complaint. Twenty-nine patients met the following inclusion criteria: (1) autoimmune epilepsy suspected based on the presence of ≥1 neural autoantibody (n = 23), personal or family history or physical stigmata of autoimmunity, and frequent or medically intractable seizures; and (2) initiated a 6- to 12-week trial of IV methylprednisolone (IVMP), IV immune globulin (IVIg), or both. Patients were defined as responders if there was a 50% or greater reduction in seizure frequency. Results: Eighteen patients (62%) responded, of whom 10 (34%) became seizure-free; 52% improved with the first agent. Of those receiving a second agent after not responding to the first, 43% improved. A favorable response correlated with shorter interval between symptom onset and treatment initiation (median 9.5 vs 22 months; p = 0.048). Responders included 14/16 (87.5%) patients with antibodies to plasma membrane antigens, 2/6 (33%) patients seropositive for glutamic acid decarboxylase 65 antibodies, and 2/6 (33%) patients without detectable antibodies. Of 13 responders followed for more than 6 months after initiating long-term oral immunosuppression, response was sustained in 11 (85%). Conclusions: These retrospective findings justify consideration of a trial of immunotherapy in patients with suspected autoimmune epilepsy. Classification of evidence: This study provides Class IV evidence that in patients with suspected autoimmune epilepsy, IVMP, IVIg, or both improve seizure control.

MRI Findings in Autoimmune Voltage-Gated Potassium Channel Complex Encephalitis with Seizures: One Potential Etiology for Mesial Temporal Sclerosis

Voltage-gated potassium channel complex encephalitis is a common form of autoimmune encephalitis presenting with intractable seizures that may respond to immunotherapy. These authors reviewed the imaging findings in 42 such patients and the most common abnormalities noted were enlargement, T2 hyperintensity, contrast enhancement, and restricted diffusion in the mesial temporal lobes with subsequent development of hippocampal atrophy. Because the disease can be confirmed easily by the presence of voltage-gated potassium channel complex antibodies, these imaging findings should prompt serologic testing. BACKGROUND AND PURPOSE: Autoimmune voltage-gated potassium channel complex encephalitis is a common form of autoimmune encephalitis. Patients with seizures due to this form of encephalitis commonly have medically intractable epilepsy and may require immunotherapy to control seizures. It is important that radiologists recognize imaging characteristics of this type of autoimmune encephalitis and suggest it in the differential diagnosis because this seizure etiology is likely under-recognized. Our purpose was to characterize MR imaging findings in this patient population. MATERIALS AND METHODS: MR imaging in 42 retrospectively identified patients (22 males; median age, 56 years; age range, 8–79 years) with seizures and voltage-gated potassium channel complex autoantibody seropositivity was evaluated for mesial and extratemporal swelling and/or atrophy, T2 hyperintensity, restricted diffusion, and enhancement. Statistical analysis was performed. RESULTS: Thirty-three of 42 patients (78.6%) demonstrated enlargement and T2 hyperintensity of mesial temporal lobe structures at some time point. Mesial temporal sclerosis was commonly identified (16/33, 48.5%) at follow-up imaging. Six of 9 patients (66.7%, P = .11) initially demonstrating hippocampal enhancement and 8/13 (61.5%, P = .013) showing hippocampal restricted diffusion progressed to mesial temporal sclerosis. Conversely, in 6 of 33 patients, abnormal imaging findings resolved. CONCLUSIONS: Autoimmune voltage-gated potassium channel complex encephalitis is frequently manifested as enlargement, T2 hyperintensity, enhancement, and restricted diffusion of the mesial temporal lobe structures in the acute phase. Recognition of these typical imaging findings may help prompt serologic diagnosis, preventing unnecessary invasive procedures and facilitating early institution of immunotherapy. Serial MR imaging may demonstrate resolution or progression of radiologic changes, including development of changes involving the contralateral side and frequent development of mesial temporal sclerosis.

Comparative diagnostic utility of 1H MRS and DWI in evaluation of temporal lobe epilepsy.

Objective: To compare the ability of diffusion-weighted MRI (DWI) and 1H MRS to lateralize to the temporal lobe of seizure onset and to predict postoperative seizure control in patients with temporal lobe epilepsy (TLE). Methods: Forty TLE patients who subsequently underwent epilepsy surgery and 20 normal subjects were studied with 1H MRS and DWI. Medial parietal and temporal lobe N-acetylaspartate (NAA)/creatine (Cr) ratios and hippocampal and temporal stem apparent diffusion coefficients (ADC) were obtained. Lateralization to either temporal lobe with each MR measurement was based on the threshold values derived from ±1-SD right/left ratios of normal subjects. Results: Temporal lobe NAA/Cr lateralized to the operated temporal lobe in 18 of 40 (45%), hippocampal ADC in 32 of 40 (80%), and temporal stem ADC in 26 of 40 (65%) patients. Almost all of the cases that lateralized to the surgical side with NAA/Cr ratios (94%) had an excellent postoperative seizure control (p = 0.01). Lateralization to the side of surgery was not associated with surgical outcome with hippocampal and temporal stem ADC (p > 0.05). Conclusion:1H MRS and DWI complement each other in the clinical setting. DWI more frequently lateralized to the operated side, and 1HMRS was a better predictor of postoperative seizure control.

Basal ganglia T1 hyperintensity in LGI1-autoantibody faciobrachial dystonic seizures.

Objective: To characterize the clinical features and MRI abnormalities of leucine-rich glioma-inactivated 1 (LGI1)-autoantibody (Ab) faciobrachial dystonic seizures (FBDS). Methods: Forty-eight patients with LGI1-Ab encephalopathy were retrospectively identified by searching our clinical and serologic database from January 1, 2002, to June 1, 2015. Of these, 26 met inclusion criteria for this case series: LGI1-Ab seropositivity and FBDS. In a separate analysis of all 48 patients initially identified, the MRIs of patients with (n = 26) and without (n = 22) FBDS were compared by 2 neuroradiologists blinded to the clinical details. Results: The median age of the 26 included patients was 62.5 years (range 37–78); 65% were men. FBDS involved arm (26), face (22), and leg (12). Ten were previously diagnosed as psychogenic. Ictal EEGs were normal in 20 of 23 assessed. Basal ganglia T1 and T2 signal abnormalities were detected in 11 patients (42%), with excellent agreement between neuroradiologists (κ scores of 0.86 and 0.93, respectively), and included T1 hyperintensity alone (2), T2 hyperintensity alone (1), or both (8). The T1 hyperintensities persisted longer than the T2 hyperintensities (median 11 weeks vs 1 week, p = 0.02). Improvement with immunotherapy (18/18) was more frequent than with antiepileptic medications (10/24). A separate analysis of all 48 patients initially identified with LGI1-Ab encephalopathy showed that basal ganglia MRI abnormalities were present in 11 of 26 with FBDS but not present in those without FBDS (0/22) (p < 0.001). In contrast, mesial temporal MRI abnormalities were less common among those with FBDS (42%) than those without (91%) (p < 0.001). Conclusions: Basal ganglia T1 hyperintensity is a clinically useful MRI biomarker of LGI1-Ab FBDS and suggests a basal ganglia localization.

The Relationship Between Quantitative T2 Relaxometry and Memory in Nonlesional Temporal Lobe Epilepsy

Summary:  Purpose: We investigated the relationship between preoperative quantitative magnetic resonance imaging (MRI) T2 relaxometry and volumetry of the hippocampi and pre‐ and postoperative verbal memory in temporal lobectomy patients who had nonlesional temporal lobe epilepsy.

Painful generalised clonic and tonic-clonic seizures with retained consciousness.

Two patients in whom consciousness and memory were retained during bilateral clonic or tonic-clonic seizures are reported on, and three patients reported on previously are reviewed. Ictal semiology differed from myoclonic and supplementary motor seizures, which are other seizure types characterised by bilateral motor movements and retained awareness. In the two new patients ictal pain was a prominent feature. It is proposed that propagation of seizure activity may be confined to the sensorimotor areas bilaterally while sparing the neural structures involved in maintaining consciousness and in processing language and memory. This unusual type of seizure may be misdiagnosed as a pseudoseizure. Detailed description of the ictal events and further laboratory evaluation including video-EEG monitoring may be necessary to make the distinction.

Influence of subtraction ictal SPECT on surgical management in focal epilepsy of indeterminate localization: A prospective study

The impact of functional imaging tests on the decision-making and planning process for epilepsy surgery has never been prospectively assessed. We prospectively evaluated 50 consecutively eligible patients whose noninvasive evaluations showed nonlocalized findings and determined how their SISCOM (subtraction ictal SPECT [single photon emission computed tomography] co-registered to MRI [magnetic resonance imaging]) data altered consensus decisions for epilepsy surgery. At an epilepsy surgery conference where each patient was discussed, consensus decisions were documented after a standardized presentation of data from the noninvasive evaluation (SISCOM findings initially were excluded). Consensus decisions were again documented after presentation of SISCOM data. Consensus decisions changed for 10 of 32 patients (31%) with localizing SISCOM results, whereas the decision changed in only 1 of 18 patients (6%) with nonlocalizing SISCOM results (P<.05). Changes in consensus decisions were as follows: (1) intracranial electrode implantation (IEI) was obviated and resective surgery was recommended (n=2); (2) resective surgery or further evaluation for patients initially not considered surgical candidates (n=2); (3) IEI in patients for whom it was not recommended initially (n=3); (4) increased IEI coverage (n=3); and (5) antiepileptic drug trial or vagal nerve stimulation was recommended instead of IEI (n=1). For some patients whose noninvasive evaluations did not clearly localize a surgical focus, SISCOM data can have a major impact on decisions to recommend resective epilepsy surgery or IEI.

Anterior nuclear deep brain stimulation guided by concordant hippocampal recording

OBJECT Anterior nuclear (AN) stimulation has been reported to reduce the frequency of seizures, in some cases dramatically; however, it has not been approved by the US Food and Drug Administration. The anterior nucleus is difficult to target because of its sequestered location, partially surrounded by the ventricle. It has traditionally been targeted by using transventricular or lateral transcortical routes. Here, the authors report a novel approach to targeting the anterior nucleus and neurophysiologically confirming effective stimulation of the target, namely evoked potentials in the hippocampus. METHODS Bilateral AN 3389 electrodes were placed in a novel trajectory followed by bilateral hippocampal 3391 electrodes from a posterior trajectory. Each patient was implanted bilaterally with a Medtronic Activa PC+S device under an investigational device exemption approval. Placement was confirmed with CT. AN stimulation-induced hippocampal evoked potentials were measured to functionally confirm placement in the anterior nucleus. RESULTS Two patients had implantations by way of a novel AN trajectory with concomitant hippocampal electrodes. There were no lead misplacements. Postoperative stimulation of the anterior nucleus with a PC+S device elicited evoked potentials in the hippocampus. Thus far, both patients have reported a > 50% improvement in seizure frequency. CONCLUSIONS Placing AN electrodes posteriorly may provide a safer trajectory than that used for traditionally placed AN electrodes. In addition, with a novel battery that is capable of electroencephalographic recording, evoked potentials can be used to functionally assess the Papez circuit. This treatment paradigm may offer increased AN stimulation efficacy for medically intractable epilepsy by assessing functional placement more effectively and thus far has proven safe.