An ordinal clinical score predicts seizure freedom after minimally invasive epilepsy surgery.

OBJECTIVE: To predict one-year seizure freedom, using a combination of relevant clinical variables, following stereotactic laser amygdalohippocampotomy for mesial temporal lobe epilepsy in a series of 101 patients. METHODS: Eight predictors of seizure freedom were selected based on their association with medial temporal lobe epilepsy: (1) MRI evidence of mesial temporal sclerosis (MTS); (2) unitemporal interictal epileptiform discharges; (3) absence of generalized tonic-clonic seizures; (4) history of febrile seizures; (5) onset of epilepsy ≤16 years; (6) absence of an auditory, visual, or vertiginous aura; and (7) unitemporal ictal onset; (8) unitemporal PET hypometabolism. We compared four multivariate models: "MTS," using just evidence of MTS; "FULL," using all eight binary predictors; "AIC" using backwards selection of variables; and "SCORE," using a 0-to-8-point ordinal score awarding one point for each binary predictor. RESULTS: In univariate analysis, significant predictors for seizure freedom were evidence of mesial temporal sclerosis (p = 0.011, Fisher exact) and unitemporal interictal discharges (p = 0.005). For multivariate prediction (using leave one-out cross-validation), the ordinal SCORE model had a significantly higher area under the curve (AUC 0.70) than the other three models: MTS (AUC 0.54, p = 0.002, Delong's test), FULL (AUC 0.62, p = 0.003), or AIC (AUC 0.53, p < 0.001). INTERPRETATION: An ordinal score incorporating eight independent binary clinical variables predicted seizure freedom better on novel data than a model using MTS alone, a full multivariate model, or a backwards selected model. The ordinal score model represents a simple clinical heuristic to identify which patients should be offered minimally invasive laser surgery.

A multicenter retrospective study of patients treated in the thalamus with responsive neurostimulation.

Introduction: For drug resistant epilepsy patients who are either not candidates for resective surgery or have already failed resective surgery, neuromodulation is a promising option. Neuromodulatory approaches include responsive neurostimulation (RNS), deep brain stimulation (DBS), and vagal nerve stimulation (VNS). Thalamocortical circuits are involved in both generalized and focal onset seizures. This paper explores the use of RNS in the centromedian nucleus of the thalamus (CMN) and in the anterior thalamic nucleus (ANT) of patients with drug resistant epilepsy. Methods: This is a retrospective multicenter study from seven different epilepsy centers in the United States. Patients that had unilateral or bilateral thalamic RNS leads implanted in the CMN or ANT for at least 6 months were included. Primary objectives were to describe the implant location and determine changes in the frequency of disabling seizures at 6 months, 1 year, 2 years, and > 2 years. Secondary objectives included documenting seizure free periods, anti-seizure medication regimen changes, stimulation side effects, and serious adverse events. In addition, the global clinical impression scale was completed. Results: Twelve patients had at least one lead placed in the CMN, and 13 had at least one lead placed in the ANT. The median baseline seizure frequency was 15 per month. Overall, the median seizure reduction was 33% at 6 months, 55% at 1 year, 65% at 2 years, and 74% at >2 years. Seizure free intervals of at least 3 months occurred in nine patients. Most patients (60%, 15/25) did not have a change in anti-seizure medications post RNS placement. Two serious adverse events were recorded, one related to RNS implantation. Lastly, overall functioning seemed to improve with 88% showing improvement on the global clinical impression scale. Discussion: Meaningful seizure reduction was observed in patients who suffer from drug resistant epilepsy with unilateral or bilateral RNS in either the ANT or CMN of the thalamus. Most patients remained on their pre-operative anti-seizure medication regimen. The device was well tolerated with few side effects. There were rare serious adverse events. Most patients showed an improvement in global clinical impression scores.

Stereoelectroencephalography-guided radiofrequency ablation of the epileptogenic zone as a treatment and predictor of future success of further surgical intervention.

OBJECTIVE: Stereoelectroencephalography (SEEG)-guided radiofrequency ablation (RFA) is increasingly being used as a treatment for drug-resistant localization-related epilepsy. The aim of this study is to analyze the successes and failures using RFA and how response correlates with surgical epilepsy treatment outcomes. METHODS: We retrospectively reviewed 62 patients who underwent RFA via SEEG electrodes. After excluding five, the remaining 57 were classified into subgroups based on procedures and outcomes. Forty patients (70%) underwent a secondary surgical procedure, of whom 32 were delayed: 26 laser interstitial thermal therapy (LITT), five resection, one neuromodulation. We determined the predictive value of RFA outcome upon subsequent surgical outcome by categorizing the delayed secondary surgery outcome as success (Engel I/II) versus failure (Engel III/IV). Demographic information, epilepsy characteristics, and the transient time of seizure freedom after RFA were calculated for each patient. RESULTS: Twelve of 49 patients (24.5%) who had RFA alone and delayed follow-up achieved Engel class I. Of the 32 patients who underwent a delayed secondary surgical procedure, 15 achieved Engel class I and nine Engel class II (24 successes), and eight were considered failures (Engel class III/IV). The transient time of seizure freedom after RFA was significantly longer in the success group (4 months, SD = 2.6) as compared to the failure group (.75 months, SD = 1.16; p < .001). Additionally, there was a higher portion of preoperative lesional findings in patients in the RFA alone and delayed surgical success group (p = .03) and a longer time to seizure recurrence in the presence of lesions (p < .05). Side effects occurred in 1% of patients. SIGNIFICANCE: In this series, RFA provided a treatment during SEEG-guided intracranial monitoring that led to seizure freedom in ~25% of patients. Of the 70% who underwent delayed surgery, longer transient time of seizure freedom after RFA was predictive of the results of the secondary surgeries, 74% of which were LITT.

Surgical Treatment of Drug-Resistant Generalized Epilepsy.

PURPOSE OF REVIEW: To summarize current evidence and recent developments in the surgical treatment of drug-resistant generalized epilepsy. RECENT FINDINGS: Current surgical treatments of drug-resistant generalized epilepsy include vagus nerve stimulation (VNS), deep brain stimulation (DBS) and corpus callosotomy (CC). Neurostimulation with VNS and/or DBS has been shown to be effective in reducing seizure frequency in patients with generalized epilepsy. DBS for generalized epilepsy is primarily consisted of open-loop stimulation directed at the centromedian (CM) nucleus in the thalamus, though closed-loop stimulation and additional targets are being explored. CC can be effective in treating some seizure types and can be performed using traditional surgical techniques or with the less invasive methods of laser ablation and radiosurgery. This current literature supports the use of VNS, DBS and CC, alone or in combination, as palliative treatments of drug-resistant generalized epilepsy.

Continuous Intraoperative Neurophysiological Monitoring of the Motor Pathways Using Depth Electrodes During Surgical Resection of an Epileptogenic Lesion: A Novel Technique.

BACKGROUND AND IMPORTANCE: Intraoperative neurophysiological monitoring of the motor pathways during epilepsy surgery is essential to safely achieve maximal resection of the epileptogenic zone. Motor evoked potential (MEP) recording is usually performed intermittently during resection using a handheld stimulator or continuously through an electrode array placed on the motor cortex. We present a novel variation of continuous MEP acquisition through previously implanted depth electrodes in the perirolandic cortex. CLINICAL PRESENTATION: A 60-yr-old woman with a history of a left frontal meningioma (World Health Organization [WHO] grade II) treated with surgical resection and radiation presented with residual right hemiparesis and refractory epilepsy. Imaging demonstrated a perirolandic lesion with surrounding edema and mass effect in the prior surgical site, suspicious for radiation necrosis versus tumor recurrence. Presurgical electrocorticography (ECoG) with orthogonal, stereotactically implanted depth electrodes (stereoelectroencephalography [SEEG]) of the perirolandic cortex captured seizure onsets from the supplementary motor area (SMA) and primary motor cortex (PMC). The patient underwent a left frontal craniotomy for repeat resection and tissue diagnosis. Intraoperative ECoG and MEPs were obtained continuously with direct cortical stimulation through the indwelling SEEG electrodes in the PMC. Maximal resection was achieved with preservation of direct cortical MEPs and without deterioration of her baseline hemiparesis. Biopsy revealed radiation necrosis. At 30-mo follow-up, the patient had only rare seizures (Engel class IIB). CONCLUSION: Intraoperative cortical MEP acquisition through implanted SEEG electrode arrays is a potentially safe and effective alternative approach to continuously monitor the motor pathways during the resection of a perirolandic epileptogenic lesion, without the need for surgical interruptions.

Recommendations for Deep Brain Stimulation Device Management During a Pandemic.

Most medical centers are postponing elective procedures and deferring non-urgent clinic visits to conserve hospital resources and prevent spread of COVID-19. The pandemic crisis presents some unique challenges for patients currently being treated with deep brain stimulation (DBS). Movement disorder (Parkinson's disease, essential tremor, dystonia), neuropsychiatric disorder (obsessive compulsive disorder, Tourette syndrome, depression), and epilepsy patients can develop varying degrees of symptom worsening from interruption of therapy due to neurostimulator battery reaching end of life, device malfunction or infection. Urgent intervention to maintain or restore stimulation may be required for patients with Parkinson's disease who can develop a rare but potentially life-threatening complication known as DBS-withdrawal syndrome. Similarly, patients with generalized dystonia can develop status dystonicus, patients with obsessive compulsive disorder can become suicidal, and epilepsy patients can experience potentially life-threatening worsening of seizures as a result of therapy cessation. DBS system infection can require urgent, and rarely emergent surgery. Elective interventions including new implantations and initial programming should be postponed. For patients with existing DBS systems, the battery status and electrical integrity interrogation can now be performed using patient programmers, and employed through telemedicine visits or by phone consultations. The decision for replacement of the implantable pulse generator to prevent interruption of DBS therapy should be made on a case-by-case basis taking into consideration battery status and a patient's tolerance to potential therapy disruption. Scheduling of the procedures, however, depends heavily on the hospital system regulations and on triage procedures with respect to safety and resource utilization during the health crisis.