Crepeau, Amy

Abstract To characterize invasive neuromodulation for insular drug‐resistant epilepsy, we retrospectively evaluated 22 patients treated with responsive neurostimulation (RNS; n = 14) or chronic subthreshold stimulation (CSS; n = 8). Stereoelectroencephalography was performed in 20 cases (91%). Median baseline seizure frequency was 10.5/month. Forty‐one percent had prior epilepsy surgery. At year 3, median seizure reduction (MSR) was 83% ( p = .01, Wilcoxon signed‐rank test), with a responder rate (RR) of 77%; MSR was 92% for CSS and 75% for RNS. There were no significant differences in MSR ( p ≥ .4) or RR ( p > .9) when comparing RNS versus CSS. Three patients achieved seizure freedom by year 3. Patients undergoing combined insular–thalamic stimulation ( n = 5) demonstrated an MSR of 84%, 86%, and 88% at 1, 2, and 3 years; seizure reduction in thalamocortical versus cortical‐only stimulation was not different ( p ≥ .1). Parasagittal lead trajectories achieved closer insular proximity than transopercular trajectories ( p < .0001, Mann–Whitney U ‐test). Median charge density at last follow‐up was 1.3 μC/cm 2 . There were no acute surgical complications and all stimulation‐related side effects resolved with programming adjustments. This study expands the limited literature on insular neuromodulation by demonstrating effectiveness of RNS and CSS, suggesting potential benefit from combined thalamocortical targeting, and defining parasagittal trajectories as a surgical approach for optimal lead proximity.

Purpose: Neuroinvasive West Nile virus (WNV) is rare, occurring in less than 1% of those infected, and may manifest as meningitis, encephalitis, and/or acute flaccid paralysis. Patients may present initially with nonspecific symptoms including fevers. Although rare, neuroinvasive WNV is associated with significant morbidity and mortality. The mainstay of treatment is supportive care. Electroencephalography (EEG) allows for identification of nonconvulsive status epilepticus and other epileptiform and nonepileptiform patterns suggestive of underlying cognitive dysfunction. Our aim was to describe specific EEG patterns observed in WNV neuroinvasive disease. Methods: A retrospective chart review was conducted. West Nile virus was confirmed with serum and/or cerebrospinal fluid markers. Patients with a history of abnormal EEG were excluded. Electroencephalography reports were classified into categories based on the presence of epileptiform activity, focal slowing, generalized periodic discharges with triphasic morphology, and frontally predominant generalized rhythmic delta activity. Results: In our cohort of 34 patients, 60% of focal EEG abnormalities were anterior-predominant, seen as epileptiform discharges, focal slowing, or frontally predominant generalized rhythmic delta activity. Nonepileptiform EEG patterns included nonspecific slowing and generalized periodic discharges with triphasic morphology. Two patients had electrographic seizures, one arising from the frontocentral head region. Conclusions: EEGs are important in the evaluation of WNV infection to rule out seizures or alternative causes of encephalopathy, and because of the risk of nonconvulsive seizures or status epilepticus in encephalitis. Although an anterior predominance of EEG abnormalities was seen in our cohort, this most likely is more correlative to encephalopathy than WNV itself. Although a specific correlative EEG pattern may not accompany all cases of WNV neuroinvasive disease, WNV should be considered as a possible etiology in patients presenting with an encephalitic or meningitic syndrome in the presence of abnormal EEG findings including encephalopathic patterns, particularly those with anterior predominant EEG changes.