Imaging haemodynamic changes related to seizures: comparison of EEG-based general linear model, independent component analysis of fMRI and intracranial EEG

Background: Simultaneous EEG-fMRI can reveal haemodynamic changes associated with epileptic activity which may contribute to understanding seizure onset and propagation. Methods: Nine of 83 patients with focal epilepsy undergoing pre-surgical evaluation had seizures during EEG-fMRI and analysed using three approaches, two based on the general linear model (GLM) and one using independent component analysis (ICA): 1. EEGs were divided into up to three phases: early ictal EEG change, clinical seizure onset and late ictal EEG change and convolved with a canonical haemodynamic response function (HRF) (canonical GLM analysis). 2. Seizures lasting three scans or longer were additionally modelled using a Fourier basis set across the entire event (Fourier GLM analysis). 3. Independent component analysis (ICA) was applied to the fMRI data to identify ictal BOLD patterns without EEG. The results were compared with intracranial EEG. Results: The canonical GLM analysis revealed significant BOLD signal changes associated with seizures on EEG in 7/9 patients, concordant with the seizure onset zone in 4/7. The Fourier GLM analysis revealed changes in BOLD signal corresponding with the results of the canonical analysis in two patients. ICA revealed components spatially concordant with the seizure onset zone in all patients (8/9 confirmed by intracranial EEG). Conclusion: Ictal EEG-fMRI visualises plausible seizure related haemodynamic changes. The GLM approach to analysing EEG-fMRI data reveals localised BOLD changes concordant with the ictal onset zone when scalp EEG reflects seizure onset. ICA provides additional information when scalp EEG does not accurately reflect seizures and may give insight into ictal haemodynamics

Valproate Use Is Associated With Posterior Cortical Thinning and Ventricular Enlargement in Epilepsy Patients

Valproate is a drug widely used to treat epilepsy, bipolar disorder, and occasionally to prevent migraine headache. Despite its clinical efficacy, prenatal exposure to valproate is associated with neurodevelopmental impairments and its use in children and adults was associated with rare cases of reversible brain atrophy and ventricular enlargement. To determine whether valproate use is related with structural brain changes we examined through a cross-sectional study cortical and subcortical structures in a group of 152 people with epilepsy and a normal clinical brain MRI. Patients were grouped into those currently using valproate (n = 54), those taking drugs other than valproate (n = 47), and drug-naïve patients (n = 51) at the time of MRI, irrespectively of their epilepsy syndrome. Cortical thickness and subcortical volumes were analyzed using Freesurfer, version 5.0. Subjects exposed to valproate (either in mono- or polytherapy) showed reduced cortical thickness in the occipital lobe, more precisely in the cuneus bilaterally, in the left lingual gyrus, and in left and right pericalcarine gyri when compared to patients who used other antiepileptic drugs, to drug-naïve epilepsy patients, and to healthy controls. Considering the subgroup of patients using valproate monotherapy (n = 25), both comparisons with healthy controls and drug-naïve groups confirmed occipital lobe cortical thickness reduction. Moreover, patients using valproate showed increased left and right lateral ventricle volume compared to all other groups. Notably, subjects who were non-valproate users at the time of MRI, but who had valproate exposure in the past (n = 27) did not show these cortical or subcortical brain changes. Cortical changes in the posterior cortex, particularly in the visual cortex, and ventricular enlargement, are present in people with epilepsy using valproate, independently from clinical and demographical variables. These findings are relevant both for the efficacy and adverse events profile of valproate use in people with epilepsy

New onset status epilepticus in influenza associated encephalopathy: The presenting manifestation of genetic generalized epilepsy

We hereby present a case of a young woman with no history of seizures or epilepsy who experienced a de novo generalized Non Convulsive Status Epilepticus (NCSE) followed by encephalopathy lasting for several days during influenza B infection. Influenza can have a broad spectrum of presentation ranging from an uncomplicated illness to many serious conditions as is the case of influenza associated encephalitis/encephalopathy (IAE). In this context however, it is possible to observe seizures and/or status epilepticus as the presenting manifestation of a genetic generalized epilepsy

Case Report: Ictal Central Apnea as First and Overlooked Symptom in Temporal Lobe Seizures

Ictal respiratory changes have been mainly described following generalized tonic-clonic seizures and recently considered to be a biomarker to assess the risk of sudden unexplained death in epilepsy (SUDEP). Nonetheless, modification of respiratory pattern can be related also to focal seizures, especially arising from the temporal lobe. Changes in cardiac function such as tachycardia or bradycardia could be often associated. We report a short case series of four patients with temporal lobe epilepsy admitted to our Epilepsy Monitoring Unit (EMU) presenting with an ictal central apnea as the first clinical manifestation of their seizures. None of these patients was aware of the occurrence of respiratory arrest. Age at onset ranged from 15 to 29 years. One patient had seizures with prolonged central apnea accompanied by a significant decrease in oxygen saturation. Neuroimaging in two patients showed alterations of mesial temporal lobe structures, including the amygdala. Recent neurophysiological studies supported the existence of a cortical network involving the limbic system that modulates downstream brainstem respiratory centers. Monitoring for respiratory changes and oxygen saturation in focal seizures is warranted for their potential value in identifying the epileptogenic zone and for a better understanding of ictal respiratory changes that could potentially define a subgroup of patients with high risk of seizure-related autonomic changes

Serum neurofilament light as biomarker of seizure-related neuronal injury in status epilepticus

Biomarkers of neuronal damage in status epilepticus (SE) would be of great relevance for clinical and research purposes. In a retrospective cross-sectional study, serum neurofilament light chain (NfL) levels were measured in patients with SE (30 subjects), patients with drug-resistant epilepsy (30 subjects), and healthy controls (30 subjects). Serum NfL levels were higher in patients with SE (median = 26.15 pg/ml) compared to both epilepsy patients (median = 7.35 pg/ml) and healthy controls (median = 6.81 pg/ml; p <.001). In patients with SE, serum NfL levels showed a high correlation with cerebrospinal fluid (CSF) NfL (τ =.68, p <.001) as well as with CSF total tau (t-tau) levels (τ =.627, p <.001); they were higher in SE lasting >24 h (p =.013), in refractory/superrefractory SE (p =.004), and in patients who died within 30 days or who presented a worsening of clinical conditions (p =.001). Values of >28.8 pg/ml predicted 30-day clinical worsening or death (odds ratio [OR] = 10.83, 95% confidence interval [CI] = 1.96–59.83, p =.006) and SE refractoriness (OR = 9.33, 95% CI = 1.51–57.65, p =.016). In conclusion, serum NfL levels are increased in SE and correlate with SE treatment response, duration, and outcomes, therefore representing a promising biomarker of seizure-related neuronal damage

Temporal Lobe Spikes Affect Distant Intrinsic Connectivity Networks

Objective: To evaluate local and distant blood oxygen level dependent (BOLD) signal changes related to interictal epileptiform discharges (IED) in drug-resistant temporal lobe epilepsy (TLE). Methods: Thirty-three TLE patients undergoing EEG–functional Magnetic Resonance Imaging (fMRI) as part of the presurgical workup were consecutively enrolled. First, a single-subject spike-related analysis was performed: (a) to verify the BOLD concordance with the presumed Epileptogenic Zone (EZ); and (b) to investigate the Intrinsic Connectivity Networks (ICN) involvement. Then, a group analysis was performed to search for common BOLD changes in TLE. Results: Interictal epileptiform discharges were recorded in 25 patients and in 19 (58%), a BOLD response was obtained at the single-subject level. In 42% of the cases, BOLD changes were observed in the temporal lobe, although only one patient had a pure concordant finding, with a single fMRI cluster overlapping (and limited to) the EZ identified by anatomo-electro-clinical correlations. In the remaining 58% of the cases, BOLD responses were localized outside the temporal lobe and the presumed EZ. In every patient, with a spike-related fMRI map, at least one ICN appeared to be involved. Four main ICNs were preferentially involved, namely, motor, visual, auditory/motor speech, and the default mode network. At the single-subject level, EEG–fMRI proved to have high specificity (above 65%) in detecting engagement of an ICN and the corresponding ictal/postictal symptom, and good positive predictive value (above 67%) in all networks except the visual one. Finally, in the group analysis of BOLD changes related to IED revealed common activations at the right precentral gyrus, supplementary motor area, and middle cingulate gyrus. Significance: Interictal temporal spikes affect several distant extra-temporal areas, and specifically the motor/premotor cortex. EEG–fMRI in patients with TLE eligible for surgery is recommended not for strictly localizing purposes rather it might be useful to investigate ICNs alterations at the single-subject level

Electrographic seizure duration and inter-seizure intervals in focal status epilepticus

Objective: To characterize the duration of seizures and inter-seizure intervals in focal status epilepticus (SE). Methods: We reviewed consecutive scalp EEG recordings from adult patients who were admitted for a first episode of focal status epilepticus. We identified electrographic seizure duration and inter-seizure intervals in the first diagnostic pretreatment EEG. We also reviewed isolated focal self-limiting seizures in epilepsy patients, as a comparison group for seizure duration. Results: We recorded 307 focal seizures in 100 consecutive focal SE episodes, with a median seizure duration of 107 s (IQR: 54–186), and 134 isolated focal self-limiting seizures in 42 epilepsy patients, with a median duration of 59 s (IQR: 30–90; p <.001). The only clinical feature of SE that significantly increased seizure duration was acute symptomatic etiology. In SE, 15% and 7% of seizures lasted longer than 300 and 600 s, respectively (t1 of the actual definition for tonic–clonic and focal SE), while only 1% of self-limiting seizures lasted longer than 300 s, and none lasted longer than 600 s. The analysis of inter-seizure intervals in SE with multiple seizures showed that 50% of the inter-seizure periods were shorter than 60 s, and 95% were shorter than 540 s (9 min). Patients who had an increase in seizure duration (last versus first) of at least 1.4 times showed an increased 30-day mortality. Significance: Focal seizures within a SE episode showed a wide range of duration, partly overlapping with the duration of focal self-limiting seizures but with a longer median duration. Inter-seizure intervals within an episode of SE were shorter than 1 min in 50% of the seizures and never lasted more than 10 min. Finally, an increase in seizure duration could represent an “electrophysiological biomarker” of a more severe SE episode, which may require more aggressive and rapid treatment