Hasan H. Sonmezturk

Cross Hippocampal Influence in Mesial Temporal Lobe Epilepsy Measured With High Temporal Resolution Functional Magnetic Resonance Imaging

Purpose  Mesial temporal lobe epilepsy (mTLE) is a chronic disorder with spontaneous seizures recurring for years, or even decades. Many structural and functional changes have been detected in both the seizure focus and distal regions throughout the brain over this duration that may reflect the development of epileptogenic networks. Resting state functional magnetic resonance imaging (fMRI) connectivity mapping has the potential to elucidate and quantify these networks. The network between the left and right hippocampus may very likely be one of the most susceptible to changes due to long‐term seizure propagation effects. Therefore, the objective of this study was to quantify cross hippocampal influence in mTLE using high temporal resolution fMRI, and to determine its relationship with disease duration.

Rhythmic delta activity represents a form of nonconvulsive status epilepticus in anti-NMDA receptor antibody encephalitis

Anti-NMDA receptor antibody encephalitis is a limbic encephalitis with psychiatric manifestations, abnormal movements, coma, and seizures. The coma and abnormal movements are not typically attributed to seizure activity, and slow activity is the most common EEG finding. We report drug-resistant nonconvulsive status epilepticus as the basis for coma in a 19-year-old woman with anti-NMDA receptor antibodies and a mediastinal teratoma. The EEG showed generalized rhythmic delta activity, with evolution in morphology, frequency, and field typical of nonconvulsive status epilepticus. The status was refractory to antiepileptic drugs, repeated drug-induced coma, resection of the tumor, intravenous steroids, rituximab, and plasmapheresis. She awoke after the addition of felbamate, and the rhythmic delta activity ceased. The rhythmic delta activity described with coma in anti-NMDA receptor antibody encephalitis may represent a pattern of status epilepticus in some patients. Felbamate, which has NMDA receptor antagonist activity, should be studied as a therapeutic agent in this condition.

Lateralization of temporal lobe epilepsy using resting functional magnetic resonance imaging connectivity of hippocampal networks

Purpose:  Early surgical intervention can be advantageous in the treatment of refractory temporal lobe epilepsy (TLE). The success of TLE surgery relies on accurate lateralization of the seizure onset. The purpose of this study was to determine whether resting functional MRI (fMRI) connectivity mapping of the hippocampus has the potential to complement conventional presurgical evaluations in distinguishing left from right TLE. In addition, we sought to determine whether this same network might separate patients with favorable from unfavorable postoperative outcomes.

Resting state functional connectivity of the hippocampus associated with neurocognitive function in left temporal lobe epilepsy.

The majority of patients with temporal lobe epilepsy (TLE) experience disturbances of episodic memory from structural damage or dysfunction of the hippocampus. The objective of this study was to use functional Magnetic Resonance Imaging (fMRI) to identify regions where resting state connectivity to the left hippocampus (LH) is correlated with neuropsychological measures of verbal memory retention in TLE patients. Eleven left TLE (LTLE) patients and 15 control subjects participated in resting state fMRI scans. All LTLE patients underwent neuropsychological testing. Resting state functional connectivity maps to the LH were calculated for each patient, and subsequently used in a multiple regression analysis with verbal memory retention scores as a covariate. The analysis identified brain regions whose connectivity to the LH was linearly related to memory retention scores across the group of patients. In LTLE patients, right sided (contralateral) clusters in the precuneus and inferior parietal lobule (IPL) exhibited increased connectivity to the LH with increased memory retention score; left sided (ipsilateral) regions in the precuneus and IPL showed increased connectivity to the LH with decreased retention score. Patients with high memory retention scores had greater connectivity between the LH–right parietal clusters than between the LH–left parietal clusters; in contrast, control subjects had significantly and consistently greater LH–left hemisphere than LH–right hemisphere connectivity. Our results suggest that increased connectivity in contralateral hippocampal functional pathways within the episodic verbal memory network represents a strengthening of alternative pathways in LTLE patients with strong verbal memory retention abilities. Hum Brain Mapp 35:735–744, 2014.

Functional Networks in Temporal-Lobe Epilepsy: A Voxel-Wise Study of Resting-State Functional Connectivity and Gray-Matter Concentration

Temporal-lobe epilepsy (TLE) involves seizures that typically originate in the hippocampus. There is evidence that seizures involve anatomically and functionally connected brain networks within and beyond the temporal lobe. Many studies have explored the effect of TLE on gray matter and resting-state functional connectivity in the brain. However, the relationship between structural and functional changes has not been fully explored. The goal of this study was to investigate the relationship between gray matter concentration (GMC) and functional connectivity in TLE at the voxel level. A voxel-wise linear regression analysis was performed between GMC maps and whole-brain resting-state functional connectivity maps to both the left thalamus (Lthal) and the left hippocampus (LH) in a group of 15 patients with left TLE. Twenty regions were found that exhibited GMC decreases linearly correlated with resting-state functional connectivity to either the LH or the Lthal in the patient group only. A subset of these regions had significantly reduced GMC, and one of these regions also had reduced functional connectivity to the LH in TLE compared to the controls. These results suggest a network of impairment in left TLE where more severe reductions in GMC accompany decreases (LH, Lthal, right midcingulate gyrus, left precuneus, and left postcentral gyrus) or increases (LH to right thalamus) in resting functional connectivity. However, direct relationships between these imaging parameters and disease characteristics in these regions have yet to be established.

Propofol withdrawal seizures: non-epileptic nature of seizures in a patient with recently controlled status epilepticus

Seizures or seizure-like phenomena which are mostly convulsive have been observed during the induction, maintenance and withdrawal phases of propofol administration. The nature and mechanism of this phenomenon are not well understood and several case reports on these phenomena have presented only indirect evidence. We report on a patient who was administered propofol in order to control status epilepticus with success. However, every attempt at propofol withdrawal was followed by convulsive seizure-like activity. Continuous EEG monitoring showed muscle artefacts without any ictal discharges. Based on this finding, the propofol treatment was withdrawn and the seizure-like activity eventually attenuated and resolved. We propose that seizure-like phenomena associated with propofol withdrawal may not be ictal in nature and should not lead to unnecessary resumption of propofol infusion without documentation of an epileptic origin by EEG.

Focal seizure propagation illustrated by fMRI

We report the pattern of seizure propagation as detected by functional MRI (fMRI) in a 24-year-old man with frequent recurrent electrographic seizures. The EEG seizure onset was left occipital with later spread to the left hemisphere and, to a lesser extent, the right hemisphere. The fMRI showed initial increase in blood oxygen level-dependent (BOLD) signal in the left occipital pole. The increased signal then propagated to the right occipital-posterotemporal region, and subsequently, the right and left mesial temporal regions. fMRI can be an effective tool to study seizure onset localization and seizure propagation in patients with frequent recurrent seizures.

Video-EEG results and clinical characteristics in patients with psychogenic nonepileptic spells: The effect of a coexistent epilepsy

RATIONALE Epilepsy and psychogenic nonepileptic spells (PNES) can coexist, often posing diagnostic and therapeutic challenges. We sought to identify clinical and historical characteristics of two groups of patients, those with coexisting epilepsy and PNES and those with PNES alone, and determine the prevalence of coexisting epilepsy/PNES with strict diagnostic criteria in a large group of epilepsy monitoring unit (EMU) patients. METHODS We reviewed the medical records of all consecutive patients admitted to the Vanderbilt University Medical Center Adult EMU between July 1, 2007 and June 30, 2012. We identified patients with recorded PNES and classified them as having coexisting epilepsy/PNES or PNES alone and then systematically compared the clinical characteristics of these two groups. RESULTS A total of 1567 patient medical records were reviewed. The prevalence rate of coexisting epilepsy/PNES was 5.2% among all EMU admissions (12.3% of all patients with epilepsy and 14.8% of all patients with PNES). These rates were lower when patients with interictal epileptiform activity (IEA) alone and no recorded ictal discharges were not included in the group with epilepsy (2.6%, 6.2%, and 7.4%, respectively). The accuracy of pre-EMU clinical suspicion was significantly higher in the group with PNES-only. Patients with epilepsy/PNES were significantly more likely to require more than one EMU admission for definitive diagnosis. The first PNES event preceded an epileptic seizure (ES) in 94.4% of patients with epilepsy/PNES. The group with PNES-only had significantly higher suggestibility, and the group with epilepsy/PNES had a significantly higher presence of epilepsy risk factors. Abnormal neurological examination and abnormal brain MRI were also significantly more common in the group with epilepsy/PNES. CONCLUSIONS Our study defined the prevalence of coexisting epilepsy/PNES in a large cohort with strict diagnostic criteria and outlined specific clinical and historical characteristics differentiating the two groups of patients with coexisting epilepsy/PNES and PNES-only. These findings should help guide clinicians to reach the correct diagnosis faster and provide appropriate treatment earlier.

Cough syncope in a 43-year-old woman with glomus jugulare tumor

We present an unusual case of recurrent cough syncope in a 43-year-old woman, which was initially thought to be seizures. Syncopal episodes were triggered by paroxysms of cough and were characterized by unresponsiveness and myoclonic jerks in her extremities. She had a left-sided glomus jugulare tumor that extended into the posterior cranial fossa with evidence of worsening communicating hydrocephalus on brain imaging. We postulate that bouts of cough produced increased intracranial pressure both by raising intrathoracic and intraabdominal pressures as well as by transient obstruction to cerebrospinal fluid flow secondary to intermittent tonsillar herniation during cough. This resulted in diffuse decrease in cerebral blood flow causing syncope. The patients syncopal episodes decreased in frequency once an external ventricular drain was placed followed by a ventriculoperitoneal shunt. Search for factors that can increase intracranial pressure seems warranted in patients with recurrent cough syncope.

Similar response to anti-epileptic medications among epileptic siblings

BACKGROUND When epilepsy does not respond to the initial anti-epileptic drug (AED) the subsequent search for an effective AED is predominantly a matter of trial and error, as only limited criteria exist for rational AED selection. Since epilepsy in siblings is likely to be relatively homogeneous, we hypothesized that an AED effective in one sibling would also be effective in the other. METHODS We reviewed the antiepileptic medication response among nine sets of epileptic siblings (19 patients) in our practice. All but one patient were drug-resistant at one point during their treatment course. RESULTS Eight sets of siblings (17 individuals) became seizure-free or almost seizure-free with treatment modification and using a medication proven effective for one sibling in the other siblings. The medication change that produced seizure freedom was lamotrigine monotherapy in two families, valproate monotherapy in one, lamotrigine adjunctive therapy in two, lamotrigine-levetiracetam combination in two, and lamotrigine-valproate combination in one family. In one remaining family with generalized epilepsy, one sibling was seizure-free on phenobarbital while the other had persistent seizures despite polytherapy. CONCLUSIONS Our results indicated that siblings with epilepsy tend to respond to the same AED monotherapy or AED combination.