Nonconvulsive status epilepticus in epileptic encephalopathies in childhood.

Epileptic encephalopathies are conditions in which the abundant epileptiform activity itself interferes with development, resulting in cognitive slowing and often regression, psychiatric and behavioral disturbances. Nonconvulsive status epilepticus has been defined as ongoing or nonrecovering nonconvulsive seizures. It has been challenging to differentiate clinical and electroencephalographic patterns in epileptic encephalopathies from those attributed to nonconvulsive status epilepticus, since several different epileptic encephalopathies may show continuous or subcontinuous epileptiform activity. Especially for patients with known epileptic encephalopathy, the new proposal for diagnosis of nonconvulsive status epilepticus suggests an increase in prominence or frequency of specific electroencephalographic features as compared to baseline correlated to clinical and EEG responsiveness to intravenous anti-seizure drugs. This clinical change may be unclear, particularly in patients with pre-existent cognitive or behavioral impairments. This review intends to organize previously published data, with available information in the literature on some of those specific epileptic syndromes and diseases, focusing on two main questions: i. When should specialists suspect of nonconvulsive status epilepticus in epileptic encephalopathies? ii. Could epileptic encephalopathies themselves be nonconvulsive status epilepticus presentations? Lastly, the rationale for definition and treatment in many of the epileptic encephalopathies is the effect of ongoing frequent epileptiform activity on development and cognition, and this will require monitoring with serial clinical, neurophysiological, functional neuroimaging, and neuropsychological assessments. Whether there would be an association or causality between epileptic encephalopathies and nonconvulsive status epilepticus is a key question demanding further research.

Clinical utility of EEG in diagnosing and monitoring epilepsy in adults.

Electroencephalography (EEG) remains an essential diagnostic tool for people with epilepsy (PWE). The International Federation of Clinical Neurophysiology produces new guidelines as an educational service for clinicians to address gaps in knowledge in clinical neurophysiology. The current guideline was prepared in response to gaps present in epilepsy-related neurophysiological assessment and is not intended to replace sound clinical judgement in the care of PWE. Furthermore, addressing specific pathophysiological conditions of the brain that produce epilepsy is of primary importance though is beyond the scope of this guideline. Instead, our goal is to summarize the scientific evidence for the utility of EEG when diagnosing and monitoring PWE.

Are adverse effects of antiepileptic drugs different in symptomatic partial and idiopathic generalized epilepsies? The Portuguese-Brazilian validation of the Liverpool Adverse Events Profile.

We report the results of administration of the Portuguese-Brazilian translation of the Liverpool Adverse Events Profile (LAEP) to 100 patients (mean age=34.5, SD=12.12; 56 females), 61 with symptomatic partial epilepsy (SPE) and 39 with idiopathic generalized epilepsy (IGE) (ILAE, 1989) who were on a stable antiepileptic drug (AED) regimen and being treated in a Brazilian tertiary epilepsy center. Carbamazepine was the most commonly used AED (43.0%), followed by valproic acid (32.0%). Two or more AEDs were used by 69.0% of patients. The mean LAEP score (19 questions) was 37.6 (SD=13.35). The most common adverse effects were sleepiness (35.0%), memory problems (35.0%), and difficulty in concentrating (25.0%). Higher LAEP scores were associated with polytherapy with three or more AEDs (P=0.005), female gender (P<0.001), older age (P<0.001), and uncontrolled seizures (P=0.045). The intraclass coefficient (test-retest reliability) for LAEP overall score was 0.848 (95% CI=0.782-0.895), with a range from 0.370 (unsteadiness) to 0.750 (memory problems). Cronbach's α coefficient (internal consistency) was 0.903. The LAEP was highly correlated with Quality of Life in Epilepsy-31 inventory (r=-0.804, P>0.001) and Hospital Anxiety and Depression Scale (Depression: r=0.637, P<0.001; Anxiety: r=0.621, P<0.001) dimensions. LAEP overall scores were similar in people with SPE and IGE and were not helpful in differentiating adverse effects in these two groups. Clinical variables that influenced global LAEP were seizure frequency (P=0.050) and generalized tonic-clonic seizures in the last month (P=0.031) in the IGE group, and polytherapy with three or more AEDs (P=0.003 and P=0.003) in both IGE and SPE groups.

Bilateral reorganization of the dentate gyrus in hippocampal sclerosis: a postmortem study.

BACKGROUND: Hippocampal sclerosis (HS) is the most common surgical pathology associated with mesial temporal lobe epilepsy (MTLE). HS is typically characterized by mossy fiber sprouting (MFS) and reorganization of neuropeptide Y (NPY) fiber networks in the dentate gyrus. One potential cause of postoperative seizure recurrence following temporal lobe surgery may be the presence of seizure-associated bilateral hippocampal damage. We aimed to investigate patterns of hippocampal abnormalities in a postmortem series as identified by NPY and dynorphin immunohistochemistry. METHODS: Analysis of dentate gyrus fiber reorganization, using dynorphin (to demonstrate MFS) and NPY immunohistochemistry, was carried out in a postmortem epilepsy series of 25 cases (age range 21-96 years). In 9 patients, previously refractory seizures had become well controlled for up to 34 years prior to death. RESULTS: Bilateral MFS or abnormal NPY patterns were seen in 15 patients including those with bilateral symmetric, asymmetric, and unilateral HS by conventional histologic criteria. MFS and NPY reorganization was present in all classical HS cases, more variably in atypical HS, present in both MTLE and non-MTLE syndromes and with seizure histories of up to 92 years, despite seizure remission in some patients. CONCLUSION: Synaptic reorganization in the dentate gyrus may be a bilateral, persistent process in epilepsy. It is unlikely to be sufficient to generate seizures and more likely to represent a seizure-induced phenomenon.

Balloon cells associated with granule cell dispersion in the dentate gyrus in hippocampal sclerosis.

Granule cell dispersion (GCD) is a common finding in hippocampal sclerosis in patients with intractable focal epilepsy. It is considered to be an acquired, post-developmental rather than a pre-existing abnormality, involving dispersion of either mature or newborn neurones, but the precise factors regulating it and its relationship to seizures are unknown. We present two cases of GCD with associated CD34-immunopositive balloon cells, a cell phenotype associated with focal cortical dysplasia type IIB, considered to be a developmental cortical lesion promoting epilepsy. This observation opens up the debate regarding the origin of balloon cells and CD34 expression and their temporal relationship to seizures.