epileptic_seizure

Epileptic seizure

Epileptic seizures (colloquially a fit) are brief episodes of “abnormal excessive or synchronous neuronal activity in the brain”.

The outward effect can vary from wild thrashing movement (tonic-clonic seizure) to as mild as a brief loss of awareness (absence seizure). The syndrome of recurrent, unprovoked seizures is termed epilepsy, but seizures can occur in people who do not have epilepsy. Additionally there are a number of conditions that look like seizures but are not.

After a first seizure, treatment is generally not needed unless specific problems are found on either electroencephalogram or imaging of the brain.

About 5–10% of all people will have an unprovoked seizure by the age of 80 and the chance of experiencing a second seizure is between 40% and 50%.

Epilepsy affects about 1% of the population currently and affects about 4% of the population at some point in time.

Most of affected, nearly 80%, live in developing countries.

Epilepsy classification

Epilepsy Etiology.

see Epilepsy Diagnosis.

see Epilepsy Complications.

see Epilepsy Treatment.

In a observational study, we reviewed the top five highly cited clinical journals within eleven specialties in the InCites Journal Citation Reports (JCR) database (2016). For each specialty, we collected 2013-2017 PubMed data on publications with MeSH Major Topic of “seizures,” “epilepsy,” or “status epilepticus.” Medical subject headings (MeSH) in PubMed are standardized terms assigned by subject analysts. MeSH Major Topic identifies articles in which a specified topic is the major focus of the article. We also retrieved author country and medical specialty affiliations. We analyzed whether author specialty affiliation was 1) concordant with journal medical specialty, 2) neurology-related, or 3) other.

Articles on “seizures,” “epilepsy,” or “status epilepticus” had the following prevalence in specialty clinical journals: cardiac and cardiovascular systems (0.01%); clinical neurology (5.34%); critical care medicine (0.20%); emergency medicine (0.47%); general and internal medicine (0.44%); neuroimaging (2.05%); neurosurgery (2.23%); obstetrics and gynecology (0.16%); oncology (0.01%); pediatrics (0.69%); and psychiatry (0.23%). Within general and internal medicine, neuroimaging, and pediatrics, seizure-related articles are more likely to be first-authored by someone with a neurology-related affiliation. Within critical care medicine, emergency medicine, neurosurgery, and obstetrics and gynecology, seizure-related articles were more likely to be first-authored by someone whose affiliation is within the field.

The study characterizes seizure and epilepsy research published in nonneurology journals. We found that there is a paucity of such research published in nonneurology journals, whether authored by neurologists or other specialists. This is not ideal since nonneurologists are often first-line providers for recognizing, diagnosing, or managing seizures prior to assessment by a neurologist. Cross-specialty collaboration should be strongly encouraged in clinical research 1).

The ideal modality for generating sensation in sensorimotor brain computer interfaces (BCI) has not been determined. Here we report the feasibility of using a high-density “mini”-electrocorticography (mECoG) grid in a somatosensory BCI system. Thirteen subjects with intractable epilepsy underwent standard clinical implantation of subdural electrodes for the purpose of seizure localization. An additional high-density mECoG grid was placed (Adtech, 8 by 8, 1.2-mm exposed, 3-mm center-to-center spacing) over the hand area of primary somatosensory cortex. Following implantation, cortical mapping was performed with stimulation parameters of frequency: 50 Hz, pulse-width: 250 µs, pulse duration: 4 s, polarity: alternating, and current that ranged from 0.5 mA to 12 mA at the discretion of the epileptologist. Location of the evoked sensory percepts was recorded along with a description of the sensation. The hand was partitioned into 48 distinct boxes. A box was included if sensation was felt anywhere within the box. The percentage of the hand covered was 63.9% (± 34.4%) (mean ± s.d.). Mean redundancy, measured as electrode pairs stimulating the same box, was 1.9 (± 2.2) electrodes per box; and mean resolution, measured as boxes included per electrode pair stimulation, was 11.4 (± 13.7) boxes with 8.1 (± 10.7) boxes in the digits and 3.4 (± 6.0) boxes in the palm. Functional utility of the system was assessed by quantifying usable percepts. Under the strictest classification, “dermatomally exclusive” percepts, the mean was 2.8 usable percepts per grid. Allowing “perceptually unique” percepts at the same anatomical location, the mean was 5.5 usable percepts per grid. Compared to the small area of coverage and redundancy of a microelectrode system, or the poor resolution of a standard ECoG grid, a mECoG is likely the best modality for a somatosensory BCI system with good coverage of the hand and minimal redundancy 2).


1)
Wong VSS, Stevenson M, Mott J, Sahaya K. Seizure and epilepsy publication in nonneurology journals. Epilepsy Behav. 2019 Feb 16;93:7-11. doi: 10.1016/j.yebeh.2019.01.032. [Epub ahead of print] PubMed PMID: 30780078.
2)
Kramer DR, Lee MB, Barbaro M, Gogia AS, Peng T, Liu C, Kellis S, Lee B. Mapping of primary somatosensory cortex of the hand area using a high-density electrocorticography grid for closed-loop brain computer interface. J Neural Eng. 2020 Mar 4. doi: 10.1088/1741-2552/ab7c8e. [Epub ahead of print] PubMed PMID: 32131064.
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