EEG patterns of status

CONVULSIVE PATTERNS

Primary generalized tonic-clonic status epilepticus

Electrographically, the seizures characteristically begin with a flattening of the normal background rhythms, followed by generalized low voltage fast activity or polyspikes that increase in amplitude and decrease in frequency until these patterns become obscured by muscle and movement artifact. As the seizure clinically moves into the clonic phase, the EEG characteristically shows a checkerboard type pattern of muscle artifact corresponding to the rhythmic jerking movements observed clinically. During breaks between seizures, the EEG shows diffuse suppression of cerebral activity.

Generalized myoclonic status epilepticus

The EEG in myoclonic status epilepticus may show generalized, bisynchronous polyspikes, spikes, or sharp waves preceding and time-locked with the clinical myoclonus, superimposed on a diffusely slow and suppressed background. A burst-suppression pattern may also be seen. Of note, due to the accompanying muscle activity associated with the myoclonic movements, discerning true epileptiform activity from muscle artifact can often be challenging. In this case, the use of a short-acting paralytic agent may aid in determining if the myoclonus is cortically generated or whether it originates lower down the neuro-axis (ie, brainstem, spinal cord, or peripheral site). Ultimately, this determination may be difficult without simultaneous EEG and electromyography (EMG) with jerk-locked back-averaging techniques.

Generalized clonic status epilepticus

The EEG typically shows generalized, synchronous spikes or spike wave complexes time-locked with the clinical movements.

Generalized tonic status epilepticus

Tonic seizures have a propensity to cluster and are more common during non–rapid eye movement (REM) sleep. The electrographic appearance of tonic seizures consists of moderate to high amplitude, frontally predominant, generalized 10-25 Hz spikes, sometimes termed generalized paroxysmal fast activity (GPFA). A second ictal tonic EEG pattern consists of an abrupt, generalized attenuation or flattening of the background EEG activity (to < 5-10 µV) that can be the sole manifestation of the ictal activity or can precede the development of the 10-25 Hz generalized spikes.

Generalized atonic status epilepticus

Atonic seizures are common in patients with Lennox-Gastaut syndrome and are a prominent feature in patients with myoclonic-astatic epilepsy of Doose. The ictal EEG during atonic seizures typically shows either generalized polyspike-and-wave or generalized slow-spike-and-wave (SWS) activity, followed by diffuse, high-amplitude, generalized slow waves maximal over the central head regions.

Simple partial status epilepticus

The ictal EEG in simple partial status epilepticus may show any of a range of patterns from focal spikes, polyspikes, spike and waves, suppression, or focal rhythmic discharges of any frequency to a completely normal background without evidence of ictal activity. Because approximately 6 cm2 of synchronously firing cortex must be involved for EEG to detect ictal activity, it should not be surprising that many focal seizures will be beyond the resolution of scalp EEG, because the ictal focus is too small, too distant, or unfavorably oriented in relation to the electrodes (ie, originating deep in a sulcus) to be detected by scalp recording.

In such instances when the focal seizures cannot be detected by scalp recording, functional imaging modalities such as cerebral positron emission tomography (PET)—which measures cerebral glucose metabolism—or single photon emission computed tomography (SPECT) scanning—which measures regional cerebral blood flow—may be helpful in confirming the diagnosis. If such studies are performed during ongoing clinical signs or symptoms, increased local glucose metabolism or regional cerebral blood flow would verify the suspected seizure focus.

Complex partial status epilepticus

Because a significant amount of cortex (ie, >6 cm2) is typically involved to produce impaired consciousness, complex partial seizures will have an ictal correlate on EEG. The ictal footprint is variable and may consist of focal spikes, polyspikes, spike waves, suppression, or focal rhythmic discharges of any frequency.

NONCONVULSIVE PATTERNS

Typical absence status epilepticus

The classic EEG finding in typical absence status epilepticus is generalized 3 Hz spike-and-wave activity (range 2.5-4 Hz). However, generalized polyspike-and-wave may also be seen. The intradischarge frequency is classically constant but may vary over the course of the seizure.

Atypical absence status epilepticus

In contrast to typical absence seizures, in atypical absences, the onsets and offsets are clinically less abrupt and distinct and the seizures are longer in duration (lasting up to minutes). Additionally, changes in tone are more prominent than in typical absence seizures. The ictal EEG shows slow (< 2.5 Hz) generalized spike-and-wave complexes that may be more irregular and asymmetric than what is classically seen in typical absence status epilepticus.

Nonconvulsive SE with Partial Onset

Primary criteria

An electrographic or nonconvulsive seizure may be demonstrated by any electrographic pattern lasting at least 10 seconds and satisfying any 1 of the following 3 primary criteria:

*Repetitive generalized or focal spikes, sharp-waves, spike-and-wave, or sharp-and-slow wave complexes at a frequency of 3 or more per second.

*Repetitive generalized or focal spikes, sharp-waves, spike-and-wave, or sharp-and-slow wave complexes at a frequency of 3 or less per second AND one of the secondary criteria below.

*Sequential rhythmic, periodic, or quasi-periodic waves at 1 or more per second and unequivocal evolution in: (1) frequency (increasing or decreasing by at least 1/sec), (2) morphology, or (3) location. Of note, evolution in amplitude alone is not sufficient to meet the criteria for evolution. Additionally, change in sharpness of the waveform without other change in morphology is also not adequate to qualify as evolution of morphology.

Secondary criteria

An electrographic or nonconvulsive seizure may be additionally demonstrated by significant improvement in the patient’s clinical state or the appearance of previously-absent normal EEG patterns (such as a posterior dominant rhythm or sleep transients) temporally coupled to the acute administration of a rapidly-acting antiepileptic drug such as a benzodiazepine. Of note, resolution of the suspected ictal pattern without clinical improvement or the appearance of previously absent normal EEG patterns would not satisfy the secondary criteria.

When rhythmic, periodic, or quasi-periodic electrographic patterns fail to fulfill these criteria in an obtunded or comatose patient who lacks other clinical signs of seizure activity, the diagnosis of nonconvulsive status epilepticus becomes more difficult and controversial. Patterns such as lateralized periodic discharges (LPDs, formerly termed PLEDs); bilateral, independent periodic discharges (BIPDs, formerly termed BIPLEDs); generalized periodic discharges (GPDs, formerly termed GPEDs); and stimulus-induced rhythmic, periodic, or ictal discharges (SIRPIDs) represent ambiguous but potentially ictal patterns whose clinical significance and management remain controversial topics.

From 

http://emedicine.medscape.com/article/1138728-overview#a1

Basics of TMS

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4890546/

A good review.

Dose of Lacosamide

Dosing: Adult (Uptodate)

Partial onset seizure:

Monotherapy: Oral, IV:

Initial: 100 mg twice daily; may be increased at weekly intervals by 50 mg twice daily based on response and tolerability.

Alternative initial dosage: Loading dose: 200 mg followed approximately 12 hours later by 100 mg twice daily for 1 week; may be increased at weekly intervals by 50 mg twice daily based on response and tolerability. Note: Administer loading doses under medical supervision because of the increased incidence of CNS adverse reactions.

Maintenance: 150 to 200 mg twice daily. Note: For patients already on a single antiepileptic and converting to lacosamide monotherapy, maintain the maintenance dose for 3 days before beginning withdrawal of the concomitant antiepileptic drug. Gradually taper the concomitant antiepileptic drug over ≥6 weeks.

Adjunctive therapy: Oral, IV:

Initial: 50 mg twice daily; may be increased at weekly intervals by 50 mg twice daily based on response and tolerability.

Alternative initial dosage: Loading dose of 200 mg followed approximately 12 hours later by 100 mg twice daily for 1 week; may be increased at weekly intervals by 50 mg twice daily based on response and tolerability. Note: Administer loading doses under medical supervision because of the increased incidence of CNS adverse reactions.

Maintenance dose: 100 to 200 mg twice daily (maximum: 400 mg daily)

Status epilepticus, refractory (off-label use): IV: 200 to 400 mg followed by a daily maintenance dose of 200 to 600 mg daily in 2 divided doses (Albers, 2011; Goodwin, 2011; Kellinghaus, 2011; NCS [Brophy, 2012]). Note: Although the Neurocritical Care Society recommends administration of the initial dose at a rate of 200 mg over 15 minutes, others have administered doses of up to 400 mg IV push over ≤5 minutes without apparent harm (Goodwin, 2011; Kellinghaus, 2011; NCS [Brophy, 2012]).

How do seizures stop? A review

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2738747/

This is an interesting article from Fred Lado and Solomon Moshe, which reviews literature on mechanisms for seizure termination.

How does a status epilepticus become super refractory?

http://brain.oxfordjournals.org/content/134/10/2802

This question is obviously crucial to successful management. It is a common clinical experience that the more severe the precipitating insult (for instance, in status epilepticus after trauma infection or stroke), the more likely is the status epilepticus to become super-refractory. However, super-refractory status epilepticus also occurs frequently in previously healthy patients without obvious cause.

In all these cases, the processes that normally terminate seizures have proved insufficient (for review, see Lado and Moshe, 2008). At a cellular level, one of the most interesting recent discoveries has been the recognition that receptors on the surface of axons are in a highly dynamic state, moving onto (externalization), away from (internalization) and along the axonal membrane. This ‘receptor trafficking’ intensifies during status epilepticus, and the overall effect is a reduction in the number of functional γ-aminobutyric acid (GABA) receptors in the cells affected in the seizure discharge (Arancibia and Kittler, 2009; Smith and Kittler, 2010). As GABA is the principle inhibitory transmitter, this reduction in GABAergic activity may be an important reason for seizures to become persistent. Furthermore, the number of glutaminergic receptors at the cell surface increases, and the reduction in the density of the GABA receptors is itself triggered it seems by activation of the glutaminergic receptor systems. Why this should happen is unknown, and from the epilepsy point of view is certainly maladaptive. This loss of GABAergic receptor density is also the likely reason for the increasing ineffectiveness of GABAergic drugs (such as benzodiazepines or barbiturates) in controlling seizures as the status epilepticus becomes prolonged (Macdonald and Kapur, 1999). It has also been repeatedly shown that the extracellular ionic environment, which can change in status epilepticus, may be an important factor in perpetuating seizures, and the normally inhibitory GABA(A)-mediated currents may become excitatory with changes in extracellular chloride concentrations (Lamsa and Taira, 2003).

Other cellular events might also be important. Mitochondrial failure or insufficiency may be one reason for the failure of seizure termination and cellular damage and mitochondrial processes are involved in cell necrosis and apoptosis (Cock et al., 2002). Another category of disease triggering persistent status epilepticus is inflammatory disease (Tan et al., 2010), and inflammatory processes may be important in the persistence of status epilepticus. The opening of the blood–brain barrier almost certainly plays a major role in the perpetuation of seizures, due to a variety of possible mechanisms (Friedman and Dingledine, 2011), and this may be especially the case in status epilepticus due to inflammation (Marchi et al., 2011). This may explain the benefits of steroids in the therapy of status epilepticus. Leakage of the blood–brain barrier will also lead to higher potassium levels and excitation (David et al., 2009). No genetic mechanism has been identified to explain the failure of seizure termination although massive changes in gene expression occur within minutes of the onset of status epilepticus.

At a systems level, it has been suggested rather fascinatingly and counter intuitively that status epilepticus results from a failure to synchronize seizure activity (Schindler et al., 2007a, b; Walker, 2011), and that the lack of synchrony somehow prevents seizure termination.

These mechanisms influence strategies for therapy. However, often overriding is the importance of establishing cause of the status epilepticus, for emergency therapy directed at the cause may be crucial in terminating the episode (for review of the influence of aetiology on prognosis, see Neligan and Shorvon, 2011).

Spinal cord section

Joint position and vibration sense in the cord

http://www.ncbi.nlm.nih.gov/pubmed/2926427

Hankey GJ, Edis RH. The utility of testing tactile perception of direction of scratch as a sensitive clinical sign of posterior column dysfunction in spinal cord disorders. J Neurol Neurosurg Psychiatry. 1989 Mar; 52(3): 395-8.

Classical beliefs about the functions of the dorsal columns of the spinal cord have been attacked following recent evidence that position and vibration sensations may be carried in the dorsal spinocerebellar tracts. There is evidence that the one specific function of the dorsal columns is for the transmission of information concerning the direction of tactile cutaneous movement. Thirty normal controls, 43 patients with spinal cord disorders and 10 patients with functional disorders were examined prospectively using an easily administered "direction of scratch" protocol. Interpretation of the direction of a 2 cm vertical tactile cutaneous movement over the lower limbs was found to be accurate in normal controls and grossly inaccurate in patients with functional disorders, exceeding the error rate of guessing. Detection of direction of 2 cm scratch was moderately impaired in 11 of 13 patients with spastic paraparesis and preserved sensation to all other modalities and 23 of 24 patients with spastic paraparesis and impaired proprioception and/or vibration sensations. Direction of 2 cm scratch, proprioception and vibration sensations were preserved in the three cases with anterior spinal cord syndromes. It is proposed that tactile perception of direction of 2 cm scratch over the lower limbs is a sensitive sign of posterior column function which can be usefully incorporated into the clinical sensory examination in the evaluation of spinal cord disorders.

Trying to understand disorders of ammonia

Questions

What is the overall flow of nitrogen in amino acid catabolism? 

Four steps = transamination, oxidative deamination, ammonia transport, urea cycle..

Why is glutamate important in amino acid catabolism? 

Transamination is the process which interconverts a pair of amino acids and a pair of keto acids by transfer of the alpha amino group. Transaminases are specific for one pair, but not for the other. For e.g. alanine transaminase is specific for pyruvate to alanine and vice versa, the other pair being any amino acid - keto acid pair. The reaction below can be catalyzed by either alanine transaminase or glutamate transaminase.

Of the various transaminases, glutamate transaminase is the most important one in urea synthesis. It is the only amino acid that undergoes oxidative deamination (the next step, see above) at an appreciable rate. Thus the nitrogen from amino acids towards urea is channeled through glutamate. Alpha ketoglutarate accepts the amino group to form L-glutamate.

How does ammonia cause toxicity in the brain OR how does the brain handle ammonia under ordinary circumstances and when the ammonia levels are high?

How are the steady state amino acid levels maintained in the blood OR what are the interactions of amino acid metabolism with carbohydrate metabolism?

What is the algorithm for diagnosis in a patient with hyperammonemia?

Trying to understand disorders of ammonia

Questions

What is the overall flow of nitrogen in amino acid catabolism? 

Four steps = transamination, oxidative deamination, ammonia transport, urea cycle..

Why is glutamate important in amino acid catabolism? 

Transamination is the process which interconverts a pair of amino acids and a pair of keto acids by transfer of the alpha amino group. Transaminases are specific for one pair, but not for the other. For e.g. alanine transaminase is specific for pyruvate to alanine and vice versa, the other pair being any amino acid - keto acid pair. The reaction below can be catalyzed by either alanine transaminase or glutamate transaminase.

Of the various transaminases, glutamate transaminase is the most important one in urea synthesis. It is the only amino acid that undergoes oxidative deamination (the next step, see above) at an appreciable rate. Thus the nitrogen from amino acids towards urea is channeled through glutamate. Alpha ketoglutarate accepts the amino group to form L-glutamate.

How does ammonia cause toxicity in the brain OR how does the brain handle ammonia under ordinary circumstances and when the ammonia levels are high?

How are the steady state amino acid levels maintained in the blood OR what are the interactions of amino acid metabolism with carbohydrate metabolism?

What is the algorithm for diagnosis in a patient with hyperammonemia?

Why does RNA have Uridine instead of Thymidine?

http://www.madsci.org/posts/archives/1997-12/879354206.Bc.r.html

Great question! However, the real question is: Why does thymine replace uracil in DNA?

First, some clarification. As you already know, the difference between RNA (ribonucleic acids) and DNA (deoxyribonucleic acids) is the existence of a hydroxyl (-OH) group on the 2' carbon of the ribose sugar in the backbone. The removal of 2' hydroxyl groups from DNA does not occur after the DNA has been synthesized, but rather the 2' hydroxyl groups are removed from the nucleotides before they are incorporated into the DNA. During nucleotide synthesis, a portion of the nucleotide monophosphates (NMP's) are dehydroxylated to 2'-deoxy-nucleotide monophosphates (dNMP's). This means that GMP, AMP, CMP, and UMP are converted into dGMP, dAMP, dCMP, and dUMP, respectively. However, before being incorporated into the chromosomes, another modification, using folic acid as a catalyst, methylates the uracil in dUMP to form a thymine making it dTMP. After further phosphorylation, dGTP, dATP, dCTP, and dTTP can be used as the building blocks to construct DNA.

The important thing to notice is that while uracil exists as both uridine (U) and deoxy-uridine (dU), thymine only exists as deoxy-thymidine (dT). So the question becomes: Why do cells go to the trouble of methylating uracil to thymine before it can be used in DNA?

The answer is: methylation protects the DNA. Beside using dT instead of dU, most organisms also use various enzymes to modify DNA after it has been synthesized. Two such enzymes, dam and dcmmethylate adenines and cytosines, respectively, along the entire DNA strand. This methylation makes the DNA unrecognizable to many Nucleases (enzymes which break down DNA and RNA), so that it cannot be easily attacked by invaders, like viruses or certain bacteria. Obviously, methylating the nucleotides before they are incorporated ensures that the entire strand of DNA is protected. Thymine also protects the DNA in another way. If you look at the components of nucleic acids, phosphates, sugars, and bases, you see that they are all very hydrophilic (water soluble). Obviously, adding a hydrophobic (water insoluble) methyl group to part of the DNA is going to change the characteristics of the molecule. The major effect is that the methyl group will be repelled by the rest of the DNA, moving it to a fixed position in the major groove of the helix. This solves an important problem with uracil - though it prefers adenine, uracil can base-pair with almost any other base, including itself, depending on how it situates itself in the helix. By tacking it down to a single conformation, the methyl group restricts uracil (thymine) to pairing only with adenine. This greatly improves the efficiency of DNA replication, by reducing the rate of mismatches, and thus mutations.

To sum up: the replacement of thymine for uracil in DNA protects the DNA from attack and maintains the fidelity of DNA replication. 

Five Patients (book)

Non-fiction book by Michael Crichton (rhymes with "frighten") regarding hospital practices in Boston in late 1960's. Crichton got his degree from Harvard, but never applied for license to practice medicine.

An Introduction to Epilepsy [Internet] NCBI Bookshelf

http://www.ncbi.nlm.nih.gov/books/NBK2508/

High frequency rhythms on EEG

13-30 Beta
30-100 Gamma
100-250 Ripple
250-1000 Fast ripple
250 and beyond also called as HFO (high frequency oscillations)
HFO's have localizing value - seizure onset zone

Cortical Spreading Depression

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3049472/

Clinical relevance of cortical spreading depression in neurological disorders: migraine, malignant stroke, subarachnoid and intracranial hemorrhage, and traumatic brain injury

Diagnosis in Epilepsy - 5 axis approach

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3865130/

For correct and complete analysis and classification of signs and symptoms the principles of the neurological diagnosis should be followed: what? (clinical diagnosis), where? (topographical diagnosis), and why ? (etiological diagnosis) (4). A detailed history, complete general clinic and neurologic examination, diagnostic hypothesis and wise choice of complementary evaluations are all important elements for epilepsy diagnosis (5).

The use of the 5-axis diagnosis, published in 2001 (6) is very useful. Adapted to daily practice and using also the new concepts and terminology proposed in 2010 by the Commission of Classification and Terminology (CCT) of ILAE (7), these axis are:

Axis 1 – are the paroxysmal events epileptic seizures? (to be diferentiated from nonepileptic events). If epileptic, the seizures semiology should be described, according to the terms from the Glossary published by ILAE in 2001 (8).

Axis 2 – define type of seizures: focal, generalized or unknown if focal or generalized (epileptic spasm belong to this last category). If focal seizures, attempts to define lateralization and localization should be done.

Axis 3 – syndrome diagnosis (electroclinical syndromes are epilepsies with particular clinical and electroencephalographic (EEG) features allowing their recognition; syndrome diagnosis is important for therapeutic approach and prog­nosis estimation).

The following features should be described: age of onset, description of seizure semiology, relation to sleep, precipitant factors, motor and cognitive development, neurological exam and the EEG features.

Axis 4 – etiologic diagnosis (genetic, structural – metabolic or unknown). Detailed description should follow.

Axis 5 – description of associated deficits.

Basic Terminology in Epilepsy

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3865130/

The Commission on Epidemiology and Prognosis (CEP) of the International League Against Epilepsy (ILAE) proposed conceptual and operational definitions of epilepsy and other paroxysmal events. These terms were established by consensus (1), initially in 1993, to provide a common language in the epidemiological, clinical and therapeutical studies and for the daily practice. Some term definitions were questioned during last years, and conceptual modifications were proposed (2). In 2011 CEP – ILAE published a document promoting consistency in methods and definitions (3). We present the useful terms in daily clinical practice:

Epileptic seizure – "a transient occurence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain" – 2005 (2). "The clinical manifestation consist of sudden and transitory abnormal phenomena which may include alterations of consciousness, motor, sensory, autonomic, or psychic events, perceived by the patient or an observer" – 1993 (1).

Status epilepticus – "a single epileptic seizure of more than 30-min duration or a series of epileptic seizures without resumption of baseline central nervous system functions interictally lasting more than 30-min" – 1993 (1).

Epilepsy – operational definition – is still recommended for epidemiological studies. According to this definition epilepsy is "a condition characterized by recurrent (two or more) epileptic seizures, unprovoked by any immediate identified cause. Multiple seizures occuring in a 24-h period are considered a single event. An episode of status epilepticus is considered a single event" – 1993 (1). The 2005 concept (2), defined epilepsy as "a disorder characterized by an enduring predisposition to generate epileptic seizures and by a neurobiologic, cognitive, psychological and social consequences of this condition. The definition requires the occurence of at least one epileptic seizure". This concept is more difficult to manage, consequently it is considered that epilepsy should be recognized by any pshysician but the epilepsy diagnosis should be established by physicians with epileptology expertise.

Nonepileptic events – "clinical manifestations presumed to be unrelated to an abnormal and excessive discharge of a set of neurons of the brain, including: disturbances in brain function (vertigo or dizziness, syncope, sleep and movement disorders, transient global amnesia, migraine, enuresis) and pseudoseizures (non­epileptic sudden behavioral episodes presumed to be of psychogenic origin; these may coexist with true epileptic seizures)" – 1993 (1)

ILAE Glossary of terms

http://www.ncbi.nlm.nih.gov/pubmed/11580774/

INTRODUCTION

This glossary intends to provide a standard terminology for health care workers to communicate what is observed and what a patient reports during a seizure. As this terminology is descriptive and phenomenologic, its use would not imply or require knowledge of ictal pathophysiology, any pathological substrate, or etiology.

Many terms are adjectives modifying “seizure,” which itself is defined under “general terms.” This pertains to seizures with single or multiple components.

Terms in this glossary (e.g., “seizure,”“ictus,” which have widespread applicability in other fields of clinical neuroscience) are herein defined according to their references to epilepsy.

Some terms of this glossary are “fundamental” (i.e., they encompass other more precise words). These can be used as the sole descriptor when data to characterize a phenomenon more precisely are not available. Such include aura, automatism, experiential, motor, and sensory.

A seizure will often consist of two or more phenomena occurring simultaneously or sequentially and should be described accordingly.

Quantitative terms, such as duration of motor events, are not intended as immutable confines, but as clarifying guides to describe clinically observed events.

Scientific progress dictates an evolution of terms to retain their relevance. However, needs of communication in everyday life require that changes be gradual and evolutionary rather than abrupt and revolutionary. The use of synonyms in this glossary reflects incidents in which gradual changes are likely.

Terminology in some areas remains unresolved. Therefore we view this glossary as a dynamic process for which feedback will be welcomed.

PRINCIPLES FOR TERMS AND DEFINITIONS

In developing the “lexique” of this report, we adopted and applied the following principles.

Terms and definitions should

• 1Contain features that distinguish or modify seizure entities.
• 2Be descriptive of the phenomena involved.
• 3Comply with terminology of clinical neuroscience.
• 4Use current terminology and definitions wherever possible.
• 5Contain new terms only if necessary.
• 6Be easily translatable to other languages.
• 7Be readily understood and used by potential users.

I GENERAL TERMS

1.0 SEMIOLOGY

That branch of linguistics concerned with signs and symptoms.

2.0 EPILEPTIC SEIZURE

Manifestation(s) of epileptic (excessive and/or hypersynchronous), usually self-limited activity of neurons in the brain.

3.0 ICTUS

A sudden neurologic occurrence such as a stroke or an epileptic seizure.

4.0 EPILEPSY

• a) Epileptic Disorder: A chronic neurologic condition characterized by recurrent epileptic seizures.
• b) Epilepsies: Those conditions involving chronic recurrent epileptic seizures that can be considered epileptic disorders.

5.0 FOCAL (syn. partial)

A seizure whose initial semiology indicates, or is consistent with, initial activation of only part of one cerebral hemisphere.

6.0 GENERALIZED (syn. bilateral)

A seizure whose initial semiology indicates, or is consistent with, more than minimal involvement of both cerebral hemispheres.

7.0 CONVULSION

Primarily a lay term. Episodes of excessive, abnormal muscle contractions, usually bilateral, which may be sustained or interrupted.

II TERMS DESCRIBING EPILEPTIC SEIZURE SEMIOLOGY

These are descriptors of seizures unless specified otherwise.

1.0 MOTOR

Involves musculature in any form. The motor event could consist of an increase (positive) or decrease (negative) in muscle contraction to produce a movement.

Unless noted, the following terms are adjectives modifying “motor seizure” or “seizure” (e.g., “tonic motor seizure or dystonic seizure”), and whose definitions can usually be understood as prefaced by “refers to …”.

1.1 ELEMENTARY MOTOR

A single type of contraction of a muscle or group of muscles that is usually stereotyped and not decomposable into phases. (However, see tonic–clonic, an elementary motor sequence).

1.1.1 TONIC

A sustained increase in muscle contraction lasting a few seconds to minutes.

1.1.1.1 EPILEPTIC SPASM (Formerly Infantile Spasm)

Noun: A sudden flexion, extension, or mixed extension–flexion of predominantly proximal and truncal muscles that is usually more sustained than a myoclonic movement but not so sustained as a tonic seizure (i.e., ∼1 s). Limited forms may occur: grimacing, head nodding. Epileptic spasms frequently occur in clusters.

1.1.1.2 POSTURAL

Adoption of a posture that may be bilaterally symmetric or asymmetric (as in a “fencing posture”).

1.1.1.2.1 VERSIVE

A sustained, forced conjugate ocular, cephalic, and/or truncal rotation or lateral deviation from the midline.

1.1.1.2.2 DYSTONIC

Sustained contractions of both agonist and antagonist muscles producing athetoid or twisting movements, which, when prolonged, may produce abnormal postures.

1.1.2 MYOCLONIC (adjective); MYOCLONUS (noun)

Sudden, brief (<100 ms) involuntary single or multiple contraction(s) of muscles(s) or muscle groups of variable topography (axial, proximal limb, distal).

1.1.2.1 NEGATIVE MYOCLONIC

Interruption of tonic muscular activity for <500 ms without evidence of preceding myoclonia.

1.1.2.2 CLONIC

Myoclonus that is regularly repetitive, involves the same muscle groups, at a frequency of ∼2–3 c/s, and is prolonged. Synonym: rhythmic myoclonus.

1.1.2.2.1 JACKSONIAN MARCH

Noun: Traditional term indicating spread of clonic movements through contiguous body parts unilaterally.

1.1.3 TONIC–CLONIC

A sequence consisting of a tonic followed by a clonic phase. Variants such as clonic–tonic–clonic may be seen.

1.1.3.1 GENERALIZED TONIC–CLONIC SEIZURE (syn. bilateral tonic–clonic seizure) (Formerly “Grand Mal” Seizure)

Noun: Bilateral symmetric tonic contraction and then bilateral clonic contractions of somatic muscles, usually associated with autonomic phenomena.

1.1.4 ATONIC

Sudden loss or diminution of muscle tone without apparent preceding myoclonic or tonic event lasting ≥1 to 2 s, involving head, trunk, jaw, or limb musculature.

1.1.5 ASTATIC

Loss of erect posture that results from an atonic, myoclonic, or tonic mechanism. Synonym: drop attack.

1.1.6 SYNCHRONOUS (Asynchronous)

Motor events occurring (not) at the same time or at the same rate in sets of body parts.

1.2 AUTOMATISM

Noun: A more or less coordinated, repetitive, motor activity usually occurring when cognition is impaired and for which the subject is usually amnesic afterward. This often resembles a voluntary movement and may consist of an inappropriate continuation of ongoing preictal motor activity.

The following adjectives are usually employed to modify “automatism.”

1.2.1 OROALIMENTARY

Lip smacking, lip pursing, chewing, licking, tooth grinding, or swallowing.

1.2.2 MIMETIC

Facial expression suggesting an emotional state, often fear.

1.2.3 MANUAL OR PEDAL

• 1Indicates principally distal components, bilateral or unilateral.
• 2Fumbling, tapping, manipulating movements.

1.2.4 GESTURAL

Often unilateral.

• 1Fumbling or exploratory movements with the hand, directed toward self or environment.
• 2Movements resembling those intended to lend further emotional tone to speech.

1.2.5 HYPERKINETIC

• 1Involves predominantly proximal limb or axial muscles producing irregular sequential ballistic movements, such as pedaling, pelvic thrusting, thrashing, rocking movements.
• 2Increase in rate of ongoing movements or inappropriately rapid performance of a movement.

1.2.6 HYPOKINETIC

A decrease in amplitude and/or rate or arrest of ongoing motor activity.

1.2.7 DYSPHASIC

Impaired communication involving language without dysfunction of relevant primary motor or sensory pathways, manifested as impaired comprehension, anomia, paraphasic errors, or a combination of these.

1.2.8 DYSPRAXIC

Inability to perform learned movements spontaneously or on command or imitation despite intact relevant motor and sensory systems and adequate comprehension and cooperation.

1.2.9 GELASTIC

Bursts of laughter or giggling, usually without an appropriate affective tone.

1.2.10 DACRYSTIC

Bursts of crying.

1.2.11 VOCAL

Single or repetitive utterances consisting of sounds such as grunts or shrieks.

1.2.12 VERBAL

Single or repetitive utterances consisting of words, phrases, or brief sentences.

1.2.13 SPONTANEOUS

Stereotyped, involve only self, virtually independent of environmental influences.

1.2.14 INTERACTIVE

Not stereotyped, involve more than self, environmentally influenced.

2.0 NONMOTOR

2.1 AURA

Noun: A subjective ictal phenomenon that, in a given patient, may precede an observable seizure; if alone, constitutes a sensory seizure.

2.2 SENSORY

A perceptual experience not caused by appropriate stimuli in the external world. Modifies “seizure” or “aura.”

2.2.1 ELEMENTARY

A single, unformed phenomenon involving one primary sensory modality (e.g., somatosensory, visual, auditory, olfactory, gustatory, epigastric, or cephalic).

2.2.1.1 SOMATOSENSORY

Tingling, numbness, electric-shock sensation, pain, sense of movement, or desire to move.

2.2.1.2 VISUAL

Flashing or flickering lights, spots, simple patterns, scotomata, or amaurosis.

2.2.1.3 AUDITORY

Buzzing, drumming sounds or single tones.

2.2.1.4 OLFACTORY

Odor, usually disagreeable.

2.2.1.5 GUSTATORY

Taste sensations including acidic, bitter, salty, sweet, or metallic.

2.2.1.6 EPIGASTRIC

Abdominal discomfort including nausea, emptiness, tightness, churning, butterflies, malaise, pain, and hunger; sensation may rise to chest or throat. Some phenomena may reflect ictal autonomic dysfunction.

2.2.1.7 CEPHALIC

Sensation in the head such as light-headedness, tingling or headache.

2.2.1.8 AUTONOMIC

A sensation consistent with involvement of the autonomic nervous system, including cardiovascular, gastrointestinal, sudomotor, vasomotor, and thermoregulatory functions. (Thus “autonomic aura”; cf. “autonomic events” 3.0).

2.2.2 EXPERIENTIAL

Affective, mnemonic, or composite perceptual phenomena including illusory or composite hallucinatory events; these may appear alone or in combination. Included are feelings of depersonalization. These phenomena have subjective qualities similar to those experienced in life but are recognized by the subject as occurring outside of actual context.

2.2.2.1 AFFECTIVE

Components include fear, depression, joy, and (rarely) anger.

2.2.2.2 MNEMONIC

Components that reflect ictal dysmnesia such as feelings of familiarity (déjà-vu) and unfamiliarity (jamais-vu).

2.2.2.3 HALLUCINATORY

A creation of composite perceptions without corresponding external stimuli involving visual, auditory, somatosensory, olfactory, and/or gustatory phenomena. Example: “hearing” and “seeing” people talking.

2.2.2.4 ILLUSORY

An alteration of actual percepts involving the visual, auditory, somatosensory, olfactory, or gustatory systems.

2.3 DYSCOGNITIVE

The term describes events in which (1) disturbance of cognition is the predominant or most apparent feature, and (2a) two or more of the following components are involved, or (2b) involvement of such components remains undetermined. Otherwise, use the more specific term (e.g., “mnemonic experiential seizure” or “hallucinatory experiential seizure”).

Components of cognition:

• • perception: symbolic conception of sensory information
• • attention: appropriate selection of a principal perception or task
• • emotion: appropriate affective significance of a perception
• • memory: ability to store and retrieve percepts or concepts
• • executive function: anticipation, selection, monitoring of consequences, and initiation of motor activity including praxis, speech

3.0 AUTONOMIC EVENTS

3.1 AUTONOMIC AURA

A sensation consistent with involvement of the autonomic nervous system, including cardiovascular, gastrointestinal, sudomotor, vasomotor, and thermoregulatory functions (see 2.2.1.8).

3.2 AUTONOMIC SEIZURE

An objectively documented and distinct alteration of autonomic nervous system function involving cardiovascular, pupillary, gastrointestinal, sudomotor, vasomotor, and thermoregularity functions.

4.0 SOMATOTOPIC MODIFIERS

4.1 LATERALITY

4.1.1 UNILATERAL

Exclusive or virtually exclusive involvement of one side as a motor, sensory, or autonomic phenomenon.

4.1.1.1 HEMI-

A prefix to other descriptors (e.g., hemiclonic).

4.1.2 GENERALIZED (syn. “bilateral”)

More than minimal involvement of each side as a motor, elementary sensory, or autonomic phenomenon.

Motor component: further modified as

4.1.2.1 ASYMMETRIC

Clear distinction in quantity and/or distribution of behavior on the two sides.

4.1.2.2 SYMMETRIC

Virtual bilateral equality in these respects.

4.2 BODY PART

Refers to area involved (i.e., arm, leg, face, trunk, and other).

4.3 CENTRICITY

Modifier describes proximity to the body axis.

4.3.1 AXIAL

Involves trunk, including neck.

4.3.2 PROXIMAL LIMB

Signifies involvement from shoulders to wrist, hip to ankle.

4.3.3 DISTAL LIMB

Indicates involvement of fingers, hands, toes, and/or feet.

5.0 MODIFIERS AND DESCRIPTORS OF SEIZURE TIMING

The following terms are listed in the form (adjective, noun, verb) according to principal usage; as adjective unless specified.

5.1 INCIDENCE

Noun: Refers to the number of epileptic seizures within a time period or the number of seizure days per unit of time.

5.1.1 REGULAR, IRREGULAR

Consistent (inconsistent) or predictable (unpredictable, chaotic) intervals between such events.

5.1.2 CLUSTER

• 1Noun: Incidence of seizures within a given period (usually one or a few days) that exceeds the average incidence over a longer period for the patient.
• 2Verb: To vary in incidence as above.

5.1.3 PROVOCATIVE FACTOR

Noun: Transient and sporadic endogenous or exogenous element capable of augmenting seizure incidence in persons with chronic epilepsy and evoking seizures in susceptible individuals without epilepsy.

5.1.3.1 REACTIVE

Occurring in association with transient systemic perturbation such as intercurrent illness, sleep loss, or emotional stress.

5.1.3.2 REFLEX

Objectively and consistently demonstrated to be evoked by a specific afferent stimulus or by activity of the patient. Afferent stimuli can be elementary[i.e., unstructured (light flashes, startle, a monotone)] orelaborate[i.e., structured, (a symphony)]. Activity may be elementary [e.g., motor (a movement)]; or elaborate [e.g., cognitive function (reading, chess playing)], or both (reading aloud).

5.2 STATE DEPENDENT

Occurring exclusively or primarily in the various stages of drowsiness, sleep, or arousal.

5.3 CATAMENIAL

Seizures occurring principally or exclusively in any one phase of the menstrual cycle.

6.0 DURATION

Time between the beginning of initial seizure manifestations, such as the aura, and the cessation of experienced or observed seizure activity. Does not include nonspecific seizure premonitions or postictal states.

6.1 STATUS EPILEPTICUS

A seizure that shows no clinical signs of arresting after a duration encompassing the great majority of seizures of that type in most patients or recurrent seizures without interictal resumption of baseline central nervous system function.

7.0 SEVERITY

A multicomponent assessment of a seizure by observers and the patient.

Components primarily of observer assessment include duration, extent of motor involvement, impairment of cognitive interaction with environment intraictally, maximal number of seizures per unit of time.

Components primarily of patient assessment: extent of injury; emotional, social, and vocational consequences of the attack.

8.0 PRODROME

A preictal phenomenon. A subjective or objective clinical alteration (e.g., ill-localized sensation or agitation) that heralds the onset of an epileptic seizure but does not form part of it.

9.0 POSTICTAL PHENOMENON

A transient clinical abnormality of central nervous system function that appears or becomes accentuated when clinical signs of the ictus have ended.

9.1 LATERALIZING [TODD'S (OR BRAVAIS')] PHENOMENON

Any unilateral postictal dysfunction relating to motor, language, sensory, and/or integrative functions including visual, auditory, or somatosensory neglect phenomena.

9.2 NONLATERALIZING PHENOMENON

Impaired cognition, amnesia, psychosis.

9.2.1 IMPAIRED COGNITION

Decreased cognitive performance involving one or more of perception, attention, emotion, memory, execution, praxis, speech (cf., Dyscognitive, 2.3).

9.2.1.1 ANTEROGRADE AMNESIA

Impaired ability to remember new material.

9.2.1.2 RETROGRADE AMNESIA

Impaired ability to recall previously remembered material.

9.2.2 PSYCHOSIS

Misinterpretation of external world in an awake, alert person; involves thought disorder of emotion and socialization.

DATA SOURCES

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Some nonmedical texts:

Sykes JB, ed. The concise Oxford dictionary. 7th ed. Oxford, England: Clarendon Press, 1982.

Dictionnaire Encyclopedique. Petit Larousse Illustre. Librairie Larousse, Paris, 1973.

Dictionary of Canadian English: the senior dictionary. Avis WS, Drysdale PD, Gregg RJ, Scargill MH, eds. Toronto, Canada: W.J. Gage, 1967.