Title: Seizures
1Seizures
2- The EEG is most useful in diagnosing and
categorizing seizures. During a seizure (ictus),
paroxysmal EEG activity may arise from either
normal or abnormal background activity.
Paroxysms, a sudden intensification of symptoms,
usually consist of bursts of spikes, slow waves,
or complexes of both.
3- An EEG should ideally be recorded during the
ictus, but seizures rarely occur during routine
recordings. When they do, EEGs may be obscured
by muscle movement artifacts. The EEGs obtained
immediately after the seizure, in the postictal
period, generally show only slow, low voltage
activity, called postictal depression.
4- Fortunately, EEGs obtained between seizures, in
the interictal period, contain specific
abnormalities that suffice for definitive
diagnosis in up to 80 percent of cases. On the
other hand, since about 20 percent of epilepsy
patients have essentially normal routine EEGs,
normal interictal EEGs do not exclude a diagnosis
of seizures.
5- Several maneuvers are used to evoke diagnostic
EEG abnormalities in suspected cases. Patients
are usually asked to hyperventilate for about 3
minutes or to look directly into a stroboscopic
light during the EEG. If these maneuvers do not
yield diagnostic information and if a strong
suspicion of seizures persists, an EEG is
performed after sleep deprivation. In about one
third of epileptic patients, this EEG reveals
abnormalities not apparent from routine studies.
6- The EEG is also useful in diagnosing the
locked-in syndrome, in which people who have
sustained pontine or medullary infarctions are
alert but cannot speak or move their trunk or
limbs. Since the cerebrum and upper brainstem
are normal, these otherwise devastated people
have normal cerebral activity, including
cognitive function, and therefore a normal EEG.
7- Patients with the locked-in syndrome must be
differentiated from ones in a persistent
vegetative state, a condition that typically
follows cerebral anoxia from cardiac arrest, drug
overdose, or carbon monoxide poisoning. These
patients have marked cerebral cortex injury and
thus profound dementia accompanied by an
inability to speak or move. As would be expected
from their extensive cerebral damage and mental
as well as physical incapacity, they have a
markedly abnormal EEG.
8- Most seizures and varieties of epilepsy are
classified either as partial, with either
elementary (simple) or complex symptoms, or as
generalized, usually absences or tonic-clonic.
Partial seizures originate from paroxysmal
electrical discharges in a focus, a discrete
region of the cerebral cortex usually injured by
a structural lesion.
9Seizure Disorders
- Important distinguishing points between types of
seizures Partial, having a defined focus in the
brain to which the seizure is limited Vs.
Generalized, widespread, most of the brain
becomes involved in the seizure - Simple, producing an alteration in consciousness
Vs. Complex, producing a loss of consciousness - Not all seizures produce a convulsion a
convulsion involving the skeletal muscles will
only occur if motor areas of the brain are
involved in the seizure.
10- In general, partial seizures with motor symptoms
have their focus in the contralateral frontal
lobe those with sensory symptoms, in the
parietal lobe those with visual symptoms, in the
occipital or temporal lobe and those with
auditory symptoms, in the temporal lobe.
11- During and between partial seizures, the EEG
typically shows abnormalities in channels
overlying the particular focus. Since neither
the entire cortex nor deep structures are
involved when seizures begin, or often throughout
their entire course, consciousness is preserved.
12A grand mal (big, bad) seizure is a complex,
generalized seizure, with convulsions. The
seizure is often preceded by subjective symptoms
of an aura. The aura symptoms result from
initial activity at a focal site. These symptoms
can be sensory, as in a foul smell or taste,
seeing flashes of light, etc., emotional as in
reports of feelings of euphoria or panic. The
symptoms of the aura reflect the focal point in
the brain in sensory cortex, limbic system, etc.
13The actual onset of the grand mal is the tonic
phase in which the persons skeletal muscles
forcefully contract and the person typically
makes a vocal outburst as air is forced from the
lungs. The tonic phase can last 15 seconds (or
more) and then is replaced with the clonic phase
in which the muscle groups contract jerkily,
relax and contract again in a convulsion. The
tonic phase involves the motor cortex firing
continuously. The tonic phase involves
subcortical structures inhibiting the former
activity.
14- Although partial seizures usually last between
several seconds and several minutes, occasionally
they continue for hours or days while the
discharge remains confined to its original focus.
In such cases, called epilepsy partialis
continua or focal status epilepticus, symptoms
persist and interfere with normal activity, but
routine activity can also continue despite the
seizure.
15- More often, discharges become more extensive and,
enlarging in a slow, brushfire-like manner,
involve adjacent areas of the cortex and create
additional symptoms. Discharges can also spread
over the entire cortex or travel through the
corpus callosum to the other cerebral hemisphere.
If the entire cerebral cortex is engulfed,
secondary generalization, patients lose
consciousness, develop bilateral motor activity,
and have generalized EEG abnormalities.
16Other Seizures...
Other less dramatic seizures may involve a
convulsion which spreads from muscle group to
muscle group as the seizure spreads along the
precentral gyrus, producing a Jacksonian march
after a famous neurologist. Complex movements
can occur involuntarily in other seizures in
which a person may walk away in an unresponsive
state or engage in habitual behaviors termed
automatisms.
17Other Seizures...
A petit mal seizure will likely just produce an
alteration in consciousness or an absence spell
in a child who appears to stare blankly, spacing
out and being unresponsive for a few
seconds. Other such simple partial seizures can
produce alterations in the behaviors composing a
personality, possibly producing self-reports of
having very different memories, emotions,
etc. Seizure activity results from uninhibited
excitatory brain activity the excessive
glutamate released in seizures and be toxic to
neurons. Brain damage can be likely in the
hippocampus from this excitotoxicity.
18- In contrast to partial seizures, discharges in
generalized seizures arise from the thalamus or
other subcortical structures and immediately
spread upward to the entire cerebral cortex.
Also, generalized seizures are usually caused by
a genetic disorder or metabolic aberration. Most
important, they are characterized by
unconsciousness and generalized EEG
abnormalities, although not necessarily by gross
motor activity. Like partial seizures,
generalized seizures can persist, in which cases
they are a life-threatening condition called
generalized status epilepticus.
19Partial Seizures
20- Partial seizures are said to have elementary
symptoms when their clinical manifestation is
only a particular movement, a single sensation,
or a simple phenomenon. However, an impaired
consciousness, with or without psychological
abnormalities or coordinated motor activity,
denotes complex symptoms.
21- Seizures with elementary motor symptoms, formerly
called focal motor seizures, usually consist of
rhythmic jerking (clonic movement) of a body part
that may be as limited as one finger or as
extensive as an entire side. These seizures can
develop into focal status epilepticus or undergo
secondary generalization. Sometimes, in a
jacksonian march, a seizure discharge spreads
along the motor cortex, and movements that began
in a finger extend to the entire arm and, then,
to the face.
22- After any partial motor seizure, affected muscles
may be weakened. A post-itcal monoparesis or
(Todds) hemiparesis may remain for up to 24
hours. Thus, the differential diagnosis of
transient hemiparesis includes transient ischemic
attacks (TIAs), hemiplegic migraines,
psychologialc aberrations, and Todds hemiparesis.
23- Seizures with elementary sensory symptoms usually
consist of tingling or burning paresthesias in
regions of the body that have extensive cortical
representation, such as the face. Sometimes a
sensory loss, a negative symptom, might be the
seizures only manifestation.
24Partial elementary seizures with special
sensory symptoms, consisting of specific but
simple auditory, visual, or olfactory sensations,
can also occur. Most important, sensory seizures
can create vivid and realistic sensations best
described as hallucinations however, they are
almost always recognized by patients as being the
result of cerebral dysfunction, rather than real
events.
25- Auditory symptoms are usually repetitive noises,
musical notes, or single words that have no
meaning. Visual symptoms usually are seen as
bright lines, spots, or splotches of color that
move slowly across the visual field or, like a
view through a kaleidoscope, as stars rotating
around the center of vision.
26- Elaborate visual phenomena alone or combined with
auditory or emotional symptoms, in contrast, are
complex symptoms that must be differentiated
from these and other visual hallucinations.
Olfactory symptoms usually consist of vaguely
recognizable smells, such as the most frequent
one, burning rubber. Since olfactory
hallucinations usually result from discharges in
the anterior inferior tip of the temporal lobe,
the uncus, partial seizures with olfactory
symptoms are often called uncinate seizures or
fits. Typically, as discharges spread from the
incus to involve larger areas of the temporal
lobe, partial complex seizures ensue.
27Partial Complex Seizures
28- Partial complex seizures begin between late
childhood and the early thirties and are the
single most frequent seizure variety, affecting
about 65 percent of epilepsy patients. Many old
studies of psychiatric disorders are misleading
because they did not acknowledge the
preponderance of patients who had partial complex
seizures, and they also relied upon patients
descriptions of nonspecific sensations and
without EEG correlation.
29- Current studies, which use telemetry, have
defined ictal and postictal seizure
manifestations and separated them from nonseizure
disturbances. Nevertheless, several issues about
partial complex seizures remain unsettled. A
major one is the genuineness of the broad range
of purported ictal symptoms, including violence.
Another is the relationship between partial
complex epilepsy and interictal mental
abnormalities, such as personality disorders,
psychosis, and cognitive impairment.
30- In the past, less cumbersome but less accurate
titles, psychomotor seizures and temporal lobe
seizures or epilepsy (TLE), have been used. The
term psychomotor seizures is properly applied
only to the rare variety of partial complex
seizures with exclusively behavioral
abnormalities. Likewise, TLE is inappropriate
because the seizures originate in the frontal and
other lobes rather than in the temporal lobe in
about 10 percent of cases, leaving this term at
risk of contradicting the location of the focus
of the seizures. TLE is also inconsistent with
the current classification of seizures based on
symptoms, rather than anatomic origin.
31- As for symptoms of partial complex seizures,
about 10 percent of patients have a premonitory
sensation, an aura, which is not only a warning
it is actually the first part of the seizure.
During most of the seizure, patients usually have
only a blank stare and are inattentive and
uncommunicative. They always (by definition)
have impaired consciousness.
32- In most cases, they have memory impairment or
total loss, amnesia, presumably because the
limbic system in the temporal lobe is beset with
seizure discharges. Since the amnesia is so
striking, it may appear to be a patients only
symptom. (Therefore, partial complex seizures
must be strongly considered among the neurologic
causes of the acute amnestic syndrome).
33- Usually the only physical sign of partial complex
seizures is automatisms, which are simple,
repetitive, and purposeless face or hand
movements, such as swallowing, kissing, and lip
smacking, or fumbling, scratching, and rubbing
the abdomen. Automatisms are present in more
than 80 percent of complex seizures and occur
more frequently than psychological aberrations.
34- Patients may sometimes assume postures of perform
simple activities, such as standing, walking,
pacing, or even driving. It is often unclear,
however, whether these usually rote activities
are manifestations of a seizure or are naturally
occurring actions that have persisted despite the
seizure.
35- Likewise, in about 25 percent of cases, patients
utter brief phrases or mutter unintelligibly.
Many time the actions and words are cued by the
environment. For example, a child with a partial
complex seizure may clutch and continually stroke
a nearby stuffed animal while repeating some
endearing word. What would distinguish this
activity from normal would be the childs
impaired consciousness, apparent self-absorption,
and subsequent failure to recall the event.
36- Symptoms might occasionally be complex visual or
auditory hallucinations accompanied by an
appropriate emotion. Special sensory phenomena
that are more elaborate than in partial
elementary seizures, however, are notorious but
rarely occurring.
37- Although a wide variety of symptoms could be
considered manifestations of seizures, certain
ones cannot be accepted in isolation. In
particular, the various experimental phenomena,
such as déjà vu, jamais vu, dream-like states,
mind-body dissociations, and floating feelings,
are rarely associated with clinical or EEG
evidence of seizures. These experimental
phenomena are too nonspecific and have been so
romanticized that they have virtually no
diagnostic value when described by a well-read or
flighty patient.
38- Another frequent disturbance that has a dubious
association with partial complex seizures is the
rising epigastric sensation. This is a
perception of a swelling in the abdomen that, as
if progressing upward within the body, turns into
tightness in the throat and then a feeling of
suffocation. Although this symptom could be an
aura, it has a striking similarity to a common
psychogenic disturbance, globus hystericus, in
which people also feel tightening of the throat
and inability to breathe.
39- Following a partial complex seizure, which
usually has a duration of 2 to 3 minutes,
patients typically have confusion, clouding of
their sensorium, and a tendency to sleep. If the
seizure involved the brains language centers,
patients may have postictal aphasia. Also, for
15 to 30 minutes after the seizure, at least 40
percent of patients have a markedly elevated
serum prolactin concentration.
40- Another important but a decidedly uncommon
complication of partial complex seizures is
partial complex status epilepticus. Despite its
prevalence in popular literature, only about two
dozen cases have been described in neurologic
journals, and many were not documented with
telemetry. When this condition does occur,
patients have 1 ½ to 24 hours of confusion that
is sometimes accompanied by aphasia, automatisms,
and other purposeless motor activity. Confusion
is so pronounced that patients are incapable of
clear thought or complicated activity, much less
the homicidal rampages portrayed in novels.
However, the attack may be disruptive enough to
merit its description, ictal psychosis.
41- Ictal Sex and Violence. In many people,
seizure-symptoms that occur during sexual
activity are simply the result of anxiety or
hyperventilation. Also, although epileptic
patients commonly fumble with buttons or tug at
their clothing, and thus may seem to partially
undress, true exhibitionism is extraordinarily
rare.
42- Nevertheless, rudimentary sexual activities, such
as masturbation, scratching of the pubic area,
thighs, and pelvic thrusting, do occur. For
example, in one study, 4 of 61 patients with
refractory partial complex seizures had such
activity, but it was not accompanied by more
complex sexual behavior. Only several times has
sexual intercourse or orgasm as a seizure symptom
been reported in the neurologic literature.
43- The extent of ictal violence, violence as a
manifestation of seizures, has been a major
controversy. However, by excluding experimental
phenomena as being equivalent to a partial
complex seizure and relying on telemetry, several
reliable observations have been made. Ictal
violence occurs in less than 0.1 percent of
seizures.
44- In most cases of apparent violence, patients are
only combating restraints that are placed during
or after the seizure, i.e., resistive violence.
When overt violence occurs, it is not
accompanied by a major affective state, such as
rage, and it is fragmented, unsustained, and
neither directed nor destructive, i.e., ictal
violence is not aggressive. It usually
consists only of random shoving, pushing, or
kicking, or of verbal abuse, such as screaming.
45- It does not consist of sequences of actions with
people or mechanical devices, such as cars or
guns it shows no signs of premeditation. Like
other seizures, those with violent manifestations
are accompanied by impaired consciousness and
usually automatisms, and they are not provoked by
social factors, such as threats.
46- Although almost all neurologists do not accept
episodic violence as the sole manifestation of
partial complex seizures, a minority have
attributed aggressive violence to seizures.
Likewise, possibly under medical or social
pressures, the legal system has occasionally
accepted such an explanation. For example, in 15
cases described between 1889 and 1981, seizures
have been used in appeal as a defense for murder,
homicide, manslaughter, or disorderly conduct.
47Interictal Mental Abnormalities
48- Personality Changes. Some studies have found
that patients with so-called temporal lobe
epilepsy had distinctive personality trait
abnormalities. They described patients as being
hypo-sexual, humorless, circumstantial, and
overly concerned with general philosophic
questions, such as the order of the universe. In
addition, those patients characteristically had
hypergraphia, a tendency to write excessively and
compulsively.
49- Related older studies also suggested that
different emotional abnormalities depended upon
whether the seizure focus was in the right or
left temporal lobe. Right-sided foci supposedly
predisposed a patient to anger, sadness, and
elation, and left-sided ones to ruminative and
intellectual tendencies.
50- Recent studies, often based on telemetry and
strict methodology, have refuted many of these
contentions. They find no distinctive
personality traits in patients with partial
complex epilepsy. Epileptic patients were found
to have the same incidence of behavioral problems
as patients with other neurologic disorders, and
with few exceptions, patients with partial
complex seizures were not beset with more
behavioral problems than patients with other
varieties of seizures.
51- Likewise, recent evidence indicates there is no
difference in personality traits when foci are in
different temporal lobes, or even other brain
areas, and there is no difference in personality
traits among patients with different varieties of
epilepsy. As a general rule, mental disturbances
are associated with a history of onset of
seizures in childhood, episodes of status
epilepticus, and multiple seizure types use of
two or more anticonvulsants in treatment and
signs of brain damage on neurologic examination
or CT or MRI scan.
52- Crime. Another established interictal trait of
epilepsy patients is a high incidence of crime.
For example, among incarcerated men, the
incidence of epilepsy is at least four times as
great as in the general population. However,
taking the association of crime and epilepsy at
face value is liable to be misleading. Crimes of
adult epileptic prisoners are no more violent
than those of nonepileptic ones.
53- Also, violence is no more prevalent among
patients with partial complex seizures than among
those with other seizures. The consensus is that
crime does not originate in epilepsy, but that
seizures, head trauma, and other brain injuries
lead to conditions, such as poor impulse control
and lower socioeconomic status, that predispose
persons to crime.
54Generalized Seizures
55- Generalized seizures are characterized by an
immediate loss of consciousness accompanied by
symmetric, synchronous, paroxysmal EEG
discharges. These seizures are usually the
result of either an autosomal dominant genetic
disorder, a physiologic disturbance, or a
metabolic aberration, including drug and alcohol
withdrawal. Unlike partial seizures, generalized
seizures lack an aura, lateralized motor or
sensory disturbances, and focal EEG
abnormalities. Also, they practically never
result from brain tumors, cerebral infarctions,
or other cerebral cortex injuries. Most
generalized seizures are of either the absence
(petit mal) or tonic-clonic (grand mal) variety.
56Absences
- Absence seizures usually begin between ages 4 and
10 years and, unlike other major seizure
varieties, usually disappear in early adulthood.
However, in about 40 percent of patients,
tonic-clonic seizures replace the absences.
57- Absences, which can occur many times daily, are
1-second to 10-second lapses in attention
accompanied in almost all cases by automatisms,
subtle clonic limb movements, and blinking.
Notably, the blinking occurs rhythmically at
3-Hz, which is the frequency of the associated
EEG abnormality. Although children do not have
retrograde amnesia and they maintain muscle tone
and bladder control, their mental and physical
activity is interrupted. After the ictus, as
though it had never occurred, there is no
confusion, agitation, or sleepiness.
58- Children with unrecognized absences may be
misdiagnosed as being inattentive or mentally
retarded. More important, they may be
misdiagnosed as having partial complex seizures,
even though the two conditions can be
differentiated. The distinction is especially
important when, on rare occasions, absence status
epilepticus or nonconvulsive generalized status
epilepticus leads to a several-hour episode of
apathy, psychomotor retardation, and confusion.
The attack can be diagnosed only with an EEG, and
it can usually be terminated by intravenous
administration of diazepam (Valium). This
condition usually develops only in children and
young adults with a history of absences or other
seizures who have suddenly stopped taking their
anticonvulsants. As discussed previously, it is
a cause of acute confusion in an epileptic
patient.
59Tonic-Clonic Seizures
- Tonic-clonic seizures, unlike absences, begin at
any age after infancy, persist into adult life,
and cause massive motor activity and profound
postictal residual symptoms. Although patients
may have a prodromal phase of malaise or mood
change, tonic-clonic seizures are usually
unheralded, explosive events. In the initial
tonic phase, patients lose consciousness, roll
their eyes upward, and extend their neck, trunk,
and limbs as if to form an arch. Subsequently,
they undergo a dramatic clonic phase in which
their limbs, neck, and trunk are wracked by
violent jerks.
60- In the postictal period, which has great
diagnostic importance, patients are usually
confused, disoriented, and amnesic, both for the
ictus and, in a retrograde pattern, the events
preceding it. They may be irrational, agitated,
and combative. Postictal behavioral
disturbances, which can last for several hours,
can be so striking as to be misdiagnosed as a
functional postictal psychosis.
61- During the tonic phase, if the superimposed
muscle artifact can be eliminated by
administering muscle relaxants, the EEG shows
repetitive, increasingly greater spikes occurring
at about 10-Hz in all channels. In the clonic
phase, the spikes, which become less frequent but
greater in amplitude, are interrupted by slow
waves.
62- Afterward, the EEG shows postictal depression.
The postictal EEG is often the only one
available, but it can confirm the diagnosis.
Similarly, the EEG is also slow after ECT.
Following either a tonic-clonic seizure or
ECT-induced seizure, the serum prolactin level
rises for 15 to 30 minutes in more than 80
percent of cases. Following a pseudoseizure, in
contrast, the EEG is relatively normal, and the
prolactin level remains at baseline.
63- Interictally, 20 to 30 percent of patients with
tonic-clonic seizures have asymptomatic, brief
bursts of spikes, polyspikes, or slow waves.
Seizures and accompanying EEG abnormalities may
be precipitated by photic stimulation or
hyperventilation.
64Disorders That Mimic Seizures
65Pseudoseizures
- Psychogenic episodes mimicking seizures,
pseudoseizures, are more prevalent in women,
children, and adolescents. Like other
psychogenic deficits, pseudoseizures are
associated with character disorders, affective
illness, and other major psychopathology. In
some epileptic patients, pseudoseizures occur
together with seizures and can be responsible for
apparently intractable epilepsy. Therefore,
although patients may appear to have only
pseudoseizures, they should undergo an
investigation for seizures, as well as a
psychiatric evaluation.
66- Unlike tonic-clonic seizures, pseudoseizures
begin slowly with gradual developing flailing,
struggling, alternating limb movements
(out-of-phase clonic movements), and similar
side-to-side head movements that are often
accompanied by sexually suggestive pelvic
thrusting. As fatigue ensues, the movements
decline in intensity and regularity, but their
duration is often greater than 2 minutes, which
is much longer than a tonic-clonic seizure.
Also, the movements usually have no tonic phase,
and there is usually no tongue-biting, other
bodily injury, or incontinence. Despite the
apparent generalized nature of the pseudoseizure,
consciousness is preserved, and subsequent
confusion and retrograde amnesia are absent.
67- If an EEG were obtained during a pseudoseizure
and muscle artifact were eliminated, it would be
normal. One performed afterward, which is more
feasible, would not show postictal depression.
In addition, the serum prolactin concentration,
which is usually elevated after a generalized or
partial complex seizure, would not rise.
68- Pseudoseizures with a tonic-clonic appearance are
usually a crude caricature, but ones mimicking
partial seizures are often subtle. Patients who
mimic partial elementary seizures usually have
apparent memory lapses, episodes of inattention,
visual aberrations, other subjective phenomena,
or nonspecific sensations, such as dizziness or
epigastric sensations.
69- Although these symptoms could be manifestations
of seizures, when they result from pseudoseizures
rarely appear to include automatisms or undergo
progression to a generalized seizure.
Nevertheless, since partial complex seizures may
induce bizarre thought and behavior, the clinical
distinction in most studies is no more reliable
than 85 to 90 percent. In difficult cases,
long-term (several day) continuous EEG cassette
recording, video-monitoring, or other telemetry
is usually required to make a reliable diagnosis.
70Episodic Dyscontrol Syndrome
71- The episodic dyscontrol syndrome, which is
roughly equivalent to recurrent rage attacks,
consists almost exclusively of violent outbursts,
for which the patient typically later claims
total amnesia, and dysphoria. In contrast to
violent partial complex seizures, episodic
dyscontrol outbursts are at least momentarily
purposeful, aggressive, and accompanied by a
highly charged affect.
72- The violence, which may be preceded by dysphoria,
is senseless destructive and consists of
screaming, punching, wrestling, and throwing
glasses or bottles. Also unlike seizures, these
attacks can be provoked by threats, various other
external circumstances, and especially by alcohol
consumption. When triggered by alcohol, they can
be called pathologic or alcohol idiosyncratic
intoxication.
73- Episodic dyscontrol attacks are commonplace is
young men with diffuse but subtle cerebral
damage, especially as a result of either
congenital cerebral injury or head trauma. Thus,
these attacks are apt to occur among teen boys
and young men with minor neurologic impediments
and borderline intelligence, who may also have
seizures. The coexistence of episodic dyscontrol
syndrome and seizures is undoubtedly responsible
for some reports of aggression in epileptic
patients. Suggested medical treatments for
episodic dyscontrol syndrome, in addition to
prohibiting alcoholic beverages, have included
stimulants, beta blockers, and anticonvulsants,
most recently carbamazepine. However, no
particular treatment has been proved effective.