Introduction to Seizure and Epilepsy Diagnosis by doctors
Archana Patel, Lauren Sham, Agnieszka Kielian, and Leslie
Hayes.
This video is intended for primary health care
practitioners in resource-limited settings and
aims to be the initial steps in seizure and epilepsy diagnosis,
including classification of seizures and initial workup to
perform in children aged one month to 18 years. Neonatal
seizures are evaluated differently and will be covered
separately. Management of epilepsy will be discussed in
another video. This video is intended to supplement the in
person training. The learning objectives of this video
include: one, understanding the definition of seizures and
epilepsy, two, being able to differentiate between provoked
and unprovoked seizures, three, being able to differentiate
between focal and generalized seizures, four, understanding
which studies should be performed to guide management.
A seizure is defined as a transient occurrence of signs
and or symptoms due to abnormal excessive or synchronous
neuronal activity in the brain. Although a complicated
definition, simply put, this means there is excessive
electrical activity, which clinically is seen as transient
change in behavior or movement. In 2017, the International
League Against Epilepsy updated the seizure classification
guidelines, which use the onset of seizure as a first step in
the operational classification of seizure type. This is why it
is very important to gather information about how the
seizure starts.
According to the guidelines, seizures can be classified as
focal, generalized or unknown in onset. They can be further
described based on what the seizure looks like. Focal onset
seizures are those that start in one hemisphere of the brain.
They can later spread to involve both hemispheres, but it is the
beginning of the seizure and not the end, that is the most
important. Generalized seizures rapidly involve the whole brain.
If the onset of seizure is missed or unclear, the seizure
is of unknown onset. They can be further classified according to
the patient's level of awareness which can be preserved or
impaired. To figure this out, you can ask whether the person
seemed to know who they are and what is going on with the
surroundings during the seizure. Awareness does not refer to
awareness of the seizure occurring. Focal seizures can be
further divided based on motor versus non-motor components. The
final feature is whether the focal seizure evolves into
bilateral tonic-clonic seizure.
Focal seizures have signs and symptoms that reflect the part
of the brain which is involved. The final feature is whether the
focal seizure evolves into bilateral tonic-clonic seizure.
A seizure which genernalized in onset involves both the right
and left hemisphere at once. Similarly to focal seizures,
generalized seizures are classified according to motor or
non-motor manifestations. The motor manifestations can vary
and include tonic-clonic, clonic, tonic or atonic. The
non-motor generalized seizures mostly refer to absence
seizures.
In evaluating a child with seizures, it is important to
determine if the seizures are provoked or unprovoked. Provoked
seizures, or acute symptomatic seizures, are due to an
immediate or transient problem. Examples include
meningoencephalitis or encephalitis, acute stroke, or
head trauma, electrolyte imbalance, or toxins, including
alcohol or other substances. A history of injury to the brain
months or years prior do not count as they are not immediate
or transient problems. To identify if a seizure is
provoked, you must pay attention to the details of the clinical
presentation, as the treatment is focused on treating the
underlying disorder, in addition to acute seizure management.
Febrile seizures are important to distinguish from other
provoked seizures as they are more common carry a more
reassuring prognosis and require less investigations. However,
provoked seizures can also occur related to CNS infection in this
age, and it is important to consider this in your
evaluation. You need to be careful in evaluation to
determine if the seizure in question is truly a febrile
seizure. Febrile seizures must meet the following criteria:
presence of fever in a child between six months and six
years, absence of a central nervous system infection, no
prior history of neonatal or unprovoked seizures, no prior
diagnosis of epilepsy, and no significant neurologic
impairment. Febrile seizures can be further classified as simple
or complex, simple febrile seizures are generalized, last
less than 15 minutes, and do not recur within 24 hours. On the
other hand, febrile seizures would be classified as complex
if any of the following are present: the seizure is focal,
lasts longer than 15 minutes, or occurs within 24 hours. Please
note, that while complex febrile seizures can be focal, you must
always consider a brain lesion if the child has repeated focal
febrile seizures affecting the same side of the body. It is
important to counsel parents that febrile seizures may recur
again. However, the risk of epilepsy is only very slightly
higher than the general population.
The recommended workup for provoked seizures including
febrile seizure is based upon the clinical appearance of the
child. If there are signs of illness and poor feeding,
consider checking the blood glucose and consider sodium as
well if there is dehydration or diarrhea. Lumbar puncture should
be considered in the following scenarios: any febrile child who
appears ill and/or with signs of meningitis, such as meningismus
and headache, a complex febrile seizure, seizure in a febrile
unimmunized child, highly considering children less than
18 months of age, and absolutely in infants under six months,
children who presented with seizure and were started on
antibiotics empirically for meningitis, based on ETAT
guidelines. Lumbar puncture should be deferred if the child
has signs of increased intracranial pressure, altered
consciousness, focal neurologic deficit, signs of shock, any
evidence of bleeding disorder, or an infection over the site of
a lumbar puncture. If any of these factors are present,
complications should be first managed, and/or neural imaging
obtained prior to the LP.
Neuroimaging can have an important role in the workup of
unprovoked seizures. Emergent neuroimaging should be obtained
in any child presenting acutely who has persistent
unresponsiveness, lack of return to baseline within a few hours,
or a persistent focal weakness that is not resolving within a
few hours. As timing is essential, the recommended study
would be CT, unless an immediate MRI is feasible. If the child is
back to baseline, a non-urgent neuroimaging study should be
considered for any child who has a focal seizure, focal EEG
findings, significant cognitive or motor impairment without
known etiology, or other unexplained abnormality on
neurological exam, particularly if unresponsiveness to
anti-epileptic drug treatment, or progressively worsening
development is noted. The type of study depends on availability
and clinical suspicion. In almost all cases, MRI would be
preferred, with the exception of when there is concern for
neurocysticercosis in which CT would be sufficient and often
more efficient to obtain. Outside of the instances
warranting emergent neuroimaging, these studies are
supportive and are not necessary in making the diagnosis of
epilepsy or initiating medication.
Identifying whether the seizure is provoked or unprovoked is
important, as this will guide your treatment. You should
always treat the acute issues such as infection or injury in
provoked seizures. Anti-epileptic medications
should be initiated if treatment for Status Epilepticus was
required. If you have loaded any child with phenobarbital or
phenytoin, maintenance dosing of these medications should be
initiated within 12 hours of the loading dose. Course of
treatment for these medications in provoked seizures depends on
the clinical scenario. However, it is recommended that the
anti-epileptics are continued for at least the duration of the
underlying illness and then tapered off slowly over a four
to eight week period. For example, if a child has
meningitis and is being treated for 21 days, the seizure
medications should be continued for this time period at full
doses and then weaned off over the following months for a total
of an approximately six to eight week course minimum. If there
are continued seizures, the duration of seizure treatment
can last months to a year.
Please note that there is a high risk in these conditions for a
future risk of epilepsy particularly in certain
infections such as cerebral malaria. Therefore, all of these
children should be continued to be monitored clinically and
families should be appropriately counseled. Febrile seizures, as
noted previously, however, are an exception. These seizures
should not be treated with daily medication, even though
recurrence of seizure with fever may be seen again, as the
overall outcomes are typically good. Counseling of possible
recurrence and how to manage seizures at home and when to
come in to the health center for care are the essential
components of management. When there is no identifiable
immediate and acute cause for the seizure, then it is
considered unprovoked. Please note, unprovoked seizures may
occur in a person with a history of brain insult, but the problem
should be old, not something currently requiring treatment.
Unprovoked seizures are important to identify, as they
indicate a risk for epilepsy.
Epilepsy per the International League Against Epilepsy is
defined as either two unprovoked seizures separated by 24 hours,
or one unprovoked seizure and a recurrence risk similar to
having two unprovoked seizures defined as greater than 60% risk
in the next 10 years. Key pieces of making a diagnosis of
epilepsy are recognizing that there must be an unprovoked
seizure and risk of future seizures, either by seeing at
least two seizures or a finding on clinical history exam
indicating risk. Examples of risk include: cerebral palsy,
history of prior provoked seizures, and brain infection or
injury. EEG is a helpful tool in determining risk of future
seizures when available and can be performed after a first
unprovoked seizure, if feasible. However, it is not necessary to
make a diagnosis of epilepsy and diagnosis and treatment should
not be dependent upon obtaining this study, particularly given
limited access in many regions.
To review, if a child presents with a first unprovoked seizure,
you should first take a careful history and physical exam,
performing laboratory testing if indicated clinically. If the
child is not back to baseline, treat seizures as appropriate,
investigate further obtain imaging as indicated, and
consult a specialist as needed. If the child is back to
baseline, assess for a risk of epilepsy by your clinical
evaluation and consider diagnostic testing, including
EEG and neuroimaging. Again, these studies are not necessary
for the diagnosis of epilepsy and should be considered
supportive. Start appropriate anti-epileptic medications if
you determine that the history indicates the child meets
criteria for epilepsy, due to risk by history or exam. All
children with an unprovoked seizure, regardless if they meet
criteria for epilepsy or not, should be seen for review within
three months to reassess.
This concludes our review of initial seizure evaluation and
epilepsy diagnosis. We will review seizure medication
management in a subsequent video.