seizure is a transient occurrence symptoms due to abnormal … · 2017. 2. 4. · seizure at age 6...

Provoked seizures, also called acute symptomatic seizures, are directly attributable to an acute, active insult to the central nervous system (CNS) or a systemic metabolic derangement (e.g., hypoglycemia). By definition, provoked seizures occur in close temporal proximity to the inciting event

Acute symptomatic seizures represent ~40% of all seizures (excluding febrile seizures in the pediatric population) and have an incidence of 29 to 39 per 100,000 person years.[2,3] Provoked seizures can occur at any age, but are most common in infants and the elderly.

In adults, the leading etiologies are cerebrovascular disease, drug and alcohol withdrawal,metabolic,.[2] Provoked seizures are usually isolated, nonrecurrent events. Treatment is aimed at the underlying cause, and long-term antiepileptic drug (AED) therapy is not indicated.

“unprovoked” implies absence of a temporary or

reversible factor lowering the threshold and producing a seizure

at that point in time.

Two seizures. A 25-year-old woman has two unprovoked

seizures, 1 year apart. Comment: This person has

epilepsy, according to both the old and new definitions.

Stroke and seizure. A 65-year-old man had a left

middle cerebral artery stroke 6 weeks ago and now

presented with an unprovoked seizure. Comment: With

a seizure in this time relation to a stroke (or brain

infection or brain trauma) the literature6 suggests a

high (>70%) risk of another unprovoked seizure.

Therefore, in the new (but not the old) definition, this

man would have epilepsy.

Photic seizures. A 6-year-old boy has had two seizures 3 days apart while playing a videogame involving flashing lights. There have been no other seizures. EEG shows an abnormal photoparoxysmal response. Comment: This boy has epilepsy according to the new definition (but not the old), even though the seizures are provoked by lights, since there is an abnormal enduring predisposition to have seizures with light flashes.

Benign Epilepsy with Centrotemporal Spikes (BECTS).

A 22-year-old man had seizures with face twitching

when falling asleep at ages 9, 10, and 14 years; he has

had none since. EEG at age 9 years demonstrated centrotemporal

spikes. Medications were discontinued at

age 16. Comment: For this young man, epilepsy is

resolved, because of passing the relevant age range of an

age-dependent syndrome. The old definition has no provision

for considering epilepsy to be resolved.

Two seizures long ago. An 85-year-old man had a focal

seizure at age 6 and another at age 8 years. EEG, MRI,

blood tests, and family history were all unrevealing. He

received antiseizure drugs from age 8 to age 10 years,

when they were discontinued. There have been no further

seizures. Comment: According to the new definition,

epilepsy is resolved, since he has been seizure-free

for >10 years and off seizure medication for at least the

last 5 years. This is not a guarantee against future

7. Long-interval seizures. A 70-year-old woman had

unprovoked seizures at ages 15 and 70. EEG, MRI, and

family history are unremarkable. Comment: Both old

and new definitions consider this woman to have epilepsy.

Despite the diagnosis, many clinicians would not

treat because of the low frequency of seizures. Should

investigations somehow show that the causes of the

two seizures were different, then epilepsy would not be

considered to be present.

The incidence of unprovoked seizures in the general population is 57 to 63 per 100,000 persons and the incidence of epilepsy is 46 to 48 per 100,000.[

An estimated 40 million individuals worldwide have epilepsy

indicates that 142,000 persons with epilepsy die annually, equating to 0.2% of all deaths worldwide

Approach:

History (from patient and witness)

Physical examination

Investigations

Event Localization

Temporal relationship

Factors

Nature

Associated features

Past medical history

Developmental history

Drug and immunization history

Family history

Social history

General

esp. syndromal or non-syndromal dysmorphic

features, neurocutaneous features

Neurological

Other system as indicated

E.g. Febrile convulsion, infantile spasm

I. Exclusion of differentials:

Bedside: urinalysis

Haematological: CBP

Biochemical: U&Es, Calcium, glucose, ABGs

Radiological: CXR, CT head

Toxicological: screen

Microbiological: LP

(Always used with justification)

Structural neuroimaging

Functional neuroimaging

Who should have a structural neuroimaging?

Status epilepticus or acute, severe epilepsy

Develop seizures when > 20 years old

Focal epilepsy (unless typical of benign focal epilepsy syndrome)

Refractory epilepsy

Evidence of neurocutaneous syndrome

Modalities available:

Magnetic Resonance Imaging (MRI)

Computerized Tomography (CT)

What sort of structural scan?

MRI better than CT

CT usually adequate if to exclude large tumor

MRI not involve ionizing radiation

I.e. not affect fetus in pregnant women (but nevertheless

avoided if possible)

Modalities available:

Positron Emission Tomography (PET)

Single Photon Emission Computerized Tomography

(SPECT)

Functional Magnetic Resonance Imaging (fMRI)

Mostly used in:

Planning epilepsy surgery

Identifying epileptogenic region

Localizing brain function