Educationals

3. Unclassified Seizures : Whether Partial or Generalised

Clinical Features
Typical absence : Blank stares, total amnesia, slight motor changes such as blinking, eye rolling or jerking. Sudden onset and cessation. Mostly associated as a part of a syndrome of idiopathic epilepsy.

Atypical absence : Blank stares, consciousness partly impaired, associated with tonic changes, automatisms and seizures are usually prolonged. Usually seen in patients with diffuse cerebral and mental retardation.

Myoclonic seizures : Brief, occur singly or in series. The intensity varies from slight movement to massive jerking leading to a fall. May be stimulus-sensitive; consciousness is not altered; occur as a part of various idiopathic and symptomatic syndromes.

Atonic seizure : Atonia with fall, astatic or drop attacks.Attacks may progress in step-wise fashion and are commonly seen in patients with diffuse brain damage.

Automatisms : Involuntary motor activity occurring during the state of clouding of consciousness either in the course of or after the epileptic seizure. They may be in the form of chewing, lip smacking, drooling, laughing, crying, anger, gestural, fiddling, tapping with fingers, rubbing, patting, undressing ambulatory , etc.

Specific features of seizures arising in different anatomical area :

Temporal lobe : Auras are common, slow evolution of seizures, prominent motor arrest of motionless stares, post ictal confusion with automatisms such as lip smacking, chewing, swallowing, fumbling, repetitive motor activity and other motor automatisms.

Duration of seizure : 15 seconds - 8 minutes, may have secondary generalisation.

Etiology : Both organic and unknown insult. Is seen following status epilepticus or following prolonged unilateral febrile convulsions. Usual pathology is mesial temporal sclerosis, neuronal migration defects etc.

Frontal lobe : Frequent attacks, more at night, prominent ictal tonic posturing, in clusters, sudden onset and cessation with bizarre automatisms.

Central Region : Simple partial onset, contralateral side jerking. The seizure may have a Jacksonian march to motor cortex. If supplementary motor area is affected adversive head and eye deviation may occur.

Parietal and occipital lobe : Subjective sensory and visual disturbances. The 'limitation' of the above classification was that it was confined to an individual seizure type. A seizure is an event with which a patient come to a physician but the condition to which this seizure belongs is the epileptic syndrome and it is also the language in which two physicians can communicate.

What are syndromes ?

Syndromes are clusters of signs and symptoms customarily occurring together and include

• Clinical event
• Age of onset
• Ictal and inter ictal EEG
• Evolution and prognosis
• Associated neurological features
• Family history
• Neuro imaging and isotopic scanning

SIt is useful to classify seizures according to the syndromic classification:

a) To institute appropriate therapeutic regimen

b) Judicious use of anti-epileptic drugs (AED)

• When to withold AED
• When to withdraw AED

c) Predict prognosis

d) For defining the likelihood of identifying the underlying pathology.

Classification of syndromes

I. Localisation related onset or generalised

II. Etiology known or unknown:

• Idiopathic : no underlying cause, may be inherited
• Symptomatic : as a consequence of known or a suspected disorder of the CNS
• Crytogenic : cause is hidden or occult wherein they do not fulfill the criteria for idiopathic while on the other hand there is no proof of their symptomatology.
  

International league against epilepsy (ILAE)-1985 - 1989(Revised)

1. Localisation related 2. Generalised 3. Undetermined 4. Special syndrome

Idiopathic Symptomatic Cryptogenic