98-6 Appendix I

DMR MEDICAL ADVISORY #98-6
APPENDIX I
INTERNATIONAL CLASSIFICATION OF EPILEPTIC SEIZURES

I. Partial (Focal) Seizures

Partial seizures are those seizures that begin in a limited part of one cerebral hemispheres. Partial seizures are classified primarily on the basis of whether or not consciousness is impaired during the attack. When consciousness is impaired the seizure is classified as a complex partial seizure. Impairment of consciousness may be the first clinical sign, or simple partial seizures may evolve into complex partial seizures. In patients with impaired consciousness, some aberration of behavior may occur. A partial seizure may not terminate, but instead progress to a generalized motor seizure. Impaired consciousness is defined as the inability to respond normally to outside stimuli of altered awareness and/or responsiveness.

Partial seizure can be classified into three fundamental groups:

A. Simple partial seizures

  1. with motor symptoms (simple jerking of a limb)
  2. with sensory symptoms (localized tingling)
  3. with autonomic symptoms (butterflies in the stomach, sweating)
  4. with psychic symptoms (fear, deja vu)

B. Complex partial seizures

1. with impairment of consciousness at onset

  1. with automatisms (purposeless simple repetitive movements
  2. without automatisms

2. Simple partial at onset (A., 1., 4) with later loss of consciousness (B., 1., a-b)

C. Partial seizures evolving to generalized tonic-clonic seizures

  1. Simple partial evolving to generalized
  2. Complex partial evolving to generalized
  3. Simple partial evolving to complex partial evolving to generalized

II. Generalized Seizures

Generalized seizures are those in which the first clinical changes indicate early involvement of both hemispheres. Consciousness may be impaired, and this first impairment may be the initial manifestation. Motor manifestations are bilateral. The EEG patterns are bilateral and reflect discharges that are widespread in both hemispheres.

A. Absence seizures

  1. Typical absence:
    Brief, abrupt loss of contact with eyelid flutter and immediate return of awareness
  2. Atypical absence
    Longer and less abrupt episodes with changes in muscle tone or behavior

B. Myoclonic seizures

Single or multiple jerks of limb or body without clear loss of contact.

C. Clonic seizure

Convulsive events with repetitive high-amplitude jerking of limbs

D. Tonic seizures

Convulsive events with continuous stiffening of limbs, sometimes with rotation of the head or body to one side

E. Tonic-clonic seizures

Sudden loss of contact with a cry and tonic stiffening of the limbs and the body.. Later the stiffness gives way to mostly synchronous shaking that increases in amplitude while decreasing in frequency. The attack may last a number of minutes before the shaking stops suddenly or gradually decreases in amplitude. The person is then unresponsive for minutes to hours.

F. Atonic seizures

Cause the sudden loss of muscle tone which can cause a fall with injury.

III. Unclassified Epileptic Seizures

 Some seizures cannot be classified because of inadequate or incomplete data. Some defy classification into the existing categories. Many of these are seizures occurring in neonates.