Epilepsy



Epilepsy





Definitions



  • Epileptic seizure: temporary dysfunction of brain caused by self-limited, abnormal hypersynchronous electrical discharge of cortical neurons (see also Chapter 3).


  • Epilepsy: group of chronic disorders characterized by recurrence of unprovoked, usually unpredictable seizures. Approximately 40 million people affected worldwide.


Classification


Seizures

Developed by International League Against Epilepsy (ILAE; Table 141.1). Seizure type most reliably indicated by initial events of seizure.


Partial Seizures

Ictal discharge in limited, circumscribed area of cortex (epileptogenic focus). Diverse symptoms may be subjective (“aura”) or overt (e.g., focal limb jerks, head turning, sensory disturbance, complex emotional phenomena).



  • Simple partial seizure: no confusion or impairment of consciousness.


  • Complex partial seizure: impaired awareness; bilateral spread of seizure discharge (at least to basal forebrain and limbic areas). Frequent auras: visceral sensation, motionless stare, automatisms (lip-smacking, buttoning shirt). Postictal confusion common. About 70% to 80% arise in temporal lobe.


Generalized Seizures



  • Generalized tonic-clonic (grand mal) seizures: abrupt loss of consciousness with bilateral tonic extension of trunk and limbs (tonic phase), followed by synchronous muscle jerking (clonic phase). Brief postictal stupor followed by lethargy,
    confusion. Vague, variable prodromal symptoms may precede seizure for hours.


  • Absence (petit mal) seizures: momentary lapse of awareness, motionless stare, arrest of any ongoing activity. Abrupt onset (without prodromal symptoms) and abrupt end.


  • Myoclonic seizures: rapid, brief unilateral or bilateral muscle jerks, may be bilateral.


  • Atonic (astatic) seizures (drop attacks): sudden loss of muscle tone: may be fragmentary (e.g., head drop) or generalized, resulting in a fall.








Table 141.1 Classification of Epileptic Seizures (International League Against Epilepsy)














Partial (focal) seizures


  1. Simple partial seizures (consciousness not impaired)

    1. With motor signs (including jacksonian, versive, and postural)
    2. With sensory symptoms (including visual, somatosensory, auditory, olfactory, gustatory, and vertiginous)
    3. With psychic symptoms (including dysphasia, hallucinations, affective changes)
    4. With autonomic symptoms (including epigastric sensation, pallor, flushing, pupillary changes)

  2. Comlex partial seizures (consciousness is impaired)

    1. Simple partial onset followed by impaired consciousness
    2. With impairment of consciousness at onset
    3. With automatisms

  3. Partial seizures evolving to secondarily generalized seizures
Generalized seizures of nonfocal origin (convulsive or nonconvulsive)


  1. Absence seizures

    1. With impaired consciousness only
    2. With one or more of the following: atonic components, tonic components, automatisms, autonomic components

  2. Myoclonic seizures, myoclonic jerks (single or multiple)
  3. Tonic-clonic seizures (may include clonic-tonic-clonic seizures)
  4. Tonic seizures
  5. Atonic seizures
Unclassified epileptic seizures
From Commission on Classification and Terminology of the International League Against Epilepsy. Proposal for revised clinical and electroencephalographic classification of epileptic seizures. Epilepsia 1981;22:489–501.









Table 141.2 Modified Classification of Epileptic Syndromes






  1. Idiopathic epilepsy syndromes (focal or generalized)

    1. Benign neonatal convulsions

      1. Familial
      2. Nonfamilial

    2. Benign childhood epilepsy

      1. With central midtemporal spikes
      2. With occipital spikes

    3. Childhood/juvenile absence epilepsy
    4. Juvenile myoclonic epilepsy (including generalized tonic-clonic seizures on awakening)
    5. Idiopathic epilepsy, otherwise unspecified

  2. Symptomatic epilepsy syndromes (focal or generalized)

    1. West syndrome (infantile spasms)
    2. Lennox-Gastaut syndrome
    3. Early myoclonic encephalopathy
    4. Epilepsia partialis continua

      1. Rasmussen syndrome (encephalitic form)
      2. Restricted form

    5. Acquired epileptic aphasia (Landau-Kleffner syndrome)
    6. Temporal lobe epilepsy
    7. Frontal lobe epilepsy
    8. Posttraumatic epilepsy
    9. Other symptomatic epilepsy, focal or generalized, not specified

  3. Other epilepsy syndromes of uncertain or mixed classification

    1. Neonatal seizures
    2. Febrile seizures
    3. Reflex epilepsy
    4. Other unspecified


Epilepsy (Epileptic Syndromes)

See Table 141.2. Syndromes mainly associated with partial seizures (localization-related epilepsies) or generalized seizures (generalized epilepsies).


Specific Generalized Epilepsy Syndromes


Infantile Spasms (West Syndrome)

Seizures characterized by sudden flexor or extensor spasms involving head, trunk, and limbs simultaneously. Onset before age 6 months. EEG: chaotic, high-voltage slow activity with multifocal spikes (hypsarrhythmia).




  • Causes: cerebral dysgenesis, tuberous sclerosis, phenylketonuria, intrauterine infections, hypoxic-ischemic injury. About 15% idiopathic.


  • Treatment: corticotropin (ACTH), prednisone, topiramate, zonisamide, vigabatrin. No effect on long-term prognosis. Severe long-term disabilities in >66%.


Childhood Absence (Petit Mal) Epilepsy

Onset at age 4 to 12 years. Recurrent absence seizures (up to hundreds a day). EEG during attack: stereotyped, bilateral 3-Hz spike-wave discharges. Generalized tonic-clonic seizures additionally in 30% to 50%. Most children otherwise normal. Treatment: ethosuximide, valproate, lamotrigine, topiramate, zonisamide.


Lennox-Gastaut Syndrome

Childhood epileptic encephalopathies characterized by mental retardation, uncontrolled seizures, distinctive EEG (slow spike wave, 1.5 to 2.5 Hz). Causes include brain malformations, perinatal asphyxia, severe head injury, CNS infection. Seizures persist into adult years in 80%.



  • Treatment: valproate, lamotrigine, topiramate, zonisamide, vagus nerve stimulation, corpus callosotomy. Felbamate often the only effective agent.


Juvenile Myoclonic Epilepsy

Onset usually 8 to 20 years. Morning myoclonic jerks, generalized tonic-clonic seizures just after waking, normal intelligence, family history of similar seizures. EEG: generalized spikes, 4- to 6-Hz spike-wave, “polyspike” discharges. Valproate controls seizures, myoclonus in >80%; also lamotrigine (may exacerbate myoclonus), zonisamide, levetiracetam, topiramate.


Specific Localization-Related Epilepsy Syndromes Benign Focal Epilepsy of Childhood

Most common: benign rolandic epilepsy; central to midtemporal spikes on EEG. Onset 4 to 13 years. Attacks mainly or exclusively at night, often with secondary generalization. Seizures uniformly disappear in adolescence. If treatment needed: carbamazepine or gabapentin in low doses.


Temporal Lobe Epilepsy

Most common epilepsy syndrome of adults. Epileptogenic region in medial temporal lobe. Seizure type almost universally
complex partial. Interictal EEG: focal temporal slowing, epileptiform discharges (sharp waves or spikes) over anterior temporal region. Surgical resection far superior to medical treatment; anterior temporal lobe resection effective in 80%.


Frontal Lobe Epilepsy

Seizure types vary but characterized by: brief duration, abrupt onset, nighttime occurrence; bizarre motor manifestations (e.g., bilateral limb thrashing); no postictal confusion; minimal EEG abnormality; history of status epilepticus.


Post-traumatic Seizures

Follow 7% of head injuries in general population. Injury severe, associated with brain contusion, intracerebral or intracranial hematoma, unconsciousness or amnesia for >24 hours, or persistent neurologic signs.

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Jul 27, 2016 | Posted by in NEUROLOGY | Comments Off on Epilepsy

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