Aetiological Classification of Seizures

Causes of seizures stratified by age-group:

Approximately 30% of those with a seizure will have a positive family history.

Infant (0-2 years)

• Perinatal hypoxia and ischaemia
• Intracranial birth injury
• Acute infection
• Metabolic disturbances
  • hypoglycaemia
  • hypocalcaemia
  • hypomagnesaemia
  • pyridoxine deficiency
  • hyponatremia
• congenital malformations
• genetic disorders

Child (2-12 years)

1. idiopathic
2. acute infection – meningitis / encephalitis
3. trauma
4. febrile convulsions – < 5 minutes duration, no abnormality → good prognosis

Adolescent (12-18 years)

1. idiopathic
2. trauma
   1. 40-50% seizure rate if post-traumatic amnesia for 24 hours
   2. depressed skull fracture
   3. cerebral contusion
3. drug, alcohol withdrawal
4. arterio-venous malformations

Young Adult (18-35 years)

1. trauma
2.  alcoholism – drugs, alcohol and drug withdrawal
3. brain tumour

Older adult (> 35 years)

1. brain tumour
2. cerebrovascular disease – most common > 50 years old
3. metabolic disorders – any age
   1. uraemia
   2. hepatic failure
   3. electrolyte abnormality
   4. hypoglycaemia
   5. acute hypoxia
   6. hypo- or hyper- calcemia, natremia, and glycemia
      1. myoclonic / tonic-clonic
4. alcoholism
5. infection – encephalitis / chronic meningitis / abscess
6. neurosurgery – any surgery to cerebral hemispheres is complicated by seizures in 10%

---

Investigations

• FBC + ESR – WCC (encephalitis, meningitis, abscess)
• EUC (C/M/P)– Na+, Ca++, uraemia
• VDRL – neurosyphilis
• lumbar puncture
• CT / MRI
• EEG + video recordings (telemetry)
• Drug levels – e.g. phenytoin, urinary drug screen, blood ethanol level