Neurosurgery notes/Vascular/Haemorrhagic diseases/SAH/SAH complication/Post SAH Seizures

Post SAH Seizures

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SAH complication

General information

  • No RCT has been performed to help guide decisions on prophylaxis or treatment of seizures.
  • There is also conflicting evidence on whether onset seizures are predictive of late seizures or post-SAH epilepsy.
  • No consensus amongst practitioners regarding
    • The need for AEDs
    • The best AED to use
    • Which patients should receive prophylactic AEDs
    • The optimal dose or duration of treatment

Numbers

  • Incidence: Variable
    • 4–26% of SAH patients had onset seizures,
      • 1–28% had early seizures (w/in first 2 weeks),
      • 1–35% had late seizures (after 2 weeks).
    • Non-convulsive status epilepticus
      • Has been reported in 3–18% of SAH patients
      • Should be suspected in patients with a poor neurological exam or in the setting of neurological deterioration.
    • Data I got from a lecture
      • 3%: Incidence (not including at the time of haemorrhage)
      • 5%: seizure in the immediate post op period, with or without SAH
      • 5-10%: in 5 yrs (ISAT data)
  • Usually occurring in the first days following the ictus
  • The reported overall long- term incidence of seizures ranges from 5% to 27%

Risk factors for post-SAH seizures.

  • Increasing age (> 65 years)
  • Aneurysm location
    • 20%: MCA
    • 10%: PCA
    • 3%: ACA
  • Volume of subarachnoid blood/thickness of clot
  • Associated intracerebral or subdural hematoma
  • Poor neurological grade
  • Rebleeding
  • Cerebral infarction
  • Vasospasm
  • Hyponatremia
  • Hydrocephalus
  • Hypertension
  • Treatment modality, see coiling vs. clipping

Mechanism

  • Seizures are due to
    • Acute intracranial hypertension
    • Vasospasm
    • Cortical dysfunction
    • Early spreading cortical depolarization
    • Temporal lobe cortical injury.
  • Seizure can cause
    • Acute raised ICP
    • Haemodynamic instability
    • Airway instability
    • Decreased oxygen utilization by the brain
    • Metabolic derangements such as acidosis
    • Rebleeding in unsecured aneurysm

Management

  • Controversial whether to use prophylactic AED
    • Because seizure rates are low in SAH
  • Give keppra 1g BD IV until aneurysm is secured
    • Phenytoin has more side effects
  • Do not use AED long term
  • If there is seizure then have to treat it with AED

Outcome

  • The association between seizures and functional outcome remain unclear.
    • One study showed that an in-hospital seizure was independently predictive of one year mortality (65% with seizures vs. 23% without seizures), but others have shown no association with a poorer prognosis.
    • Two large, retrospective, single-institution studies of patients with aSAH found that nonconvulsive status epilepticus is a very strong predictor of poor outcome.
  • AEDs Studies have assessed neurological outcome following short- and long-term phenytoin use, with higher doses and longer duration associated with poorer outcomes.
  • When compared to phenytoin, Keppra is associated with a higher rate of short-term seizure recurrence, but improved long term outcomes and fewer side effects.