Epilepsy

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Epilepsy is due to abnormal electrical activity within the central nervous system.


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Contents

First epileptic fit

The ideal management of a first fit would include completing the special investigations - currently EEG and MRI - on that or the following day so as to decide on treatment and advice respectably soon. A fit commonly places an adult's life on hold, and the balance between not treating those who will prove not to need it, and allowing people to have a second fit while waiting for investigation has not been made well in the UK as yet.

Fitness to drive

According to the DVLA website, Epileptic attacks are the most frequent medical cause of collapse at the wheel.

Diagnosis

  • Those with a recent-onset suspected seizure should be seen urgently by a specialist aiming for:
    • Precise and early diagnosis to determine:
      • Seizure type(s)
      • Epilepsy syndrome
      • Causes
      • Co-morbidities
    • Initiation of appropriate therapy

Treatment

Should be individualised considering:

  • Seizure type
  • Epilepsy syndrome
  • Co-medication
  • Co-morbidity
  • Individual
    • Lifestyle (e.g. ketogenic diet[1])
    • Preferences
    • Social issues

The SANAD study has provided useful guidance as to likely first choice drugs all other matters being equal for:

Partial epilepsy

Time to monotherapy treatment failure is in the order:[2]

  1. Lamotrigine
  2. Oxcarbazepine (not significantly different to Lamotrigine)
  3. Carbamazepine
  4. Gabapentin
  5. Topiramate
  • Time to 12- months remission was only significantly worse for Gabapentin, with Carbamazepine, Oxcarbazepine, Lamotrigine and Topiramate having similar efficiencies.
  • UK cost benefit analysis at 2006 prices is to the benefit of Carbamazepine by over £1000 per seizure avoided.

Generalised epilepsy

For generalised and unclassifiable epilepsy time to monotherapy failure is in the order: [3]

  1. Valproate
  2. Lamotrigine (no significant difference to Valproate]]
  3. Topiramate
  • Valproate was better tolerated than topiramate and is more efficacious than lamotrigine.
  • UK cost benefit analysis at 2006 prices is to the benefit of Valproate by £500 per seizure avoided.

Drug withdrawal

In adults monotherapy withdrawal after 2 years seizure free is associated with twice the risk of seizure relapse (15%/annum, 27% after median of 41 months) than continuing therapy at a year and quality of life is not improved by withdrawal. Most withdrawn patients go back on treatment [4].

Pathophysiology

  • Usually dysfunction of an oscillatory network
  • In some cases mutations in say the SCN1A gene might modulate sodium channel characteristics[5].
  • Transition to epileptiform behaviour is secondary to
    • Enhanced connectivity
    • Enhanced excitatory transmission
    • Failure of inhibitory mechanisms
    • Changes in intrinsic neuron properties

Interestingly the EEG becomes less chaotic before a seizure suggesting widespread synchronisation

Seizure threshold lowering drugs

See also neurotoxins. Note that using the wrong antiepileptic agent for the wrong type of seizure can make things worse. For example carbamazepine, oxcarbazepine, phenytoin, pregabalin or gabapentin can cause in primary generalised epilepsy, absence attacks, myoclonic seizures and generalised seizures[6].

See also

External links

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References

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