Terminology

 

A seizure is defined as transient signs or symptoms due to abnormal, excessive or synchronous neuronal activity in the brain.

  • Incidence: approx 80/100 000 per year
  • Lifetime prevalence: 9% (1/3 benign febrile convulsions)

 

Epilepsy is a tendency towards recurrent seizures unprovoked by systemic or neurological insults. It is a functional disorder of complex cortical circuits. For a given patient, seizures tend to be stereotyped.

  • Incidence: approx 50/100 000 per year
  • Prevelance: 0.5-1% (5x higher in developing countries).

 

A convulsion is the motor signs of a seizure.

 

Types of epilepsy

Causes of epilepsy

Status epilepticus

 

  • Medical Emergency (10-15% mortality)
  • Continuous seizures without regaining consciousness
  • 50% cases occur without previous history of epilepsy

 

    1. Ensure airway is maintained during seizure and postictal coma.
    2. Treat prolonged seizure with rectal (10mg) or IV diazapem or midazolam. If hypoglycaemic, administer IV glucose.
    3. Treat quickly in ITU with cardiorespiratory support

       

        Sudden Unexpected Death in Epilepsy (SUDEP)

         

        • Mortality rate is 3x higher in epilepsy patients than general population.
        • More common in uncontrolled epilepsy.
        • May be related to nocturnal seizure-associated apnoea or asystole.

         

         

        Diagnosis

         

        EEG

        • Epileptic activity indicated by spike and wave abnormalities.
        • Patients with epilepsy can have normal EEG between seizures.

         

        CT/MR Imaging

        • Indicated for all focal cases with associated symptoms e.g. first onset status epilepticus and headache.
        • Aids diagnosis of tumors.

         

        Treatment

         

        Anti-epileptic drugs (AEDs)

        • Indicated where there is a confirmed diagnosis of epilepsy and the risk of reccurence is high.
        • Drug levels should be closely monitored. There may be side effects (e.g. ataxia, nystagmus, dysarthria).
        • Dual therapy necessary in <10%.
        • Despite AED therapy, in 20-35% seizures persist.
        • Controlled epilepsy may remain in remission. It is possible to withdraw AEDs, although less than 50% of attempts at AED withdrawal are successful.

         

          AED Treatments for Epilepsy

           

          Neurosurgical treatment

          If a single epileptogenic focus can be identified such as hippocampal sclerosis or a small low-grade tumor, neurological resection e.g. temporal lobectomy may be indicated and offers up to 70% chance of cure.

           

          Vagal nerve stimulation

          Vagal nerve stimulation has been shown to reduce seizure frequency and duration in 1/3 of patients.

           

          Driving and epilepsy

           

          Patients with epilepsy must be seizure free for at least 12 months to be legally permitted to drive in the UK/EU. The patient must inform the DVLA.

          Women and AEDs

           

          Teratogenicity of AEDs: 5 mg/d folic acid supplements should be taken by all women of child-bearing age. Valproate should be avoided. Lamotrigine is recommended.

          The risk of fetal abnormality is 5%. Pre-conceptual counselling should be offered.

           

          Breastfeeding: Most AEDs present in breast milk (except carbemazepine and valproate). Lamotrigine is is not known to be harmful to infants.

           

          Enzyme inducing AEDs may interfere with the effectiveness of oral contraceptives, so higher doses may be required (≥50µg oestrogen).

           

          References

           

          Clark M, Kumar P. 2009 Kumar & Clark’s Clinical Medicine 7/e Saunders

          Longmore M, Wilkinson I, Davidson E, Foulkes A, Mafi A. 2010 Oxford Handbook of Clinical Medicine 8/e Oxford OUP

           

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