1. Anaesthesia in epilepsy Dr.S.Parthasarathy MD DA DNB, D.Diab. Dip. Software based statistics PhD (physio) Mahatma Gandhi medical college and research institute, puducherry – India

2. Why should we know??  Epilepsy is relevant to us ??  medication and drug interactions,  postoperative seizures,  intensive care management of status epilepticus.

3. Seizure and epilepsy  A seizure is the term for the clinical event defined as a paroxysmal alteration in neurologic function caused by a synchronous, rhythmic depolarization of brain cortical neurons.  Epilepsy is the condition manifested by recurrent, unprovoked seizures, ? Cause

4. Classification . Partial seizures a. Simple partial seizures (with motor, sensory, autonomic, or psychic signs) b. Complex partial seizures c. Partial seizures with secondary generalization  2. Primarily generalized seizures a. Absence (petit mal) b. Tonic-clonic (grand mal) c. Tonic d. Atonic e. Myoclonic  3. Unclassified seizures a. Neonatal seizures b. Infantile spasms

5. On the whole  Seizure 10 %  and epilepsy – 1 %

6. Seizures - treatment  partial seizures carbamazepine, phenytoin, and valproate.  Generalized seizures  carbamazepine, phenytoin, valproate,  barbiturates, gabapentin, or lamotrigine

7. Preop evaluation  Thorough investigations  Neuro evaluation  Drug treatment  Concurrent diseases  Airway problems

8. Drugs and anaesthesia  Carbamazepine, phenytoin, and barbiturates cause enzyme induction, and long-term treatment with these drugs can alter the rate of their own metabolism and that of other drugs

9. The three drugs  Phenytoin  Valproate  Carbamazepine

10. Phenytoin - many side effects hypotension, cardiac arrhythmias, gingival hyperplasia, aplastic anemia Extravasation or intra-arterial injection of phenytoin can induce significant vasoconstriction – hence fos phenytoin for IV use – OK

11. Carbamazepine can cause  Ataxia  diplopia,  dose-related leukopenia,  hyponatremia

12. Valproate  Hepatic damage  Pancreatitis  Thrombocytopenia  Decreased factor 8

13. Management of anaesthesia  In patients with seizure disorders  the impact of antiepileptic drugs on organ function  the effect of anaesthetic drugs on seizures

14. Other than routine  Liver  Renal  Cardiac  Coagulation  Total count  Electrolytes  Drugs on organ function

15. Periop antiepileptics  Interruption of antiepileptic drugs (AEDs) may result from orders to be NPO before anaesthesia  Short procedures  Oral drugs → recovery → next dose  Cant take oral before half life → Ryle s tube or IV

16. How to give ?  Parenteral forms- available  phenytoin, valproic acid, or phenobarbital.  Lamotrigine - per rectal forms √  Maintain blood levels of AEDs periop Both phenytoin and sodium valproate have the same intravenous dose as oral dose and are given twice daily.

17. Peri op. think about  alcohol or drug withdrawal seizures  Other epileptogenic drugs  repeated insulin-induced hypoglycemia.  Metabolic derangements corrected  Original disease like mentally retarded child, neuro fibromatoses

18. Premed  Benzodiazepines  Glycopyrollate  AEDs  H2 blockers SOS

19. Induction agents  Thiopentone powerful anticonvulsant Definite OK in seizure patients  Methohexitone - can precipitate fits Hence NO

20.  Propofol (2,6 diisopropylphenol) has been associated with excitatory effects on the CNS in up to 10% of patients.  It is likely that this is not true cortical seizure activity  The drug is OK but if possible  Avoid Propofol use Thio

21.  Given its cerebral excitatory effects ketamine should be avoided in epileptics  Etomidate has a high incidence of extraneous muscle movements -- ?? Epilepsy  Flumazanil – sometimes used in recovery – may provoke fits.

22. Inh agents – no enflurane  The majority of inhaled anaesthetics cause burst suppression on the EEG, and are thus safe for use in epileptics.  The one exception is enflurane which causes epileptiform activity and therefore should be avoided.

23. Non-depolarizing muscle relaxants two chemical groupings  Aminosteroidal compounds – vecuronium, pancuronium, rocuronium  anticonvulsants → enzyme induction in the liver → markedly reduced duration of action of the aminosteroidal muscle relaxants

24. Non-depolarizing muscle relaxants  Benzylisoquinolinium compounds – (cis)atracurium, mivacurium  When selecting muscle relaxants, the central nervous system–stimulating effects of laudanosine, a proconvulsant metabolite of atracurium and cisatracurium

25. Opioids, intra op environment  All opioids are OK  But  remifentanil and tramadol ??  Pethidine and nor pethidine  Periop avoidance of hypoxemia, hypocarbia and electrolyte imbalance

26. Avoid periop CNS stimulants

27. antiemetics  anti emetics dopamine antagonists are well documented to cause extrapyramidal effects and dystonic reactions- beware  Domperidone does not cross BBB safe

28. Be epidural or brachial plexus block

29. Regional anaesthesia  Local anaesthetic toxicity  Maximum dose for infiltration (mg/kg)  Lidocaine 4  With adrenaline 7  Bupivacaine 2  With adrenaline 3  These are general guidelines only

30. Post op seizures  Zonisamide, an antiepileptic agent with antiepileptogenic, free radical scavenging and neuro protective actions  new drug for  postoperative epilepsy in cranial surgeries

31. Pseudo-epileptic seizures  relatively common in the postoperative period.  These are seizures that resemble tonic clonic seizures but are not associated with abnormal electrical discharges in the brain.  Pseudo-seizures tend to be associated with a history of convulsions.  No postictal period, no drugs, normal prolactin

32. Status epilepticus  Status epilepticus is defined as continuous seizure activity of at least 30 min duration  or  intermittent seizure activity of at least 30 min duration during which consciousness is not regained  Partial or generalised  Convulsive or nonconvulsive

33. Complications  CVS, RS, CNS, DIC,  Renal,  fractures,  metabolic,  hepatic necrosis,  pancreatitis

34. Treatment of status epilepticus  ABC, 100% O 2 ↓  Lorazepam 4 mg IV,midazolam (3-10mg), diazepam (5-15mg) ↓  Phenytoin 15 mg/ Kg (, < 50 mg/ min.) ↓  ICU → thio → intubate → ventilate  Cause ??

35. A B C D E F G  A – AIRWAY  B - BREATHE  C – CIRCULATION  D – DIAZEPAM  E – EPTOIN  F – FiO2 100 %  G – GENERAL ANAESTHETICS

36. to find the cause  ECG, EEG  arterial pressure and pulse oximetry,  fluid resuscitation  full blood count, urea and electrolytes, glucose, arterial gases, liver function,.  Hypoglycaemia should be treated with 50% glucose 50 ml.  Neuro opinion and CT, MRI sos

37. MUSCLE RELAXANTS  Neuro muscular blockers  Use them to protect airway and ventilation  Remember that they suppress muscle activity but not neuronal discharges

38. Summary  Preop drugs and diseases  Benzodiazepines  Thio, vec ok  Beware – laudonosine  Morphine, fentanyl –ok  Avoid hypotension, hypoxia, hypocarbia.  Maintain electrolytes  No enflurane  Continue AEDs post op

39. THANK YOU ALL