Anaesthesia in epilepsy

1. Anaesthesia in epilepsy Dr.S.Parthasarathy MD DA DNB, D.Diab. Dip. Software based statisticsPhD (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, aplasticanemia Extravasation or intra-arterial injection of phenytoin can induce significant vasoconstriction – hence fosphenytoin 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. Periopantiepileptics • 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, neurofibromatoses

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) • Lidocaine4 • With adrenaline 7 • Bupivacaine2 • 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% O2 ↓ • 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