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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
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Why should we know?? Epilepsy is relevant to us ?? medication and drug interactions, postoperative seizures, intensive care management of status epilepticus.
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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
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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
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On the whole Seizure 10 % and epilepsy – 1 %
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Seizures - treatment partial seizures carbamazepine, phenytoin, and valproate. Generalized seizures carbamazepine, phenytoin, valproate, barbiturates, gabapentin, or lamotrigine
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Preop evaluation Thorough investigations Neuro evaluation Drug treatment Concurrent diseases Airway problems
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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
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The three drugs Phenytoin Valproate Carbamazepine
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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
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Carbamazepine can cause Ataxia diplopia, dose-related leukopenia, hyponatremia
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Valproate Hepatic damage Pancreatitis Thrombocytopenia Decreased factor 8
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Management of anaesthesia In patients with seizure disorders the impact of antiepileptic drugs on organ function the effect of anaesthetic drugs on seizures
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Other than routine Liver Renal Cardiac Coagulation Total count Electrolytes Drugs on organ function
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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
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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.
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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
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Premed Benzodiazepines Glycopyrollate AEDs H2 blockers SOS
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Induction agents Thiopentone powerful anticonvulsant Definite OK in seizure patients Methohexitone - can precipitate fits Hence NO
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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
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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.
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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.
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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
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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
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Opioids, intra op environment All opioids are OK But remifentanil and tramadol ?? Pethidine and nor pethidine Periop avoidance of hypoxemia, hypocarbia and electrolyte imbalance
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Avoid periop CNS stimulants
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antiemetics anti emetics dopamine antagonists are well documented to cause extrapyramidal effects and dystonic reactions- beware Domperidone does not cross BBB safe
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Be epidural or brachial plexus block
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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
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Post op seizures Zonisamide, an antiepileptic agent with antiepileptogenic, free radical scavenging and neuro protective actions new drug for postoperative epilepsy in cranial surgeries
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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
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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
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Complications CVS, RS, CNS, DIC, Renal, fractures, metabolic, hepatic necrosis, pancreatitis
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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 ??
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A B C D E F G A – AIRWAY B - BREATHE C – CIRCULATION D – DIAZEPAM E – EPTOIN F – FiO2 100 % G – GENERAL ANAESTHETICS
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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
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MUSCLE RELAXANTS Neuro muscular blockers Use them to protect airway and ventilation Remember that they suppress muscle activity but not neuronal discharges
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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
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THANK YOU ALL
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