Download 2 MB - epilepsy - anaesthetic concerns

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