What is the perioperative management of epilepsy medications?

Updated: Jan 09, 2018
  • Author: Nafisa K Kuwajerwala, MD; Chief Editor: William A Schwer, MD  more...
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Answer

Answer

Grand mal seizures can substantially increase the risks of surgery. Considerable morbidity may follow grand mal seizures in the perioperative period (eg, pulmonary aspiration, wound dehiscence, disruption of reduced fractures and prostheses). Identifying patients with preexisting seizure disorders assures that their anticonvulsant medications can be continued. On the other hand, neither absence nor focal seizures appreciably increase the risk of surgery and anesthesia.

As a general principle, if control of epilepsy has been adequate during the year before surgery, measuring blood levels of antiepileptic medications or repeating an electroencephalogram evaluation is not necessary.

Phenytoin and phenobarbital should be continued in the perioperative period with parenteral formulations, if needed. However, carbamazepine and valproic acid are not available in parenteral form. [12]

Patients taking these drugs must be loaded with phenytoin at 18 mg/kg and maintained on 4-8 mg/kg in 3 divided doses until they resume eating. Those who are intolerant of or allergic to phenytoin may be loaded with phenobarbital in a dose of 6 mg/kg.

If a patient is allergic to both and the risk of major seizure is high, premedication with prednisone in a dose of 60 mg/d for 2 days usually prevents allergic reactions. Loading the patient with oral dosages and then giving intravenous maintenance doses is better. However, in emergency cases, the loading may be performed intravenously using the same doses. Maintaining the serum levels in the upper half of the therapeutic range (ie, 15-20 mcg/mL for phenytoin, 30-40 mcg/mL for phenobarbital) minimizes the risk of intraoperative seizures.

Phenytoin and phenobarbital are usually effective for all types of seizures except true absences, which require ethosuximide or valproic acid (not available in parenteral form). However, pure absence seizures pose little threat, and their treatment can be safely interrupted until after surgery.

Table 4: Perioperative Medication Management in Patients With Epilepsy (Open Table in a new window)

Drug

Day Before Surgery

Day of Surgery

During Surgery

After Procedure

Substitute Drug if Needed

Phenytoin

Usual dose

Usual dose on morning of surgery with sip of water

IV phenytoin

Continue IV dose until medication can be taken PO

 

Phenobarbital

Usual dose

Usual dose on morning of surgery with sip of water

IV phenobarbital

Continue IV dose until medication can be taken PO

 

Carbamazepine

PO loading dose of phenytoin or phenobarbital

PO phenytoin or phenobarbital

IV phenytoin or IV phenobarbital

Continue IV dose until medication can be taken PO

Phenytoin/ phenobarbital

Valproic acid

PO loading dose of phenytoin or phenobarbital

PO phenytoin or phenobarbital

IV phenytoin or IV phenobarbital

Continue IV dose until medication can be taken PO

PO phenytoin or phenobarbital


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