Procedures in children and adults with epilepsy raise the following issues:
- defining the risks of the procedure for the patient with epilepsy
- steps to be taken before the procedure to reduce the risk of seizures
- educating health care providers about a patient's seizures and medications and first aid for seizures
- defining the effects of anesthetics or analgesics used for the procedure on seizure threshold and the potential for interaction with antiepileptic drugs (AEDs). (This is the topic of the following pages.)
- differential diagnosis of paroxysmal behavioral events that occur around the time of procedures
Defining the risks
Epileptic seizures during procedures can be dangerous—think of the onset of uncontrolled movements in an extremity in which a microsurgical procedure is being performed under local anesthesia. (On the other hand, the onset of status epilepticus is less dangerous when it occurs in a physician's office than when it occurs in a patient who is at home alone.) Patients with epilepsy are often considered at high risk during routine procedures, based primarily on the risk of seizures occurring during or shortly after the procedure, and, to a lesser degree, on the potential interaction between drugs for the procedure and for seizure control. Increased risks among patients with epilepsy have been documented for few medical or dental procedures, however.
Most general and local anesthetics have proconvulsant and anticonvulsant properties. Except for enflurane, which has been associated with a higher risk for seizures, all of the anesthetics in use may be safely administered to epilepsy patients if the proper approach in epilepsy patient care is observed. The risk of seizures during or after a surgical or dental procedure is minimal when routine precautions and guidelines are followed.
Steps to reduce risk
Some simple precautions should be taken before a person with epilepsy undergoes a procedure. Proper history taking with attention to the patient's seizure type and frequency as well as medication compliance and response is of basic importance. Blood levels of AEDs should be measured before and after a procedure and adjusted individually (if needed) to minimize the risk of seizures or side effects. Drug interactions should be considered in adjusting maintenance doses.
Factors that can precipitate seizures should be avoided. Because missed medications are a common cause of breakthrough seizures,1 emphasize compliance and ensure that patients continue taking medication up until shortly before the procedure. Although patients are instructed not to eat or drink for at least 8 hours before surgery, medications are often administered with sips of water within a few hours of surgery. AEDs also should be given at this time.
Sleep deprivation, common before many procedures, should be avoided. When needed, low doses of chloral hydrate or benzodiazepines can be safely used for insomnia the night before a procedure.
Patients with epilepsy, who should always avoid excessive alcohol intake (i.e., greater than two beverages per day), should avoid alcohol for a week before surgery.2
Educating health care providers
Much of the concern regarding patients with epilepsy results from perceived as well as real risks associated with seizures. Health care workers often receive little education concerning seizure classification, phenomenology, duration, and first aid. This lack of understanding fosters fear and conservatism that can lead to excessive precautions and restrictions and management errors.
For example, induced labor and cesarean section are examples of interventions and procedures that may be undertaken more often in women with epilepsy than medical reasons alone would justify—two to four times more often than in other pregnancies.3 Epilepsy alone is not an indication for either of these interventions. In selected cases, however, labor should be induced or a cesarean section should be performed. These interventions may be on an elective basis, such as when weekly tonic-clonic seizures occur during the last trimester, or on an emergency basis, when a tonic-clonic seizure occurs during labor or when active maternal contribution is lacking.4
Physicians, nurses, dentists, technicians, and other health care workers involved with procedures in patients with epilepsy should have a basic understanding of the patient's seizure types, medications, and first aid for the seizures. A complex partial seizure during a routine dental procedure can frighten the dentist and the technologist. If previously informed of the possibility and educated about the need for calm observation as opposed to intervention, fears and chances of inappropriate responses can be reduced. For example, restraint during a complex partial seizure or after a tonic-clonic seizure can provoke an aggressive reaction, which leads to a dangerous cycle that requires greater restraint. In such cases, restraint should be removed, and the patient should be reassured in a comforting manner.
Differential diagnosis of events
Paroxysmal behavioral events that occur during or after procedures have a differential diagnosis that extends well beyond epileptic seizures.5 Occasionally, a patient with psychogenic seizures has events mainly around the time of medical procedures. More commonly, patients with convulsive syncope develop symptoms during painful or emotional procedures. In such cases, which can occur in procedures such as venipuncture, excision of moles under local anesthesia, and electromyography, the patient experiences a tonic-clonic seizure secondary to a fall in heart rate or blood pressure.6 These seizures are typically brief, lasting less than 2 minutes, but they may be followed by prominent postictal confusion. No specific therapy is required, and AEDs should not be prescribed. In selected cases of recurrent convulsive syncope associated with medical procedures, an anticholinergic agent may be beneficial.
Perioperative epileptic seizures have numerous potential etiologies. They usually are not the result of anesthetics. Seizures are a frequent occurrence after operation and irradiation for supratentorial gliomas, and anticonvulsants may be effective in reducing the incidence of those seizures.7
Cardiac surgery is also associated with a higher incidence of perioperative epileptic paroxysms owing to the complex and sometimes severe metabolic, hemodynamic, or blood modifications that are induced by cardiopulmonary bypass and may alter cerebral electrogenesis.8 It seems that normothermic light hemodilution and elimination of neuroleptic drugs for analgesia prevent preoperative and postoperative epileptic paroxysms.
Adapted from: Najjar S, Devinsky O, Rosenberg AD, et al. Procedures in epilepsy patients. In: Ettinger AB and Devinsky O, eds. Managing epilepsy and co-existing disorders. Boston: Butterworth-Heinemann; 2002;499–513.
With permission from Elsevier (www.elsevier.com).