Anaesthesia and epilepsy - a review

It is of essential importance for the anaesthesiologist to know about the specific side effects of drugs used for premedication and about possible concomitant diseases in order to perform a safe anaesthesia in patients with epileptic disorders who need to undergo general surgery or therapeutic treatment. Epileptic seizures most typically occur during the (physiological) transition from wakefulness to sleep. For that reason, almost all anaesthetic agents have been connected with "seizure-like" incidents. However, the controversial discussion about the epileptogenic properties of individual anaesthetics is largely based on an inadequate conception and consideration of the definition of "epilepsy" and, consequently, the exact meaning of the term "epileptogenic". Since epilepsy is a disorder which is associated with unpredictable, recurrent seizures that can either be of a partial or generalized type or marked by paroxysmal changes of consciousness or personality, and which is often characterized by EEG alterations, a single seizure alone does not present an epilepsy already, even though it may signify the beginning of an epileptic disease. There are a variety of different causes that can trigger a "cataclysmic reaction of the brain" and induce an incidental seizure. A single seizure occurring during anaesthesia can therefore only be described as an attack associated with generalized or partial convulsions, even if epileptiform EEG activity is recorded. Knowledge of the epileptogenic properties of the different anaesthetics helps the clinician to choose the appropriate drug combination for anaesthesia in patients with epilepsy. According to the current knowledge, the following drugs are considered recommendable: all benzodiazepines, the inhalation anaesthetics N2O and Isoflurane (and, possibly, Desflurane), of the hypnotic drugs the barbiturates and Propofol (both in hypnotic concentrations), of the opioid analgesics Sufentanil, Remifentanil and Piritramide, all muscle relaxant drugs, and of the local anaesthetic agents Mepivacaine, Ropivacaine, Bupivacaine and Lidocaine.