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30-09-2010 | Anaesthesiology | Article

Peri-operative seizures unrelated to anesthesia variables


Free abstract

MedWire News: Seizures during surgery are rare and are related to the patient's underlying condition rather than to anesthesia or surgical variables, say US researchers.

Over a 6-year period, 641 patients with a known seizure disorder underwent surgery at the Mayo Clinic in Rochester, Minnesota, and remained in hospital for at least 24 hours postoperatively. Twenty-two (3.4%) of these patients suffered a peri-operative seizure, defined as occurring within 3 days of anesthesia.

Patients' risk for seizures was not affected by whether they underwent general anesthesia, regional anesthesia, or monitored anesthesia care, or by the type of regional block they received (if any), or whether they were given benzodiazepine.

Their seizure risk was also unaffected by the type of surgery they underwent, report Sandra Kopp and team from the Mayo Clinic.

Patients who suffered seizures were younger than those who did not, at an average of 40 versus 50 years, with patients younger than 18 years suffering the highest proportion of seizures (8%).

The risk for peri-operative seizures rose with the number of antiepileptic medications taken, fell with increasing time since last seizure, and rose with frequency of seizures prior to surgery.

For example, seizures occurred in 37.5% of the 16 patients who suffered daily seizures, compared with 0.2% of the 429 patients who had seizures less than once a year.

The researchers believe that disruptions to antiepileptic medication caused by hospitalization may have contributed to the patients' seizures. They note that six of the patients who suffered seizures had known subtherapeutic levels of antiepileptic drugs. Another two, who were not tested, had missed at least one dose of their medication for reasons such as postoperative nausea and vomiting.

"This underscores the importance of maintaining an inpatient dosing regimen as close as possible to what the patient is accustomed to as an outpatient," say Kopp et al in the journal Anesthesia and Analgesia.

They advise: "The patient's usual antiepileptic medication regimen should be followed as closely as possible the day of surgery and while hospitalized, with parenteral formulations of the patient's usual medications used if gastrointestinal access is contraindicated or if absorption could be affected."

MedWire ( is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2010

By Eleanor McDermid