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PROPHYLAXIS PRIOR TO CRANIOTOMY DEMONSTRATES DUBIOUS EFFICACY
PHILADELPHIA—Results of a new study suggest that anticonvulsant prophylaxis before open craniotomy confers no particular benefit in terms of seizure prevention in the first seven days after surgery. In fact, as the results of a retrospective study presented at the 53rd Annual Meeting of the American Academy of Neurology attest, a slight trend toward more seizures was seen in the group that had received prophylaxis by 30 days postsurgery.
IN PURSUIT OF A STANDARD OPERATING PROCEDURE
Based on the results of their retrospective study, the researchers, led by Joseph I. Sirven, MD, and Vicki Shanker, MD, of the Mayo Clinic in Scottsdale, Arizona, suggested that a randomized trial of anticonvulsant prophylaxis in the setting of craniotomy should be carried out. In their own institution, Dr. Sirven told Neurology Reviews, “we prophylax about 35% of patients; why we do is not clear.” He added that the practice is not universal among Mayo Clinic surgeons. “We need to design a trial that would help to answer the question, because the best thing is the judicious use of medications, rather than just using them on everyone.”
Information from the Agency for Health Care Policy and Research indicates that about 65,000 craniotomies are performed in the United States every year. The researchers point out that while the increased risk of seizures after craniotomy is well documented, it is not clearly established that anticonvulsant therapy given preoperatively will reduce that risk.
RISK VERSUS REWARD
If there were no risk associated with anticonvulsants, Dr. Sirven said, then their use as prophylactics would not be a great issue. However, the drugs can be a costly addition to the hospital and medical expenses, and they are not without risk of adverse effects. “Some people report up to 5% to 8% of patients experience adverse effects, including serious rash, hypotension, phlebitis, tissue irritation, even immuno-suppression,” he said. “So is this risk, which is still a low risk, justified by the benefit of what you’re preventing, which is the seizure?”
To help answer that question, Dr. Sirven and colleagues retrospectively identified 216 patients who had undergone craniotomy at their institution between January 1994 and June 2000, and had at least seven-day postsurgical follow-up available for evaluation. Patients had a mean age of 65, and none had any history of seizure prior to the operation. All postoperative records were then reviewed, and incidences of new seizure, including onset and type, were recorded.
Of the 216 patients, 76 had received prophylactic phenytoin. The researchers noted that the decision to use anticonvulsant therapy was more common among patients undergoing left-sided surgical entry than right; 62% of those given prophylaxis were undergoing left-sided surgery, compared with 34% of those not given prophylaxis. Patients undergoing tumor resection were also more likely to receive anticonvulsant therapy before the operation.
NO SIGNIFICANT DIFFERENCE
The overall incidence of seizures was about 4% within seven days of surgery, 7% within 30 days, 19% within 180 days, and 27% within 360 days. Seizures were most common among patients with abscesses or those with non-pituitary tumors. However, researchers found that there was no significant difference in the risk of developing new seizures whether prophylaxis was given or not. Within seven days, 3.6% of patients receiving prophylaxis had seizures, compared with 4% of those who did not.
At one year, those who had received an anticonvulsant actually had a slightly higher incidence of new seizures: Kaplan-Meier estimates of one-year seizure rates were 21% for the group with prophylaxis, compared with 11% for the group without. Dr. Sirven stressed, however, that these results should not be interpreted as the medication having increased risk; only that in these conditions, treatment did not prevent new-onset seizures.
PROGNOSIS NEGATIVE
The researchers concluded that in this retrospective study, at least, no benefit was seen with prophylactic therapy, but pointed out that a randomized trial is required to settle the question. However, they did note that their findings are consistent with those of other recently published trials.
“If you show that [anticonvulsant prophylaxis] helps in a controlled setting, then so be it,” Dr. Sirven said. “However, there have been a lot of other trials looking at it. Not just in craniotomy, but in penetrating head injury in the Vietnam Head Injury Study; the study in subarachnoid hemorrhage that came out in Neurology last summer; and the practice guidelines for tumor, which said there is no reason to prophylax patients.” Dr. Sirven hopes to initiate a randomized trial, possibly in collaboration with other centers, with a target of several hundred patients, to better answer this question.
NR
—Susan Jeffrey
Suggested Reading
1. Rhoney DH, Tipps LB, Murry KR, et al. Anticonvulsant prophylaxis and timing of seizures after aneurysmal subarachnoid hemorrhage. Neurology. 2000;55:258-265.
2. Salazar M, Jabbari B, Vance SC, et al. Epilepsy after penetrating head injury. I. Clinical correlates: a report of the Vietnam Head Injury Study. Neurology. 1985;35:1406-1414.
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