EMBARGOED FOR RELEASE UNTIL 4 PM ET, December 09, 2002
Antiepileptic Drugs May Reduce Risk of Seizure Recurrence in Patients with Tapeworm Infection of the Central Nervous System
St. Paul, Minn. -
As many as one in 10 people in developing countries are carriers of the pork tapeworm taenia solium. This tapeworm’s prevalence is becoming increasingly common in more developed countries due to immigration, poverty, and areas of poor hygiene or minimum sanitation services. Neurocysticercosis (NC), an infection of the central nervous system caused by the larval form of the tapeworm, is associated with seizures, headache, and other neurological symptoms. Of these, seizures are the most common, occurring in nearly 90 percent of all patients, according to a study published in the December 10 issue of Neurology, the scientific journal of the American Academy of Neurology. Previous studies have offered no agreement on prognosis for seizure recurrence in patients who have contracted the infection and have experienced their first seizure. Researchers from the University of Cuenca in Ecuador, and Columbia University in New York have recently identified the persistence of active NC brain lesions as key predictors of seizure recurrence. “Our objective was to determine the likelihood of seizure recurrence in NC patients and to evaluate risk factors that may contribute to – or reduce – seizure recurrence,” says study author W. Allen Hauser, MD. The study was conducted with patients seen for a first NC-related seizure at the Vicente Corral Moscoso Hospital of Cuenca. The study group included 36 men and 41 women, ranging in age from three to 78. Baseline computer tomography (CT) scans were conducted upon initial diagnosis to identify lesions, or cysts, caused by the NC infection. Treatment for the infection included use of steroids and anti-epileptic drugs, and some patients also received antihelminthics (to destroy the tapeworm), depending on physician preference. If a patient had no further seizures for one year, medication was withdrawn over a one-month period. If a patient experienced a seizure recurrence upon withdrawal, the anti-epileptic drugs were restarted. Patients were followed through clinical interviews every two months, over an average of 24 months. Follow-up CT scans were conducted in 72 patients between six and 12 months after the initial scan to track resolution of cysts or lesions. By the end of the study period, seizures recurred in nearly one-quarter of the 17 patients who had experienced multiple seizures during the acute clinical phase, and in nearly half of the 59 patients who had experienced only a single seizure. The cumulative estimate of a seizure recurrence for all patients was 22 percent at 6 months, 32 percent at 12 months, 39 percent at 24 months and 49 percent thereafter. Overall recurrence risk was 40 percent. Of those who remained seizure-free for one year, the estimated recurrence was 18 percent. Contrary to previous study indications, there was no significant decrease in risk for seizure recurrence among patients treated with antihelminthic drugs. “Among a large array of variables that we assessed as potential risk factors for recurrence, we find only persistence of lesions or cysts as discovered through follow-up CT scans to be predictive of seizure recurrence,” concludes Hauser, “Yet the natural course of neurocysticercosis remains largely unknown.” Because recurrent seizure risk is substantial as long as there is ongoing evidence of lesions, these researchers recommend CT scanning for treatment decisions and continued use of anti-epileptic drugs until lesions are resolved. Continued study regarding the use of antihelminthic drug therapy is also recommended.