Abstracts

Rationale: An estimated 50 million Americans are considered to be obese. Bariatric surgery has been shown to produce weight loss by limiting food intake and by reducing nutrient absorption. Since the 1980's, the Roux-en-Y gastric bypass (RYGB) has been the most common form of bariatric surgery performed in the U.S. A review of epilepsy patient-oriented websites such as Epilepsy.com reveals many reports of either new-onset seizures or exacerbation of existing seizures following RYGB. Neurologic complications reported after bariatric surgery include Wernicke-Korsakoff, polyradiculoneuropathy, myelopathy, and optic neuropathy. However, few studies have examined a potential connection between gastric bypass and epilepsy. The objectives of this chart review study are to explore outcomes for patients with a pre-existing seizure disorder who underwent RYGB surgery AND to find out how many diagnoses of new-onset epilepsy were made in patients after undergoing RYGB.Methods: A case series was formed using retrospective chart review. Patient questionnaire was used to supplement where data was lacking. 1779 RYGB procedures were performed at Mayo Clinic from September 1997 to September 2007. Excluded were 227 patient due to less than one year of follow-up, two patients who underwent surgery for reasons other than morbid obesity, three patients who were found to have non-epileptic spells, and five patients who were under 18 years of age at the time of surgery. Antiepileptic drug levels pre- and post-surgery were documented where available. Charts were examined for evidence of seizure exacerbation post-surgery, defined as an increase in seizure frequency above pre-operative baseline where another cause was not identified. After exclusions, 1542 patients were selected.Results: Out of the 1542 patients selected, twelve had a pre-existing diagnosis of epilepsy. Of these twelve, eight were found to have no decrease in drug levels, either based on patient report or on serum testing before and after surgery. One patient had a low drug level documented in the setting of suspected poor compliance. None of the twelve patients had exacerbation of a preexisting seizure disorder. Only five of 1542 patients developed new-onset epilepsy after surgery. Of these five, two had structural lesions (abscess and meningioma) felt to be responsible for their seizures.Conclusions: Based on reviewed data, no exacerbation of pre-existing epilepsy was seen following gastric bypass. Even patients with significant seizure risk factors did not demonstrate epilepsy exacerbation. Stable serum drug levels for phenytoin, carbamazepine, and levetiracetam were documented before and after surgery without requiring dose adjustment. Of the five patients who developed new seizures after surgery, none had intractable epilepsy. While interpretation of the data is subjective, there does not appear to be a notable increase in new-onset seizure disorder as a result of undergoing gastric bypass surgery.