Follow-up studies suggest that the procedure also has produced positive long-term effects that illustrate 63 percent of patients still remaining seizure-free.[14] Although the procedure produces positive outcomes for patients regarding seizure control, the surgery can also produce negative outcomes such as memory impairment. Impairment depends on the hemisphere of resection; temporal lobe resection of the dominant hemisphere often causes verbal memory impairment while temporal lobe resection of the non-dominant hemisphere often causes visual memory impairment.[15]