Three months after surgery, patients with surgery performed on either the left or right brain tissue showed signs of verbal memory loss. Initially, the resulting loss of memory was thought to be a possible effect of the trauma of surgery. However, 12 months later 30% -50% of those patients who experienced surgery to the left temporal lobe showed no recovery of verbal memory, while patients who had surgery on the right side of their brain regained their memory. The results indicate that the decline observed in a small portion of patients who had surgery on the right side of their brains was temporary and most likely the effects of complications in surgery. Verbal memory loss mainly affects those patients whose surgery was performed on the left side of the brain.
Selective Amygdalohippocampectomy (SAH), or mesial temporal lobectomy, was the type of surgery performed on the 115 patients studied. "It was not clear from existing studies to what extent an SAH can lead to significant declines in memory functions, which memory functions are at risk of becoming impaired, and which determinants of outcome can be discerned," observed author Ulrike Gleissner, PhD.
As a type of epilepsy surgery, SAH was originally developed to spare unaffected brain tissue from resection and thus to minimize the negative consequences of anterior temporal lobectomy, a more conventional surgical technique. Most often SAH is sufficient to eliminate recurrent seizures in patients.