NEW YORK (Reuters Health) - Successful epilepsy surgery appears to correct disturbances in brainstem functional connectivity, researchers report. "Seizures lead to brain network perturbations which may be related to cognitive deficits seen in patients with epilepsy," Hernan F. J. Gonzalez from Vanderbilt University Medical Center, in Nashville, Tennessee, told Reuters Health by email. "Our new results show some brain network activity can improve with successful epilepsy surgery that stops seizures." Recent studies have shown reduced connectivity between brainstem ascending reticular activating system (ARAS) nuclei and neocortex that were related to disease severity and neurocognitive deficits in patients with temporal lobe epilepsy (TLE). Gonzalez and colleagues used fMRI to examine brainstem connectivity in 15 patients with TLE before and 3.4 years, on average, after epilepsy surgery, compared with 15 matched healthy control participants. Among the 10 TLE patients who achieved seizure freedom after surgery, there was significantly increased connectivity between ARAS structures and bilateral fronto-parietal-insular cortical regions compared with the preoperative baseline. This postoperative connectivity was similar to that of controls. The increase in postoperative connectivity was comparable in patients who stopped or reduced preoperative epilepsy medications versus those continuing similar medication regimens. Patients who continued to experience seizures postoperatively showed no significant differences in ARAS functional connectivity after surgery, the team reports in Neurosurgery, online May 16. Patients with more-frequent preoperative focal impaired-consciousness seizures showed larger postoperative connectivity increases, but there was no relationship between postoperative connectivity change and epilepsy duration. Individuals with worse verbal IQ and memory showed greater increases in postoperative functional connectivity between some areas but not others. Unlike functional connectivity, structural connectivity patterns did not change after surgery. "In a future study, we would like to examine if after epilepsy surgery patients see improvement in neurocognition and quality of life accompanying the recovery of brain networks connectivity," Gonzalez said. Co-author Dr. Dario J. Englot told Reuters Health by email, "Surgery is an underutilized treatment for individuals with epilepsy who continue to experiences seizures despite trialing multiple antiepileptic medications. Additionally, early surgery can help improve quality of life for epilepsy patients, and through this work we are learning that epilepsy surgery may lead to changes in brain networks." Source
