Stereoelectroencephalography for Epilepsy Presurgical Assessment: A Nationwide Survey of Evolution of Practice in Australia.

Background and objectives: Stereoelectroencephalography (SEEG) is increasingly used worldwide for epilepsy presurgical evaluation. A data-driven view of SEEG practice evolution is lacking for any world region. We aimed to perform a nationwide survey of SEEG use in Australian adult epilepsy centers. We predicted that the proportion of nonlesional MRI cases, number of electrodes, and radiofrequency thermocoagulation (RF-TC) use would increase over time.

Methods: All epilepsy centers in Australia undertaking SEEG in patients older than 16 years at any time were invited to participate in a nationwide survey. Data were retrospectively and/or prospectively collected on patient demographics and SEEG exploration. Descriptive statistics were used.

Results: A total of 281 SEEG explorations were performed in 8 centers from 2012 until 2023, 278 of which (99%) are reported here. A definite epileptogenic MRI lesion was present in 30.6% with no overall significant growth in the proportion of nonlesional cases (χ² [1, N = 278] = 0.067, p = 0.79), although this varied per center. Patients identifying as Indigenous Australians comprised 1.6% of this national SEEG survey vs an estimated national indigenous population of 3.8%. The median number of electrodes increased from 8 in 2012 to 15 in 2023. A total of 174 patients (62.6%) were offered resective surgery after SEEG. Surgery was performed with 1-year follow-up in 114, of whom 72.8% were seizure-free at the last follow-up. The presence/absence of an MRI lesion was not associated with postoperative seizure-free outcomes (χ² [1, N = 114] = 0.06, p = 0.80). RF-TC use differed between centers and evolved, with a crossover to the majority use of RF-TC occurring 5 years after regulatory approval.

Discussion: This comprehensive nationwide and regional survey of SEEG practice comprises full ascertainment of all centers and allows analysis of changes in practice over time. Whole cohort results show a high proportion of nonlesional MRI cases achieving satisfactory surgical outcomes and evolution to increased RF-TC use. Indigenous access to SEEG seems to be lower than expected, consistent with broader health care access issues for this population group. Nationwide collaboration on SEEG data provides a basis for analysis of practice at the individual center and state and national levels to optimize health care planning and sharing of expertise.