US Regional Differences Found in Presurgical Testing for Drug-Resistant Epilepsy

A study found that the characteristics and location of epilepsy centers in the United States are associated with differences in presurgical testing for drug-0resistant epilepsy.

The location and characteristics of an epilepsy center in the United States could affect the types of presurgical testing given to patients with drug-resistant epilepsy, according to study findings published in Epilepsia. This could have implications on disparities in treatment for these patients.

Epilepsy affects nearly 3.5 million people in the United States and surgery is just one way of treating the disease. Surgical candidacy is assessed through presurgical evaluations, but there are different ways for evaluation and treatment approaches. However, the quality of evidence for these techniques remains low. This study aimed to evaluate and detail the variability in diagnostic testing and describe center features associated with specific test utilization patterns.

The study used data from the 2019 National Association of Epilepsy Centers (NAEC) annual report and a supplemental epilepsy surgery practice survey from level 3 and level 4 NAEC epilepsy centers. All data reflect prepandemic practices.

Data from combined adult and pediatric center annual surveys were divided into 2 groups: 18 years and younger and 19 years and older. The data were then linked to the supplemental survey from the demographic center director.

The survey response rate was 100%, although all surveys were not complete. There were 342 observations included in the study, with 206 (60%) reporting as adult epilepsy monitoring unit (EMU) directors; 274 (80%) of these observations were from level 4 EMU centers and 211 (62%) were from academic/university institutions.

Utilizations of diagnostic tests for presurgical evaluation varied in level 3 and 4 centers. Long-term monitoring with video electroencephalography (LTM EEG) and brain MRIs were used in all evaluations in most centers. However, neuropsychological testing and interictal brain fluorodeoxyglucose-positron emission tomography (FDG-PET) use varied between centers.

Testing practices also varied between epilepsy center population types. Pediatric-only centers had a higher median utilization percentage with FDG-PET, single-photon emission CT (SPECT), functional MRI, EEG source imaging, genetic testing, and social work evaluation. Neuropsychological testing and psychiatry evaluation were utilized less often in pediatric patients.

There were 278 observations included in the multivariable model, which found that the most common tests were brain MRI, LTM EEG for seizure capture, neuropsychological testing, and FDG-PET. More epileptologists with 2 or more years of fellowship training were associated with lower use of MRI (odds ratio [OR], 0.93; 95% CI, 0.87-0.99). Centers with multidisciplinary epilepsy patient management conference (MEPMC) weekly meetings (OR, 15; 95% CI, 4.3-52.1) or MEPMC meetings as needed (OR, 8.39; 95% CI, 2.27-31.0) more commonly used LTM EEG for seizure capture vs those who had no formal meetings.

Centers in the Midwest more commonly used neuropsychological testing (OR, 2.87; 95%CI, 1.2-6.86) compared with the South. This testing was also more commonly used in those capable of resective or ablative surgery (OR, 15.7; 95% CI, 1.99-124) and those with weekly MEPMC (OR, 54.4; 95% CI, 6.79-435) vs those who had no MEPMC.

Midwest centers used PET more often (OR, 2.74; 95% CI, 1.14-6.61) compared with those in the South, pediatric center directors had decreased FDG-PET use (OR, 0.24; 95% CI, 0.09-0.67), and SPECT was more commonly used in the South than in the Northeast (OR, 0.46; 95% CI, 0.23-0.93) or West (OR, 0.41; 95% CI, 0.19-0.87).

Centers with lower EMU admission volume used Wada testing (OR, 0.89; 95% CI, 0.80-1.00). Wada testing was also used in centers with a lower intracranial monitoring rate (OR, 0.92; 95% CI, 0.86-0.98).

Genetic testing had the highest OR in pediatric center directors (OR, 16; 95% CI, 8.64-29.8). A negative association was found between psychiatry consultations and centers that offered surgery with intracranial electrodes (OR, 0.19; 95% CI, 0.04-0.82).

There were some limitations to this study. Medical directors were asked to estimate the percentage of presurgical patients who had a diagnostic test rather than giving actual percentages. NAEC member centers also do not provide the entirety of epilepsy care in the United States, although the authors feel that they likely represent most of the specialized evaluations and procedures for those with drug-resistant epilepsy.

The researchers concluded that their research gave a critical foundation to evaluating outcomes for people with drug-resistant epilepsy and highlighted the difficulty in developing standardized testing algorithms.


Ahrens SM, Arredondo KH, Bagic AI, et al. Epilepsy center characteristics and geographic region influence presurgical testing in the United States. Epilepsia. Published online November 1, 2022. doi:10.1111/epi.17452

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