Invasive epilepsy monitoring: Stereoelectroencephalography vs subdural electrodes
Between the two most common invasive monitoring approaches, stereoelectroencephalography (SEEG) leads to fewer surgical resections yet more favourable seizure freedom outcomes in epilepsy patients scheduled to undergo resections compared with subdural electrodes (SDE), as reported in a systematic review. Additionally, SEEG is associated with lower morbidity and mortality.
Researchers searched three electronic databases for studies that presented primary quantitative patient data for postresection seizure freedom with ≥1 year of follow-up or complication rates of SEEG- or SDE-monitored patients with epilepsy.
The systemic review included 48 studies involving 1,973 SEEG patients and 2,036 SDE patients. In the entire population, the mean age was 24.9 years, and more than half were male. Researchers used weighted mean differences (WMDs) with 95 percent CIs to estimate the association of SEEG or SDE with seizure freedom and with adverse event outcomes.
Seizure freedom rate following resection was significantly higher with SEEG vs SDE (61.0 percent vs 56.4 percent (WMD, 5.8 percent, 4.7–6.9; p=0.001). Moreover, SEEG was associated with substantially lower morbidity (4.8 percent vs 15.5 percent; WMD, –10.6 percent, –11.6 to –9.6; p=0.001) and mortality (0.2 percent vs 0.4 percent; WMD, –0.2 percent, –0.3 to –0.1; p=0.001).
The researchers emphasized the need for clinical studies directly comparing the SEEG and SDE to understand the relative rates of seizure freedom, morbidity and mortality associated with these techniques.
SEEG and SDE are the most common neurosurgical techniques for implanting electrodes to localize the epileptogenic zone, and different epilepsy centres may prefer one over the other based on their own experience. Generally, SEEG allows deep or bilateral brain recordings while avoiding a craniotomy, whereas SDE facilitates contiguous coverage over a large area and mapping of eloquent cortex using direct cortical stimulation in the epilepsy monitoring unit. [Epilepsy Behav 2018;80:68-74; Neurosurg Focus 2008;25:E21]