Supplementary Material for: Electrode tract oedema in stereo electroencephalography (SEEG)

Introduction – Stereo-electroencephalography (SEEG) is a safe and effective procedure for the identification of the epileptogenic zone to guide epilepsy surgery. Electrode tract oedema in SEEG is poorly understood. This study reports on its incidence and its clinical and biochemical correlations.
Methods – The presence of oedema along the electrode tract on patients after removal of SEEG electrodes was recorded and described. The trend of serum inflammatory markers of patients with and without oedema were compared with non-linear regression using 2nd and 3rd order polynomial models and the extra sum-of-squares F test.
Results – 79.2% of patients had radiographic oedema. Two radiographic distributions of oedema are described. No statistical differences were found between the trends of serum inflammatory markers of patients with and without oedema. 8.6% of patients had isolated fevers of non-infectious origin. 11.4% of patients had subclinical haematomas. No patients had infective or thromboembolic complications.
Conclusions – Radiographic electrode tract oedema is common in SEEG and runs a benign clinical course in our series.