Subclinical focal seizures as a sign of progression in gliomas

Subclinical seizures are ictal electrographic discharges lacking signs of clinical seizures, behavioural alteration or subjective symptoms. The diagnosis and detection of this type of non-convulsive seizures remain challenging, and information is scarce regarding this electroclinical picture in subjects with gliomas. The aim of this report is to describe two patients with gliomas who, after treatment with surgery and radiotherapy, exhibited subclinical seizures on video-EEG monitoring, as a manifestation of recurrence or progression of their brain tumour.

Case report and video-EEG monitoring analysis.

Two patients with gliomas were admitted to our neurosurgical unit after a generalized tonic-clonic seizure. Brain MRI revealed a recurrence of their tumour. The use of video-EEG monitoring allowed the detection and characterization of subclinical seizures in both patients that otherwise would have gone undetected. In both cases, subclinical seizures arose from the frontal lobe and were not associated with motor manifestations or subjective symptoms.

We emphasize that the existence of subclinical seizures in patients with gliomas is likely to be underestimated, and can occur in advanced progressive tumours. It is important to carry out continuous video-EEG monitoring in brain tumour patients who have had recent clinical seizures in order to be able to detect subclinical seizures and make appropriate diagnosis.