Monthly Case

A 26-year-old male patient has suffered from epilepsy for the lasts 7 years. Seizures are characterized by impaired awareness and few oral automatisms, duration is 40 sec. On specific questioning, the patient reports some kind of warning sign which he cannot describe very well, but which most likely corresponds to pressuring sensations in the gastric area. The patient is currently treated with 400 mg lacosamide and 10 mg peramapanel. Prior to that, we had already been administered three other anticonvulsants. Seizures frequency is 3-4 per month. Brain MRI demonstrated some cortical alteration which likely corresponds to focal cortical dysplasia.

Due to drug-resistant focal epilepsy, the patient underwent presurgical assessment in our center. At first, video-EEG monitoring was performed with surface electrodes. Three typical seizures were captured, and the seizure onset pattern was seen left temporo-anteriorly. As both seizure semiology and ictal EEG were compatible with a seizure onset zone in left temporo-mesial structures, it became obvious that the cortical alternation in the left parietal lobe likely is not the seizure focus. Cranial MRI and glucose PET were normal, in particular no changes in left temporo-mesial structures were identified. Using subdural strip and grid electrodes, we were able to localize the seizure onset zone in the left hippocampus. The patient underwent anterior temporal lobe resection and since then – after 3 months – has been seizure-free.

Multiple studies on outcome after epilepsy surgery have demonstrated that the identification of a putatively epileptogenic lesion in MRI significantly increases the chance for post-operative seizure freedom. Interestingly, the current case demonstrates that even alterations pointing to focal cortical dysplasia do not necessarily turn out to be the epileptogenic focus. Thus, beyond detailed history taking, recording of at least one typical seizure – by video and simultaneously by EEG – is the prerequisite for successful epilepsy surgery.

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