The Temporal Lobe as a Symptomatogenic Zone in Medial Parietal Lobe Epilepsy

Area of Science:

• Neurology
• Neurosurgery
• Epileptology

Background:

• Surgical failures in temporal lobe epilepsy (TLE) can occur due to undetected extratemporal epileptogenic zones.
• The medial parietal lobe (MPL) is a potential source of seizures due to its connections with mesial temporal structures.
• Seizures originating in the MPL may present with subtle or absent clinical signs before temporal lobe propagation.

Purpose of the Study:

• To provide a comprehensive overview of medial parietal lobe epilepsy (MPLE).
• To highlight the importance of considering the MPL in cases of TLE with discordant presurgical findings.
• To present clinical cases illustrating MPL-originating seizures.

Main Methods:

• Review of anatomical connectivity, semiology, and radiological findings in MPLE.
• Analysis of electroencephalography (EEG) and neuropsychological data in MPLE.
• Presentation of two case studies of seizures originating from the precuneus and posterior cingulate cortex.

Main Results:

• The MPL's connectivity supports its role as an extratemporal epileptogenic zone.
• MPLE can present with clinically silent seizures that propagate to the temporal lobe.
• Detailed review of diagnostic modalities and outcomes for MPLE.

Conclusions:

• The medial parietal lobe is a critical region to consider in nonlesional TLE.
• Intracranial electrode sampling of the MPL should be strongly considered in presurgical evaluations with discordant findings.
• Accurate localization of the epileptogenic zone, including the MPL, is essential for successful epilepsy surgery.