Abstracts

Rationale: Gerstmann Syndrome (GS) has always been controversial. In 1930, Gerstmann described a tetrad of symptoms, including finger agnosia, left-right disorientation (L-RD), agraphia, and acalculia, as a result of a lesion located in the left angular gyrus. It has been debated because it usually appears as an incomplete tetrad. Ictal GS is a rare finding. EEG is often non-localizing in Parietal Lobe (PL) epilepsy, and Stereo-EEG (SEEG) can help. So far, only four cases of ictal GS have been reported with all or part of the symptoms, and none of them investigated with SEEG.

Methods: We present a case of ictal L-RD, which underwent a presurgical evaluation. We performed a multi-modality approach, including EEG, MRI, PET, and SEEG. We placed EEG scalp electrodes simultaneously with the SEEG intracerebral electrodes to correlate the findings. Additionally, we developed segmentation in the MRI using 3D Slicer software, CerebrA atlas, and Montreal Neurological Institute (MNI) space to precisely localize the lesion.

Results: A 35-year-old right-handed man with refractory epilepsy was admitted. His seizures started with a whole-body numbness from the neck down; then, he felt like he was on a roller coaster and dropping. During those events, he had L-RD with expressive aphasia. EEG showed interictal left centroparietal and posterior temporal spikes and ictal with left centroparietal onset of high-frequency low-voltage polyspikes. MRI revealed a small area of cortical thickening in the left PL, and PET a questionable hypometabolism area in the same region. SEEG showed continuous Lateralized Periodic Discharges (LPDs) plus fast activity in the anterior (mainly) and posterior regions of the lesion, and ictal SEEG identified the Epileptogenic Zone (EZ) on the anterior region of the lesion. Symptoms began once the epileptiform activity decreased in the seizure termination phase. EEG-SEEG correlation showed SEEG ictal onset much earlier than EEG onset, scalp EEG epileptiform activity was visible only during the spreading of the main epileptiform activity seen in SEEG. SEEG and MRI segmentation localized the EZ in the Supramarginal Gyrus. Subsequently, radiofrequency thermal ablation, and then resective surgery were done. Pathology revealed Focal Cortical Dysplasia Type IIb.

Conclusions: GS is still a mystery and a rare manifestation of a seizure. We support the idea that GS is not an autonomous entity, and the tetrad of symptoms of GS are neither associated nor have a common anatomical-functional origin. The four reported cases of ictal GS had Status Epilepticus (SE), and in our case, we believe that also had SE, manifested as non-convulsive SE since SEEG showed continuous LPDs. Symptoms began once the epileptiform activity decreased in the seizure termination phase, suggesting that a phenomenon similar to Todd paresis may have developed during short transient wane phases of ictal activity. This fact suggests that L-RD may be due to a disconnection of fiber tracts located in the left parietal white matter. Understanding the characteristics of functional networks involved in epilepsy as a network disease will provide us with an accurate localization and lead to novel therapeutic interventions.


Funding: None.