Evidence of Functional Anterior Commissure in Medial Temporal Lobe Epilepsy
Abstract number :
1.135
Submission category :
Year :
2001
Submission ID :
2120
Source :
www.aesnet.org
Presentation date :
12/1/2001 12:00:00 AM
Published date :
Dec 1, 2001, 06:00 AM
Authors :
S. Dupont, MD, Neurology, La Salpetriere, Paris, France, Metropolitan; D. Hasboun, MD, PhD, Neurology, La Salpetriere, Paris, France, Metropolitan; S. Clemenceau, MD, Neurosurgery, La Salpetriere, Paris; P. Hazemann, MD, Neurophysiology, La Salpetriere, P
RATIONALE: Electrical stimulations can be used to trace the functional link between the different parts of the brain. The inter-temporo-limbic spread of temporal lobe seizures has been thought to travel through the frontal lobes or the dorsal hippocampal commissure.
METHODS: A 45-year-old patient suffering from a medial temporal lobe epilepsy, insufficiently lateralized on non-invasive data, was explored intracranially with depth and subdural electrodes. Trains of 50 Hz, 5 Hz or 1 Hz (biphasic shocks of 1 ms, stimulator Grass S12) were applied in a bipolar fashion.
RESULTS: The stimulations of the perirhinal cortex produced a clear and reproducible rhythmic response of the contralateral hippocampal formation that was sclerotic on MRI. That response was obtained at 50 Hz and 5 Hz. The stimulations of the adjacent amygdala and hippocampus did not induce the same responses. The sole possible pathway explaining these evoked responses is the Anterior Commissure (AC). The spontaneous seizures seemed to travel by the same interhemispheric pathway.
CONCLUSIONS: The Anterior Commissure may constitute a direct functional route between the two temporal lobes for the spread of seizures of medio-temporal origin. That assumption is in good accordance with the anatomical importance of AC that interconnects the temporal lobes, namely most of their anterior two-thirds.