[Progressive study of EEG and evoked potentials in Lafora disease]

The aim of this paper is to present a simultaneous evolutionary study of EEG and multimodality evoked potentials (EP) in a patient with progressive myoclonus epilepsy (PME) with Lafora bodies in the sweat glands from the axillary skin biopsy.

The EEG showed progressive deterioration characteristic of this entity. Epileptiform activity was modified in distribution and morphology throughout the sickness. Abnormalities appeared in serial sleep records, although with acceptable preservation of its structure. The EEG findings supported the diagnosis of PME prior to clinical suspicion. A gradual increase in the somatosensory EP amplitude was observed, leading to an early giant configuration. However, an asymmetry persisted between both hemispheres, with the right cortex being more affected. Recording simultaneously on C3 and C4 after unilateral stimulation, a high-amplitude ipsilateral response was found in both hemispheres, suggesting hyperexcitability of cortical and subcortical neural structures.

These somatosensory EP findings--progressive deterioration, interhemispheric asymmetry and ipsilateral giant response--have not, to our knowledge, been previously described.