[Electrophysiological development under thalamic stimulation of post-traumatic persistent vegetative states. Apropos of 25 cases].

We have studied the electrophysiological evolution, with the aid of long-term, quantitative E.E.G. (Holter method) and sensory evoked potentials (visual, auditory and somatosensory) on 25 severe traumatic head injury patients (initial Glasgow scale--between 3 and 5) aged from 5 to 42 years having evolved towards a persistent vegetative state and being object of a protocol of thalamic stimulation. Electrophysiological exploration was practised before placement of the stimulation, then at 2 weeks, 1 month, 2 months and finally 3 months after. The electrophysiological parameters appear to have no predictive value on the clinical evolution after stimulation. However, changes such as long-term quantitative EEG as well as evoked potentials mostly precede clinical progress when present. Cortical evoked potentials are the first to change significantly (J15) followed by long-term quantitative EEG and brain stem evoked potentials (J30); the latter improving more completely. Also the consideration of the chronobiological aspects of the recordings of the long term EEG allow the proposal of "waking targeted" stimulations at the most favorable moments of the nyctohemeral period.