DBS therapy for a persistent vegetative state: ten years follow-up results

Twenty-one cases of a persistent vegetative state (PVS) caused by various kinds of brain damage were evaluated neurologically and electrophysiologically at 3 months after the brain injury. The 21 cases were treated by deep brain stimulation (DBS) therapy, and followed up for over 10 years. The stimulation sites were the mesencephalic reticular formation (2 cases) and CM-pf complex (19 cases). Eight of the patients emerged from the PVS, and became able to obey verbal commands. However, they remained in a bedridden state. These 8 cases revealed a desynchronization on continuous EEG frequency analysis. The Vth wave of the ABR and N20 of the SEP could be recorded even with a prolonged latency, and the pain-related P250 was recorded with an amplitude of over 7 microV. The mean survival time of these 8 cases was 6.1 years, as compared to 3.1 years for the other 13 cases. Overall, 4 cases are alive after more than 10 years. DBS therapy may be useful for allowing patients to emerge from a PVS, if the candidates are selected according to neurophysiological criteria. The fact that 19% (4/21) of the PVS cases treated with DBS survived for over 10 years should be stressed in comparison with the usual survival period for the untreated PVS.