Studies have suggested that patients in a vegetative state have disconnections in long-range cortico-cortical and thalamo-cortical pathways. The neural signature of spontaneous recovery is linked to an increase in thalamo-cortical activity and improved fronto-parietal functional connectivity. This study evaluated the effect of thalamo-cortical stimulation through vagus nerve stimulation in a patient in a vegetative state.

This case study included a 35-year-old male with a history of traumatic brain injury, who had been in a persistent vegetative state for 15 years. Baseline evaluations included behavioral, electroencephalographic, and 18F-FDG PET recordings. The patient then underwent the surgical implant of a vagus nerve stimulator, with stimulation increased to a maximum intensity of 1.5 mA. The effects were monitored for 6 months.

At one month, the patient demonstrated reproducible and consistent improvements in general arousal, sustained attention, body motility and visual pursuit. Scores on the Coma Recovery Scale-Revised test (CRS-R) improved, with the greatest improvement in the visual domain. The change in these scores suggested an improvement from vegetative state to minimally conscious state. The EEG data revealed a significant increase in theta band power (P<0.0001), distributed over the occipito-parietal, inferior temporal and fronto-central regions. As an index of consciousness, a weighted symbolic mutual information (wSMI) was calculated, demonstrating that this increase correlated with CRS-R scores of clinical improvement (P＝0.0015). The PET data revealed increases activity in the occipital-parietal-frontal, and basal ganglionregions as early as three months after surgery.

This case study of a patient 15 years in a vegetative state found that a surgically implanted vagal nerve stimulator could improve his cognitive state to a minimally conscious state. BACKGROUND AND OBJECTIVE Studies have suggested that patients in a vegetative state have disconnections in long-range cortico-cortical and thalamo-cortical pathways. The neural signature of spontaneous recovery is linked to an increase in thalamo-cortical activity and improved fronto-parietal functional connectivity. This study evaluated the effect of thalamo-cortical stimulation through vagus nerve stimulation in a patient in a vegetative state. METHODS This case study included a 35-year-old male with a history of traumatic brain injury, who had been in a persistent vegetative state for 15 years. Baseline evaluations included behavioral, electroencephalographic, and 18F-FDG PET recordings. The patient then underwent the surgical implant of a vagus nerve stimulator, with stimulation increased to a maximum intensity of 1.5 mA. The effects were monitored for 6 months. RESULTS At one month, the patient demonstrated reproducible and consistent improvements in general arousal, sustained attention, body motility and visual pursuit. Scores on the Coma Recovery Scale-Revised test (CRS-R) improved, with the greatest improvement in the visual domain. The change in these scores suggested an improvement from vegetative state to minimally conscious state. The EEG data revealed a significant increase in theta band power (P<0.0001), distributed over the occipito-parietal, inferior temporal and fronto-central regions. As an index of consciousness, a weighted symbolic mutual information (wSMI) was calculated, demonstrating that this increase correlated with CRS-R scores of clinical improvement (P＝0.0015). The PET data revealed increases activity in the occipital-parietal-frontal, and basal ganglionregions as early as three months after surgery.