Thalamic Stimulation of Patients in Vegetative or Minimally Conscious State

Inclusion Criteria

• •Male and female patients stably in VS or MCS from at least 6 months, 10 to 65 years old.
• •Patients must fulfil the neuroimaging criteria described later
• •Patients must fulfil neurophysiologic criteria as described later
• •Before inclusion into the study all patients will be submitted to a complete MRI of the brain comprehensive of T1 and T2 weighted and flair sequences. Patients with a history of traumatic injury that were not submitted to cervical MRI at the time or after the initial injury will be submitted to a cervical MRI before admission to the study. A MRI scanner with field strength of at least 1.5 tesla will be used for imaging the brain and the cervical spinal cord. The volumetric extent of the damage will be estimated by using an image analysis program (e.g. IMAGE, NIH) after the neuroradiologist has traced the contour of the injured structures in all MRI images of the brain.
• •Thalamus: bilateral absence of damage of the centromedian/parafascicularis complex and of the entire area of the intralaminar nuclei. The remaining structures of the thalami should not be damaged for an extent greater than 40% of the total volume of the two thalami.
• •Frontal lobes: at least one lobe should not be damaged to an extent superior to 20% of the volume. Absence of lesion of the Broca's area in the left (or dominant) hemisphere.
• •Temporal lobes: absence of damage to the posterior two third of the left or dominant temporal lobe. The extent of the lesions in the remaining structures of the temporal lobes should be less than 70% of the total volume of the lobes.
• •Parietal lobes: lesion volume in at least one parietal lobe should be less than 30%.
• •Occipital lobes: lesion volume in at least one occipital lobe should be less than 30%. The visual cortex should be spared in at least one lobe.
• •Hypothalamus: absence of lesions. Mesencephalon: absence of lesions in the region located between the substantia nigra and the bases of the colliculi. Unilateral lesions ventral to the substantia nigra are permitted.
• •Pons: absence of lesions unless unilateral and limited to the ventral third of the pons.
• •Cerebellum: Absence of lesions larger than 80% of the total volume; the deep nuclei of at least one side of the cerebellum should be intact.
• •Medulla: absence of lesions unless limited to one pyramid. Cervical spinal cord: absence of lesions All patients should be free from hydrocephalus or the hydrocephalus should be treated with a shunt prior to thalamic implant.
• •Patients will be studied by continuous electroencephalography. Patients showing EEG desynchronization for at least 5% of the period studied will be included.
• •Acoustic evoked potentials must be present at least at one side. V wave prolongation will be accepted.
• •Somato-sensory evoked potentials must be present at least at one side. Increased latency of N20 will be accepted.