A Cuban perspective on management of persistent vegetative state.

The Cuban Group for Study of Disorders of Consciousness is developing several research protocols to search for possible preservation of residual brain and autonomic functions in cases of persistent vegetative and minimally conscious states. We present examples showing the importance of 3D anatomic reconstruction of brain structures and MRI tractography for assessing white matter connectivity. We also present results of use of proton magnetic resonance spectroscopy technique to follow up cognitive recovery in persistent vegetative state patients transitioning to minimally conscious state. We have demonstrated recognition of a mother's voice with emotional content after zolpidem administration, indicating high-level residual linguistic processing and brain activation despite the patient's apparent inability to communicate. Hence we differ with current thinking that, by definition, subjects in persistent vegetative state are isolated from the outside world and cannot experience pain and suffering. We also consider "vegetative state" a pejorative term that should be replaced. KEYWORDS Persistent vegetative state, minimally conscious state, consciousness disorders, magnetic resonance imaging, electroencephalography, heart rate variability.

TCD diastolic velocity decay and pulsatility index increment in PVS cases.

BACKGROUND: Functional neuroimaging has provided new insights for assessing cerebral function in persistent vegetative state patients (PVS). Compared to controls, positron emission tomography and single photon emission tomography have shown a substantial reduction of global brain cerebral glucose metabolism and perfusion in PVS. Doppler ultrasonography (TCD) assesses local blood flow velocity and direction in the proximal portions of large intracranial arteries; it is a noninvasive technique, and it can be carried out at the bedside. To date, few studies have applied TCD to study PVS. METHODS: We assessed intracranial circulation by TCD in five PVS patients. The cause of brain insult was hypoxic encephalopathy in four cases, and the other suffered an embolic cerebral infarct causing a top of the basilar artery syndrome. The sample volume was set at 12 mm; power output and gain settings were maximized as needed. The temporal bone acoustic window was not suitable for intracranial vessel insonation in all patients. As an alternative, the internal carotid artery siphon was assessed by orbital insonation between 55-70 mm. RESULTS: Systolic velocity was within a normal range, between 44 and 62 cm/second in all cases. However, the diastolic amplitude was reduced, as well as the end diastolic velocity, and the pulsatility index was increased in all patients. CONCLUSIONS: We conclude that TCD diastolic velocity decrement and PI augmentation in our cases might be related to uncoupling of cerebral blood flow and cerebral metabolic rate, arising from reduced cerebral glucose consumption and oxygen uptake, after extensive brain injury.

Brain anatomy, cerebral blood flow, and connectivity in the transition from PVS to MCS.

BACKGROUND: We report a 15 year-old girl with sickle cell disease, who developed important cognitive impairment due to multiple strokes, and who had been diagnosed with PVS. Nonetheless, when she was later admitted to our Institute, according to the presence of inconsistent but clearly demonstrable behavioral evidence of consciousness awareness, we changed our diagnosis to MCS. METHODS: This patient was studied by T1 MRI images, co-registration of fractional anisotropy (FA), and SPECT with MRI. RESULTS: Brain structures were mainly preserved in posterior areas of both cerebral hemispheres, although small tissue islands were present in both frontal lobes, mainly preserved in the right one. SPECT showed CBF preservation in posterior brain regions and in the cerebellum, and in those frontal small islands of tissue lateralized to the right frontal lobe; meanwhile FA showed preservation of anatomical connectivity among posterior and frontal brain regions. These remaining cortical regions are also connected with the thalami. CONCLUSION: These results showing connectivity among posterior and frontal cortical and probably with other subcortical regions, and CBF preservation in these areas, might explain the recovery of minimum awareness despite huge anatomical brain lesions.

Persistent vegetative and minimally conscious states.

The diagnosis and management of patients with persistent vegetative (PVS) and minimally conscious (MCS) states entail powerful medical, ethical and legal debates. The recent description of the MCS highlights the crucial role of unexpected and well-documented recoveries of cognitive functions. Functional neuroimaging has provided new insights for assessing neuropathology and cerebral activity in these patients, providing information on the presence, degree, and location of any residual brain function in patients with PVS or MCS. We present a review on this topic, emphasizing the clinical and neuroimaging assessment of these states, with some of our recent results in this area. We conclude that the development of rehabilitation techniques for patients with PVS and others suffering long-lasting effects of brain injury is a crucial challenge for actual and future generations of neuroscientists.