Irreversibility: cardiac death versus brain death.

The acceptance of brain death (BD) as death of the human being has been progressively accepted beginning in the early 1960s. The issue of irreversibility is directly related to the diagnosis of human death, and it is closely associated with the concept of potentiality, i.e., that some patients still have the potentiality of living. In recent years several authors have proposed to use a cardiocirculatory criterion for death determination in transplant donors. This has aroused ethical and medical controversies regarding concerns to accept that a non-heart-beating donor is really dead. We conclude that the cardiocirculatory criterion of death only assures irreversibility when asystole is prolonged enough to assure that ischemia and anoxia have destroyed the brain. On the contrary, BD fulfills both requirements for death determination: cessation of functions and irreversibility

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.

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.