Moreover, a preliminary fMRI examination revealed partially intact responses to semantically ambiguous stimuli, which are known to tap higher aspects of speech comprehension.Furthermore, several studies have used PET to assess the central processing of noxious somatosensory stimuli in patients in PVS. Noxious somatosensory stimulation activated midbrain, contralateral thalamus, and primary somatosensory cortex in each and every PVS patient, even in the absence of detectable cortical evoked potentials. In conclusion, somatosensory stimulation of PVS patients, at intensities that elicited pain in controls, resulted in increased neuronal activity in primary somatosensory cortex, even if resting brain metabolism was severely impaired. However, this activation of primary cortex seems to be isolated and dissociated from higher-order associative cortices.Also, there is evidence of partially functional cerebral regions in catastrophically injured brains. To study five patients in PVS with different behavioral features, researchers employed PET, MRI and magnetoencephalographic (MEG) responses to sensory stimulation. In three of the five patients, co-registered PET/MRI correlate areas of relatively preserved brain metabolism with isolated fragments of behavior. Two patients had had anoxic injuries and demonstrated marked decreases in overall cerebral metabolism to 30–40% of normal. Two other patients with non-anoxic, multifocal brain injuries demonstrated several isolated brain regions with higher metabolic rates, that ranged up to 50–80% of normal. Nevertheless, their global metabolic rates remained <50% of normal. MEG recordings from three PVS patients provide clear evidence for the absence, abnormality or reduction of evoked responses. Despite major abnormalities, however, these data also provide evidence for localized residual activity at the cortical level.
Notable cases
Tony Bland – first patient in English legal history to be allowed to die
Paul Brophy – first American to die after court-authorization
Sunny von Bülow – lived almost 28 years in a persistent vegetative state until her death
Gustavo Cerati – Argentine singer-songwriter, composer and producer who died after four years in a coma
Prichard Colón – Puerto Rican former professional boxer and gold medal winner who spent years in a vegetative state after a bout
Nancy Cruzan – American woman involved in a landmark United States Supreme Court case
Gary Dockery – American police officer who entered, emerged and later reentered a persistent vegetative state
Eluana Englaro – Italian woman from Lecco whose life was ended after a legal case after spending 17 years in a vegetative state
Elaine Esposito – American woman who was a previous record holder for having spent 37 years in a coma
Lia Lee – Hmong person who spent 26 years in a vegetative state and was the subject of a 1997 book by Anne Fadiman
Martin Pistorius South African man who is a rare example of a survivor as his state progressed to minimally conscious after 3 years, locked in syndrome after another 4 more years, and fully came out of a coma after another 5 years. He is now a web designer, developer, and author. In 2011, he wrote a book called Ghost Boy, in which he describes his many years of being comatose.